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TOR(1) Tor Manual TOR(1)

NAME
tor - The second-generation onion router

SYNOPSIS
tor [OPTION value]...

DESCRIPTION
Tor is a connection-oriented anonymizing communication service. Users
choose a source-routed path through a set of nodes, and negotiate a "vir-
tual circuit" through the network. Each node in a virtual circuit knows its
predecessor and successor nodes, but no other nodes. Traffic flowing down
the circuit is unwrapped by a symmetric key at each node, which reveals the
downstream node.

Basically, Tor provides a distributed network of servers or relays ("onion
routers"). Users bounce their TCP streams, including web traffic, ftp, ssh,
etc., around the network, so that recipients, observers, and even the re-
lays themselves have difficulty tracking the source of the stream.

Note

By default, tor acts as a client only. To help the network by providing
bandwidth as a relay, change the ORPort configuration option as men-
tioned below. Please also consult the documentation on the Tor
Project's website.

COMMAND-LINE OPTIONS
Tor has a powerful command-line interface. This section lists optional ar-
guments you can specify at the command line using the tor command.

Configuration options can be specified on the command line in the format
--OptionName OptionValue, on the command line in the format OptionName Op-
tionValue, or in a configuration file. For instance, you can tell Tor to
start listening for SOCKS connections on port 9999 by passing either
--SocksPort 9999 or SocksPort 9999 on the command line, or by specifying
SocksPort 9999 in the configuration file. On the command line, quote option
values that contain spaces. For instance, if you want Tor to log all debug-
ging messages to debug.log, you must specify --Log "debug file debug.log".

Note

Configuration options on the command line override those in configura-
tion files. See THE CONFIGURATION FILE FORMAT for more information.

The following options in this section are only recognized on the tor com-
mand line, not in a configuration file.

-h, --help
Display a short help message and exit.

-f, --torrc-file FILE
Specify a new configuration file to contain further Tor configuration
options, or pass - to make Tor read its configuration from standard in-
put. (Default: /usr/local/etc/tor/torrc, or $HOME/.torrc if that file
is not found.)

--allow-missing-torrc
Allow the configuration file specified by -f to be missing, if the de-
faults-torrc file (see below) is accessible.

--defaults-torrc FILE
Specify a file in which to find default values for Tor options. The
contents of this file are overridden by those in the regular configura-
tion file, and by those on the command line. (Default: /usr/lo-
cal/etc/tor/torrc-defaults.)

--ignore-missing-torrc
Specify that Tor should treat a missing torrc file as though it were
empty. Ordinarily, Tor does this for missing default torrc files, but
not for those specified on the command line.

--hash-password PASSWORD
Generate a hashed password for control port access.

--list-fingerprint [key type]
Generate your keys and output your nickname and fingerprint. Option-
ally, you can specify the key type as rsa (default) or ed25519.

--verify-config
Verify whether the configuration file is valid.

--dump-config short|full
Write a list of Tor's configured options to standard output. When the
short flag is selected, only write the options that are different from
their default values. When full is selected, write every option.

--service install [--options command-line options]
Install an instance of Tor as a Windows service, with the provided com-
mand-line options. Current instructions can be found at
https://www.torproject.org/docs/faq#NTService

--service remove|start|stop
Remove, start, or stop a configured Tor Windows service.

--nt-service
Used internally to implement a Windows service.

--list-torrc-options
List all valid options.

--list-deprecated-options
List all valid options that are scheduled to become obsolete in a fu-
ture version. (This is a warning, not a promise.)

--list-modules
List whether each optional module has been compiled into Tor. (Any mod-
ule not listed is not optional in this version of Tor.)

--version
Display Tor version and exit. The output is a single line of the format
"Tor version [version number]." (The version number format is as speci-
fied in version-spec.txt.)

--quiet|--hush
Override the default console logging behavior. By default, Tor starts
out logging messages at level "notice" and higher to the console. It
stops doing so after it parses its configuration, if the configuration
tells it to log anywhere else. These options override the default con-
sole logging behavior. Use the --hush option if you want Tor to log
only warnings and errors to the console, or use the --quiet option if
you want Tor not to log to the console at all.

--keygen [--newpass]
Running tor --keygen creates a new ed25519 master identity key for a
relay, or only a fresh temporary signing key and certificate, if you
already have a master key. Optionally, you can encrypt the master iden-
tity key with a passphrase. When Tor asks you for a passphrase and you
don't want to encrypt the master key, just don't enter any passphrase
when asked.

Use the --newpass option with --keygen only when you need to add,
change, or remove a passphrase on an existing ed25519 master identity
key. You will be prompted for the old passphrase (if any), and the new
passphrase (if any).

Note
When generating a master key, you may want to use --DataDirectory
to control where the keys and certificates will be stored, and
--SigningKeyLifetime to control their lifetimes. See SERVER OPTIONS
to learn more about the behavior of these options. You must have
write access to the specified DataDirectory.
To use the generated files, you must copy them to the DataDirec-
tory/keys directory of your Tor daemon, and make sure that they are
owned by the user actually running the Tor daemon on your system.

--keygen-family basename
Generate a new family ID key in basename.secret_family_key. To use this
key, install it on every relay in your family. (Put it in the relay's
KeyDirectory.) Also, store the corresponding family ID in basename.pub-
lic_family_id. Then enable the corresponding FamilyID option on your
relays. This command overwrites these files if they already exist. See
https://community.torproject.org/relay/setup/post-install/family-ids/
for more information.

--passphrase-fd FILEDES
File descriptor to read the passphrase from. Note that unlike with the
tor-gencert program, the entire file contents are read and used as the
passphrase, including any trailing newlines. If the file descriptor is
not specified, the passphrase is read from the terminal by default.

--key-expiration [purpose] [--format iso8601|timestamp]
The purpose specifies which type of key certificate to determine the
expiration of. The only currently recognised purpose is "sign".

Running tor --key-expiration sign will attempt to find your signing key
certificate and will output, both in the logs as well as to stdout. The
optional --format argument lets you specify the time format. Currently,
iso8601 and timestamp are supported. If --format is not specified, the
signing key certificate's expiration time will be in ISO-8601 format.
For example, the output sent to stdout will be of the form: "sign-
ing-cert-expiry: 2017-07-25 08:30:15 UTC". If --format timestamp is
specified, the signing key certificate's expiration time will be in
Unix timestamp format. For example, the output sent to stdout will be
of the form: "signing-cert-expiry: 1500971415".

--dbg-...
Tor may support other options beginning with the string "dbg". These
are intended for use by developers to debug and test Tor. They are not
supported or guaranteed to be stable, and you should probably not use
them.

THE CONFIGURATION FILE FORMAT
All configuration options in a configuration are written on a single line
by default. They take the form of an option name and a value, or an option
name and a quoted value (option value or option "value"). Anything after a
# character is treated as a comment. Options are case-insensitive. C-style
escaped characters are allowed inside quoted values. To split one configu-
ration entry into multiple lines, use a single backslash character (\) be-
fore the end of the line. Comments can be used in such multiline entries,
but they must start at the beginning of a line.

Configuration options can be imported from files or folders using the %in-
clude option with the value being a path. This path can have wildcards.
Wildcards are expanded first, then sorted using lexical order. Then, for
each matching file or folder, the following rules are followed: if the path
is a file, the options from the file will be parsed as if they were written
where the %include option is. If the path is a folder, all files on that
folder will be parsed following lexical order. Files starting with a dot
are ignored. Files in subfolders are ignored. The %include option can be
used recursively. New configuration files or directories cannot be added to
already running Tor instance if Sandbox is enabled.

The supported wildcards are * meaning any number of characters including
none and ? meaning exactly one character. These characters can be escaped
by preceding them with a backslash, except on Windows. Files starting with
a dot are not matched when expanding wildcards unless the starting dot is
explicitly in the pattern, except on Windows.

By default, an option on the command line overrides an option found in the
configuration file, and an option in a configuration file overrides one in
the defaults file.

This rule is simple for options that take a single value, but it can become
complicated for options that are allowed to occur more than once: if you
specify four SocksPorts in your configuration file, and one more SocksPort
on the command line, the option on the command line will replace all of the
SocksPorts in the configuration file. If this isn't what you want, prefix
the option name with a plus sign (+), and it will be appended to the previ-
ous set of options instead. For example, setting SocksPort 9100 will use
only port 9100, but setting +SocksPort 9100 will use ports 9100 and 9050
(because this is the default).

Alternatively, you might want to remove every instance of an option in the
configuration file, and not replace it at all: you might want to say on the
command line that you want no SocksPorts at all. To do that, prefix the op-
tion name with a forward slash (/). You can use the plus sign (+) and the
forward slash (/) in the configuration file and on the command line.

GENERAL OPTIONS
AccelDir DIR
Specify this option if using dynamic hardware acceleration and the en-
gine implementation library resides somewhere other than the OpenSSL
default. Can not be changed while tor is running.

AccelName NAME
When using OpenSSL hardware crypto acceleration attempt to load the dy-
namic engine of this name. This must be used for any dynamic hardware
engine. Names can be verified with the openssl engine command. Can not
be changed while tor is running.

If the engine name is prefixed with a "!", then Tor will exit if the
engine cannot be loaded.

AlternateBridgeAuthority [nickname] [flags] ipv4address:port fingerprint,
AlternateDirAuthority [nickname] [flags] ipv4address:port fingerprint
These options behave as DirAuthority, but they replace fewer of the de-
fault directory authorities. Using AlternateDirAuthority replaces the
default Tor directory authorities, but leaves the default bridge au-
thorities in place. Similarly, AlternateBridgeAuthority replaces the
default bridge authority, but leaves the directory authorities alone.

AvoidDiskWrites 0|1
If non-zero, try to write to disk less frequently than we would other-
wise. This is useful when running on flash memory or other media that
support only a limited number of writes. (Default: 0)

BandwidthRate N bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
A token bucket limits the average incoming bandwidth usage on this node
to the specified number of bytes per second, and the average outgoing
bandwidth usage to that same value. If you want to run a relay in the
public network, this needs to be at the very least 75 KBytes for a re-
lay (that is, 600 kbits) or 50 KBytes for a bridge (400 kbits) -- but
of course, more is better; we recommend at least 250 KBytes (2 mbits)
if possible. (Default: 1 GByte)

Note that this option, and other bandwidth-limiting options, apply to
TCP data only: They do not count TCP headers or DNS traffic.

Tor uses powers of two, not powers of ten, so 1 GByte is 1024*1024*1024
bytes as opposed to 1 billion bytes.

With this option, and in other options that take arguments in bytes,
KBytes, and so on, other formats are also supported. Notably, "KBytes"
can also be written as "kilobytes" or "kb"; "MBytes" can be written as
"megabytes" or "MB"; "kbits" can be written as "kilobits"; and so
forth. Case doesn't matter. Tor also accepts "byte" and "bit" in the
singular. The prefixes "tera" and "T" are also recognized. If no units
are given, we default to bytes. To avoid confusion, we recommend writ-
ing "bytes" or "bits" explicitly, since it's easy to forget that "B"
means bytes, not bits.

CacheDirectory DIR
Store cached directory data in DIR. Can not be changed while tor is
running. (Default: uses the value of DataDirectory.)

CacheDirectoryGroupReadable 0|1|auto
If this option is set to 0, don't allow the filesystem group to read
the CacheDirectory. If the option is set to 1, make the CacheDirectory
readable by the default GID. If the option is "auto", then we use the
setting for DataDirectoryGroupReadable when the CacheDirectory is the
same as the DataDirectory, and 0 otherwise. (Default: auto)

CircuitPriorityHalflife NUM
If this value is set, we override the default algorithm for choosing
which circuit's cell to deliver or relay next. It is delivered first to
the circuit that has the lowest weighted cell count, where cells are
weighted exponentially according to this value (in seconds). If the
value is -1, it is taken from the consensus if possible else it will
fallback to the default value of 30. Minimum: 1, Maximum: 2147483647.
This can be defined as a float value. This is an advanced option; you
generally shouldn't have to mess with it. (Default: -1)

ClientTransportPlugin transport socks4|socks5 IP:PORT, ClientTransportPlu-
gin transport exec path-to-binary [options]
In its first form, when set along with a corresponding Bridge line, the
Tor client forwards its traffic to a SOCKS-speaking proxy on "IP:PORT".
(IPv4 addresses should written as-is; IPv6 addresses should be wrapped
in square brackets.) It's the duty of that proxy to properly forward
the traffic to the bridge.

In its second form, when set along with a corresponding Bridge line,
the Tor client launches the pluggable transport proxy executable in
path-to-binary using options as its command-line options, and forwards
its traffic to it. It's the duty of that proxy to properly forward the
traffic to the bridge. (Default: none)

ConfluxEnabled 0|1|auto
If this option is set to 1, general purpose traffic will use Conflux
which is traffic splitting among multiple legs (circuits). Onion ser-
vices are not supported at the moment. Default value is set to "auto"
meaning the consensus is used to decide unless set. (Default: auto)

ConfluxClientUX throughput|latency|throughput_lowmem|latency_lowmem
This option configures the user experience that the client requests
from the exit, for data that the exit sends to the client. The default
is "throughput", which maximizes throughput. "Latency" will tell the
exit to only use the circuit with lower latency for all data. The
lowmem versions minimize queue usage memory at the client. (Default:
"throughput")

ConnLimit NUM
The minimum number of file descriptors that must be available to the
Tor process before it will start. Tor will ask the OS for as many file
descriptors as the OS will allow (you can find this by "ulimit -H -n").
If this number is less than ConnLimit, then Tor will refuse to start.

Tor relays need thousands of sockets, to connect to every other relay.
If you are running a private bridge, you can reduce the number of sock-
ets that Tor uses. For example, to limit Tor to 500 sockets, run
"ulimit -n 500" in a shell. Then start tor in the same shell, with
ConnLimit 500. You may also need to set DisableOOSCheck 0.

Unless you have severely limited sockets, you probably don't need to
adjust ConnLimit itself. It has no effect on Windows, since that plat-
form lacks getrlimit(). (Default: 1000)

ConstrainedSockets 0|1
If set, Tor will tell the kernel to attempt to shrink the buffers for
all sockets to the size specified in ConstrainedSockSize. This is use-
ful for virtual servers and other environments where system level TCP
buffers may be limited. If you're on a virtual server, and you en-
counter the "Error creating network socket: No buffer space available"
message, you are likely experiencing this problem.

The preferred solution is to have the admin increase the buffer pool
for the host itself via /proc/sys/net/ipv4/tcp_mem or equivalent facil-
ity; this configuration option is a second-resort.

The DirPort option should also not be used if TCP buffers are scarce.
The cached directory requests consume additional sockets which exacer-
bates the problem.

You should not enable this feature unless you encounter the "no buffer
space available" issue. Reducing the TCP buffers affects window size
for the TCP stream and will reduce throughput in proportion to round
trip time on long paths. (Default: 0)

ConstrainedSockSize N bytes|KBytes
When ConstrainedSockets is enabled the receive and transmit buffers for
all sockets will be set to this limit. Must be a value between 2048 and
262144, in 1024 byte increments. Default of 8192 is recommended.

ControlPort [address:]port|unix:path|auto [flags]
If set, Tor will accept connections on this port and allow those con-
nections to control the Tor process using the Tor Control Protocol (de-
scribed in control-spec.txt in torspec). Note: unless you also specify
one or more of HashedControlPassword or CookieAuthentication, setting
this option will cause Tor to allow any process on the local host to
control it. (Setting both authentication methods means either method is
sufficient to authenticate to Tor.) This option is required for many
Tor controllers; most use the value of 9051. If a unix domain socket is
used, you may quote the path using standard C escape sequences. You can
specify this directive multiple times, to bind to multiple address/port
pairs. Set it to "auto" to have Tor pick a port for you. (Default: 0)

Recognized flags are:

GroupWritable
Unix domain sockets only: makes the socket get created as
group-writable.

WorldWritable
Unix domain sockets only: makes the socket get created as
world-writable.

RelaxDirModeCheck
Unix domain sockets only: Do not insist that the directory that
holds the socket be read-restricted.

ControlPortFileGroupReadable 0|1
If this option is set to 0, don't allow the filesystem group to read
the control port file. If the option is set to 1, make the control port
file readable by the default GID. (Default: 0)

ControlPortWriteToFile Path
If set, Tor writes the address and port of any control port it opens to
this address. Usable by controllers to learn the actual control port
when ControlPort is set to "auto".

ControlSocket Path
Like ControlPort, but listens on a Unix domain socket, rather than a
TCP socket. 0 disables ControlSocket. (Unix and Unix-like systems
only.) (Default: 0)

ControlSocketsGroupWritable 0|1
If this option is set to 0, don't allow the filesystem group to read
and write unix sockets (e.g. ControlSocket). If the option is set to 1,
make the control socket readable and writable by the default GID. (De-
fault: 0)

CookieAuthentication 0|1
If this option is set to 1, allow connections on the control port when
the connecting process knows the contents of a file named "con-
trol_auth_cookie", which Tor will create in its data directory. This
authentication method should only be used on systems with good filesys-
tem security. (Default: 0)

CookieAuthFile Path
If set, this option overrides the default location and file name for
Tor's cookie file. (See CookieAuthentication.)

CookieAuthFileGroupReadable 0|1
If this option is set to 0, don't allow the filesystem group to read
the cookie file. If the option is set to 1, make the cookie file read-
able by the default GID. [Making the file readable by other groups is
not yet implemented; let us know if you need this for some reason.]
(Default: 0)

CountPrivateBandwidth 0|1
If this option is set, then Tor's rate-limiting applies not only to re-
mote connections, but also to connections to private addresses like
127.0.0.1 or 10.0.0.1. This is mostly useful for debugging rate-limit-
ing. (Default: 0)

DataDirectory DIR
Store working data in DIR. Can not be changed while tor is running.
(Default: ~/.tor if your home directory is not /; otherwise,
/var/db/tor. On Windows, the default is your ApplicationData folder.)

DataDirectoryGroupReadable 0|1
If this option is set to 0, don't allow the filesystem group to read
the DataDirectory. If the option is set to 1, make the DataDirectory
readable by the default GID. (Default: 0)

DirAuthority [nickname] [flags] ipv4address:dirport fingerprint
Use a nonstandard authoritative directory server at the provided ad-
dress and port, with the specified key fingerprint. This option can be
repeated many times, for multiple authoritative directory servers.
Flags are separated by spaces, and determine what kind of an authority
this directory is. By default, an authority is not authoritative for
any directory style or version unless an appropriate flag is given.

Tor will use this authority as a bridge authoritative directory if the
"bridge" flag is set. If a flag "orport=orport" is given, Tor will use
the given port when opening encrypted tunnels to the dirserver. If a
flag "weight=num" is given, then the directory server is chosen ran-
domly with probability proportional to that weight (default 1.0). If a
flag "v3ident=fp" is given, the dirserver is a v3 directory authority
whose v3 long-term signing key has the fingerprint fp. Lastly, if an
"ipv6=[ipv6address]:orport" flag is present, then the directory author-
ity is listening for IPv6 connections on the indicated IPv6 address and
OR Port.

Tor will contact the authority at ipv4address to download directory
documents. Clients always use the ORPort. Relays usually use the Dir-
Port, but will use the ORPort in some circumstances. If an IPv6 ORPort
is supplied, clients will also download directory documents at the IPv6
ORPort, if they are configured to use IPv6.

If no DirAuthority line is given, Tor will use the default directory
authorities. NOTE: this option is intended for setting up a private Tor
network with its own directory authorities. If you use it, you will be
distinguishable from other users, because you won't believe the same
authorities they do.

DirAuthorityFallbackRate NUM
When configured to use both directory authorities and fallback directo-
ries, the directory authorities also work as fallbacks. They are chosen
with their regular weights, multiplied by this number, which should be
1.0 or less. The default is less than 1, to reduce load on authorities.
(Default: 0.1)

DisableAllSwap 0|1
If set to 1, Tor will attempt to lock all current and future memory
pages, so that memory cannot be paged out. Windows, OS X and Solaris
are currently not supported. We believe that this feature works on mod-
ern Gnu/Linux distributions, and that it should work on *BSD systems
(untested). This option requires that you start your Tor as root, and
you should use the User option to properly reduce Tor's privileges. Can
not be changed while tor is running. (Default: 0)

DisableDebuggerAttachment 0|1
If set to 1, Tor will attempt to prevent basic debugging attachment at-
tempts by other processes. This may also keep Tor from generating core
files if it crashes. It has no impact for users who wish to attach if
they have CAP_SYS_PTRACE or if they are root. We believe that this fea-
ture works on modern Gnu/Linux distributions, and that it may also work
on *BSD systems (untested). Some modern Gnu/Linux systems such as
Ubuntu have the kernel.yama.ptrace_scope sysctl and by default enable
it as an attempt to limit the PTRACE scope for all user processes by
default. This feature will attempt to limit the PTRACE scope for Tor
specifically - it will not attempt to alter the system wide ptrace
scope as it may not even exist. If you wish to attach to Tor with a de-
bugger such as gdb or strace you will want to set this to 0 for the du-
ration of your debugging. Normal users should leave it on. Disabling
this option while Tor is running is prohibited. (Default: 1)

DisableNetwork 0|1
When this option is set, we don't listen for or accept any connections
other than controller connections, and we close (and don't reattempt)
any outbound connections. Controllers sometimes use this option to
avoid using the network until Tor is fully configured. Tor will make
still certain network-related calls (like DNS lookups) as a part of its
configuration process, even if DisableNetwork is set. (Default: 0)

ExtendByEd25519ID 0|1|auto
If this option is set to 1, we always try to include a relay's Ed25519
ID when telling the preceding relay in a circuit to extend to it. If
this option is set to 0, we never include Ed25519 IDs when extending
circuits. If the option is set to "auto", we obey a parameter in the
consensus document. (Default: auto)

ExtORPort [address:]port|auto
Open this port to listen for Extended ORPort connections from your
pluggable transports.

(Default: DataDirectory/extended_orport_auth_cookie)

ExtORPortCookieAuthFile Path
If set, this option overrides the default location and file name for
the Extended ORPort's cookie file -- the cookie file is needed for
pluggable transports to communicate through the Extended ORPort.

ExtORPortCookieAuthFileGroupReadable 0|1
If this option is set to 0, don't allow the filesystem group to read
the Extended OR Port cookie file. If the option is set to 1, make the
cookie file readable by the default GID. [Making the file readable by
other groups is not yet implemented; let us know if you need this for
some reason.] (Default: 0)

FallbackDir ipv4address:dirport orport=orport id=fingerprint [weight=num]
[ipv6=[ipv6address]:orport]
When tor is unable to connect to any directory cache for directory info
(usually because it doesn't know about any yet) it tries a hard-coded
directory. Relays try one directory authority at a time. Clients try
multiple directory authorities and FallbackDirs, to avoid hangs on
startup if a hard-coded directory is down. Clients wait for a few sec-
onds between each attempt, and retry FallbackDirs more often than di-
rectory authorities, to reduce the load on the directory authorities.

FallbackDirs should be stable relays with stable IP addresses, ports,
and identity keys. They must have a DirPort.

By default, the directory authorities are also FallbackDirs. Specifying
a FallbackDir replaces Tor's default hard-coded FallbackDirs (if any).
(See DirAuthority for an explanation of each flag.)

FetchDirInfoEarly 0|1
If set to 1, Tor will always fetch directory information like other di-
rectory caches, even if you don't meet the normal criteria for fetching
early. Normal users should leave it off. (Default: 0)

FetchDirInfoExtraEarly 0|1
If set to 1, Tor will fetch directory information before other direc-
tory caches. It will attempt to download directory information closer
to the start of the consensus period. Normal users should leave it off.
(Default: 0)

FetchHidServDescriptors 0|1
If set to 0, Tor will never fetch any hidden service descriptors from
the rendezvous directories. This option is only useful if you're using
a Tor controller that handles hidden service fetches for you. (Default:
1)

FetchServerDescriptors 0|1
If set to 0, Tor will never fetch any network status summaries or
server descriptors from the directory servers. This option is only use-
ful if you're using a Tor controller that handles directory fetches for
you. (Default: 1)

FetchUselessDescriptors 0|1
If set to 1, Tor will fetch every consensus flavor, and all server de-
scriptors and authority certificates referenced by those consensuses,
except for extra info descriptors. When this option is 1, Tor will also
keep fetching descriptors, even when idle. If set to 0, Tor will avoid
fetching useless descriptors: flavors that it is not using to build
circuits, and authority certificates it does not trust. When Tor hasn't
built any application circuits, it will go idle, and stop fetching de-
scriptors. This option is useful if you're using a tor client with an
external parser that uses a full consensus. This option fetches all
documents except extrainfo descriptors, DirCache fetches and serves all
documents except extrainfo descriptors, DownloadExtraInfo* fetches ex-
trainfo documents, and serves them if DirCache is on, and UseMicrode-
scriptors changes the flavor of consensuses and descriptors that is
fetched and used for building circuits. (Default: 0)

HardwareAccel 0|1
If non-zero, try to use built-in (static) crypto hardware acceleration
when available. Can not be changed while tor is running. (Default: 0)

HashedControlPassword hashed_password
Allow connections on the control port if they present the password
whose one-way hash is hashed_password. You can compute the hash of a
password by running "tor --hash-password password". You can provide
several acceptable passwords by using more than one HashedControlPass-
word line.

HTTPProxy host[:port]
Tor will make all its directory requests through this host:port (or
host:80 if port is not specified), rather than connecting directly to
any directory servers. (DEPRECATED: As of 0.3.1.0-alpha you should use
HTTPSProxy.)

HTTPProxyAuthenticator username:password
If defined, Tor will use this username:password for Basic HTTP proxy
authentication, as in RFC 2617. This is currently the only form of HTTP
proxy authentication that Tor supports; feel free to submit a patch if
you want it to support others. (DEPRECATED: As of 0.3.1.0-alpha you
should use HTTPSProxyAuthenticator.)

HTTPSProxy host[:port]
Tor will make all its OR (SSL) connections through this host:port (or
host:443 if port is not specified), via HTTP CONNECT rather than con-
necting directly to servers. You may want to set FascistFirewall to re-
strict the set of ports you might try to connect to, if your HTTPS
proxy only allows connecting to certain ports.

HTTPSProxyAuthenticator username:password
If defined, Tor will use this username:password for Basic HTTPS proxy
authentication, as in RFC 2617. This is currently the only form of
HTTPS proxy authentication that Tor supports; feel free to submit a
patch if you want it to support others.

KeepalivePeriod NUM
To keep firewalls from expiring connections, send a padding keepalive
cell every NUM seconds on open connections that are in use. (Default: 5
minutes)

KeepBindCapabilities 0|1|auto
On Linux, when we are started as root and we switch our identity using
the User option, the KeepBindCapabilities option tells us whether to
try to retain our ability to bind to low ports. If this value is 1, we
try to keep the capability; if it is 0 we do not; and if it is auto, we
keep the capability only if we are configured to listen on a low port.
Can not be changed while tor is running. (Default: auto.)

Log minSeverity[-maxSeverity] stderr|stdout|syslog
Send all messages between minSeverity and maxSeverity to the standard
output stream, the standard error stream, or to the system log. (The
"syslog" value is only supported on Unix.) Recognized severity levels
are debug, info, notice, warn, and err. We advise using "notice" in
most cases, since anything more verbose may provide sensitive informa-
tion to an attacker who obtains the logs. If only one severity level is
given, all messages of that level or higher will be sent to the listed
destination.

Some low-level logs may be sent from signal handlers, so their destina-
tion logs must be signal-safe. These low-level logs include backtraces,
logging function errors, and errors in code called by logging func-
tions. Signal-safe logs are always sent to stderr or stdout. They are
also sent to a limited number of log files that are configured to log
messages at error severity from the bug or general domains. They are
never sent as syslogs, control port log events, or to any API-based log
destinations.

Log minSeverity[-maxSeverity] file FILENAME
As above, but send log messages to the listed filename. The "Log" op-
tion may appear more than once in a configuration file. Messages are
sent to all the logs that match their severity level.

Log [domain,...]minSeverity[-maxSeverity] ... file FILENAME

Log [domain,...]minSeverity[-maxSeverity] ... stderr|stdout|syslog
As above, but select messages by range of log severity and by a set of
"logging domains". Each logging domain corresponds to an area of func-
tionality inside Tor. You can specify any number of severity ranges for
a single log statement, each of them prefixed by a comma-separated list
of logging domains. You can prefix a domain with ~ to indicate nega-
tion, and use * to indicate "all domains". If you specify a severity
range without a list of domains, it matches all domains.

This is an advanced feature which is most useful for debugging one or
two of Tor's subsystems at a time.

The currently recognized domains are: general, crypto, net, config, fs,
protocol, mm, http, app, control, circ, rend, bug, dir, dirserv, or,
edge, acct, hist, handshake, heartbeat, channel, sched, guard, consd-
iff, dos, process, pt, btrack, and mesg. Domain names are case-insensi-
tive.

For example, "Log [handshake]debug [~net,~mm]info notice stdout" sends
to stdout: all handshake messages of any severity, all info-and-higher
messages from domains other than networking and memory management, and
all messages of severity notice or higher.

LogMessageDomains 0|1
If 1, Tor includes message domains with each log message. Every log
message currently has at least one domain; most currently have exactly
one. This doesn't affect controller log messages. (Default: 0)

LogTimeGranularity NUM
Set the resolution of timestamps in Tor's logs to NUM milliseconds. NUM
must be positive and either a divisor or a multiple of 1 second. Note
that this option only controls the granularity written by Tor to a file
or console log. Tor does not (for example) "batch up" log messages to
affect times logged by a controller, times attached to syslog messages,
or the mtime fields on log files. (Default: 1 second)

MaxAdvertisedBandwidth N
bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
If set, we will not advertise more than this amount of bandwidth for
our BandwidthRate. Server operators who want to reduce the number of
clients who ask to build circuits through them (since this is propor-
tional to advertised bandwidth rate) can thus reduce the CPU demands on
their server without impacting network performance.

MaxUnparseableDescSizeToLog N bytes|KBytes|MBytes|GBytes|TBytes
Unparseable descriptors (e.g. for votes, consensuses, routers) are
logged in separate files by hash, up to the specified size in total.
Note that only files logged during the lifetime of this Tor process
count toward the total; this is intended to be used to debug problems
without opening live servers to resource exhaustion attacks. (Default:
10 MBytes)

MetricsPort [address:]port [format]
WARNING: Before enabling this, it is important to understand that ex-
posing tor metrics publicly is dangerous to the Tor network users.
Please take extra precaution and care when opening this port. Set a
very strict access policy with MetricsPortPolicy and consider using
your operating systems firewall features for defense in depth.

We recommend, for the prometheus format, that the only address that can
access this port should be the Prometheus server itself. Remember that
the connection is unencrypted (HTTP) hence consider using a tool like
stunnel to secure the link from this port to the server.

If set, open this port to listen for an HTTP GET request to "/metrics".
Upon a request, the collected metrics in the the tor instance are for-
matted for the given format and then sent back. If this is set, Metric-
sPortPolicy must be defined else every request will be rejected.

Supported format is "prometheus" which is also the default if not set.
The Prometheus data model can be found here:
https://prometheus.io/docs/concepts/data_model/

The tor metrics are constantly collected and they solely consists of
counters. Thus, asking for those metrics is very lightweight on the tor
process. (Default: None)

As an example, here only 5.6.7.8 will be allowed to connect:

MetricsPort 1.2.3.4:9035
MetricsPortPolicy accept 5.6.7.8

MetricsPortPolicy policy,policy,...
Set an entrance policy for the MetricsPort, to limit who can access it.
The policies have the same form as exit policies below, except that
port specifiers are ignored. For multiple entries, this line can be
used multiple times. It is a reject all by default policy. (Default:
None)

Please, keep in mind here that if the server collecting metrics on the
MetricsPort is behind a NAT, then everything behind it can access it.
This is similar for the case of allowing localhost, every users on the
server will be able to access it. Again, strongly consider using a tool
like stunnel to secure the link or to strengthen access control.

NoExec 0|1
If this option is set to 1, then Tor will never launch another exe-
cutable, regardless of the settings of ClientTransportPlugin or Server-
TransportPlugin. Once this option has been set to 1, it cannot be set
back to 0 without restarting Tor. (Default: 0)

OutboundBindAddress IP
Make all outbound connections originate from the IP address specified.
This is only useful when you have multiple network interfaces, and you
want all of Tor's outgoing connections to use a single one. This option
may be used twice, once with an IPv4 address and once with an IPv6 ad-
dress. IPv6 addresses should be wrapped in square brackets. This set-
ting will be ignored for connections to the loopback addresses
(127.0.0.0/8 and ::1), and is not used for DNS requests as well.

OutboundBindAddressExit IP
Make all outbound exit connections originate from the IP address speci-
fied. This option overrides OutboundBindAddress for the same IP ver-
sion. This option may be used twice, once with an IPv4 address and once
with an IPv6 address. IPv6 addresses should be wrapped in square brack-
ets. This setting will be ignored for connections to the loopback ad-
dresses (127.0.0.0/8 and ::1).

OutboundBindAddressOR IP
Make all outbound non-exit (relay and other) connections originate from
the IP address specified. This option overrides OutboundBindAddress for
the same IP version. This option may be used twice, once with an IPv4
address and once with an IPv6 address. IPv6 addresses should be wrapped
in square brackets. This setting will be ignored for connections to the
loopback addresses (127.0.0.0/8 and ::1).

__OwningControllerProcess PID
Make Tor instance periodically check for presence of a controller
process with given PID and terminate itself if this process is no
longer alive. Polling interval is 15 seconds.

OutboundBindAddressPT IP
Request that pluggable transports makes all outbound connections origi-
nate from the IP address specified. Because outgoing connections are
handled by the pluggable transport itself, it is not possible for Tor
to enforce whether the pluggable transport honors this option. This op-
tion overrides OutboundBindAddress for the same IP version. This option
may be used twice, once with an IPv4 address and once with an IPv6 ad-
dress. IPv6 addresses should be wrapped in square brackets. This set-
ting will be ignored for connections to the loopback addresses
(127.0.0.0/8 and ::1).

PidFile FILE
On startup, write our PID to FILE. On clean shutdown, remove FILE. Can
not be changed while tor is running.

ProtocolWarnings 0|1
If 1, Tor will log with severity 'warn' various cases of other parties
not following the Tor specification. Otherwise, they are logged with
severity 'info'. (Default: 0)

RelayBandwidthBurst N
bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
If not 0, limit the maximum token bucket size (also known as the burst)
for _relayed traffic_ to the given number of bytes in each direction.
They do not include directory fetches by the relay (from authority or
other relays), because that is considered "client" activity. (Default:
0) RelayBandwidthBurst defaults to the value of RelayBandwidthRate if
unset.

RelayBandwidthRate N
bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
If not 0, a separate token bucket limits the average incoming bandwidth
usage for _relayed traffic_ on this node to the specified number of
bytes per second, and the average outgoing bandwidth usage to that same
value. Relayed traffic currently is calculated to include answers to
directory requests, but that may change in future versions. They do not
include directory fetches by the relay (from authority or other re-
lays), because that is considered "client" activity. (Default: 0) Re-
layBandwidthRate defaults to the value of RelayBandwidthBurst if unset.

RephistTrackTime N seconds|minutes|hours|days|weeks
Tells an authority, or other node tracking node reliability and his-
tory, that fine-grained information about nodes can be discarded when
it hasn't changed for a given amount of time. (Default: 24 hours)

RunAsDaemon 0|1
If 1, Tor forks and daemonizes to the background. This option has no
effect on Windows; instead you should use the --service command-line
option. Can not be changed while tor is running. (Default: 0)

SafeLogging 0|1|relay
Tor can scrub potentially sensitive strings from log messages (e.g. ad-
dresses) by replacing them with the string [scrubbed]. This way logs
can still be useful, but they don't leave behind personally identifying
information about what sites a user might have visited.

If this option is set to 0, Tor will not perform any scrubbing, if it
is set to 1, all potentially sensitive strings are replaced. If it is
set to relay, all log messages generated when acting as a relay are
sanitized, but all messages generated when acting as a client are not.
Note: Tor may not heed this option when logging at log levels more ver-
bose than Notice. (Default: 1)

Sandbox 0|1
If set to 1, Tor will run securely through the use of a syscall sand-
box. Otherwise the sandbox will be disabled. The option only works on
Linux-based operating systems, and only when Tor has been built with
the libseccomp library. Note that this option may be incompatible with
some versions of libc, and some kernel versions. This option can not be
changed while tor is running.

When the Sandbox is 1, the following options can not be changed when
tor is running: Address, ConnLimit, CookieAuthFile, DirPortFrontPage,
ExtORPortCookieAuthFile, Logs, ServerDNSResolvConfFile, ClientOnionAu-
thDir (and any files in it won't reload on HUP signal).

Launching new Onion Services through the control port is not supported
with current syscall sandboxing implementation.

Tor must remain in client or server mode (some changes to ClientOnly
and ORPort are not allowed). Currently, if Sandbox is 1, ControlPort
command "GETINFO address" will not work.

When using %include in the tor configuration files, reloading the tor
configuration is not supported after adding new configuration files or
directories.

(Default: 0)

Schedulers KIST|KISTLite|Vanilla
Specify the scheduler type that tor should use. The scheduler is re-
sponsible for moving data around within a Tor process. This is an or-
dered list by priority which means that the first value will be tried
first and if unavailable, the second one is tried and so on. It is pos-
sible to change these values at runtime. This option mostly effects re-
lays, and most operators should leave it set to its default value. (De-
fault: KIST,KISTLite,Vanilla)

The possible scheduler types are:

KIST: Kernel-Informed Socket Transport. Tor will use TCP information
from the kernel to make informed decisions regarding how much data to
send and when to send it. KIST also handles traffic in batches (see
KISTSchedRunInterval) in order to improve traffic prioritization deci-
sions. As implemented, KIST will only work on Linux kernel version
2.6.39 or higher.

KISTLite: Same as KIST but without kernel support. Tor will use all the
same mechanics as with KIST, including the batching, but its decisions
regarding how much data to send will not be as good. KISTLite will work
on all kernels and operating systems, and the majority of the benefits
of KIST are still realized with KISTLite.

Vanilla: The scheduler that Tor used before KIST was implemented. It
sends as much data as possible, as soon as possible. Vanilla will work
on all kernels and operating systems.

KISTSchedRunInterval NUM msec
If KIST or KISTLite is used in the Schedulers option, this controls at
which interval the scheduler tick is. If the value is 0 msec, the value
is taken from the consensus if possible else it will fallback to the
default 10 msec. Maximum possible value is 100 msec. (Default: 0 msec)

KISTSockBufSizeFactor NUM
If KIST is used in Schedulers, this is a multiplier of the per-socket
limit calculation of the KIST algorithm. (Default: 1.0)

Socks4Proxy host[:port]
Tor will make all OR connections through the SOCKS 4 proxy at host:port
(or host:1080 if port is not specified).

Socks5Proxy host[:port]
Tor will make all OR connections through the SOCKS 5 proxy at host:port
(or host:1080 if port is not specified).

Socks5ProxyUsername username

Socks5ProxyPassword password
If defined, authenticate to the SOCKS 5 server using username and pass-
word in accordance to RFC 1929. Both username and password must be be-
tween 1 and 255 characters.

SyslogIdentityTag tag
When logging to syslog, adds a tag to the syslog identity such that log
entries are marked with "Tor-tag". Can not be changed while tor is run-
ning. (Default: none)

TCPProxy protocol host:port
Tor will use the given protocol to make all its OR (SSL) connections
through a TCP proxy on host:port, rather than connecting directly to
servers. You may want to set FascistFirewall to restrict the set of
ports you might try to connect to, if your proxy only allows connecting
to certain ports. There is no equivalent option for directory connec-
tions, because all Tor client versions that support this option down-
load directory documents via OR connections.

The only protocol supported right now is 'haproxy'. This option is only for
clients. (Default: none) +

The HAProxy version 1 proxy protocol is described in detail at
https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt +

Both source IP address and source port will be set to zero.

TruncateLogFile 0|1
If 1, Tor will overwrite logs at startup and in response to a HUP sig-
nal, instead of appending to them. (Default: 0)

UnixSocksGroupWritable 0|1
If this option is set to 0, don't allow the filesystem group to read
and write unix sockets (e.g. SocksPort unix:). If the option is set to
1, make the Unix socket readable and writable by the default GID. (De-
fault: 0)

UseDefaultFallbackDirs 0|1
Use Tor's default hard-coded FallbackDirs (if any). (When a FallbackDir
line is present, it replaces the hard-coded FallbackDirs, regardless of
the value of UseDefaultFallbackDirs.) (Default: 1)

User Username
On startup, setuid to this user and setgid to their primary group. Can
not be changed while tor is running.

CLIENT OPTIONS
The following options are useful only for clients (that is, if SocksPort,
HTTPTunnelPort, TransPort, DNSPort, or NATDPort is non-zero):

AllowNonRFC953Hostnames 0|1
When this option is disabled, Tor blocks hostnames containing illegal
characters (like @ and :) rather than sending them to an exit node to
be resolved. This helps trap accidental attempts to resolve URLs and so
on. (Default: 0)

AutomapHostsOnResolve 0|1
When this option is enabled, and we get a request to resolve an address
that ends with one of the suffixes in AutomapHostsSuffixes, we map an
unused virtual address to that address, and return the new virtual ad-
dress. This is handy for making ".onion" addresses work with applica-
tions that resolve an address and then connect to it. (Default: 0)

AutomapHostsSuffixes SUFFIX,SUFFIX,...
A comma-separated list of suffixes to use with AutomapHostsOnResolve.
The "." suffix is equivalent to "all addresses." (Default:
.exit,.onion).

Bridge [transport] IP:ORPort [fingerprint]
When set along with UseBridges, instructs Tor to use the relay at
"IP:ORPort" as a "bridge" relaying into the Tor network. If "finger-
print" is provided (using the same format as for DirAuthority), we will
verify that the relay running at that location has the right finger-
print. We also use fingerprint to look up the bridge descriptor at the
bridge authority, if it's provided and if UpdateBridgesFromAuthority is
set too.

If "transport" is provided, it must match a ClientTransportPlugin line.
We then use that pluggable transport's proxy to transfer data to the
bridge, rather than connecting to the bridge directly. Some transports
use a transport-specific method to work out the remote address to con-
nect to. These transports typically ignore the "IP:ORPort" specified in
the bridge line.

Tor passes any "key=val" settings to the pluggable transport proxy as
per-connection arguments when connecting to the bridge. Consult the
documentation of the pluggable transport for details of what arguments
it supports.

CircuitPadding 0|1
If set to 0, Tor will not pad client circuits with additional cover
traffic. Only clients may set this option. This option should be of-
fered via the UI to mobile users for use where bandwidth may be expen-
sive. If set to 1, padding will be negotiated as per the consensus and
relay support (unlike ConnectionPadding, CircuitPadding cannot be
force-enabled). (Default: 1)

ReducedCircuitPadding 0|1
If set to 1, Tor will only use circuit padding algorithms that have low
overhead. Only clients may set this option. This option should be of-
fered via the UI to mobile users for use where bandwidth may be expen-
sive. (Default: 0)

ClientBootstrapConsensusAuthorityDownloadInitialDelay N
Initial delay in seconds for when clients should download consensuses
from authorities if they are bootstrapping (that is, they don't have a
usable, reasonably live consensus). Only used by clients fetching from
a list of fallback directory mirrors. This schedule is advanced by (po-
tentially concurrent) connection attempts, unlike other schedules,
which are advanced by connection failures. (Default: 6)

ClientBootstrapConsensusAuthorityOnlyDownloadInitialDelay N
Initial delay in seconds for when clients should download consensuses
from authorities if they are bootstrapping (that is, they don't have a
usable, reasonably live consensus). Only used by clients which don't
have or won't fetch from a list of fallback directory mirrors. This
schedule is advanced by (potentially concurrent) connection attempts,
unlike other schedules, which are advanced by connection failures. (De-
fault: 0)

ClientBootstrapConsensusFallbackDownloadInitialDelay N
Initial delay in seconds for when clients should download consensuses
from fallback directory mirrors if they are bootstrapping (that is,
they don't have a usable, reasonably live consensus). Only used by
clients fetching from a list of fallback directory mirrors. This sched-
ule is advanced by (potentially concurrent) connection attempts, unlike
other schedules, which are advanced by connection failures. (Default:
0)

ClientBootstrapConsensusMaxInProgressTries NUM
Try this many simultaneous connections to download a consensus before
waiting for one to complete, timeout, or error out. (Default: 3)

ClientDNSRejectInternalAddresses 0|1
If true, Tor does not believe any anonymously retrieved DNS answer that
tells it that an address resolves to an internal address (like
127.0.0.1 or 192.168.0.1). This option prevents certain browser-based
attacks; it is not allowed to be set on the default network. (Default:
1)

ClientOnionAuthDir path
Path to the directory containing v3 hidden service authorization files.
Each file is for a single onion address, and the files MUST have the
suffix ".auth_private" (i.e. "bob_onion.auth_private"). The content
format MUST be:

<onion-address>:descriptor:x25519:<base32-encoded-privkey>

The <onion-address> MUST NOT have the ".onion" suffix. The <base32-en-
coded-privkey> is the base32 representation of the raw key bytes only
(32 bytes for x25519). See Appendix G in the rend-spec-v3.txt file of
torspec for more information.

ClientOnly 0|1
If set to 1, Tor will not run as a relay or serve directory requests,
even if the ORPort, ExtORPort, or DirPort options are set. (This config
option is mostly unnecessary: we added it back when we were considering
having Tor clients auto-promote themselves to being relays if they were
stable and fast enough. The current behavior is simply that Tor is a
client unless ORPort, ExtORPort, or DirPort are configured.) (Default:
0)

ClientPreferIPv6DirPort 0|1|auto
If this option is set to 1, Tor prefers a directory port with an IPv6
address over one with IPv4, for direct connections, if a given direc-
tory server has both. (Tor also prefers an IPv6 DirPort if IPv4Client
is set to 0.) If this option is set to auto, clients prefer IPv4. Other
things may influence the choice. This option breaks a tie to the favor
of IPv6. (Default: auto) (DEPRECATED: This option has had no effect for
some time.)

ClientPreferIPv6ORPort 0|1|auto
If this option is set to 1, Tor prefers an OR port with an IPv6 address
over one with IPv4 if a given entry node has both. (Tor also prefers an
IPv6 ORPort if IPv4Client is set to 0.) If this option is set to auto,
Tor bridge clients prefer the configured bridge address, and other
clients prefer IPv4. Other things may influence the choice. This option
breaks a tie to the favor of IPv6. (Default: auto)

ClientRejectInternalAddresses 0|1
If true, Tor does not try to fulfill requests to connect to an internal
address (like 127.0.0.1 or 192.168.0.1) unless an exit node is specifi-
cally requested (for example, via a .exit hostname, or a controller re-
quest). If true, multicast DNS hostnames for machines on the local net-
work (of the form *.local) are also rejected. (Default: 1)

ClientUseIPv4 0|1
If this option is set to 0, Tor will avoid connecting to directory
servers and entry nodes over IPv4. Note that clients with an IPv4 ad-
dress in a Bridge, proxy, or pluggable transport line will try connect-
ing over IPv4 even if ClientUseIPv4 is set to 0. (Default: 1)

ClientUseIPv6 0|1
If this option is set to 1, Tor might connect to directory servers or
entry nodes over IPv6. For IPv6 only hosts, you need to also set Clien-
tUseIPv4 to 0 to disable IPv4. Note that clients configured with an
IPv6 address in a Bridge, proxy, or pluggable transportline will try
connecting over IPv6 even if ClientUseIPv6 is set to 0. (Default: 1)

ConnectionPadding 0|1|auto
This option governs Tor's use of padding to defend against some forms
of traffic analysis. If it is set to auto, Tor will send padding only
if both the client and the relay support it. If it is set to 0, Tor
will not send any padding cells. If it is set to 1, Tor will still send
padding for client connections regardless of relay support. Only
clients may set this option. This option should be offered via the UI
to mobile users for use where bandwidth may be expensive. (Default:
auto)

ReducedConnectionPadding 0|1
If set to 1, Tor will not not hold OR connections open for very long,
and will send less padding on these connections. Only clients may set
this option. This option should be offered via the UI to mobile users
for use where bandwidth may be expensive. (Default: 0)

DNSPort [address:]port|auto [isolation flags]
If non-zero, open this port to listen for UDP DNS requests, and resolve
them anonymously. This port only handles A, AAAA, and PTR requests---it
doesn't handle arbitrary DNS request types. Set the port to "auto" to
have Tor pick a port for you. This directive can be specified multiple
times to bind to multiple addresses/ports. See SocksPort for an expla-
nation of isolation flags. (Default: 0)

DownloadExtraInfo 0|1
If true, Tor downloads and caches "extra-info" documents. These docu-
ments contain information about servers other than the information in
their regular server descriptors. Tor does not use this information for
anything itself; to save bandwidth, leave this option turned off. (De-
fault: 0)

EnforceDistinctSubnets 0|1
If 1, Tor will not put two servers whose IP addresses are "too close"
on the same circuit. Currently, two addresses are "too close" if they
lie in the same /16 range. (Default: 1)

FascistFirewall 0|1
If 1, Tor will only create outgoing connections to ORs running on ports
that your firewall allows (defaults to 80 and 443; see FirewallPorts).
This will allow you to run Tor as a client behind a firewall with re-
strictive policies, but will not allow you to run as a server behind
such a firewall. If you prefer more fine-grained control, use Reach-
ableAddresses instead.

FirewallPorts PORTS
A list of ports that your firewall allows you to connect to. Only used
when FascistFirewall is set. This option is deprecated; use Reach-
ableAddresses instead. (Default: 80, 443)

HTTPTunnelPort [address:]port|auto [isolation flags]
Open this port to listen for proxy connections using the "HTTP CONNECT"
protocol instead of SOCKS. Set this to 0 if you don't want to allow
"HTTP CONNECT" connections. Set the port to "auto" to have Tor pick a
port for you. This directive can be specified multiple times to bind to
multiple addresses/ports. If multiple entries of this option are
present in your configuration file, Tor will perform stream isolation
between listeners by default. See SocksPort for an explanation of iso-
lation flags. (Default: 0)

LongLivedPorts PORTS
A list of ports for services that tend to have long-running connections
(e.g. chat and interactive shells). Circuits for streams that use these
ports will contain only high-uptime nodes, to reduce the chance that a
node will go down before the stream is finished. Note that the list is
also honored for circuits (both client and service side) involving hid-
den services whose virtual port is in this list. (Default: 21, 22, 706,
1863, 5050, 5190, 5222, 5223, 6523, 6667, 6697, 8300)

MapAddress address newaddress
When a request for address arrives to Tor, it will transform to newad-
dress before processing it. For example, if you always want connections
to www.example.com to exit via torserver (where torserver is the fin-
gerprint of the server), use "MapAddress www.example.com www.exam-
ple.com.torserver.exit". If the value is prefixed with a "*.", matches
an entire domain. For example, if you always want connections to exam-
ple.com and any if its subdomains to exit via torserver (where
torserver is the fingerprint of the server), use "MapAddress *.exam-
ple.com *.example.com.torserver.exit". (Note the leading "*." in each
part of the directive.) You can also redirect all subdomains of a do-
main to a single address. For example, "MapAddress *.example.com
www.example.com". If the specified exit is not available, or the exit
can not connect to the site, Tor will fail any connections to the
mapped address.+

NOTES:

1. When evaluating MapAddress expressions Tor stops when it hits the
most recently added expression that matches the requested address.
So if you have the following in your torrc, www.torproject.org will
map to 198.51.100.1:

MapAddress www.torproject.org 192.0.2.1
MapAddress www.torproject.org 198.51.100.1

2. Tor evaluates the MapAddress configuration until it finds no
matches. So if you have the following in your torrc, www.torpro-
ject.org will map to 203.0.113.1:

MapAddress 198.51.100.1 203.0.113.1
MapAddress www.torproject.org 198.51.100.1

3. The following MapAddress expression is invalid (and will be ig-
nored) because you cannot map from a specific address to a wildcard
address:

MapAddress www.torproject.org *.torproject.org.torserver.exit

4. Using a wildcard to match only part of a string (as in *ample.com)
is also invalid.

5. Tor maps hostnames and IP addresses separately. If you MapAddress a
DNS name, but use an IP address to connect, then Tor will ignore
the DNS name mapping.

6. MapAddress does not apply to redirects in the application protocol.
For example, HTTP redirects and alt-svc headers will ignore map-
pings for the original address. You can use a wildcard mapping to
handle redirects within the same site.

MaxCircuitDirtiness NUM
Feel free to reuse a circuit that was first used at most NUM seconds
ago, but never attach a new stream to a circuit that is too old. For
hidden services, this applies to the last time a circuit was used, not
the first. Circuits with streams constructed with SOCKS authentication
via SocksPorts that have KeepAliveIsolateSOCKSAuth also remain alive
for MaxCircuitDirtiness seconds after carrying the last such stream.
(Default: 10 minutes)

MaxClientCircuitsPending NUM
Do not allow more than NUM circuits to be pending at a time for han-
dling client streams. A circuit is pending if we have begun construct-
ing it, but it has not yet been completely constructed. (Default: 32)

NATDPort [address:]port|auto [isolation flags]
Open this port to listen for connections from old versions of ipfw (as
included in old versions of FreeBSD, etc) using the NATD protocol. Use
0 if you don't want to allow NATD connections. Set the port to "auto"
to have Tor pick a port for you. This directive can be specified multi-
ple times to bind to multiple addresses/ports. If multiple entries of
this option are present in your configuration file, Tor will perform
stream isolation between listeners by default. See SocksPort for an ex-
planation of isolation flags.

This option is only for people who cannot use TransPort. (Default: 0)

NewCircuitPeriod NUM
Every NUM seconds consider whether to build a new circuit. (Default: 30
seconds)

PathBiasCircThreshold NUM

PathBiasDropGuards NUM

PathBiasExtremeRate NUM

PathBiasNoticeRate NUM

PathBiasWarnRate NUM

PathBiasScaleThreshold NUM
These options override the default behavior of Tor's (currently experi-
mental) path bias detection algorithm. To try to find broken or misbe-
having guard nodes, Tor looks for nodes where more than a certain frac-
tion of circuits through that guard fail to get built.

The PathBiasCircThreshold option controls how many circuits we need to
build through a guard before we make these checks. The PathBiasNoticeR-
ate, PathBiasWarnRate and PathBiasExtremeRate options control what
fraction of circuits must succeed through a guard so we won't write log
messages. If less than PathBiasExtremeRate circuits succeed and PathBi-
asDropGuards is set to 1, we disable use of that guard.

When we have seen more than PathBiasScaleThreshold circuits through a
guard, we scale our observations by 0.5 (governed by the consensus) so
that new observations don't get swamped by old ones.

By default, or if a negative value is provided for one of these op-
tions, Tor uses reasonable defaults from the networkstatus consensus
document. If no defaults are available there, these options default to
150, .70, .50, .30, 0, and 300 respectively.

PathBiasUseThreshold NUM

PathBiasNoticeUseRate NUM

PathBiasExtremeUseRate NUM

PathBiasScaleUseThreshold NUM
Similar to the above options, these options override the default behav-
ior of Tor's (currently experimental) path use bias detection algo-
rithm.

Where as the path bias parameters govern thresholds for successfully
building circuits, these four path use bias parameters govern thresh-
olds only for circuit usage. Circuits which receive no stream usage are
not counted by this detection algorithm. A used circuit is considered
successful if it is capable of carrying streams or otherwise receiving
well-formed responses to RELAY cells.

PathsNeededToBuildCircuits NUM
Tor clients don't build circuits for user traffic until they know about
enough of the network so that they could potentially construct enough
of the possible paths through the network. If this option is set to a
fraction between 0.25 and 0.95, Tor won't build circuits until it has
enough descriptors or microdescriptors to construct that fraction of
possible paths. Note that setting this option too low can make your Tor
client less anonymous, and setting it too high can prevent your Tor
client from bootstrapping. If this option is negative, Tor will use a
default value chosen by the directory authorities. If the directory au-
thorities do not choose a value, Tor will default to 0.6. (Default: -1)

ReachableAddresses IP[/MASK][:PORT]...
A comma-separated list of IP addresses and ports that your firewall al-
lows you to connect to. The format is as for the addresses in ExitPol-
icy, except that "accept" is understood unless "reject" is explicitly
provided. For example, 'ReachableAddresses 99.0.0.0/8, reject
18.0.0.0/8:80, accept *:80' means that your firewall allows connections
to everything inside net 99, rejects port 80 connections to net 18, and
accepts connections to port 80 otherwise. (Default: 'accept *:*'.)

ReachableDirAddresses IP[/MASK][:PORT]...
Like ReachableAddresses, a list of addresses and ports. Tor will obey
these restrictions when fetching directory information, using standard
HTTP GET requests. If not set explicitly then the value of ReachableAd-
dresses is used. If HTTPProxy is set then these connections will go
through that proxy. (DEPRECATED: This option has had no effect for some
time.)

ReachableORAddresses IP[/MASK][:PORT]...
Like ReachableAddresses, a list of addresses and ports. Tor will obey
these restrictions when connecting to Onion Routers, using TLS/SSL. If
not set explicitly then the value of ReachableAddresses is used. If
HTTPSProxy is set then these connections will go through that proxy.

The separation between ReachableORAddresses and ReachableDirAddresses
is only interesting when you are connecting through proxies (see HTTP-
Proxy and HTTPSProxy). Most proxies limit TLS connections (which Tor
uses to connect to Onion Routers) to port 443, and some limit HTTP GET
requests (which Tor uses for fetching directory information) to port
80.

SafeSocks 0|1
When this option is enabled, Tor will reject application connections
that use unsafe variants of the socks protocol -- ones that only pro-
vide an IP address, meaning the application is doing a DNS resolve
first. Specifically, these are socks4 and socks5 when not doing remote
DNS. (Default: 0)

TestSocks 0|1
When this option is enabled, Tor will make a notice-level log entry for
each connection to the Socks port indicating whether the request used a
safe socks protocol or an unsafe one (see SafeSocks). This helps to de-
termine whether an application using Tor is possibly leaking DNS re-
quests. (Default: 0)

WarnPlaintextPorts port,port,...
Tells Tor to issue a warnings whenever the user tries to make an anony-
mous connection to one of these ports. This option is designed to alert
users to services that risk sending passwords in the clear. (Default:
23,109,110,143)

RejectPlaintextPorts port,port,...
Like WarnPlaintextPorts, but instead of warning about risky port uses,
Tor will instead refuse to make the connection. (Default: None)

SocksPolicy policy,policy,...
Set an entrance policy for this server, to limit who can connect to the
SocksPort and DNSPort ports. The policies have the same form as exit
policies below, except that port specifiers are ignored. Any address
not matched by some entry in the policy is accepted.

SocksPort [address:]port|unix:path|auto [flags] [isolation flags]
Open this port to listen for connections from SOCKS-speaking applica-
tions. Set this to 0 if you don't want to allow application connections
via SOCKS. Set it to "auto" to have Tor pick a port for you. This di-
rective can be specified multiple times to bind to multiple ad-
dresses/ports. If a unix domain socket is used, you may quote the path
using standard C escape sequences. Most flags are off by default, ex-
cept where specified. Flags that are on by default can be disabled by
putting "No" before the flag name. (Default: 9050)

NOTE: Although this option allows you to specify an IP address other
than localhost, you should do so only with extreme caution. The SOCKS
protocol is unencrypted and (as we use it) unauthenticated, so exposing
it in this way could leak your information to anybody watching your
network, and allow anybody to use your computer as an open proxy.

If multiple entries of this option are present in your configuration
file, Tor will perform stream isolation between listeners by default.
The isolation flags arguments give Tor rules for which streams received
on this SocksPort are allowed to share circuits with one another. Rec-
ognized isolation flags are:

IsolateClientAddr
Don't share circuits with streams from a different client address.
(On by default and strongly recommended when supported; you can
disable it with NoIsolateClientAddr. Unsupported and force-disabled
when using Unix domain sockets.)

IsolateSOCKSAuth
Don't share circuits with streams for which different SOCKS authen-
tication was provided. (For HTTPTunnelPort connections, this option
looks at the Proxy-Authorization and X-Tor-Stream-Isolation head-
ers. On by default; you can disable it with NoIsolateSOCKSAuth.)

IsolateClientProtocol
Don't share circuits with streams using a different protocol.
(SOCKS 4, SOCKS 5, HTTPTunnelPort connections, TransPort connec-
tions, NATDPort connections, and DNSPort requests are all consid-
ered to be different protocols.)

IsolateDestPort
Don't share circuits with streams targeting a different destination
port.

IsolateDestAddr
Don't share circuits with streams targeting a different destination
address.

KeepAliveIsolateSOCKSAuth
If IsolateSOCKSAuth is enabled, keep alive circuits while they have
at least one stream with SOCKS authentication active. After such a
circuit is idle for more than MaxCircuitDirtiness seconds, it can
be closed.

SessionGroup=INT
If no other isolation rules would prevent it, allow streams on this
port to share circuits with streams from every other port with the
same session group. (By default, streams received on different
SocksPorts, TransPorts, etc are always isolated from one another.
This option overrides that behavior.)

Other recognized flags for a SocksPort are:

NoIPv4Traffic
Tell exits to not connect to IPv4 addresses in response to SOCKS
requests on this connection.

IPv6Traffic
Tell exits to allow IPv6 addresses in response to SOCKS requests on
this connection, so long as SOCKS5 is in use. (SOCKS4 can't handle
IPv6.)

PreferIPv6
Tells exits that, if a host has both an IPv4 and an IPv6 address,
we would prefer to connect to it via IPv6. (IPv4 is the default.)

NoDNSRequest
Do not ask exits to resolve DNS addresses in SOCKS5 requests. Tor
will connect to IPv4 addresses, IPv6 addresses (if IPv6Traffic is
set) and .onion addresses.

NoOnionTraffic
Do not connect to .onion addresses in SOCKS5 requests.

OnionTrafficOnly
Tell the tor client to only connect to .onion addresses in response
to SOCKS5 requests on this connection. This is equivalent to
NoDNSRequest, NoIPv4Traffic, NoIPv6Traffic. The corresponding NoO-
nionTrafficOnly flag is not supported.

CacheIPv4DNS
Tells the client to remember IPv4 DNS answers we receive from exit
nodes via this connection.

CacheIPv6DNS
Tells the client to remember IPv6 DNS answers we receive from exit
nodes via this connection.

GroupWritable
Unix domain sockets only: makes the socket get created as
group-writable.

WorldWritable
Unix domain sockets only: makes the socket get created as
world-writable.

CacheDNS
Tells the client to remember all DNS answers we receive from exit
nodes via this connection.

UseIPv4Cache
Tells the client to use any cached IPv4 DNS answers we have when
making requests via this connection. (NOTE: This option, or
UseIPv6Cache or UseDNSCache, can harm your anonymity, and probably
won't help performance as much as you might expect. Use with care!)

UseIPv6Cache
Tells the client to use any cached IPv6 DNS answers we have when
making requests via this connection.

UseDNSCache
Tells the client to use any cached DNS answers we have when making
requests via this connection.

NoPreferIPv6Automap
When serving a hostname lookup request on this port that should get
automapped (according to AutomapHostsOnResolve), if we could return
either an IPv4 or an IPv6 answer, prefer an IPv4 answer. (Tor
prefers IPv6 by default.)

PreferSOCKSNoAuth
Ordinarily, when an application offers both "username/password au-
thentication" and "no authentication" to Tor via SOCKS5, Tor se-
lects username/password authentication so that IsolateSOCKSAuth can
work. This can confuse some applications, if they offer a user-
name/password combination then get confused when asked for one. You
can disable this behavior, so that Tor will select "No authentica-
tion" when IsolateSOCKSAuth is disabled, or when this option is
set.

ExtendedErrors
Return extended error code in the SOCKS reply. So far, the possible
errors are:

X'F0' Onion Service Descriptor Can Not be Found

The requested onion service descriptor can't be found on the
hashring and thus not reachable by the client. (v3 only)

X'F1' Onion Service Descriptor Is Invalid

The requested onion service descriptor can't be parsed or
signature validation failed. (v3 only)

X'F2' Onion Service Introduction Failed

All introduction attempts failed either due to a combination of
NACK by the intro point or time out. (v3 only)

X'F3' Onion Service Rendezvous Failed

Every rendezvous circuit has timed out and thus the client is
unable to rendezvous with the service. (v3 only)

X'F4' Onion Service Missing Client Authorization

Client was able to download the requested onion service descriptor
but is unable to decrypt its content because it is missing client
authorization information. (v3 only)

X'F5' Onion Service Wrong Client Authorization

Client was able to download the requested onion service descriptor
but is unable to decrypt its content using the client
authorization information it has. This means the client access
were revoked. (v3 only)

X'F6' Onion Service Invalid Address

The given .onion address is invalid. In one of these cases this
error is returned: address checksum doesn't match, ed25519 public
key is invalid or the encoding is invalid. (v3 only)

X'F7' Onion Service Introduction Timed Out

Similar to X'F2' code but in this case, all introduction attempts
have failed due to a time out. (v3 only)

Flags are processed left to right. If flags conflict, the last flag on
the line is used, and all earlier flags are ignored. No error is issued
for conflicting flags.

TokenBucketRefillInterval NUM [msec|second]
Set the refill delay interval of Tor's token bucket to NUM millisec-
onds. NUM must be between 1 and 1000, inclusive. When Tor is out of
bandwidth, on a connection or globally, it will wait up to this long
before it tries to use that connection again. Note that bandwidth lim-
its are still expressed in bytes per second: this option only affects
the frequency with which Tor checks to see whether previously exhausted
connections may read again. Can not be changed while tor is running.
(Default: 100 msec)

TrackHostExits host,.domain,...
For each value in the comma separated list, Tor will track recent con-
nections to hosts that match this value and attempt to reuse the same
exit node for each. If the value is prepended with a '.', it is treated
as matching an entire domain. If one of the values is just a '.', it
means match everything. This option is useful if you frequently connect
to sites that will expire all your authentication cookies (i.e. log you
out) if your IP address changes. Note that this option does have the
disadvantage of making it more clear that a given history is associated
with a single user. However, most people who would wish to observe this
will observe it through cookies or other protocol-specific means any-
how.

TrackHostExitsExpire NUM
Since exit servers go up and down, it is desirable to expire the asso-
ciation between host and exit server after NUM seconds. The default is
1800 seconds (30 minutes).

TransPort [address:]port|auto [isolation flags]
Open this port to listen for transparent proxy connections. Set this to
0 if you don't want to allow transparent proxy connections. Set the
port to "auto" to have Tor pick a port for you. This directive can be
specified multiple times to bind to multiple addresses/ports. If multi-
ple entries of this option are present in your configuration file, Tor
will perform stream isolation between listeners by default. See Sock-
sPort for an explanation of isolation flags.

TransPort requires OS support for transparent proxies, such as BSDs' pf
or Linux's IPTables. If you're planning to use Tor as a transparent
proxy for a network, you'll want to examine and change VirtualAddrNet-
work from the default setting. (Default: 0)

TransProxyType default|TPROXY|ipfw|pf-divert
TransProxyType may only be enabled when there is transparent proxy lis-
tener enabled.

Set this to "TPROXY" if you wish to be able to use the TPROXY Linux
module to transparently proxy connections that are configured using the
TransPort option. Detailed information on how to configure the TPROXY
feature can be found in the Linux kernel source tree in the file Docu-
mentation/networking/tproxy.txt.

Set this option to "ipfw" to use the FreeBSD ipfw interface.

On *BSD operating systems when using pf, set this to "pf-divert" to
take advantage of divert-to rules, which do not modify the packets like
rdr-to rules do. Detailed information on how to configure pf to use di-
vert-to rules can be found in the pf.conf(5) manual page. On OpenBSD,
divert-to is available to use on versions greater than or equal to
OpenBSD 4.4.

Set this to "default", or leave it unconfigured, to use regular IPTa-
bles on Linux, or to use pf rdr-to rules on *BSD systems.

(Default: "default")

UpdateBridgesFromAuthority 0|1
When set (along with UseBridges), Tor will try to fetch bridge descrip-
tors from the configured bridge authorities when feasible. It will fall
back to a direct request if the authority responds with a 404. (De-
fault: 0)

UseBridges 0|1
When set, Tor will fetch descriptors for each bridge listed in the
"Bridge" config lines, and use these relays as both entry guards and
directory guards. (Default: 0)

UseEntryGuards 0|1
If this option is set to 1, we pick a few long-term entry servers, and
try to stick with them. This is desirable because constantly changing
servers increases the odds that an adversary who owns some servers will
observe a fraction of your paths. Entry Guards can not be used by Di-
rectory Authorities or Single Onion Services. In these cases, this op-
tion is ignored. (Default: 1)

UseGuardFraction 0|1|auto
This option specifies whether clients should use the guardfraction in-
formation found in the consensus during path selection. If it's set to
auto, clients will do what the UseGuardFraction consensus parameter
tells them to do. (Default: auto)

GuardLifetime N days|weeks|months
If UseEntryGuards is set, minimum time to keep a guard on our guard
list before picking a new one. If less than one day, we use defaults
from the consensus directory. (Default: 0)

NumDirectoryGuards NUM
If UseEntryGuards is set to 1, we try to make sure we have at least NUM
routers to use as directory guards. If this option is set to 0, use the
value from the guard-n-primary-dir-guards-to-use consensus parameter,
and default to 3 if the consensus parameter isn't set. (Default: 0)

NumEntryGuards NUM
If UseEntryGuards is set to 1, we will try to pick a total of NUM
routers as long-term entries for our circuits. If NUM is 0, we try to
learn the number from the guard-n-primary-guards-to-use consensus para-
meter, and default to 1 if the consensus parameter isn't set. (Default:
0)

NumPrimaryGuards NUM
If UseEntryGuards is set to 1, we will try to pick NUM routers for our
primary guard list, which is the set of routers we strongly prefer when
connecting to the Tor network. If NUM is 0, we try to learn the number
from the guard-n-primary-guards consensus parameter, and default to 3
if the consensus parameter isn't set. (Default: 0)

VanguardsLiteEnabled 0|1|auto
This option specifies whether clients should use the vanguards-lite
subsystem to protect against guard discovery attacks. If it's set to
auto, clients will do what the vanguards-lite-enabled consensus parame-
ter tells them to do, and will default to enable the subsystem if the
consensus parameter isn't set. (Default: auto)

UseMicrodescriptors 0|1|auto
Microdescriptors are a smaller version of the information that Tor
needs in order to build its circuits. Using microdescriptors makes Tor
clients download less directory information, thus saving bandwidth. Di-
rectory caches need to fetch regular descriptors and microdescriptors,
so this option doesn't save any bandwidth for them. For legacy reasons,
auto is accepted, but it has the same effect as 1. (Default: auto)

VirtualAddrNetworkIPv4 IPv4Address/bits

VirtualAddrNetworkIPv6 [IPv6Address]/bits
When Tor needs to assign a virtual (unused) address because of a MAPAD-
DRESS command from the controller or the AutomapHostsOnResolve feature,
Tor picks an unassigned address from this range. (Defaults:
127.192.0.0/10 and [FE80::]/10 respectively.)

When providing proxy server service to a network of computers using a
tool like dns-proxy-tor, change the IPv4 network to "10.192.0.0/10" or
"172.16.0.0/12" and change the IPv6 network to "[FC00::]/7". The de-
fault VirtualAddrNetwork address ranges on a properly configured ma-
chine will route to the loopback or link-local interface. The maximum
number of bits for the network prefix is set to 104 for IPv6 and 16 for
IPv4. However, a larger network (that is, one with a smaller prefix
length) is preferable, since it reduces the chances for an attacker to
guess the used IP. For local use, no change to the default VirtualAddr-
Network setting is needed.

CIRCUIT TIMEOUT OPTIONS
The following options are useful for configuring timeouts related to build-
ing Tor circuits and using them:

CircuitsAvailableTimeout NUM
Tor will attempt to keep at least one open, unused circuit available
for this amount of time. This option governs how long idle circuits are
kept open, as well as the amount of time Tor will keep a circuit open
to each of the recently used ports. This way when the Tor client is en-
tirely idle, it can expire all of its circuits, and then expire its TLS
connections. Note that the actual timeout value is uniformly randomized
from the specified value to twice that amount. (Default: 30 minutes;
Max: 24 hours)

LearnCircuitBuildTimeout 0|1
If 0, CircuitBuildTimeout adaptive learning is disabled. (Default: 1)

CircuitBuildTimeout NUM
Try for at most NUM seconds when building circuits. If the circuit
isn't open in that time, give up on it. If LearnCircuitBuildTimeout is
1, this value serves as the initial value to use before a timeout is
learned. If LearnCircuitBuildTimeout is 0, this value is the only value
used. (Default: 60 seconds)

CircuitStreamTimeout NUM
If non-zero, this option overrides our internal timeout schedule for
how many seconds until we detach a stream from a circuit and try a new
circuit. If your network is particularly slow, you might want to set
this to a number like 60. (Default: 0)

SocksTimeout NUM
Let a socks connection wait NUM seconds handshaking, and NUM seconds
unattached waiting for an appropriate circuit, before we fail it. (De-
fault: 2 minutes)

DORMANT MODE OPTIONS
Tor can enter dormant mode to conserve power and network bandwidth. The
following options control when Tor enters and leaves dormant mode:

DormantCanceledByStartup 0|1
By default, Tor starts in active mode if it was active the last time it
was shut down, and in dormant mode if it was dormant. But if this op-
tion is true, Tor treats every startup event as user activity, and Tor
will never start in Dormant mode, even if it has been unused for a long
time on previous runs. (Default: 0)

Note: Packagers and application developers should change the value of
this option only with great caution: it has the potential to create
spurious traffic on the network. This option should only be used if Tor
is started by an affirmative user activity (like clicking on an appli-
cation or running a command), and not if Tor is launched for some other
reason (for example, by a startup process, or by an application that
launches itself on every login.)

DormantClientTimeout N minutes|hours|days|weeks
If Tor spends this much time without any client activity, enter a dor-
mant state where automatic circuits are not built, and directory infor-
mation is not fetched. Does not affect servers or onion services. Must
be at least 10 minutes. (Default: 24 hours)

DormantOnFirstStartup 0|1
If true, then the first time Tor starts up with a fresh DataDirectory,
it starts in dormant mode, and takes no actions until the user has made
a request. (This mode is recommended if installing a Tor client for a
user who might not actually use it.) If false, Tor bootstraps the first
time it is started, whether it sees a user request or not.

After the first time Tor starts, it begins in dormant mode if it was
dormant before, and not otherwise. (Default: 0)

DormantTimeoutDisabledByIdleStreams 0|1
If true, then any open client stream (even one not reading or writing)
counts as client activity for the purpose of DormantClientTimeout. If
false, then only network activity counts. (Default: 1)

DormantTimeoutEnabled 0|1
If false, then no amount of time without activity is sufficient to make
Tor go dormant. Setting this option to zero is only recommended for
special-purpose applications that need to use the Tor binary for some-
thing other than sending or receiving Tor traffic. (Default: 1)

NODE SELECTION OPTIONS
The following options restrict the nodes that a tor client (or onion ser-
vice) can use while building a circuit. These options can weaken your
anonymity by making your client behavior different from other Tor clients:

EntryNodes node,node,...
A list of identity fingerprints and country codes of nodes to use for
the first hop in your normal circuits. Normal circuits include all cir-
cuits except for direct connections to directory servers. The Bridge
option overrides this option; if you have configured bridges and Use-
Bridges is 1, the Bridges are used as your entry nodes.

This option can appear multiple times: the values from multiple lines
are spliced together.

The ExcludeNodes option overrides this option: any node listed in both
EntryNodes and ExcludeNodes is treated as excluded. See ExcludeNodes
for more information on how to specify nodes.

ExcludeNodes node,node,...
A list of identity fingerprints, country codes, and address patterns of
nodes to avoid when building a circuit. Country codes are 2-letter
ISO3166 codes, and must be wrapped in braces; fingerprints may be pre-
ceded by a dollar sign. (Example: ExcludeNodes
ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc}, 255.254.0.0/8)

This option can appear multiple times: the values from multiple lines
are spliced together.

By default, this option is treated as a preference that Tor is allowed
to override in order to keep working. For example, if you try to con-
nect to a hidden service, but you have excluded all of the hidden ser-
vice's introduction points, Tor will connect to one of them anyway. If
you do not want this behavior, set the StrictNodes option (documented
below).

Note also that if you are a relay, this (and the other node selection
options below) only affects your own circuits that Tor builds for you.
Clients can still build circuits through you to any node. Controllers
can tell Tor to build circuits through any node.

Country codes are case-insensitive. The code "\{??}" refers to nodes
whose country can't be identified. No country code, including \{??},
works if no GeoIPFile can be loaded. See also the GeoIPExcludeUnknown
option below.

ExcludeExitNodes node,node,...
A list of identity fingerprints, country codes, and address patterns of
nodes to never use when picking an exit node---that is, a node that de-
livers traffic for you outside the Tor network. Note that any node
listed in ExcludeNodes is automatically considered to be part of this
list too. See ExcludeNodes for more information on how to specify
nodes. See also the caveats on the ExitNodes option below.

This option can appear multiple times: the values from multiple lines
are spliced together.

ExitNodes node,node,...
A list of identity fingerprints, country codes, and address patterns of
nodes to use as exit node---that is, a node that delivers traffic for
you outside the Tor network. See ExcludeNodes for more information on
how to specify nodes.

This option can appear multiple times: the values from multiple lines
are spliced together.

Note that if you list too few nodes here, or if you exclude too many
exit nodes with ExcludeExitNodes, you can degrade functionality. For
example, if none of the exits you list allows traffic on port 80 or
443, you won't be able to browse the web.

Note also that not every circuit is used to deliver traffic outside of
the Tor network. It is normal to see non-exit circuits (such as those
used to connect to hidden services, those that do directory fetches,
those used for relay reachability self-tests, and so on) that end at a
non-exit node. To keep a node from being used entirely, see ExcludeN-
odes and StrictNodes.

The ExcludeNodes option overrides this option: any node listed in both
ExitNodes and ExcludeNodes is treated as excluded.

The .exit address notation, if enabled via MapAddress, overrides this
option.

GeoIPExcludeUnknown 0|1|auto
If this option is set to auto, then whenever any country code is set in
ExcludeNodes or ExcludeExitNodes, all nodes with unknown country (\{??}
and possibly {A1}) are treated as excluded as well. If this option is
set to 1, then all unknown countries are treated as excluded in Exclu-
deNodes and ExcludeExitNodes. This option has no effect when a GeoIP
file isn't configured or can't be found. (Default: auto)

HSLayer2Nodes node,node,...
A list of identity fingerprints, nicknames, country codes, and address
patterns of nodes that are allowed to be used as the second hop in all
client or service-side Onion Service circuits. This option mitigates
attacks where the adversary runs middle nodes and induces your client
or service to create many circuits, in order to discover your primary
guard node. (Default: Any node in the network may be used in the second
hop.)

(Example: HSLayer2Nodes ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc},
255.254.0.0/8)

This option can appear multiple times: the values from multiple lines
are spliced together.

When this is set, the resulting hidden service paths will look like:

C - G - L2 - M - Rend

C - G - L2 - M - HSDir

C - G - L2 - M - Intro

S - G - L2 - M - Rend

S - G - L2 - M - HSDir

S - G - L2 - M - Intro

where C is this client, S is the service, G is the Guard node, L2 is a
node from this option, and M is a random middle node. Rend, HSDir, and
Intro point selection is not affected by this option.

This option may be combined with HSLayer3Nodes to create paths of the
form:

C - G - L2 - L3 - Rend

C - G - L2 - L3 - M - HSDir

C - G - L2 - L3 - M - Intro

S - G - L2 - L3 - M - Rend

S - G - L2 - L3 - HSDir

S - G - L2 - L3 - Intro

ExcludeNodes have higher priority than HSLayer2Nodes, which means that
nodes specified in ExcludeNodes will not be picked.

When either this option or HSLayer3Nodes are set, the /16 subnet and
node family restrictions are removed for hidden service circuits. Addi-
tionally, we allow the guard node to be present as the Rend, HSDir, and
IP node, and as the hop before it. This is done to prevent the adver-
sary from inferring information about our guard, layer2, and layer3
node choices at later points in the path.

This option is meant to be managed by a Tor controller such as
https://github.com/mikeperry-tor/vanguards that selects and updates
this set of nodes for you. Hence it does not do load balancing if fewer
than 20 nodes are selected, and if no nodes in HSLayer2Nodes are cur-
rently available for use, Tor will not work. Please use extreme care if
you are setting this option manually.

HSLayer3Nodes node,node,...
A list of identity fingerprints, nicknames, country codes, and address
patterns of nodes that are allowed to be used as the third hop in all
client and service-side Onion Service circuits. This option mitigates
attacks where the adversary runs middle nodes and induces your client
or service to create many circuits, in order to discover your primary
or Layer2 guard nodes. (Default: Any node in the network may be used in
the third hop.)

(Example: HSLayer3Nodes ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc},
255.254.0.0/8)

This option can appear multiple times: the values from multiple lines
are spliced together.

When this is set by itself, the resulting hidden service paths will
look like:

C - G - M - L3 - Rend

C - G - M - L3 - M - HSDir

C - G - M - L3 - M - Intro

S - G - M - L3 - M - Rend

S - G - M - L3 - HSDir

S - G - M - L3 - Intro

where C is this client, S is the service, G is the Guard node, L2 is a
node from this option, and M is a random middle node. Rend, HSDir, and
Intro point selection is not affected by this option.

While it is possible to use this option by itself, it should be com-
bined with HSLayer2Nodes to create paths of the form:

C - G - L2 - L3 - Rend

C - G - L2 - L3 - M - HSDir

C - G - L2 - L3 - M - Intro

S - G - L2 - L3 - M - Rend

S - G - L2 - L3 - HSDir

S - G - L2 - L3 - Intro

ExcludeNodes have higher priority than HSLayer3Nodes, which means that
nodes specified in ExcludeNodes will not be picked.

When either this option or HSLayer2Nodes are set, the /16 subnet and
node family restrictions are removed for hidden service circuits. Addi-
tionally, we allow the guard node to be present as the Rend, HSDir, and
IP node, and as the hop before it. This is done to prevent the adver-
sary from inferring information about our guard, layer2, and layer3
node choices at later points in the path.

This option is meant to be managed by a Tor controller such as
https://github.com/mikeperry-tor/vanguards that selects and updates
this set of nodes for you. Hence it does not do load balancing if fewer
than 20 nodes are selected, and if no nodes in HSLayer3Nodes are cur-
rently available for use, Tor will not work. Please use extreme care if
you are setting this option manually.

MiddleNodes node,node,...
A list of identity fingerprints and country codes of nodes to use for
"middle" hops in your normal circuits. Normal circuits include all cir-
cuits except for direct connections to directory servers. Middle hops
are all hops other than exit and entry.

This option can appear multiple times: the values from multiple lines
are spliced together.

This is an experimental feature that is meant to be used by researchers
and developers to test new features in the Tor network safely. Using it
without care will strongly influence your anonymity. Other tor features
may not work with MiddleNodes. This feature might get removed in the
future.

The HSLayer2Node and HSLayer3Node options override this option for onion
service circuits, if they are set. The vanguards addon will read this
option, and if set, it will set HSLayer2Nodes and HSLayer3Nodes to nodes
from this set.

The ExcludeNodes option overrides this option: any node listed in both
MiddleNodes and ExcludeNodes is treated as excluded. See
the <<ExcludeNodes,ExcludeNodes>> for more information on how to specify nodes.

NodeFamily node,node,...
The Tor servers, defined by their identity fingerprints, constitute a
"family" of similar or co-administered servers, so never use any two of
them in the same circuit. Defining a NodeFamily is only needed when a
server doesn't list the family itself (with MyFamily). This option can
be used multiple times; each instance defines a separate family. In ad-
dition to nodes, you can also list IP address and ranges and country
codes in {curly braces}. See ExcludeNodes for more information on how
to specify nodes.

StrictNodes 0|1
If StrictNodes is set to 1, Tor will treat solely the ExcludeNodes op-
tion as a requirement to follow for all the circuits you generate, even
if doing so will break functionality for you (StrictNodes does not ap-
ply to ExcludeExitNodes, ExitNodes, MiddleNodes, or MapAddress). If
StrictNodes is set to 0, Tor will still try to avoid nodes in the Ex-
cludeNodes list, but it will err on the side of avoiding unexpected er-
rors. Specifically, StrictNodes 0 tells Tor that it is okay to use an
excluded node when it is necessary to perform relay reachability
self-tests, connect to a hidden service, provide a hidden service to a
client, fulfill a .exit request, upload directory information, or down-
load directory information. (Default: 0)

SERVER OPTIONS
The following options are useful only for servers (that is, if ORPort is
non-zero):

AccountingMax N bytes|KBytes|MBytes|GBytes|TBytes|KBits|MBits|GBits|TBits
Limits the max number of bytes sent and received within a set time pe-
riod using a given calculation rule (see AccountingStart and Accountin-
gRule). Useful if you need to stay under a specific bandwidth. By de-
fault, the number used for calculation is the max of either the bytes
sent or received. For example, with AccountingMax set to 1 TByte, a
server could send 900 GBytes and receive 800 GBytes and continue run-
ning. It will only hibernate once one of the two reaches 1 TByte. This
can be changed to use the sum of the both bytes received and sent by
setting the AccountingRule option to "sum" (total bandwidth in/out).
When the number of bytes remaining gets low, Tor will stop accepting
new connections and circuits. When the number of bytes is exhausted,
Tor will hibernate until some time in the next accounting period. To
prevent all servers from waking at the same time, Tor will also wait
until a random point in each period before waking up. If you have band-
width cost issues, enabling hibernation is preferable to setting a low
bandwidth, since it provides users with a collection of fast servers
that are up some of the time, which is more useful than a set of slow
servers that are always "available".

Note that (as also described in the Bandwidth section) Tor uses powers
of two, not powers of ten: 1 GByte is 1024*1024*1024, not one billion.
Be careful: some internet service providers might count GBytes differ-
ently.

AccountingRule sum|max|in|out
How we determine when our AccountingMax has been reached (when we
should hibernate) during a time interval. Set to "max" to calculate us-
ing the higher of either the sent or received bytes (this is the de-
fault functionality). Set to "sum" to calculate using the sent plus re-
ceived bytes. Set to "in" to calculate using only the received bytes.
Set to "out" to calculate using only the sent bytes. (Default: max)

AccountingStart day|week|month [day] HH:MM
Specify how long accounting periods last. If month is given, each ac-
counting period runs from the time HH:MM on the dayth day of one month
to the same day and time of the next. The relay will go at full speed,
use all the quota you specify, then hibernate for the rest of the pe-
riod. (The day must be between 1 and 28.) If week is given, each ac-
counting period runs from the time HH:MM of the dayth day of one week
to the same day and time of the next week, with Monday as day 1 and
Sunday as day 7. If day is given, each accounting period runs from the
time HH:MM each day to the same time on the next day. All times are lo-
cal, and given in 24-hour time. (Default: "month 1 0:00")

Address address
The address of this server, or a fully qualified domain name of this
server that resolves to an address. You can leave this unset, and Tor
will try to guess your address. If a domain name is provided, Tor will
attempt to resolve it and use the underlying IPv4/IPv6 address as its
publish address (taking precedence over the ORPort configuration). The
publish address is the one used to tell clients and other servers where
to find your Tor server; it doesn't affect the address that your server
binds to. To bind to a different address, use the ORPort and Outbound-
BindAddress options.

AddressDisableIPv6 0|1
By default, Tor will attempt to find the IPv6 of the relay if there is
no IPv4Only ORPort. If set, this option disables IPv6 auto discovery.
This disables IPv6 address resolution, IPv6 ORPorts, and IPv6 reacha-
bility checks. Also, the relay won't publish an IPv6 ORPort in its de-
scriptor. (Default: 0)

AssumeReachable 0|1
This option is used when bootstrapping a new Tor network. If set to 1,
don't do self-reachability testing; just upload your server descriptor
immediately. (Default: 0)

AssumeReachableIPv6 0|1|auto
Like AssumeReachable, but affects only the relay's own IPv6 ORPort. If
this value is set to "auto", then Tor will look at AssumeReachable in-
stead. (Default: auto)

BridgeRelay 0|1
Sets the relay to act as a "bridge" with respect to relaying connec-
tions from bridge users to the Tor network. It mainly causes Tor to
publish a server descriptor to the bridge database, rather than to the
public directory authorities.

Note: make sure that no MyFamily lines are present in your torrc when
relay is configured in bridge mode.

BridgeDistribution string
If set along with BridgeRelay, Tor will include a new line in its
bridge descriptor which indicates to the BridgeDB service how it would
like its bridge address to be given out. Set it to "none" if you want
BridgeDB to avoid distributing your bridge address, or "any" to let
BridgeDB decide. See https://bridges.torproject.org/info for a more
up-to-date list of options. (Default: any)

ContactInfo email_address
Administrative contact information for this relay or bridge. This line
can be used to contact you if your relay or bridge is misconfigured or
something else goes wrong. Note that we archive and publish all de-
scriptors containing these lines and that Google indexes them, so spam-
mers might also collect them. You may want to obscure the fact that
it's an email address and/or generate a new address for this purpose.

ContactInfo must be set to a working address if you run more than one
relay or bridge. (Really, everybody running a relay or bridge should
set it.)

DisableOOSCheck 0|1
This option disables the code that closes connections when Tor notices
that it is running low on sockets. Right now, it is on by default,
since the existing out-of-sockets mechanism tends to kill OR connec-
tions more than it should. (Default: 1)

ExitPolicy policy,policy,...
Set an exit policy for this server. Each policy is of the form "ac-
cept[6]|reject[6] ADDR[/MASK][:PORT]". If /MASK is omitted then this
policy just applies to the host given. Instead of giving a host or net-
work you can also use "*" to denote the universe (0.0.0.0/0 and ::/0),
or *4 to denote all IPv4 addresses, and *6 to denote all IPv6 ad-
dresses. PORT can be a single port number, an interval of ports
"FROM_PORT-TO_PORT", or "*". If PORT is omitted, that means "*".

For example, "accept 18.7.22.69:*,reject 18.0.0.0/8:*,accept *:*" would
reject any IPv4 traffic destined for MIT except for web.mit.edu, and
accept any other IPv4 or IPv6 traffic.

Tor also allows IPv6 exit policy entries. For instance, "reject6
[FC00::]/7:*" rejects all destinations that share 7 most significant
bit prefix with address FC00::. Respectively, "accept6 [C000::]/3:*"
accepts all destinations that share 3 most significant bit prefix with
address C000::.

accept6 and reject6 only produce IPv6 exit policy entries. Using an
IPv4 address with accept6 or reject6 is ignored and generates a warn-
ing. accept/reject allows either IPv4 or IPv6 addresses. Use *4 as an
IPv4 wildcard address, and *6 as an IPv6 wildcard address. accept/re-
ject * expands to matching IPv4 and IPv6 wildcard address rules.

To specify all IPv4 and IPv6 internal and link-local networks (includ-
ing 0.0.0.0/8, 169.254.0.0/16, 127.0.0.0/8, 192.168.0.0/16, 10.0.0.0/8,
172.16.0.0/12, [::]/8, [FC00::]/7, [FE80::]/10, [FEC0::]/10,
[FF00::]/8, and [::]/127), you can use the "private" alias instead of
an address. ("private" always produces rules for IPv4 and IPv6 ad-
dresses, even when used with accept6/reject6.)

Private addresses are rejected by default (at the beginning of your
exit policy), along with any configured primary public IPv4 and IPv6
addresses. These private addresses are rejected unless you set the Ex-
itPolicyRejectPrivate config option to 0. For example, once you've done
that, you could allow HTTP to 127.0.0.1 and block all other connections
to internal networks with "accept 127.0.0.1:80,reject private:*",
though that may also allow connections to your own computer that are
addressed to its public (external) IP address. See RFC 1918 and RFC
3330 for more details about internal and reserved IP address space. See
ExitPolicyRejectLocalInterfaces if you want to block every address on
the relay, even those that aren't advertised in the descriptor.

This directive can be specified multiple times so you don't have to put
it all on one line.

Policies are considered first to last, and the first match wins. If you
want to allow the same ports on IPv4 and IPv6, write your rules using
accept/reject *. If you want to allow different ports on IPv4 and IPv6,
write your IPv6 rules using accept6/reject6 *6, and your IPv4 rules us-
ing accept/reject *4. If you want to _replace_ the default exit policy,
end your exit policy with either a reject *:* or an accept *:*. Other-
wise, you're _augmenting_ (prepending to) the default exit policy.

If you want to use a reduced exit policy rather than the default exit
policy, set "ReducedExitPolicy 1". If you want to replace the default
exit policy with your custom exit policy, end your exit policy with ei-
ther a reject : or an accept :. Otherwise, you're augmenting (prepend-
ing to) the default or reduced exit policy.

The default exit policy is:

reject *:25
reject *:119
reject *:135-139
reject *:445
reject *:563
reject *:1214
reject *:4661-4666
reject *:6346-6429
reject *:6699
reject *:6881-6999
accept *:*

Since the default exit policy uses accept/reject *, it applies to both
IPv4 and IPv6 addresses.

ExitPolicyRejectLocalInterfaces 0|1
Reject all IPv4 and IPv6 addresses that the relay knows about, at the
beginning of your exit policy. This includes any OutboundBindAddress,
the bind addresses of any port options, such as ControlPort or DNSPort,
and any public IPv4 and IPv6 addresses on any interface on the relay.
(If IPv6Exit is not set, all IPv6 addresses will be rejected anyway.)
See above entry on ExitPolicy. This option is off by default, because
it lists all public relay IP addresses in the ExitPolicy, even those
relay operators might prefer not to disclose. (Default: 0)

ExitPolicyRejectPrivate 0|1
Reject all private (local) networks, along with the relay's advertised
public IPv4 and IPv6 addresses, at the beginning of your exit policy.
See above entry on ExitPolicy. (Default: 1)

ExitRelay 0|1|auto
Tells Tor whether to run as an exit relay. If Tor is running as a
non-bridge server, and ExitRelay is set to 1, then Tor allows traffic
to exit according to the ExitPolicy option, the ReducedExitPolicy op-
tion, or the default ExitPolicy (if no other exit policy option is
specified).

If ExitRelay is set to 0, no traffic is allowed to exit, and the Exit-
Policy, ReducedExitPolicy, and IPv6Exit options are ignored.

If ExitRelay is set to "auto", then Tor checks the ExitPolicy, Re-
ducedExitPolicy, and IPv6Exit options. If at least one of these options
is set, Tor behaves as if ExitRelay were set to 1. If none of these
exit policy options are set, Tor behaves as if ExitRelay were set to 0.
(Default: auto)

ReevaluateExitPolicy 0|1
If set, reevaluate the exit policy on existing connections when reload-
ing configuration.

When the exit policy of an exit node change while reloading configura-
tion, connections made prior to this change could violate the new pol-
icy. By setting this to 1, Tor will check if such connections exist,
and mark them for termination. (Default: 0)

ExtendAllowPrivateAddresses 0|1
When this option is enabled, Tor will connect to relays on localhost,
RFC1918 addresses, and so on. In particular, Tor will make direct OR
connections, and Tor routers allow EXTEND requests, to these private
addresses. (Tor will always allow connections to bridges, proxies, and
pluggable transports configured on private addresses.) Enabling this
option can create security issues; you should probably leave it off.
(Default: 0)

GeoIPFile filename
A filename containing IPv4 GeoIP data, for use with by-country statis-
tics.

GeoIPv6File filename
A filename containing IPv6 GeoIP data, for use with by-country statis-
tics.

HeartbeatPeriod N minutes|hours|days|weeks
Log a heartbeat message every HeartbeatPeriod seconds. This is a log
level notice message, designed to let you know your Tor server is still
alive and doing useful things. Settings this to 0 will disable the
heartbeat. Otherwise, it must be at least 30 minutes. (Default: 6
hours)

IPv6Exit 0|1
If set, and we are an exit node, allow clients to use us for IPv6 traf-
fic. When this option is set and ExitRelay is auto, we act as if Ex-
itRelay is 1. (Default: 0)

KeyDirectory DIR
Store secret keys in DIR. Can not be changed while tor is running. (De-
fault: the "keys" subdirectory of DataDirectory.)

KeyDirectoryGroupReadable 0|1|auto
If this option is set to 0, don't allow the filesystem group to read
the KeyDirectory. If the option is set to 1, make the KeyDirectory
readable by the default GID. If the option is "auto", then we use the
setting for DataDirectoryGroupReadable when the KeyDirectory is the
same as the DataDirectory, and 0 otherwise. (Default: auto)

MainloopStats 0|1
Log main loop statistics every HeartbeatPeriod seconds. This is a log
level notice message designed to help developers instrumenting Tor's
main event loop. (Default: 0)

MaxHSDirCacheBytes N bytes|KBytes|MBytes|GBytes
This option configures a threshold of Hidden Service Directory memory
consumption above which your Tor relay will begin to prune the
least-frequently accessed hidden service descriptors from the relay's
HSDir cache. If set to 0, this will default to 20% of MaxMemInQueues.
(Default: 0)

This pruning used to be done as part of MaxMemInQueues, but it has been
decoupled to allow more fine-grained control of descriptor cache size
under DDoS conditions.

MaxMemInQueues N bytes|KBytes|MBytes|GBytes
This option configures a threshold above which Tor will assume that it
needs to stop queueing or buffering data because it's about to run out
of memory. If it hits this threshold, it will begin killing circuits
until it has recovered at least 10% of this memory. Do not set this op-
tion too low, or your relay may be unreliable under load. This option
only affects some queues, so the actual process size will be larger
than this. If this option is set to 0, Tor will try to pick a reason-
able default based on your system's physical memory. (Default: 0)

MaxOnionQueueDelay NUM [msec|second]
If we have more onionskins queued for processing than we can process in
this amount of time, reject new ones. (Default: 1750 msec)

MyFamily fingerprint,fingerprint,...
Declare that this Tor relay is controlled or administered by a group or
organization identical or similar to that of the other relays, defined
by their (possibly $-prefixed) identity fingerprints. This option can
be repeated many times, for convenience in defining large families: all
fingerprints in all MyFamily lines are merged into one list. When two
relays both declare that they are in the same 'family', Tor clients
will not use them in the same circuit. (Each relay only needs to list
the other servers in its family; it doesn't need to list itself, but it
won't hurt if it does.) Do not list any bridge relay as it would com-
promise its concealment.

If you run more than one relay, the MyFamily option on each relay must
list all other relays, as described above.

Note: do not use MyFamily when configuring your Tor instance as a
bridge.

FamilyId ident
Configure this relay to be part of a family identified by a shared se-
cret family key with the given key identity. A corresponding family key
must be stored in the relay's key directory, with a filename ending
with ".secret_family_key". This option can appear multiple times. Fam-
ily keys are generated with "--keygen-family"; this also generates the
value you should use in the ident field in a file ending with ".pub-
lic_family_id". For information on generating and installing a family
key, see https://community.torproject.org/relay/setup/post-install/fam-
ily-ids/

In the future, this will be the preferred way for relays to advertise
family membership. But for now, relay families should configure both
this option and MyFamily, so older clients will still recognize the re-
lays' family membership.

(Note that if the seccomp2 Sandbox feature is enabled, it is not possi-
ble to change the key filenames while Tor is running.)

FamilyId *
Configure this relay to be part of every family identified by any fam-
ily ID key found in the family key directory. Only filenames ending
with ".secret\_family\_key" are considered. Specifying family IDs in
this way makes it unnecessary to adjust the configuration file if the
family key is rotated, but it increases the likelihood of accidentally
using a different set of family keys than the ones you had expected.

FamilyKeyDirectory directory: Configure a directory to use, in place of the
key directory, when searching for family ID keys.

Nickname name
Set the server's nickname to 'name'. Nicknames must be between 1 and 19
characters inclusive, and must contain only the characters [a-zA-Z0-9].
If not set, Unnamed will be used. Relays can always be uniquely identi-
fied by their identity fingerprints.

NumCPUs num
How many processes to use at once for decrypting onionskins and other
parallelizable operations. If this is set to 0, Tor will try to detect
how many CPUs you have, defaulting to 1 if it can't tell. (Default: 0)

OfflineMasterKey 0|1
If non-zero, the Tor relay will never generate or load its master se-
cret key. Instead, you'll have to use "tor --keygen" to manage the per-
manent ed25519 master identity key, as well as the corresponding tempo-
rary signing keys and certificates. (Default: 0)

ORPort [address:]PORT|auto [flags]
Advertise this port to listen for connections from Tor clients and
servers. This option is required to be a Tor server. Set it to "auto"
to have Tor pick a port for you. Set it to 0 to not run an ORPort at
all. This option can occur more than once. (Default: 0)

Tor recognizes these flags on each ORPort:

NoAdvertise
By default, we bind to a port and tell our users about it. If NoAd-
vertise is specified, we don't advertise, but listen anyway. This
can be useful if the port everybody will be connecting to (for ex-
ample, one that's opened on our firewall) is somewhere else.

NoListen
By default, we bind to a port and tell our users about it. If No-
Listen is specified, we don't bind, but advertise anyway. This can
be useful if something else (for example, a firewall's port for-
warding configuration) is causing connections to reach us.

IPv4Only
If the address is absent, or resolves to both an IPv4 and an IPv6
address, only listen to the IPv4 address.

IPv6Only
If the address is absent, or resolves to both an IPv4 and an IPv6
address, only listen to the IPv6 address.

For obvious reasons, NoAdvertise and NoListen are mutually exclusive,
and IPv4Only and IPv6Only are mutually exclusive.

PublishServerDescriptor 0|1|v3|bridge,...
This option specifies which descriptors Tor will publish when acting as
a relay. You can choose multiple arguments, separated by commas.

If this option is set to 0, Tor will not publish its descriptors to any
directories. (This is useful if you're testing out your server, or if
you're using a Tor controller that handles directory publishing for
you.) Otherwise, Tor will publish its descriptors of all type(s) speci-
fied. The default is "1", which means "if running as a relay or bridge,
publish descriptors to the appropriate authorities". Other possibili-
ties are "v3", meaning "publish as if you're a relay", and "bridge",
meaning "publish as if you're a bridge".

ReducedExitPolicy 0|1
If set, use a reduced exit policy rather than the default one.

The reduced exit policy is an alternative to the default exit policy.
It allows as many Internet services as possible while still blocking
the majority of TCP ports. Currently, the policy allows approximately
65 ports. This reduces the odds that your node will be used for
peer-to-peer applications.

The reduced exit policy is:

accept *:20-21
accept *:22
accept *:23
accept *:43
accept *:53
accept *:79
accept *:80-81
accept *:88
accept *:110
accept *:143
accept *:194
accept *:220
accept *:389
accept *:443
accept *:464
accept *:465
accept *:531
accept *:543-544
accept *:554
accept *:563
accept *:587
accept *:636
accept *:706
accept *:749
accept *:873
accept *:902-904
accept *:981
accept *:989-990
accept *:991
accept *:992
accept *:993
accept *:994
accept *:995
accept *:1194
accept *:1220
accept *:1293
accept *:1500
accept *:1533
accept *:1677
accept *:1723
accept *:1755
accept *:1863
accept *:2082
accept *:2083
accept *:2086-2087
accept *:2095-2096
accept *:2102-2104
accept *:3128
accept *:3389
accept *:3690
accept *:4321
accept *:4643
accept *:5050
accept *:5190
accept *:5222-5223
accept *:5228
accept *:5900
accept *:6660-6669
accept *:6679
accept *:6697
accept *:8000
accept *:8008
accept *:8074
accept *:8080
accept *:8082
accept *:8087-8088
accept *:8232-8233
accept *:8332-8333
accept *:8443
accept *:8888
accept *:9418
accept *:9999
accept *:10000
accept *:11371
accept *:19294
accept *:19638
accept *:50002
accept *:64738
reject *:*

(Default: 0)

RefuseUnknownExits 0|1|auto
Prevent nodes that don't appear in the consensus from exiting using
this relay. If the option is 1, we always block exit attempts from such
nodes; if it's 0, we never do, and if the option is "auto", then we do
whatever the authorities suggest in the consensus (and block if the
consensus is quiet on the issue). (Default: auto)

ServerDNSAllowBrokenConfig 0|1
If this option is false, Tor exits immediately if there are problems
parsing the system DNS configuration or connecting to nameservers. Oth-
erwise, Tor continues to periodically retry the system nameservers un-
til it eventually succeeds. (Default: 1)

ServerDNSAllowNonRFC953Hostnames 0|1
When this option is disabled, Tor does not try to resolve hostnames
containing illegal characters (like @ and :) rather than sending them
to an exit node to be resolved. This helps trap accidental attempts to
resolve URLs and so on. This option only affects name lookups that your
server does on behalf of clients. (Default: 0)

ServerDNSDetectHijacking 0|1
When this option is set to 1, we will test periodically to determine
whether our local nameservers have been configured to hijack failing
DNS requests (usually to an advertising site). If they are, we will at-
tempt to correct this. This option only affects name lookups that your
server does on behalf of clients. (Default: 1)

ServerDNSRandomizeCase 0|1
When this option is set, Tor sets the case of each character randomly
in outgoing DNS requests, and makes sure that the case matches in DNS
replies. This so-called "0x20 hack" helps resist some types of DNS poi-
soning attack. For more information, see "Increased DNS Forgery Resis-
tance through 0x20-Bit Encoding". This option only affects name lookups
that your server does on behalf of clients. (Default: 1)

ServerDNSResolvConfFile filename
Overrides the default DNS configuration with the configuration in file-
name. The file format is the same as the standard Unix "resolv.conf"
file (7). This option, like all other ServerDNS options, only affects
name lookups that your server does on behalf of clients. (Defaults to
use the system DNS configuration or a localhost DNS service in case no
nameservers are found in a given configuration.)

ServerDNSSearchDomains 0|1
If set to 1, then we will search for addresses in the local search do-
main. For example, if this system is configured to believe it is in
"example.com", and a client tries to connect to "www", the client will
be connected to "www.example.com". This option only affects name
lookups that your server does on behalf of clients. (Default: 0)

ServerDNSTestAddresses hostname,hostname,...
When we're detecting DNS hijacking, make sure that these valid ad-
dresses aren't getting redirected. If they are, then our DNS is com-
pletely useless, and we'll reset our exit policy to "reject *:*". This
option only affects name lookups that your server does on behalf of
clients. (Default: "www.google.com, www.mit.edu, www.yahoo.com,
www.slashdot.org")

ServerTransportListenAddr transport IP:PORT
When this option is set, Tor will suggest IP:PORT as the listening ad-
dress of any pluggable transport proxy that tries to launch transport.
(IPv4 addresses should written as-is; IPv6 addresses should be wrapped
in square brackets.) (Default: none)

ServerTransportOptions transport k=v k=v ...
When this option is set, Tor will pass the k=v parameters to any plug-
gable transport proxy that tries to launch transport.

(Example: ServerTransportOptions obfs45 shared-secret=bridgepasswd
cache=/var/db/tor/cache) (Default: none)

ServerTransportPlugin transport exec path-to-binary [options]
The Tor relay launches the pluggable transport proxy in path-to-binary
using options as its command-line options, and expects to receive prox-
ied client traffic from it. (Default: none)

ShutdownWaitLength NUM
When we get a SIGINT and we're a server, we begin shutting down: we
close listeners and start refusing new circuits. After NUM seconds, we
exit. If we get a second SIGINT, we exit immediately. (Default: 30 sec-
onds)

SigningKeyLifetime N days|weeks|months
For how long should each Ed25519 signing key be valid? Tor uses a per-
manent master identity key that can be kept offline, and periodically
generates new "signing" keys that it uses online. This option config-
ures their lifetime. (Default: 30 days)

SSLKeyLifetime N minutes|hours|days|weeks
When creating a link certificate for our outermost SSL handshake, set
its lifetime to this amount of time. If set to 0, Tor will choose some
reasonable random defaults. (Default: 0)

STATISTICS OPTIONS
Relays publish most statistics in a document called the extra-info docu-
ment. The following options affect the different types of statistics that
Tor relays collect and publish:

BridgeRecordUsageByCountry 0|1
When this option is enabled and BridgeRelay is also enabled, and we
have GeoIP data, Tor keeps a per-country count of how many client ad-
dresses have contacted it so that it can help the bridge authority
guess which countries have blocked access to it. If ExtraInfoStatistics
is enabled, it will be published as part of the extra-info document.
(Default: 1)

CellStatistics 0|1
Relays only. When this option is enabled, Tor collects statistics about
cell processing (i.e. mean time a cell is spending in a queue, mean
number of cells in a queue and mean number of processed cells per cir-
cuit) and writes them into disk every 24 hours. Onion router operators
may use the statistics for performance monitoring. If ExtraInfoStatis-
tics is enabled, it will published as part of the extra-info document.
(Default: 0)

ConnDirectionStatistics 0|1
Relays only. When this option is enabled, Tor writes statistics on the
amounts of traffic it passes between itself and other relays to disk
every 24 hours. Enables relay operators to monitor how much their relay
is being used as middle node in the circuit. If ExtraInfoStatistics is
enabled, it will be published as part of the extra-info document. (De-
fault: 0)

DirReqStatistics 0|1
Relays and bridges only. When this option is enabled, a Tor directory
writes statistics on the number and response time of network status re-
quests to disk every 24 hours. Enables relay and bridge operators to
monitor how much their server is being used by clients to learn about
Tor network. If ExtraInfoStatistics is enabled, it will published as
part of the extra-info document. (Default: 1)

EntryStatistics 0|1
Relays only. When this option is enabled, Tor writes statistics on the
number of directly connecting clients to disk every 24 hours. Enables
relay operators to monitor how much inbound traffic that originates
from Tor clients passes through their server to go further down the Tor
network. If ExtraInfoStatistics is enabled, it will be published as
part of the extra-info document. (Default: 0)

ExitPortStatistics 0|1
Exit relays only. When this option is enabled, Tor writes statistics on
the number of relayed bytes and opened stream per exit port to disk
every 24 hours. Enables exit relay operators to measure and monitor
amounts of traffic that leaves Tor network through their exit node. If
ExtraInfoStatistics is enabled, it will be published as part of the ex-
tra-info document. (Default: 0)

ExtraInfoStatistics 0|1
When this option is enabled, Tor includes previously gathered statis-
tics in its extra-info documents that it uploads to the directory au-
thorities. Disabling this option also removes bandwidth usage statis-
tics, and GeoIPFile and GeoIPv6File hashes from the extra-info file.
Bridge ServerTransportPlugin lines are always included in the ex-
tra-info file, because they are required by BridgeDB. (Default: 1)

HiddenServiceStatistics 0|1
Relays and bridges only. When this option is enabled, a Tor relay
writes obfuscated statistics on its role as hidden-service directory,
introduction point, or rendezvous point to disk every 24 hours. If Ex-
traInfoStatistics is enabled, it will be published as part of the ex-
tra-info document. (Default: 1)

OverloadStatistics 0|1*
Relays and bridges only. When this option is enabled, a Tor relay will
write an overload general line in the server descriptor if the relay is
considered overloaded. (Default: 1)

A relay is considered overloaded if at least one of these conditions is
met:

* A certain ratio of ntor onionskins are dropped.

* The OOM was invoked.

* TCP Port exhaustion.

+
If ExtraInfoStatistics is enabled, it can also put two more specific
overload lines in the extra-info document if at least one of these
conditions is met:
- Connection rate limits have been reached (read and write side).
- File descriptors are exhausted.

PaddingStatistics 0|1
Relays and bridges only. When this option is enabled, Tor collects sta-
tistics for padding cells sent and received by this relay, in addition
to total cell counts. These statistics are rounded, and omitted if
traffic is low. This information is important for load balancing deci-
sions related to padding. If ExtraInfoStatistics is enabled, it will be
published as a part of the extra-info document. (Default: 1)

DIRECTORY SERVER OPTIONS
The following options are useful only for directory servers. (Relays with
enough bandwidth automatically become directory servers; see DirCache for
details.)

DirCache 0|1
When this option is set, Tor caches all current directory documents ex-
cept extra info documents, and accepts client requests for them. If
DownloadExtraInfo is set, cached extra info documents are also cached.
Setting DirPort is not required for DirCache, because clients connect
via the ORPort by default. Setting either DirPort or BridgeRelay and
setting DirCache to 0 is not supported. (Default: 1)

DirPolicy policy,policy,...
Set an entrance policy for this server, to limit who can connect to the
directory ports. The policies have the same form as exit policies
above, except that port specifiers are ignored. Any address not matched
by some entry in the policy is accepted.

DirPort [address:]PORT|auto [flags]
If this option is nonzero, advertise the directory service on this
port. Set it to "auto" to have Tor pick a port for you. This option can
occur more than once, but only one advertised DirPort is supported: all
but one DirPort must have the NoAdvertise flag set. (Default: 0)

The same flags are supported here as are supported by ORPort. This port
can only be IPv4.

As of Tor 0.4.6.1-alpha, non-authoritative relays (see AuthoritativeDi-
rectory) will not publish the DirPort but will still listen on it.
Clients don't use the DirPorts on relays, so it is safe for you to re-
move the DirPort from your torrc configuration.

DirPortFrontPage FILENAME
When this option is set, it takes an HTML file and publishes it as "/"
on the DirPort. Now relay operators can provide a disclaimer without
needing to set up a separate webserver. There's a sample disclaimer in
contrib/operator-tools/tor-exit-notice.html.

MaxConsensusAgeForDiffs N minutes|hours|days|weeks
When this option is nonzero, Tor caches will not try to generate con-
sensus diffs for any consensus older than this amount of time. If this
option is set to zero, Tor will pick a reasonable default from the cur-
rent networkstatus document. You should not set this option unless your
cache is severely low on disk space or CPU. If you need to set it,
keeping it above 3 or 4 hours will help clients much more than setting
it to zero. (Default: 0)

DENIAL OF SERVICE MITIGATION OPTIONS
Tor has a series of built-in denial of service mitigation options that can
be individually enabled/disabled and fine-tuned, but by default Tor direc-
tory authorities will define reasonable values for the network and no ex-
plicit configuration is required to make use of these protections.

The following is a series of configuration options for relays and then op-
tions for onion services and how they work.

The mitigations take place at relays, and are as follows:

1. If a single client address makes too many concurrent connections (this
is configurable via DoSConnectionMaxConcurrentCount), hang up on fur-
ther connections.

2. If a single client IP address (v4 or v6) makes circuits too quickly
(default values are more than 3 per second, with an allowed burst of
90, see DoSCircuitCreationRate and DoSCircuitCreationBurst) while also
having too many connections open (default is 3, see DoSCircuitCreation-
MinConnections), tor will refuse any new circuit (CREATE cells) for the
next while (random value between 1 and 2 hours).

3. If a client asks to establish a rendezvous point to you directly (ex:
Tor2Web client), ignore the request.

These defenses can be manually controlled by torrc options, but relays will
also take guidance from consensus parameters using these same names, so
there's no need to configure anything manually. In doubt, do not change
those values.

The values set by the consensus, if any, can be found here: https://consen-
sus-health.torproject.org/#consensusparams

If any of the DoS mitigations are enabled, a heartbeat message will appear
in your log at NOTICE level which looks like:

DoS mitigation since startup: 429042 circuits rejected, 17 marked addresses.
2238 connections closed. 8052 single hop clients refused.

The following options are useful only for a public relay. They control the
Denial of Service mitigation subsystem described above.

DoSCircuitCreationEnabled 0|1|auto
Enable circuit creation DoS mitigation. If set to 1 (enabled), tor will
cache client IPs along with statistics in order to detect circuit DoS
attacks. If an address is positively identified, tor will activate de-
fenses against the address. See DoSCircuitCreationDefenseType option
for more details. This is a client to relay detection only. "auto"
means use the consensus parameter. If not defined in the consensus, the
value is 0. (Default: auto)

DoSCircuitCreationBurst NUM
The allowed circuit creation burst per client IP address. If the cir-
cuit rate and the burst are reached, a client is marked as executing a
circuit creation DoS. "0" means use the consensus parameter. If not de-
fined in the consensus, the value is 90. (Default: 0)

DoSCircuitCreationDefenseTimePeriod N seconds|minutes|hours
The base time period in seconds that the DoS defense is activated for.
The actual value is selected randomly for each activation from N+1 to
3/2 * N. "0" means use the consensus parameter. If not defined in the
consensus, the value is 3600 seconds (1 hour). (Default: 0)

DoSCircuitCreationDefenseType NUM
This is the type of defense applied to a detected client address. The
possible values are:

1: No defense.

2: Refuse circuit creation for the DoSCircuitCreationDefenseTimePeriod
period of time.

"0" means use the consensus parameter. If not defined in the consensus,
the value is 2. (Default: 0)

DoSCircuitCreationMinConnections NUM
Minimum threshold of concurrent connections before a client address can
be flagged as executing a circuit creation DoS. In other words, once a
client address reaches the circuit rate and has a minimum of NUM con-
current connections, a detection is positive. "0" means use the consen-
sus parameter. If not defined in the consensus, the value is 3. (De-
fault: 0)

DoSCircuitCreationRate NUM
The allowed circuit creation rate per second applied per client IP ad-
dress. If this option is 0, it obeys a consensus parameter. If not de-
fined in the consensus, the value is 3. (Default: 0)

DoSConnectionEnabled 0|1|auto
Enable the connection DoS mitigation. If set to 1 (enabled), for client
address only, this allows tor to mitigate against large number of con-
current connections made by a single IP address. "auto" means use the
consensus parameter. If not defined in the consensus, the value is 0.
(Default: auto)

DoSConnectionDefenseType NUM
This is the type of defense applied to a detected client address for
the connection mitigation. The possible values are:

1: No defense.

2: Immediately close new connections.

"0" means use the consensus parameter. If not defined in the consensus,
the value is 2. (Default: 0)

DoSConnectionMaxConcurrentCount NUM
The maximum threshold of concurrent connection from a client IP ad-
dress. Above this limit, a defense selected by DoSConnectionDefenseType
is applied. "0" means use the consensus parameter. If not defined in
the consensus, the value is 100. (Default: 0)

DoSConnectionConnectRate NUM
The allowed rate of client connection from a single address per second.
Coupled with the burst (see below), if the limit is reached, the ad-
dress is marked and a defense is applied (DoSConnectionDefenseType) for
a period of time defined by DoSConnectionConnectDefenseTimePeriod. If
not defined or set to 0, it is controlled by a consensus parameter.
(Default: 0)

DoSConnectionConnectBurst NUM
The allowed burst of client connection from a single address per sec-
ond. See the DoSConnectionConnectRate for more details on this detec-
tion. If not defined or set to 0, it is controlled by a consensus para-
meter. (Default: 0)

DoSConnectionConnectDefenseTimePeriod N seconds|minutes|hours
The base time period in seconds that the client connection defense is
activated for. The actual value is selected randomly for each activa-
tion from N+1 to 3/2 * N. If not defined or set to 0, it is controlled
by a consensus parameter. (Default: 24 hours)

DoSRefuseSingleHopClientRendezvous 0|1|auto
Refuse establishment of rendezvous points for single hop clients. In
other words, if a client directly connects to the relay and sends an
ESTABLISH_RENDEZVOUS cell, it is silently dropped. "auto" means use the
consensus parameter. If not defined in the consensus, the value is 0.
(Default: auto)

The following options are useful only for a exit relay.

DoSStreamCreationEnabled 0|1|auto
Enable the stream DoS mitigation. If set to 1 (enabled), tor will apply
rate limit on the creation of new streams and dns requests per circuit.
"auto" means use the consensus parameter. If not defined in the consen-
sus, the value is 0. (Default: auto)

DoSStreamCreationDefenseType NUM
This is the type of defense applied to a detected circuit or stream for
the stream mitigation. The possible values are:

1: No defense.

2: Reject the stream or resolve request.

3: Close the circuit creating too many streams.

"0" means use the consensus parameter. If not defined in the consensus,
the value is 2. (Default: 0)

DoSStreamCreationRate NUM
The allowed rate of stream creation from a single circuit per second.
Coupled with the burst (see below), if the limit is reached, actions
can be taken against the stream or circuit (DoSStreamCreationDefense-
Type). If not defined or set to 0, it is controlled by a consensus pa-
rameter. If not defined in the consensus, the value is 100. (Default:
0)

DoSStreamCreationBurst NUM
The allowed burst of stream creation from a circuit per second. See the
DoSStreamCreationRate for more details on this detection. If not de-
fined or set to 0, it is controlled by a consensus parameter. If not
defined in the consensus, the value is 300. (Default: 0)

For onion services, mitigations are a work in progress and multiple options
are currently available.

The introduction point defense is a rate limit on the number of introduc-
tion requests that will be forwarded to a service by each of its honest in-
troduction point routers. This can prevent some types of overwhelming
floods from reaching the service, but it will also prevent legitimate
clients from establishing new connections.

The following options are per onion service:

HiddenServiceEnableIntroDoSDefense 0|1
Enable DoS defense at the intropoint level. When this is enabled, the
rate and burst parameter (see below) will be sent to the intro point
which will then use them to apply rate limiting for introduction re-
quest to this service.

The introduction point honors the consensus parameters except if this
is specifically set by the service operator using this option. The ser-
vice never looks at the consensus parameters in order to enable or dis-
able this defense. (Default: 0)

HiddenServiceEnableIntroDoSBurstPerSec NUM
The allowed client introduction burst per second at the introduction
point. If this option is 0, it is considered infinite and thus if Hid-
denServiceEnableIntroDoSDefense is set, it then effectively disables
the defenses. (Default: 200)

HiddenServiceEnableIntroDoSRatePerSec NUM
The allowed client introduction rate per second at the introduction
point. If this option is 0, it is considered infinite and thus if Hid-
denServiceEnableIntroDoSDefense is set, it then effectively disables
the defenses. (Default: 25)

The rate is the maximum number of clients a service will ask its introduc-
tion points to allow every seconds. And the burst is a parameter that al-
lows that many within one second.

For example, the default values of 25 and 200 respectively means that for
every introduction points a service has (default 3 but can be configured
with HiddenServiceNumIntroductionPoints), 25 clients per seconds will be
allowed to reach the service and 200 at most within 1 second as a burst.
This means that if 200 clients are seen within 1 second, it will take 8
seconds (200/25) for another client to be able to be allowed to introduce
due to the rate of 25 per second.

This might be too much for your use case or not, fine tuning these values
is hard and are likely different for each service operator.

Why is this not helping reachability of the service? Because the defenses
are at the introduction point, an attacker can easily flood all introduc-
tion point rendering the service unavailable due to no client being able to
pass through. But, the service itself is not overwhelmed with connections
allowing it to function properly for the few clients that were able to go
through or other any services running on the same tor instance.

The bottom line is that this protects the network by preventing an onion
service to flood the network with new rendezvous circuits that is reducing
load on the network.

A secondary mitigation is available, based on prioritized dispatch of ren-
dezvous circuits for new connections. The queue is ordered based on effort
a client chooses to spend at computing a proof-of-work function.

The following options are per onion service:

HiddenServicePoWDefensesEnabled 0|1
Enable proof-of-work based service DoS mitigation. If set to 1 (en-
abled), tor will include parameters for an optional client puzzle in
the encrypted portion of this hidden service's descriptor. Incoming
rendezvous requests will be prioritized based on the amount of effort a
client chooses to make when computing a solution to the puzzle. The
service will periodically update a suggested amount of effort, based on
attack load, and disable the puzzle entirely when the service is not
overloaded. (Default: 0)

HiddenServicePoWQueueRate NUM
The sustained rate of rendezvous requests to dispatch per second from
the priority queue. Has no effect when proof-of-work is disabled. If
this is set to 0 there's no explicit limit and we will process requests
as quickly as possible. (Default: 250)

HiddenServicePoWQueueBurst NUM
The maximum burst size for rendezvous requests handled from the prior-
ity queue at once. (Default: 2500)

These options are applicable to both onion services and their clients:

CompiledProofOfWorkHash 0|1|auto
When proof-of-work DoS mitigation is active, both the services them-
selves and the clients which connect will use a dynamically generated
hash function as part of the puzzle computation.

If this option is set to 1, puzzles will only be solved and verified
using the compiled implementation (about 20x faster) and we choose to
fail rather than using a slower fallback. If it's 0, the compiler will
never be used. By default, the compiler is always tried if possible but
the interpreter is available as a fallback. (Default: auto)

See also --list-modules, these proof of work options have no effect unless
the "pow" module is enabled at compile time.

DIRECTORY AUTHORITY SERVER OPTIONS
The following options enable operation as a directory authority, and con-
trol how Tor behaves as a directory authority. You should not need to ad-
just any of them if you're running a regular relay or exit server on the
public Tor network.

AuthoritativeDirectory 0|1
When this option is set to 1, Tor operates as an authoritative direc-
tory server. Instead of caching the directory, it generates its own
list of good servers, signs it, and sends that to the clients. Unless
the clients already have you listed as a trusted directory, you proba-
bly do not want to set this option.

BridgeAuthoritativeDir 0|1
When this option is set in addition to AuthoritativeDirectory, Tor ac-
cepts and serves server descriptors, but it caches and serves the main
networkstatus documents rather than generating its own. (Default: 0)

V3AuthoritativeDirectory 0|1
When this option is set in addition to AuthoritativeDirectory, Tor gen-
erates version 3 network statuses and serves descriptors, etc as de-
scribed in dir-spec.txt file of torspec (for Tor clients and servers
running at least 0.2.0.x).

AuthDirBadExit AddressPattern...
Authoritative directories only. A set of address patterns for servers
that will be listed as bad exits in any network status document this
authority publishes, if AuthDirListBadExits is set.

(The address pattern syntax here and in the options below is the same
as for exit policies, except that you don't need to say "accept" or
"reject", and ports are not needed.)

AuthDirMiddleOnly AddressPattern...
Authoritative directories only. A set of address patterns for servers
that will be listed as middle-only in any network status document this
authority publishes, if AuthDirListMiddleOnly is set.

AuthDirHasIPv6Connectivity 0|1
Authoritative directories only. When set to 0, OR ports with an IPv6
address are not included in the authority's votes. When set to 1, IPv6
OR ports are tested for reachability like IPv4 OR ports. If the reacha-
bility test succeeds, the authority votes for the IPv6 ORPort, and
votes Running for the relay. If the reachability test fails, the au-
thority does not vote for the IPv6 ORPort, and does not vote Running
(Default: 0)

The content of the consensus depends on the number of voting authorities
that set AuthDirHasIPv6Connectivity:

If no authorities set AuthDirHasIPv6Connectivity 1, there will be no
IPv6 ORPorts in the consensus.

If a minority of authorities set AuthDirHasIPv6Connectivity 1,
unreachable IPv6 ORPorts will be removed from the consensus. But the
majority of IPv4-only authorities will still vote the relay as Running.
Reachable IPv6 ORPort lines will be included in the consensus

If a majority of voting authorities set AuthDirHasIPv6Connectivity 1,
relays with unreachable IPv6 ORPorts will not be listed as Running.
Reachable IPv6 ORPort lines will be included in the consensus
(To ensure that any valid majority will vote relays with unreachable
IPv6 ORPorts not Running, 75% of authorities must set
AuthDirHasIPv6Connectivity 1.)

AuthDirInvalid AddressPattern...
Authoritative directories only. A set of address patterns for servers
that will never be listed as "valid" in any network status document
that this authority publishes.

AuthDirListBadExits 0|1
Authoritative directories only. If set to 1, this directory has some
opinion about which nodes are unsuitable as exit nodes. (Do not set
this to 1 unless you plan to list non-functioning exits as bad; other-
wise, you are effectively voting in favor of every declared exit as an
exit.)

AuthDirListMiddleOnly 0|1
Authoritative directories only. If set to 1, this directory has some
opinion about which nodes should only be used in the middle position.
(Do not set this to 1 unless you plan to list questionable relays as
"middle only"; otherwise, you are effectively voting against mid-
dle-only status for every relay.)

AuthDirMaxServersPerAddr NUM
Authoritative directories only. The maximum number of servers that we
will list as acceptable on a single IP address. Set this to "0" for "no
limit". (Default: 2)

AuthDirPinKeys 0|1
Authoritative directories only. If non-zero, do not allow any relay to
publish a descriptor if any other relay has reserved its <Ed25519,RSA>
identity keypair. In all cases, Tor records every keypair it accepts in
a journal if it is new, or if it differs from the most recently ac-
cepted pinning for one of the keys it contains. (Default: 1)

AuthDirReject AddressPattern...
Authoritative directories only. A set of address patterns for servers
that will never be listed at all in any network status document that
this authority publishes, or accepted as an OR address in any descrip-
tor submitted for publication by this authority.

AuthDirRejectRequestsUnderLoad 0|1
If set, the directory authority will start rejecting directory requests
from non relay connections by sending a 503 error code if it is under
bandwidth pressure (reaching the configured limit if any). Relays will
always be answered even if this is on. (Default: 1)

AuthDirBadExitCCs CC,...

AuthDirInvalidCCs CC,...

AuthDirMiddleOnlyCCs CC,...

AuthDirRejectCCs CC,...
Authoritative directories only. These options contain a comma-separated
list of country codes such that any server in one of those country
codes will be marked as a bad exit/invalid for use, or rejected en-
tirely.

AuthDirSharedRandomness 0|1
Authoritative directories only. Switch for the shared random protocol.
If zero, the authority won't participate in the protocol. If non-zero
(default), the flag "shared-rand-participate" is added to the authority
vote indicating participation in the protocol. (Default: 1)

AuthDirTestEd25519LinkKeys 0|1
Authoritative directories only. If this option is set to 0, then we
treat relays as "Running" if their RSA key is correct when we probe
them, regardless of their Ed25519 key. We should only ever set this op-
tion to 0 if there is some major bug in Ed25519 link authentication
that causes us to label all the relays as not Running. (Default: 1)

AuthDirTestReachability 0|1
Authoritative directories only. If set to 1, then we periodically check
every relay we know about to see whether it is running. If set to 0, we
vote Running for every relay, and don't perform these tests. (Default:
1)

AuthDirVoteGuard node,node,...
A list of identity fingerprints or country codes or address patterns of
nodes to vote Guard for regardless of their uptime and bandwidth. See
ExcludeNodes for more information on how to specify nodes.

AuthDirVoteGuardBwThresholdFraction FRACTION
The Guard flag bandwidth performance threshold fraction that is the
fraction representing who gets the Guard flag out of all measured band-
width. (Default: 0.75)

AuthDirVoteGuardGuaranteeTimeKnown N seconds|minutes|hours|days|weeks
A relay with at least this much weighted time known can be considered
familiar enough to be a guard. (Default: 8 days)

AuthDirVoteGuardGuaranteeWFU FRACTION
A level of weighted fractional uptime (WFU) is that is sufficient to be
a Guard. (Default: 0.98)

AuthDirVoteStableGuaranteeMinUptime N seconds|minutes|hours|days|weeks
If a relay's uptime is at least this value, then it is always consid-
ered stable, regardless of the rest of the network. (Default: 30 days)

AuthDirVoteStableGuaranteeMTBF N seconds|minutes|hours|days|weeks
If a relay's mean time between failures (MTBF) is least this value,
then it will always be considered stable. (Default: 5 days)

BridgePassword Password
If set, contains an HTTP authenticator that tells a bridge authority to
serve all requested bridge information. Used by the (only partially im-
plemented) "bridge community" design, where a community of bridge relay
operators all use an alternate bridge directory authority, and their
target user audience can periodically fetch the list of available com-
munity bridges to stay up-to-date. (Default: not set)

ConsensusParams STRING
STRING is a space-separated list of key=value pairs that Tor will in-
clude in the "params" line of its networkstatus vote. This directive
can be specified multiple times so you don't have to put it all on one
line.

DirAllowPrivateAddresses 0|1
If set to 1, Tor will accept server descriptors with arbitrary "Ad-
dress" elements. Otherwise, if the address is not an IP address or is a
private IP address, it will reject the server descriptor. Additionally,
Tor will allow exit policies for private networks to fulfill Exit flag
requirements. (Default: 0)

GuardfractionFile FILENAME
V3 authoritative directories only. Configures the location of the
guardfraction file which contains information about how long relays
have been guards. (Default: unset)

MinMeasuredBWsForAuthToIgnoreAdvertised N
A total value, in abstract bandwidth units, describing how much mea-
sured total bandwidth an authority should have observed on the network
before it will treat advertised bandwidths as wholly unreliable. (De-
fault: 500)

MinUptimeHidServDirectoryV2 N seconds|minutes|hours|days|weeks
Minimum uptime of a relay to be accepted as a hidden service directory
by directory authorities. (Default: 96 hours)

RecommendedClientVersions STRING
STRING is a comma-separated list of Tor versions currently believed to
be safe for clients to use. This information is included in version 2
directories. If this is not set then the value of RecommendedVersions
is used. When this is set then VersioningAuthoritativeDirectory should
be set too.

RecommendedServerVersions STRING
STRING is a comma-separated list of Tor versions currently believed to
be safe for servers to use. This information is included in version 2
directories. If this is not set then the value of RecommendedVersions
is used. When this is set then VersioningAuthoritativeDirectory should
be set too.

RecommendedVersions STRING
STRING is a comma-separated list of Tor versions currently believed to
be safe. The list is included in each directory, and nodes which pull
down the directory learn whether they need to upgrade. This option can
appear multiple times: the values from multiple lines are spliced to-
gether. When this is set then VersioningAuthoritativeDirectory should
be set too.

MinimalAcceptedServerVersion STRING
STRING is the oldest Tor version accepted by the directory authority
for relays and bridge. Any older version will be rejected. (Default:
0.4.7.0-alpha-dev)

V3AuthDistDelay N seconds|minutes|hours
V3 authoritative directories only. Configures the server's preferred
delay between publishing its consensus and signature and assuming it
has all the signatures from all the other authorities. Note that the
actual time used is not the server's preferred time, but the consensus
of all preferences. (Default: 5 minutes)

V3AuthNIntervalsValid NUM
V3 authoritative directories only. Configures the number of VotingIn-
tervals for which each consensus should be valid for. Choosing high
numbers increases network partitioning risks; choosing low numbers in-
creases directory traffic. Note that the actual number of intervals
used is not the server's preferred number, but the consensus of all
preferences. Must be at least 2. (Default: 3)

V3AuthUseLegacyKey 0|1
If set, the directory authority will sign consensuses not only with its
own signing key, but also with a "legacy" key and certificate with a
different identity. This feature is used to migrate directory authority
keys in the event of a compromise. (Default: 0)

V3AuthVoteDelay N seconds|minutes|hours
V3 authoritative directories only. Configures the server's preferred
delay between publishing its vote and assuming it has all the votes
from all the other authorities. Note that the actual time used is not
the server's preferred time, but the consensus of all preferences. (De-
fault: 5 minutes)

V3AuthVotingInterval N minutes|hours
V3 authoritative directories only. Configures the server's preferred
voting interval. Note that voting will actually happen at an interval
chosen by consensus from all the authorities' preferred intervals. This
time SHOULD divide evenly into a day. (Default: 1 hour)

V3BandwidthsFile FILENAME
V3 authoritative directories only. Configures the location of the band-
width-authority generated file storing information on relays' measured
bandwidth capacities. To avoid inconsistent reads, bandwidth data
should be written to temporary file, then renamed to the configured
filename. (Default: unset)

VersioningAuthoritativeDirectory 0|1
When this option is set to 1, Tor adds information on which versions of
Tor are still believed safe for use to the published directory. Each
version 1 authority is automatically a versioning authority; version 2
authorities provide this service optionally. See RecommendedVersions,
RecommendedClientVersions, and RecommendedServerVersions.

HIDDEN SERVICE OPTIONS
The following options are used to configure a hidden service. Some options
apply per service and some apply for the whole tor instance.

The next section describes the per service options that can only be set af-
ter the HiddenServiceDir directive

PER SERVICE OPTIONS:

HiddenServiceAllowUnknownPorts 0|1
If set to 1, then connections to unrecognized ports do not cause the
current hidden service to close rendezvous circuits. (Setting this to 0
is not an authorization mechanism; it is instead meant to be a mild in-
convenience to port-scanners.) (Default: 0)

HiddenServiceDir DIRECTORY
Store data files for a hidden service in DIRECTORY. Every hidden ser-
vice must have a separate directory. You may use this option multiple
times to specify multiple services. If DIRECTORY does not exist, Tor
will create it. Please note that you cannot add new Onion Service to
already running Tor instance if Sandbox is enabled. (Note: in current
versions of Tor, if DIRECTORY is a relative path, it will be relative
to the current working directory of Tor instance, not to its DataDirec-
tory. Do not rely on this behavior; it is not guaranteed to remain the
same in future versions.)

HiddenServiceDirGroupReadable 0|1
If this option is set to 1, allow the filesystem group to read the hid-
den service directory and hostname file. If the option is set to 0,
only owner is able to read the hidden service directory. (Default: 0)
Has no effect on Windows.

HiddenServiceExportCircuitID protocol
The onion service will use the given protocol to expose the global cir-
cuit identifier of each inbound client circuit. The only protocol sup-
ported right now 'haproxy'. This option is only for v3 services. (De-
fault: none)

The haproxy option works in the following way: when the feature is en-
abled, the Tor process will write a header line when a client is con-
necting to the onion service. The header will look like this:

"PROXY TCP6 fc00:dead:beef:4dad::ffff:ffff ::1 65535 42\r\n"

We encode the "global circuit identifier" as the last 32-bits of the
first IPv6 address. All other values in the header can safely be ig-
nored. You can compute the global circuit identifier using the follow-
ing formula given the IPv6 address "fc00:dead:beef:4dad::AABB:CCDD":

global_circuit_id = (0xAA << 24) + (0xBB << 16) + (0xCC << 8) + 0xDD;

In the case above, where the last 32-bits are 0xffffffff, the global
circuit identifier would be 4294967295. You can use this value together
with Tor's control port to terminate particular circuits using their
global circuit identifiers. For more information about this see con-
trol-spec.txt.

The HAProxy version 1 protocol is described in detail at
https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt

HiddenServiceOnionBalanceInstance 0|1
If set to 1, this onion service becomes an OnionBalance instance and
will accept client connections destined to an OnionBalance frontend. In
this case, Tor expects to find a file named "ob_config" inside the Hid-
denServiceDir directory with content:

MasterOnionAddress <frontend_onion_address>

where <frontend_onion_address> is the onion address of the OnionBalance
frontend (e.g. wrxdvcaqpuzakbfww5sxs6r2uybczwi-
jzfn2ezy2osaj7iox7kl7nhad.onion).

HiddenServiceMaxStreams N
The maximum number of simultaneous streams (connections) per rendezvous
circuit. The maximum value allowed is 65535. (Setting this to 0 will
allow an unlimited number of simultaneous streams.) (Default: 0)

HiddenServiceMaxStreamsCloseCircuit 0|1
If set to 1, then exceeding HiddenServiceMaxStreams will cause the of-
fending rendezvous circuit to be torn down, as opposed to stream cre-
ation requests that exceed the limit being silently ignored. (Default:
0)

HiddenServiceNumIntroductionPoints NUM
Number of introduction points the hidden service will have. You can't
have more than 20. (Default: 3)

HiddenServicePort VIRTPORT [TARGET]
Configure a virtual port VIRTPORT for a hidden service. You may use
this option multiple times; each time applies to the service using the
most recent HiddenServiceDir. By default, this option maps the virtual
port to the same port on 127.0.0.1 over TCP. You may override the tar-
get port, address, or both by specifying a target of addr, port,
addr:port, or unix:path. (You can specify an IPv6 target as
[addr]:port. Unix paths may be quoted, and may use standard C escapes.)
You may also have multiple lines with the same VIRTPORT: when a user
connects to that VIRTPORT, one of the TARGETs from those lines will be
chosen at random. Note that address-port pairs have to be comma-sepa-
rated.

HiddenServiceVersion 3
A list of rendezvous service descriptor versions to publish for the
hidden service. Currently, only version 3 is supported. (Default: 3)

PER INSTANCE OPTIONS:

HiddenServiceSingleHopMode 0|1
Experimental - Non Anonymous Hidden Services on a tor instance in Hid-
denServiceSingleHopMode make one-hop (direct) circuits between the
onion service server, and the introduction and rendezvous points.
(Onion service descriptors are still posted using 3-hop paths, to avoid
onion service directories blocking the service.) This option makes
every hidden service instance hosted by a tor instance a Single Onion
Service. One-hop circuits make Single Onion servers easily locatable,
but clients remain location-anonymous. However, the fact that a client
is accessing a Single Onion rather than a Hidden Service may be statis-
tically distinguishable.

WARNING: Once a hidden service directory has been used by a tor in-
stance in HiddenServiceSingleHopMode, it can NEVER be used again for a
hidden service. It is best practice to create a new hidden service di-
rectory, key, and address for each new Single Onion Service and Hidden
Service. It is not possible to run Single Onion Services and Hidden
Services from the same tor instance: they should be run on different
servers with different IP addresses.

HiddenServiceSingleHopMode requires HiddenServiceNonAnonymousMode to be
set to 1. Since a Single Onion service is non-anonymous, you can not
configure a SOCKSPort on a tor instance that is running in HiddenSer-
viceSingleHopMode. Can not be changed while tor is running. (Default:
0)

HiddenServiceNonAnonymousMode 0|1
Makes hidden services non-anonymous on this tor instance. Allows the
non-anonymous HiddenServiceSingleHopMode. Enables direct connections in
the server-side hidden service protocol. If you are using this option,
you need to disable all client-side services on your Tor instance, in-
cluding setting SOCKSPort to "0". Can not be changed while tor is run-
ning. (Default: 0)

PublishHidServDescriptors 0|1
If set to 0, Tor will run any hidden services you configure, but it
won't advertise them to the rendezvous directory. This option is only
useful if you're using a Tor controller that handles hidserv publishing
for you. (Default: 1)

CLIENT AUTHORIZATION
Service side:

To configure client authorization on the service side, the
"<HiddenServiceDir>/authorized_clients/" directory needs to exist. Each file
in that directory should be suffixed with ".auth" (i.e. "alice.auth"; the
file name is irrelevant) and its content format MUST be:

<auth-type>:<key-type>:<base32-encoded-public-key>

The supported <auth-type> are: "descriptor". The supported <key-type> are:
"x25519". The <base32-encoded-public-key> is the base32 representation of
the raw key bytes only (32 bytes for x25519).

Each file MUST contain one line only. Any malformed file will be
ignored. Client authorization will only be enabled for the service if tor
successfully loads at least one authorization file.

Note that once you've configured client authorization, anyone else with the
address won't be able to access it from this point on. If no authorization is
configured, the service will be accessible to anyone with the onion address.

Revoking a client can be done by removing their ".auth" file, however the
revocation will be in effect only after the tor process gets restarted or if
a SIGHUP takes place.

Client side:

To access a v3 onion service with client authorization as a client, make sure
you have ClientOnionAuthDir set in your torrc. Then, in the
<ClientOnionAuthDir> directory, create an .auth_private file for the onion
service corresponding to this key (i.e. 'bob_onion.auth_private'). The
contents of the <ClientOnionAuthDir>/<user>.auth_private file should look like:

<56-char-onion-addr-without-.onion-part>:descriptor:x25519:<x25519 private key in base32>

For more information, please see https://2019.www.torpro-
ject.org/docs/tor-onion-service.html.en#ClientAuthorization .

TESTING NETWORK OPTIONS
The following options are used for running a testing Tor network.

TestingTorNetwork 0|1
If set to 1, Tor adjusts default values of the configuration options
below, so that it is easier to set up a testing Tor network. May only
be set if non-default set of DirAuthorities is set. Cannot be unset
while Tor is running. (Default: 0)

DirAllowPrivateAddresses 1
EnforceDistinctSubnets 0
AuthDirMaxServersPerAddr 0
ClientBootstrapConsensusAuthorityDownloadInitialDelay 0
ClientBootstrapConsensusFallbackDownloadInitialDelay 0
ClientBootstrapConsensusAuthorityOnlyDownloadInitialDelay 0
ClientDNSRejectInternalAddresses 0
ClientRejectInternalAddresses 0
CountPrivateBandwidth 1
ExitPolicyRejectPrivate 0
ExtendAllowPrivateAddresses 1
V3AuthVotingInterval 5 minutes
V3AuthVoteDelay 20 seconds
V3AuthDistDelay 20 seconds
TestingV3AuthInitialVotingInterval 150 seconds
TestingV3AuthInitialVoteDelay 20 seconds
TestingV3AuthInitialDistDelay 20 seconds
TestingAuthDirTimeToLearnReachability 0 minutes
MinUptimeHidServDirectoryV2 0 minutes
TestingServerDownloadInitialDelay 0
TestingClientDownloadInitialDelay 0
TestingServerConsensusDownloadInitialDelay 0
TestingClientConsensusDownloadInitialDelay 0
TestingBridgeDownloadInitialDelay 10
TestingBridgeBootstrapDownloadInitialDelay 0
TestingClientMaxIntervalWithoutRequest 5 seconds
TestingDirConnectionMaxStall 30 seconds
TestingEnableConnBwEvent 1
TestingEnableCellStatsEvent 1

TestingAuthDirTimeToLearnReachability N seconds|minutes|hours
After starting as an authority, do not make claims about whether
routers are Running until this much time has passed. Changing this re-
quires that TestingTorNetwork is set. (Default: 30 minutes)

TestingAuthKeySlop N seconds|minutes|hours

TestingBridgeBootstrapDownloadInitialDelay N
Initial delay in seconds for how long clients should wait before down-
loading a bridge descriptor for a new bridge. Changing this requires
that TestingTorNetwork is set. (Default: 0)

TestingBridgeDownloadInitialDelay N
How long to wait (in seconds) once clients have successfully downloaded
a bridge descriptor, before trying another download for that same
bridge. Changing this requires that TestingTorNetwork is set. (Default:
10800)

TestingClientConsensusDownloadInitialDelay N
Initial delay in seconds for when clients should download consensuses.
Changing this requires that TestingTorNetwork is set. (Default: 0)

TestingClientDownloadInitialDelay N
Initial delay in seconds for when clients should download things in
general. Changing this requires that TestingTorNetwork is set. (De-
fault: 0)

TestingClientMaxIntervalWithoutRequest N seconds|minutes
When directory clients have only a few descriptors to request, they
batch them until they have more, or until this amount of time has
passed. Changing this requires that TestingTorNetwork is set. (Default:
10 minutes)

TestingDirAuthVoteExit node,node,...
A list of identity fingerprints, country codes, and address patterns of
nodes to vote Exit for regardless of their uptime, bandwidth, or exit
policy. See ExcludeNodes for more information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork has to
be set. See ExcludeNodes for more information on how to specify nodes.

TestingDirAuthVoteExitIsStrict 0|1
If True (1), a node will never receive the Exit flag unless it is spec-
ified in the TestingDirAuthVoteExit list, regardless of its uptime,
bandwidth, or exit policy.

In order for this option to have any effect, TestingTorNetwork has to
be set.

TestingDirAuthVoteGuard node,node,...
A list of identity fingerprints and country codes and address patterns
of nodes to vote Guard for regardless of their uptime and bandwidth.
See ExcludeNodes for more information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork has to
be set.

TestingDirAuthVoteGuardIsStrict 0|1
If True (1), a node will never receive the Guard flag unless it is
specified in the TestingDirAuthVoteGuard list, regardless of its uptime
and bandwidth.

In order for this option to have any effect, TestingTorNetwork has to
be set.

TestingDirAuthVoteHSDir node,node,...
A list of identity fingerprints and country codes and address patterns
of nodes to vote HSDir for regardless of their uptime and DirPort. See
ExcludeNodes for more information on how to specify nodes.

In order for this option to have any effect, TestingTorNetwork must be
set.

TestingDirAuthVoteHSDirIsStrict 0|1
If True (1), a node will never receive the HSDir flag unless it is
specified in the TestingDirAuthVoteHSDir list, regardless of its uptime
and DirPort.

In order for this option to have any effect, TestingTorNetwork has to
be set.

TestingDirConnectionMaxStall N seconds|minutes
Let a directory connection stall this long before expiring it. Changing
this requires that TestingTorNetwork is set. (Default: 5 minutes)

TestingEnableCellStatsEvent 0|1
If this option is set, then Tor controllers may register for CELL_STATS
events. Changing this requires that TestingTorNetwork is set. (Default:
0)

TestingEnableConnBwEvent 0|1
If this option is set, then Tor controllers may register for CONN_BW
events. Changing this requires that TestingTorNetwork is set. (Default:
0)

TestingLinkKeySlop N seconds|minutes|hours

TestingMinTimeToReportBandwidth N seconds|minutes|hours
Do not report our measurements for our maximum observed bandwidth for
any time period that has lasted for less than this amount of time. Val-
ues over 1 day have no effect. (Default: 1 day)

TestingServerConsensusDownloadInitialDelay N
Initial delay in seconds for when servers should download consensuses.
Changing this requires that TestingTorNetwork is set. (Default: 0)

TestingServerDownloadInitialDelay N
Initial delay in seconds for when servers should download things in
general. Changing this requires that TestingTorNetwork is set. (De-
fault: 0)

TestingSigningKeySlop N seconds|minutes|hours
How early before the official expiration of a an Ed25519 signing key do
we replace it and issue a new key? (Default: 3 hours for link and auth;
1 day for signing.)

TestingV3AuthInitialDistDelay N seconds|minutes|hours
Like V3AuthDistDelay, but for initial voting interval before the first
consensus has been created. Changing this requires that TestingTorNet-
work is set. (Default: 5 minutes)

TestingV3AuthInitialVoteDelay N seconds|minutes|hours
Like V3AuthVoteDelay, but for initial voting interval before the first
consensus has been created. Changing this requires that TestingTorNet-
work is set. (Default: 5 minutes)

TestingV3AuthInitialVotingInterval N seconds|minutes|hours
Like V3AuthVotingInterval, but for initial voting interval before the
first consensus has been created. Changing this requires that Testing-
TorNetwork is set. (Default: 30 minutes)

TestingV3AuthVotingStartOffset N seconds|minutes|hours
Directory authorities offset voting start time by this much. Changing
this requires that TestingTorNetwork is set. (Default: 0)

NON-PERSISTENT OPTIONS
These options are not saved to the torrc file by the "SAVECONF" controller
command. Other options of this type are documented in control-spec.txt,
section 5.4. End-users should mostly ignore them.

__ControlPort, __DirPort, __DNSPort, __ExtORPort, __NATDPort, __ORPort,
__SocksPort, __TransPort
These underscore-prefixed options are variants of the regular Port op-
tions. They behave the same, except they are not saved to the torrc
file by the controller's SAVECONF command.

SIGNALS
Tor catches the following signals:

SIGTERM
Tor will catch this, clean up and sync to disk if necessary, and exit.

SIGINT
Tor clients behave as with SIGTERM; but Tor servers will do a con-
trolled slow shutdown, closing listeners and waiting 30 seconds before
exiting. (The delay can be configured with the ShutdownWaitLength con-
fig option.)

SIGHUP
The signal instructs Tor to reload its configuration (including closing
and reopening logs), and kill and restart its helper processes if ap-
plicable.

SIGUSR1
Log statistics about current connections, past connections, and
throughput.

SIGUSR2
Switch all logs to loglevel debug. You can go back to the old loglevels
by sending a SIGHUP.

SIGCHLD
Tor receives this signal when one of its helper processes has exited,
so it can clean up.

SIGPIPE
Tor catches this signal and ignores it.

SIGXFSZ
If this signal exists on your platform, Tor catches and ignores it.

FILES
/usr/local/etc/tor/torrc
Default location of the configuration file.

$HOME/.torrc
Fallback location for torrc, if /usr/local/etc/tor/torrc is not found.

/var/db/tor/
The tor process stores keys and other data here.

CacheDirectory/cached-certs
Contains downloaded directory key certificates that are used to verify
authenticity of documents generated by the Tor directory authorities.

CacheDirectory/cached-consensus and/or cached-microdesc-consensus
The most recent consensus network status document we've downloaded.

CacheDirectory/cached-descriptors and cached-descriptors.new
These files contain the downloaded router statuses. Some routers may
appear more than once; if so, the most recently published descriptor is
used. Lines beginning with @-signs are annotations that contain more
information about a given router. The .new file is an append-only jour-
nal; when it gets too large, all entries are merged into a new
cached-descriptors file.

CacheDirectory/cached-extrainfo and cached-extrainfo.new
Similar to cached-descriptors, but holds optionally-downloaded "ex-
tra-info" documents. Relays use these documents to send inessential in-
formation about statistics, bandwidth history, and network health to
the authorities. They aren't fetched by default. See DownloadExtraInfo
for more information.

CacheDirectory/cached-microdescs and cached-microdescs.new
These files hold downloaded microdescriptors. Lines beginning with
@-signs are annotations that contain more information about a given
router. The .new file is an append-only journal; when it gets too
large, all entries are merged into a new cached-microdescs file.

DataDirectory/state
Contains a set of persistent key-value mappings. These include:

* the current entry guards and their status.

* the current bandwidth accounting values.

* when the file was last written

* what version of Tor generated the state file

* a short history of bandwidth usage, as produced in the server de-
scriptors.

DataDirectory/sr-state
Authority only. This file is used to record information about the cur-
rent status of the shared-random-value voting state.

CacheDirectory/diff-cache
Directory cache only. Holds older consensuses and diffs from oldest to
the most recent consensus of each type compressed in various ways. Each
file contains a set of key-value arguments describing its contents,
followed by a single NUL byte, followed by the main file contents.

DataDirectory/bw_accounting
This file is obsolete and the data is now stored in the state file in-
stead. Used to track bandwidth accounting values (when the current pe-
riod starts and ends; how much has been read and written so far this
period).

DataDirectory/control_auth_cookie
This file can be used only when cookie authentication is enabled. Used
for cookie authentication with the controller. Location can be overrid-
den by the CookieAuthFile configuration option. Regenerated on startup.
See control-spec.txt in torspec for details.

DataDirectory/lock
This file is used to prevent two Tor instances from using the same data
directory. If access to this file is locked, data directory is already
in use by Tor.

DataDirectory/key-pinning-journal
Used by authorities. A line-based file that records mappings between
RSA1024 and Ed25519 identity keys. Authorities enforce these mappings,
so that once a relay has picked an Ed25519 key, stealing or factoring
the RSA1024 key will no longer let an attacker impersonate the relay.

KeyDirectory/authority_identity_key
A v3 directory authority's master identity key, used to authenticate
its signing key. Tor doesn't use this while it's running. The
tor-gencert program uses this. If you're running an authority, you
should keep this key offline, and not put it in this file.

KeyDirectory/authority_certificate
Only directory authorities use this file. A v3 directory authority's
certificate which authenticates the authority's current vote- and con-
sensus-signing key using its master identity key.

KeyDirectory/authority_signing_key
Only directory authorities use this file. A v3 directory authority's
signing key that is used to sign votes and consensuses. Corresponds to
the authority_certificate cert.

KeyDirectory/legacy_certificate
As authority_certificate; used only when V3AuthUseLegacyKey is set. See
documentation for V3AuthUseLegacyKey.

KeyDirectory/legacy_signing_key
As authority_signing_key: used only when V3AuthUseLegacyKey is set. See
documentation for V3AuthUseLegacyKey.

KeyDirectory/secret_id_key
A relay's RSA1024 permanent identity key, including private and public
components. Used to sign router descriptors, and to sign other keys.

KeyDirectory/ed25519_master_id_public_key
The public part of a relay's Ed25519 permanent identity key.

KeyDirectory/ed25519_master_id_secret_key
The private part of a relay's Ed25519 permanent identity key. This key
is used to sign the medium-term ed25519 signing key. This file can be
kept offline or encrypted. If so, Tor will not be able to generate new
signing keys automatically; you'll need to use tor --keygen to do so.

KeyDirectory/ed25519_signing_secret_key
The private and public components of a relay's medium-term Ed25519
signing key. This key is authenticated by the Ed25519 master key, which
in turn authenticates other keys (and router descriptors).

KeyDirectory/ed25519_signing_cert
The certificate which authenticates "ed25519_signing_secret_key" as
having been signed by the Ed25519 master key.

KeyDirectory/secret_onion_key and secret_onion_key.old
A relay's RSA1024 short-term onion key. Used to decrypt old-style
("TAP") circuit extension requests. The .old file holds the previously
generated key, which the relay uses to handle any requests that were
made by clients that didn't have the new one.

KeyDirectory/secret_onion_key_ntor and secret_onion_key_ntor.old
A relay's Curve25519 short-term onion key. Used to handle modern
("ntor") circuit extension requests. The .old file holds the previously
generated key, which the relay uses to handle any requests that were
made by clients that didn't have the new one.

KeyDirectory/keyname.secret_family_key
A relay family's family identity key. Used to prove membership in a re-
lay family. See https://community.torproject.org/relay/setup/post-in-
stall/family-ids/ for more information.

DataDirectory/fingerprint
Only used by servers. Contains the fingerprint of the server's RSA
identity key.

DataDirectory/fingerprint-ed25519
Only used by servers. Contains the fingerprint of the server's ed25519
identity key.

DataDirectory/hashed-fingerprint
Only used by bridges. Contains the hashed fingerprint of the bridge's
identity key. (That is, the hash of the hash of the identity key.)

DataDirectory/bridgelines
Only used by bridges. Contains the bridge lines that clients can use to
connect using pluggable transports.

DataDirectory/approved-routers
Only used by authoritative directory servers. Each line lists a status
and an identity, separated by whitespace. Identities can be hex-encoded
RSA fingerprints, or base-64 encoded ed25519 public keys. See the fin-
gerprint file in a tor relay's DataDirectory for an example fingerprint
line. If the status is !reject, then descriptors from the given iden-
tity are rejected by this server. If it is !invalid then descriptors
are accepted, but marked in the vote as not valid. If it is !badexit,
then the authority will vote for it to receive a BadExit flag, indicat-
ing that it shouldn't be used for traffic leaving the Tor network. If
it is !middleonly, then the authority will vote for it to only be used
in the middle of circuits. (Neither rejected nor invalid relays are in-
cluded in the consensus.)

DataDirectory/v3-status-votes
Only for v3 authoritative directory servers. This file contains status
votes from all the authoritative directory servers.

CacheDirectory/unverified-consensus
Contains a network consensus document that has been downloaded, but
which we didn't have the right certificates to check yet.

CacheDirectory/unverified-microdesc-consensus
Contains a microdescriptor-flavored network consensus document that has
been downloaded, but which we didn't have the right certificates to
check yet.

DataDirectory/unparseable-desc
Onion server descriptors that Tor was unable to parse are dumped to
this file. Only used for debugging.

DataDirectory/router-stability
Only used by authoritative directory servers. Tracks measurements for
router mean-time-between-failures so that authorities have a fair idea
of how to set their Stable flags.

DataDirectory/stats/dirreq-stats
Only used by directory caches and authorities. This file is used to
collect directory request statistics.

DataDirectory/stats/entry-stats
Only used by servers. This file is used to collect incoming connection
statistics by Tor entry nodes.

DataDirectory/stats/bridge-stats
Only used by servers. This file is used to collect incoming connection
statistics by Tor bridges.

DataDirectory/stats/exit-stats
Only used by servers. This file is used to collect outgoing connection
statistics by Tor exit routers.

DataDirectory/stats/buffer-stats
Only used by servers. This file is used to collect buffer usage his-
tory.

DataDirectory/stats/conn-stats
Only used by servers. This file is used to collect approximate connec-
tion history (number of active connections over time).

DataDirectory/stats/hidserv-stats
Only used by servers. This file is used to collect approximate counts
of what fraction of the traffic is hidden service rendezvous traffic,
and approximately how many hidden services the relay has seen.

DataDirectory/networkstatus-bridges
Only used by authoritative bridge directories. Contains information
about bridges that have self-reported themselves to the bridge author-
ity.

HiddenServiceDirectory/hostname
The <base32-encoded-fingerprint>.onion domain name for this hidden ser-
vice. If the hidden service is restricted to authorized clients only,
this file also contains authorization data for all clients.

Note
The clients will ignore any extra subdomains prepended to a hidden
service hostname. Supposing you have "xyz.onion" as your hostname,
you can ask your clients to connect to "www.xyz.onion" or
"irc.xyz.onion" for virtual-hosting purposes.

HiddenServiceDirectory/private_key
Contains the private key for this hidden service.

HiddenServiceDirectory/client_keys
Contains authorization data for a hidden service that is only accessi-
ble by authorized clients.

HiddenServiceDirectory/onion_service_non_anonymous
This file is present if a hidden service key was created in HiddenSer-
viceNonAnonymousMode.

SEE ALSO
For more information, refer to the Tor Project website at https://www.tor-
project.org/ and the Tor specifications at https://spec.torproject.org. See
also torsocks(1) and torify(1).

BUGS
Because Tor is still under development, there may be plenty of bugs. Please
report them at https://bugs.torproject.org/.

Tor 05/02/2026 TOR(1)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=tor&manpath=FreeBSD+15.1-RELEASE+and+Ports>

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