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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
"virtual 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 relays 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 mentioned 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
arguments 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 OptionValue, 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 debugging messages to debug.log, you must
specify --Log "debug file debug.log".

Note
Configuration options on the command line override those in
configuration files. See THE CONFIGURATION FILE FORMAT for more
information.

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

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

-f FILE
Specify a new configuration file to contain further Tor
configuration options, or pass - to make Tor read its configuration
from standard input. (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
defaults-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
configuration file, and by those on the command line. (Default:
/usr/local/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
Generate your keys and output your nickname and fingerprint.

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

--dump-config short|full|non-builtin
Write a complete 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 non-builtin is
selected, write options that are not zero or the empty string. 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
command-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
future version. (This is a warning, not a promise.)

--list-modules
List whether each optional module has been compiled into Tor. (Any
module 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 specified 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 console 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 identity 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 passphase (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
DataDirectory/keys directory of your Tor daemon, and make sure that
they are owned by the user actually running the Tor daemon on your
system.

--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]
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 signing key certificate's expiration time in ISO-8601
format. For example, the output sent to stdout will be of the form:
"signing-cert-expiry: 2017-07-25 08:30:15 UTC"

--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 configuration entry into multiple lines, use a
single backslash character (\) before 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
%include option with the value being a path. 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 on 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.

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 previous 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 option 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
engine 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
dynamic 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
default directory authorities. Using AlternateDirAuthority replaces
the default Tor directory authorities, but leaves the default
bridge authorities in place. Similarly, AlternateBridgeAuthority
replaces the default bridge authority, but leaves the directory
authorities alone.

AndroidIdentityTag tag
When logging to Android's logging subsystem, adds a tag to the log
identity such that log entries are marked with "Tor-tag". Can not
be changed while tor is running. (Default: none)

AvoidDiskWrites 0|1
If non-zero, try to write to disk less frequently than we would
otherwise. 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 relay (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 writing "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,
ClientTransportPlugin 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)

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 sockets 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
platform 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 useful for virtual servers and other environments where system
level TCP buffers may be limited. If you're on a virtual server,
and you encounter 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 facility; 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 exacerbates 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
connections to control the Tor process using the Tor Control
Protocol (described 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. (Default: 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
"control_auth_cookie", which Tor will create in its data directory.
This authentication method should only be used on systems with good
filesystem 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 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)

CountPrivateBandwidth 0|1
If this option is set, then Tor's rate-limiting applies not only to
remote 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-limiting. (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
address 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 randomly 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
authority 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
DirPort, 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
directories, 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 modern 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
attempts 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 feature 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 debugger such as gdb or strace you
will want to set this to 0 for the duration 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 seconds between each attempt, and retry FallbackDirs
more often than directory 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
directory 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
directory 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
useful 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
descriptors 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 descriptors. 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 extrainfo
documents, and serves them if DirCache is on, and
UseMicrodescriptors changes the flavour of consensues 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
HashedControlPassword 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 connecting directly to servers. You may want to set
FascistFirewall to restrict 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 information 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
destination logs must be signal-safe. These low-level logs include
backtraces, logging function errors, and errors in code called by
logging functions. 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, android logs,
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"
option 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
functionality 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 negation, 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, consdiff, dos, process, pt, btrack, and mesg. Domain
names are case-insensitive.

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 proportional 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)

NoExec 0|1
If this option is set to 1, then Tor will never launch another
executable, regardless of the settings of ClientTransportPlugin or
ServerTransportPlugin. 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 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), and is
not used for DNS requests as well.

OutboundBindAddressExit IP
Make all outbound exit 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).

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.

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)

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 relays), because that is considered
"client" activity. (Default: 0)

RephistTrackTime N seconds|minutes|hours|days|weeks
Tells an authority, or other node tracking node reliability and
history, 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.
addresses) 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 below Notice. (Default: 1)

Sandbox 0|1
If set to 1, Tor will run securely through the use of a syscall
sandbox. Otherwise the sandbox will be disabled. The option is
currently an experimental feature. It only works on Linux-based
operating systems, and only when Tor has been built with the
libseccomp library. 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, ClientOnionAuthDir (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
responsible for moving data around within a Tor process. This is an
ordered 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 possible to change these values at runtime. This option
mostly effects relays, and most operators should leave it set to
its default value. (Default: 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 decisions. 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)

ServerTransportListenAddr transport IP:PORT
When this option is set, Tor will suggest IP:PORT as the listening
address 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
pluggable 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 proxied client traffic from it. (Default: none)

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
password in accordance to RFC 1929. Both username and password must
be between 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 running. (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 connections, because all Tor client
versions that support this option download directory documents via
OR connections.

The only protocol supported right now '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
signal, 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. (Default: 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 address. This is handy for making ".onion" addresses
work with applications 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
"fingerprint" is provided (using the same format as for
DirAuthority), we will verify that the relay running at that
location has the right fingerprint. 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 connect 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
offered via the UI to mobile users for use where bandwidth may be
expensive. 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 offered via the UI to mobile users for use where bandwidth may
be expensive. (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 (potentially 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. (Default: 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 schedule 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-encoded-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
directory 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 specifically requested (for example, via a .exit hostname,
or a controller request). If true, multicast DNS hostnames for
machines on the local network (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
address in a Bridge, proxy, or pluggable transport line will try
connecting 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
ClientUseIPv4 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: 0)

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 explanation of isolation flags. (Default: 0)

DownloadExtraInfo 0|1
If true, Tor downloads and caches "extra-info" documents. These
documents 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. (Default: 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 restrictive policies, but will not allow you to run
as a server behind such a firewall. If you prefer more fine-grained
control, use ReachableAddresses 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
ReachableAddresses instead. (Default: 80, 443)

HidServAuth onion-address auth-cookie [service-name]
Client authorization for a v2 hidden service. Valid onion addresses
contain 16 characters in a-z2-7 plus ".onion", and valid auth
cookies contain 22 characters in A-Za-z0-9+/. The service name is
only used for internal purposes, e.g., for Tor controllers. This
option may be used multiple times for different hidden services. If
a hidden service uses authorization and this option is not set, the
hidden service is not accessible. Hidden services can be configured
to require authorization using the HiddenServiceAuthorizeClient
option.

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 isolation 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 hidden 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
newaddress before processing it. For example, if you always want
connections to www.example.com to exit via torserver (where
torserver is the fingerprint of the server), use "MapAddress
www.example.com www.example.com.torserver.exit". If the value is
prefixed with a "*.", matches an entire domain. For example, if you
always want connections to example.com and any if its subdomains to
exit via torserver (where torserver is the fingerprint of the
server), use "MapAddress *.example.com
*.example.com.torserver.exit". (Note the leading "*." in each part
of the directive.) You can also redirect all subdomains of a domain
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.torproject.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
ignored) 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 mappings 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
handling client streams. A circuit is pending if we have begun
constructing 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 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 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)

OptimisticData 0|1|auto
When this option is set, and Tor is using an exit node that
supports the feature, it will try optimistically to send data to
the exit node without waiting for the exit node to report whether
the connection succeeded. This can save a round-trip time for
protocols like HTTP where the client talks first. If OptimisticData
is set to auto, Tor will look at the UseOptimisticData parameter in
the networkstatus. (Default: auto)

PathBiasCircThreshold NUM

PathBiasDropGuards NUM

PathBiasExtremeRate NUM

PathBiasNoticeRate NUM

PathBiasWarnRate NUM

PathBiasScaleThreshold NUM
These options override the default behavior of Tor's (currently
experimental) path bias detection algorithm. To try to find broken
or misbehaving guard nodes, Tor looks for nodes where more than a
certain fraction 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
PathBiasNoticeRate, 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 PathBiasDropGuards 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
options, 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
behavior of Tor's (currently experimental) path use bias detection
algorithm.

Where as the path bias parameters govern thresholds for
successfully building circuits, these four path use bias parameters
govern thresholds 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 authorities 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
allows you to connect to. The format is as for the addresses in
ExitPolicy, 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
ReachableAddresses 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 HTTPProxy 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 provide 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 determine whether an application using
Tor is possibly leaking DNS requests. (Default: 0)

WarnPlaintextPorts port,port,...
Tells Tor to issue a warnings whenever the user tries to make an
anonymous 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
applications. 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 directive can be specified multiple times to bind to
multiple addresses/ports. If a unix domain socket is used, you may
quote the path using standard C escape sequences. Most flags are
off by default, except 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. Recognized 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
authentication was provided. (For HTTPTunnelPort connections,
this option looks at the Proxy-Authorization and
X-Tor-Stream-Isolation headers. 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
connections, NATDPort connections, and DNSPort requests are all
considered 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 NoOnionTrafficOnly 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
authentication" and "no authentication" to Tor via SOCKS5, Tor
selects username/password authentication so that
IsolateSOCKSAuth can work. This can confuse some applications,
if they offer a username/password combination then get confused
when asked for one. You can disable this behavior, so that Tor
will select "No authentication" 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
milliseconds. 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 limits 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
connections 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 anyhow.

TrackHostExitsExpire NUM
Since exit servers go up and down, it is desirable to expire the
association 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 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 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
VirtualAddrNetwork from the default setting. (Default: 0)

TransProxyType default|TPROXY|ipfw|pf-divert
TransProxyType may only be enabled when there is transparent proxy
listener 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 Documentation/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 divert-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
IPTables 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
descriptors from the configured bridge authorities when feasible.
It will fall back to a direct request if the authority responds
with a 404. (Default: 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 Directory Authorities or Single Onion Services. In these
cases, this option is ignored. (Default: 1)

UseGuardFraction 0|1|auto
This option specifies whether clients should use the guardfraction
information 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 parameter, 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)

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. Directory 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
MAPADDRESS 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 default VirtualAddrNetwork address ranges on a
properly configured machine 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 wider
network - smaller prefix length

o is preferable since it reduces the chances for an attacker to
guess the used IP. For local use, no change to the default
VirtualAddrNetwork setting is needed.

CIRCUIT TIMEOUT OPTIONS
The following options are useful for configuring timeouts related to
building 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 entirely 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. (Default: 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 option 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 applcation 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
dormant state where automatic circuits are not built, and directory
information 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)

NODE SELECTION OPTIONS
The following options restrict the nodes that a tor client (or onion
service) 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 circuits except for direct connections to directory servers.
The Bridge option overrides this option; if you have configured
bridges and UseBridges is 1, the Bridges are used as your entry
nodes.

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 preceded by a dollar sign. (Example:
ExcludeNodes ABCD1234CDEF5678ABCD1234CDEF5678ABCD1234, {cc},
255.254.0.0/8)

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 connect to a hidden service, but you have excluded all of
the hidden service'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 delivers 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.

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.

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 ExcludeNodes 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 ExcludeNodes 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)

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. Additionally, 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 adversary 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 currently 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)

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
combined 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. Additionally, 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 adversary 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 currently 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 circuits except for direct connections to directory servers.
Middle hops are all hops other than exit and entry.

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. 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 addition 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
option as a requirement to follow for all the circuits you
generate, even if doing so will break functionality for you
(StrictNodes does not apply to ExcludeExitNodes, ExitNodes,
MiddleNodes, or MapAddress). If StrictNodes is set to 0, Tor will
still try to avoid nodes in the ExcludeNodes list, but it will err
on the side of avoiding unexpected errors. 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 download
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
period using a given calculation rule (see AccountingStart and
AccountingRule). Useful if you need to stay under a specific
bandwidth. By default, 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 running. 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 bandwidth 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 differently.

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
using the higher of either the sent or received bytes (this is the
default functionality). Set to "sum" to calculate using the sent
plus received 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
accounting 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 period. (The day must be between 1 and 28.) If week is
given, each accounting 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 local, and given in 24-hour
time. (Default: "month 1 0:00")

Address address
The IPv4 address of this server, or a fully qualified domain name
of this server that resolves to an IPv4 address. You can leave this
unset, and Tor will try to guess your IPv4 address. This IPv4
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
OutboundBindAddress options.

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. If AuthoritativeDirectory is also set, this
option instructs the dirserver to bypass remote reachability
testing too and list all connected servers as running.

BridgeRelay 0|1
Sets the relay to act as a "bridge" with respect to relaying
connections 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.

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
addresses 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)

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. (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 descriptors containing these lines and that Google
indexes them, so spammers 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 connections more than it should. (Default: 1)

ExitPolicy policy,policy,...
Set an exit policy for this server. Each policy is of the form
"accept[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 network 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 addresses. 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
warning. accept/reject allows either IPv4 or IPv6 addresses. Use *4
as an IPv4 wildcard address, and *6 as an IPv6 wildcard address.
accept/reject * expands to matching IPv4 and IPv6 wildcard address
rules.

To specify all IPv4 and IPv6 internal and link-local networks
(including 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 addresses, 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 ExitPolicyRejectPrivate 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 using accept/reject *4. If you want to _replace_ the
default exit policy, end your exit policy with either a reject *:*
or an accept *:*. Otherwise, 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 either a reject : or an accept :. Otherwise, you're
augmenting (prepending 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 option, 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
ExitPolicy, ReducedExitPolicy, and IPv6Exit options are ignored.

If ExitRelay is set to "auto", then Tor checks the ExitPolicy,
ReducedExitPolicy, 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)

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
statistics.

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

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
traffic. When this option is set and ExitRelay is auto, we act as
if ExitRelay is 1. (Default: 0)

KeyDirectory DIR
Store secret keys in DIR. Can not be changed while tor is running.
(Default: 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)

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 option 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 reasonable 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
compromise 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.

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 identified 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
secret key. Instead, you'll have to use "tor --keygen" to manage
the permanent ed25519 master identity key, as well as the
corresponding temporary 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
NoAdvertise is specified, we don't advertise, but listen
anyway. This can be useful if the port everybody will be
connecting to (for example, 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
NoListen is specified, we don't bind, but advertise anyway.
This can be useful if something else (for example, a firewall's
port forwarding 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) specified. The default is "1", which means "if running
as a relay or bridge, publish descriptors to the appropriate
authorities". Other possibilities 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. Otherwise, Tor continues to periodically retry the
system nameservers until 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 attempt 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 poisoning attack. For more information, see
"Increased DNS Forgery Resistance 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
filename. 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
domain. 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
addresses aren't getting redirected. If they are, then our DNS is
completely 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")

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 seconds)

SigningKeyLifetime N days|weeks|months
For how long should each Ed25519 signing key be valid? Tor uses a
permanent master identity key that can be kept offline, and
periodically generates new "signing" keys that it uses online. This
option configures 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
document. The following options affect the different types of
statistics that Tor relays collect and publish:

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 circuit) and writes them into disk every 24 hours. Onion
router operators may use the statistics for performance monitoring.
If ExtraInfoStatistics 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. (Default: 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 requests 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 extra-info document. (Default: 0)

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

HiddenServiceStatistics 0|1
Relays 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
ExtraInfoStatistics is enabled, it will be published as part of the
extra-info document. (Default: 1)

PaddingStatistics 0|1
Relays and bridges only. When this option is enabled, Tor collects
statistics 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 decisions 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
except 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.

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
consensus 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 current 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 three built-in mitigation options that can be individually
enabled/disabled and fine-tuned, but by default Tor directory
authorities will define reasonable values for relays and no explicit
configuration is required to make use of these protections. 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 further 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
DoSCircuitCreationMinConnections), 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://consensus-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 defenses 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
circuit rate and the burst are reached, a client is marked as
executing a circuit creation DoS. "0" means use the consensus
parameter. If not defined 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 concurrent connections, a detection is positive. "0" means use
the consensus parameter. If not defined in the consensus, the value
is 3. (Default: 0)

DoSCircuitCreationRate NUM
The allowed circuit creation rate per second applied per client IP
address. If this option is 0, it obeys a consensus parameter. If
not defined 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 concurrent 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
address. 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)

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)

DIRECTORY AUTHORITY SERVER OPTIONS
The following options enable operation as a directory authority, and
control how Tor behaves as a directory authority. You should not need
to adjust 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
directory 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 probably do not want to set this option.

BridgeAuthoritativeDir 0|1
When this option is set in addition to AuthoritativeDirectory, Tor
accepts 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
generates version 3 network statuses and serves descriptors, etc as
described 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.)

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 reachability test succeeds, the authority votes for the IPv6
ORPort, and votes Running for the relay. If the reachability test
fails, the authority 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; otherwise, you are effectively voting in favor of every
declared exit as an exit.)

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 accepted 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 descriptor submitted for publication by this
authority.

AuthDirBadExitCCs CC,...

AuthDirInvalidCCs CC,...

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 tried to be answered even if this is on.
(Default: 1)

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 entirely.

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
option 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)

BridgePassword Password
If set, contains an HTTP authenticator that tells a bridge
authority to serve all requested bridge information. Used by the
(only partially implemented) "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 community bridges to stay
up-to-date. (Default: not set)

ConsensusParams STRING
STRING is a space-separated list of key=value pairs that Tor will
include in the "params" line of its networkstatus vote.

DirAllowPrivateAddresses 0|1
If set to 1, Tor will accept server descriptors with arbitrary
"Address" 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
measured total bandwidth an authority should have observed on the
network before it will treat advertised bandwidths as wholly
unreliable. (Default: 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 together. When this is set then
VersioningAuthoritativeDirectory should be set too.

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
VotingIntervals for which each consensus should be valid for.
Choosing high numbers increases network partitioning risks;
choosing low numbers increases 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. (Default: 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
bandwidth-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
after 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 inconvenience to port-scanners.) (Default: 0)

HiddenServiceAuthorizeClient auth-type client-name,client-name,...
If configured, the v2 hidden service is accessible for authorized
clients only. The auth-type can either be 'basic' for a
general-purpose authorization protocol or 'stealth' for a less
scalable protocol that also hides service activity from
unauthorized clients. Only clients that are listed here are
authorized to access the hidden service. Valid client names are 1
to 16 characters long and only use characters in A-Za-z0-9+-_ (no
spaces). If this option is set, the hidden service is not
accessible for clients without authorization any more. Generated
authorization data can be found in the hostname file. Clients need
to put this authorization data in their configuration file using
HidServAuth. This option is only for v2 services; v3 services
configure client authentication in a subdirectory of
HiddenServiceDir instead (see CLIENT AUTHORIZATION).

HiddenServiceDir DIRECTORY
Store data files for a hidden service in DIRECTORY. Every hidden
service 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 DataDirectory. 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
hidden 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.

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 request to this service.

The introduction point honors the consensus parameters except if
this is specifically set by the service operator using this option.
The service never looks at the consensus parameters in order to
enable or disable 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 HiddenServiceEnableIntroDoSDefense 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
HiddenServiceEnableIntroDoSDefense is set, it then effectively
disables the defenses. (Default: 25)

HiddenServiceExportCircuitID protocol
The onion service will use the given protocol to expose the global
circuit identifier of each inbound client circuit. The only
protocol supported right now 'haproxy'. This option is only for v3
services. (Default: none)

The haproxy option works in the following way: when the feature is
enabled, the Tor process will write a header line when a client is
connecting 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 ignored. You can compute the global circuit identifier using the
following 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 control-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 HiddenServiceDir directory with content:

MasterOnionAddress <frontend_onion_address>

where <frontend_onion_address> is the onion address of the
OnionBalance frontend (e.g.
wrxdvcaqpuzakbfww5sxs6r2uybczwijzfn2ezy2osaj7iox7kl7nhad.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
offending rendezvous circuit to be torn down, as opposed to stream
creation 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 10 for v2 service and 20 for v3. (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 target 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-separated.

HiddenServiceVersion 2|3
A list of rendezvous service descriptor versions to publish for the
hidden service. Currently, versions 2 and 3 are supported.
(Default: 3)

RendPostPeriod N seconds|minutes|hours|days|weeks
Every time the specified period elapses, Tor uploads any rendezvous
service descriptors to the directory servers. This information is
also uploaded whenever it changes. Minimum value allowed is 10
minutes and maximum is 3.5 days. This option is only for v2
services. (Default: 1 hour)

PER INSTANCE OPTIONS:

HiddenServiceSingleHopMode 0|1
Experimental - Non Anonymous Hidden Services on a tor instance in
HiddenServiceSingleHopMode 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 statistically distinguishable.

WARNING: Once a hidden service directory has been used by a tor
instance in HiddenServiceSingleHopMode, it can NEVER be used again
for a hidden service. It is best practice to create a new hidden
service directory, 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
HiddenServiceSingleHopMode. 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, including setting SOCKSPort to "0". Can not be
changed while tor is running. (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
(Version 3 only)

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 even 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.torproject.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
AssumeReachable 1
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
RendPostPeriod 2 minutes

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
requires that TestingTorNetwork is set. (Default: 30 minutes)

TestingAuthKeySlop N seconds|minutes|hours

TestingBridgeBootstrapDownloadInitialDelay N
Initial delay in seconds for when clients should download each
bridge descriptor when they have just started, or when they can not
contact any of their bridges. Changing this requires that
TestingTorNetwork is set. (Default: 0)

TestingBridgeDownloadInitialDelay N
Initial delay in seconds for when clients should download each
bridge descriptor when they know that one or more of their
configured bridges are running. 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.
(Default: 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
specified 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

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.
(Default: 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
TestingTorNetwork 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
TestingTorNetwork 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
TestingTorNetwork 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
options. 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
controlled slow shutdown, closing listeners and waiting 30 seconds
before exiting. (The delay can be configured with the
ShutdownWaitLength config option.)

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

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 journal; 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
"extra-info" documents. Relays use these documents to send
inessential information 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:

o the current entry guards and their status.

o the current bandwidth accounting values.

o when the file was last written

o what version of Tor generated the state file

o a short history of bandwidth usage, as produced in the server
descriptors.

DataDirectory/sr-state
Authority only. This file is used to record information about the
current 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
instead. Used to track bandwidth accounting values (when the
current period 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
overridden 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 consensus-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.

DataDirectory/fingerprint
Only used by servers. Contains the fingerprint of the server's
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/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 fingerprint file in a tor relay's DataDirectory for
an example fingerprint line. If the status is !reject, then
descriptors from the given identity are rejected by this server. If
it is !invalid then descriptors are accepted, but marked in the
directory as not valid, that is, not recommended. In either case,
the corresponding relays are not included 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
history.

DataDirectory/stats/conn-stats
Only used by servers. This file is used to collect approximate
connection 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
authority.

HiddenServiceDirectory/hostname
The <base32-encoded-fingerprint>.onion domain name for this hidden
service. 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
accessible by authorized clients.

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

SEE ALSO
For more information, refer to the Tor Project website at
https://www.torproject.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://trac.torproject.org/.

AUTHORS
Roger Dingledine [arma at mit.edu], Nick Mathewson [nickm at
alum.mit.edu].

Tor 08/21/2020 TOR(1)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=tor&sektion=1&manpath=FreeBSD+12.1-RELEASE+and+Ports>

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