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gnutls-cli(1) User Commands gnutls-cli(1)

NAME
gnutls-cli - GnuTLS client

SYNOPSIS
gnutls-cli [-flags] [-flag [value]] [--option-name[[=| ]value]] [hostname]

Operands and options may be intermixed. They will be reordered.

DESCRIPTION
Simple client program to set up a TLS connection to some other computer.
It sets up a TLS connection and forwards data from the standard input to
the secured socket and vice versa. Note that this program is only meant
for testing and diagnostic purposes. For more practical use-cases, consider
using alternatives like GNU Wget.

OPTIONS
-d num, --debug=num Enable debugging. This option takes an integer number
as its argument. The value of num is constrained to being:
in the range 0 through 9999

Specifies the debug level.

-V, --verbose More verbose output.

--tofu, --no-tofu Enable trust on first use authentication. The no-tofu
form will disable the option.

This option will, in addition to certificate authentication, perform au-
thentication based on previously seen public keys, a model similar to SSH
authentication. Note that when tofu is specified (PKI) and DANE authentica-
tion will become advisory to assist the public key acceptance process.

--strict-tofu, --no-strict-tofu Fail to connect if a certificate is unknown
or a known certificate has changed. The no-strict-tofu form will disable
the option.

This option will perform authentication as with option --tofu; however, no
questions shall be asked whatsoever, neither to accept an unknown certifi-
cate nor a changed one.

--dane, --no-dane Enable DANE certificate verification (DNSSEC). The
no-dane form will disable the option.

This option will, in addition to certificate authentication using the
trusted CAs, verify the server certificates using on the DANE information
available via DNSSEC.

--local-dns, --no-local-dns Use the local DNS server for DNSSEC resolving.
The no-local-dns form will disable the option.

This option will use the local DNS server for DNSSEC. This is disabled by
default due to many servers not allowing DNSSEC.

--ca-verification, --no-ca-verification Enable CA certificate verification.
The no-ca-verification form will disable the option. This option is en-
abled by default.

This option can be used to enable or disable CA certificate verification.
It is to be used with the --dane or --tofu options.

--ocsp, --no-ocsp Enable OCSP certificate verification. The no-ocsp form
will disable the option.

This option will enable verification of the peer's certificate using ocsp

-r, --resume Establish a session and resume.

Connect, establish a session, reconnect and resume.

--earlydata=str Send early data on resumption from the specified file.

-e, --rehandshake Establish a session and rehandshake.

Connect, establish a session and rehandshake immediately.

--sni-hostname=str Server's hostname for server name indication extension.

Set explicitly the server name used in the TLS server name indication ex-
tension. That is useful when testing with servers setup on different DNS
name than the intended. If not specified, the provided hostname is used.
Even with this option server certificate verification still uses the host-
name passed on the main commandline. Use --verify-hostname to change this.

--verify-hostname=str Server's hostname to use for validation.

Set explicitly the server name to be used when validating the server's cer-
tificate.

-s, --starttls Connect, establish a plain session and start TLS.

The TLS session will be initiated when EOF or a SIGALRM is received.

--app-proto This is an alias for the --starttls-proto option.

--starttls-proto=str The application protocol to be used to obtain the
server's certificate (https, ftp, smtp, imap, ldap, xmpp, lmtp, pop3, nntp,
sieve, postgres). This option must not appear in combination with any of
the following options: starttls.

Specify the application layer protocol for STARTTLS. If the protocol is
supported, gnutls-cli will proceed to the TLS negotiation.

--starttls-name=str The hostname presented to the application protocol for
STARTTLS (for smtp, xmpp, lmtp). This option must not appear in combina-
tion with any of the following options: starttls. This option must appear
in combination with the following options: starttls-proto.

Specify the hostname presented to the application protocol for STARTTLS.

-u, --udp Use DTLS (datagram TLS) over UDP.

--mtu=num Set MTU for datagram TLS. This option takes an integer number as
its argument. The value of num is constrained to being:
in the range 0 through 17000

--crlf Send CR LF instead of LF.

--fastopen Enable TCP Fast Open.

--x509fmtder Use DER format for certificates to read from.

--print-cert Print peer's certificate in PEM format.

--save-cert=str Save the peer's certificate chain in the specified file in
PEM format.

--save-ocsp=str Save the peer's OCSP status response in the provided file.
This option must not appear in combination with any of the following op-
tions: save-ocsp-multi.

--save-ocsp-multi=str Save all OCSP responses provided by the peer in this
file. This option must not appear in combination with any of the following
options: save-ocsp.

The file will contain a list of PEM encoded OCSP status responses if any
were provided by the peer, starting with the one for the peer's server cer-
tificate.

--save-server-trace=str Save the server-side TLS message trace in the pro-
vided file.

--save-client-trace=str Save the client-side TLS message trace in the pro-
vided file.

--dh-bits=num The minimum number of bits allowed for DH. This option takes
an integer number as its argument.

This option sets the minimum number of bits allowed for a Diffie-Hellman
key exchange. You may want to lower the default value if the peer sends a
weak prime and you get an connection error with unacceptable prime.

--priority=str Priorities string.

TLS algorithms and protocols to enable. You can use predefined sets of ci-
phersuites such as PERFORMANCE, NORMAL, PFS, SECURE128, SECURE256. The de-
fault is NORMAL.

Check the GnuTLS manual on section "Priority strings" for more infor-
mation on the allowed keywords

--x509cafile=str Certificate file or PKCS #11 URL to use.

--x509crlfile=file CRL file to use.

--x509keyfile=str X.509 key file or PKCS #11 URL to use.

--x509certfile=str X.509 Certificate file or PKCS #11 URL to use. This op-
tion must appear in combination with the following options: x509keyfile.

--rawpkkeyfile=str Private key file (PKCS #8 or PKCS #12) or PKCS #11 URL
to use.

In order to instruct the application to negotiate raw public keys one must
enable the respective certificate types via the priority strings (i.e.
CTYPE-CLI-* and CTYPE-SRV-* flags).

Check the GnuTLS manual on section "Priority strings" for more infor-
mation on how to set certificate types.

--rawpkfile=str Raw public-key file to use. This option must appear in
combination with the following options: rawpkkeyfile.

In order to instruct the application to negotiate raw public keys one must
enable the respective certificate types via the priority strings (i.e.
CTYPE-CLI-* and CTYPE-SRV-* flags).

Check the GnuTLS manual on section "Priority strings" for more infor-
mation on how to set certificate types.

--srpusername=str SRP username to use.

--srppasswd=str SRP password to use.

--pskusername=str PSK username to use.

--pskkey=str PSK key (in hex) to use.

-p str, --port=str The port or service to connect to.

--insecure Don't abort program if server certificate can't be validated.

--verify-allow-broken Allow broken algorithms, such as MD5 for certificate
verification.

--ranges Use length-hiding padding to prevent traffic analysis.

When possible (e.g., when using CBC ciphersuites), use length-hiding
padding to prevent traffic analysis.

NOTE: THIS OPTION IS DEPRECATED

--benchmark-ciphers Benchmark individual ciphers.

By default the benchmarked ciphers will utilize any capabilities of the lo-
cal CPU to improve performance. To test against the raw software implemen-
tation set the environment variable GNUTLS_CPUID_OVERRIDE to 0x1.

--benchmark-tls-kx Benchmark TLS key exchange methods.

--benchmark-tls-ciphers Benchmark TLS ciphers.

-l, --list Print a list of the supported algorithms and modes. This option
must not appear in combination with any of the following options: port.

Print a list of the supported algorithms and modes. If a priority string is
given then only the enabled ciphersuites are shown.

--priority-list Print a list of the supported priority strings.

Print a list of the supported priority strings. The ciphersuites corre-
sponding to each priority string can be examined using -l -p.

--noticket Don't allow session tickets.

Disable the request of receiving of session tickets under TLS1.2 or earlier

--srtp-profiles=str Offer SRTP profiles.

--alpn=str Application layer protocol. This option may appear an unlimited
number of times.

This option will set and enable the Application Layer Protocol Negotiation
(ALPN) in the TLS protocol.

--compress-cert=str Compress certificate. This option may appear an unlim-
ited number of times.

This option sets a supported compression method for certificate compres-
sion.

-b, --heartbeat Activate heartbeat support.

--recordsize=num The maximum record size to advertise. This option takes
an integer number as its argument. The value of num is constrained to be-
ing:
in the range 0 through 4096

--disable-sni Do not send a Server Name Indication (SNI).

--disable-extensions Disable all the TLS extensions.

This option disables all TLS extensions. Deprecated option. Use the prior-
ity string.

NOTE: THIS OPTION IS DEPRECATED

--single-key-share Send a single key share under TLS1.3.

This option switches the default mode of sending multiple key shares, to
send a single one (the top one).

--post-handshake-auth Enable post-handshake authentication under TLS1.3.

This option enables post-handshake authentication when under TLS1.3.

--inline-commands Inline commands of the form ^<cmd>^.

Enable inline commands of the form ^<cmd>^. The inline commands are ex-
pected to be in a line by themselves. The available commands are: resume,
rekey1 (local rekey), rekey (rekey on both peers) and renegotiate.

--inline-commands-prefix=str Change the default delimiter for inline com-
mands.

Change the default delimiter (^) used for inline commands. The delimiter is
expected to be a single US-ASCII character (octets 0 - 127). This option is
only relevant if inline commands are enabled via the inline-commands option

--provider=file Specify the PKCS #11 provider library.

This will override the default options in /usr/local/etc/gnutls/pkcs11.conf

--fips140-mode Reports the status of the FIPS140-2 mode in gnutls library.

--list-config Reports the configuration of the library.

--logfile=str Redirect informational messages to a specific file.

Redirect informational messages to a specific file. The file may be
/dev/null also to make the gnutls client quiet to use it in piped server
connections where only the server communication may appear on stdout.

--keymatexport=str Label used for exporting keying material.

--keymatexportsize=num Size of the exported keying material. This option
takes an integer number as its argument.

--waitresumption Block waiting for the resumption data under TLS1.3.

This option makes the client to block waiting for the resumption data under
TLS1.3. The option has effect only when --resume is provided.

--ca-auto-retrieve, --no-ca-auto-retrieve Enable automatic retrieval of
missing CA certificates. The no-ca-auto-retrieve form will disable the op-
tion.

This option enables the client to automatically retrieve the missing inter-
mediate CA certificates in the certificate chain, based on the Authority
Information Access (AIA) extension.

--attime=timestamp Perform validation at the timestamp instead of the sys-
tem time.

timestamp is an instance in time encoded as Unix time or in a human
readable timestring such as "29 Feb 2004", "2004-02-29". Full documenta-
tion available at <https://www.gnu.org/software/coreutils/man-
ual/html_node/Date-input-formats.html> or locally via info '(coreutils)
date invocation'.

-v arg, --version=arg Output version of program and exit. The default mode
is `v', a simple version. The `c' mode will print copyright information
and `n' will print the full copyright notice.

-h, --help Display usage information and exit.

-!, --more-help Pass the extended usage information through a pager.

EXAMPLES
Connecting using PSK authentication
To connect to a server using PSK authentication, you need to enable
the choice of PSK by using a cipher priority parameter such as in
the example below.
$ ./gnutls-cli -p 5556 localhost --pskusername psk_identity --pskkey 88f3824b3e5659f52d00e959bacab954b6540344 --priority NORMAL:-KX-ALL:+ECDHE-PSK:+DHE-PSK:+PSK
Resolving 'localhost'...
Connecting to '127.0.0.1:5556'...
- PSK authentication.
- Version: TLS1.1
- Key Exchange: PSK
- Cipher: AES-128-CBC
- MAC: SHA1
- Compression: NULL
- Handshake was completed

- Simple Client Mode:
By keeping the --pskusername parameter and removing the --pskkey pa-
rameter, it will query only for the password during the handshake.

Connecting using raw public-key authentication
To connect to a server using raw public-key authentication, you need
to enable the option to negotiate raw public-keys via the priority
strings such as in the example below.
$ ./gnutls-cli -p 5556 localhost --priority NORMAL:-CTYPE-CLI-ALL:+CTYPE-CLI-RAWPK --rawpkkeyfile cli.key.pem --rawpkfile cli.rawpk.pem
Processed 1 client raw public key pair...
Resolving 'localhost'...
Connecting to '127.0.0.1:5556'...
- Successfully sent 1 certificate(s) to server.
- Server has requested a certificate.
- Certificate type: X.509
- Got a certificate list of 1 certificates.
- Certificate[0] info:
- skipped
- Description: (TLS1.3-Raw Public Key-X.509)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
- Options:
- Handshake was completed

- Simple Client Mode:

Connecting to STARTTLS services

You could also use the client to connect to services with starttls
capability.
$ gnutls-cli --starttls-proto smtp --port 25 localhost

Listing ciphersuites in a priority string
To list the ciphersuites in a priority string:
$ ./gnutls-cli --priority SECURE192 -l
Cipher suites for SECURE192
TLS_ECDHE_ECDSA_AES_256_CBC_SHA384 0xc0, 0x24 TLS1.2
TLS_ECDHE_ECDSA_AES_256_GCM_SHA384 0xc0, 0x2e TLS1.2
TLS_ECDHE_RSA_AES_256_GCM_SHA384 0xc0, 0x30 TLS1.2
TLS_DHE_RSA_AES_256_CBC_SHA256 0x00, 0x6b TLS1.2
TLS_DHE_DSS_AES_256_CBC_SHA256 0x00, 0x6a TLS1.2
TLS_RSA_AES_256_CBC_SHA256 0x00, 0x3d TLS1.2

Certificate types: CTYPE-X.509
Protocols: VERS-TLS1.2, VERS-TLS1.1, VERS-TLS1.0, VERS-SSL3.0, VERS-DTLS1.0
Compression: COMP-NULL
Elliptic curves: CURVE-SECP384R1, CURVE-SECP521R1
PK-signatures: SIGN-RSA-SHA384, SIGN-ECDSA-SHA384, SIGN-RSA-SHA512, SIGN-ECDSA-SHA512

Connecting using a PKCS #11 token
To connect to a server using a certificate and a private key present
in a PKCS #11 token you need to substitute the PKCS 11 URLs in the
x509certfile and x509keyfile parameters.

Those can be found using "p11tool --list-tokens" and then listing
all the objects in the needed token, and using the appropriate.
$ p11tool --list-tokens

Token 0:
URL: pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test
Label: Test
Manufacturer: EnterSafe
Model: PKCS15
Serial: 1234

$ p11tool --login --list-certs "pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test"

Object 0:
URL: pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test;object=client;type=cert
Type: X.509 Certificate
Label: client
ID: 2a:97:0d:58:d1:51:3c:23:07:ae:4e:0d:72:26:03:7d:99:06:02:6a

$ MYCERT="pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test;object=client;type=cert"
$ MYKEY="pkcs11:model=PKCS15;manufacturer=MyMan;serial=1234;token=Test;object=client;type=private"
$ export MYCERT MYKEY

$ gnutls-cli www.example.com --x509keyfile $MYKEY --x509certfile $MYCERT
Notice that the private key only differs from the certificate in the
type.

EXIT STATUS
One of the following exit values will be returned:

0 (EXIT_SUCCESS) Successful program execution.

1 (EXIT_FAILURE) The operation failed or the command syntax was not valid.

SEE ALSO
gnutls-cli-debug(1), gnutls-serv(1)

BUGS
Please send bug reports to: bugs@gnutls.org

3.8.13 29 Apr 2026 gnutls-cli(1)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=gnutls-cli&sektion=1&manpath=FreeBSD+Ports+15.1.quarterly>

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