gnutls-cli

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.

Options

-d number, --debug=number

Enable debugging. This option takes an integer number as its argument. The value of number is constrained to being:

in the range  0 through 9999

Specifies the debug level.

-V, --verbose

More verbose output. This option may appear an unlimited number of times.

--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 authentication based on previously seen public keys, a model similar to SSH authentication. Note that when tofu  is specified (PKI) and DANE authentication 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 certificate 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 enabled 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=string

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=string

Server's hostname for server name indication extension.

Set explicitly the server name used in the TLS server name indication extension. 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 hostname passed on the main commandline. Use --verify-hostname to change this.

--verify-hostname=string

Server's hostname to use for validation.

Set explicitly the server name to be used when validating the server's certificate.

-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=string

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.

-u, --udp

Use DTLS (datagram TLS) over UDP.

--mtu=number

Set MTU for datagram TLS. This option takes an integer number as its argument. The value of number 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=string

Save the peer's certificate chain in the specified file in PEM format.

--save-ocsp=string

Save the peer's OCSP status response in the provided file.

--save-server-trace=string

Save the server-side TLS message trace in the provided file.

--save-client-trace=string

Save the client-side TLS message trace in the provided file.

--dh-bits=number

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=string

Priorities string.

TLS algorithms and protocols to enable. You can use predefined sets of ciphersuites such as PERFORMANCE, NORMAL, PFS, SECURE128, SECURE256. The default is NORMAL.

Check  the  GnuTLS  manual  on  section  “Priority strings” for more information on the allowed keywords

--x509cafile=string

Certificate file or PKCS #11 URL to use.

--x509crlfile=file

CRL file to use.

--x509keyfile=string

X.509 key file or PKCS #11 URL to use.

--x509certfile=string

X.509 Certificate file or PKCS #11 URL to use. This option must appear in combination with the following options: x509keyfile.

--srpusername=string

SRP username to use.

--srppasswd=string

SRP password to use.

--pskusername=string

PSK username to use.

--pskkey=string

PSK key (in hex) to use.

-p string, --port=string

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 local CPU to improve performance. To test against the raw software implementation set the environment variable GNUTLS_CPUID_OVERRIDE to 0x1.

--benchmark-tls-kx

Benchmark TLS key exchange methods.

--benchmark-tls-ciphers

Benchmark TLS ciphers.

By default the benchmarked ciphers will utilize any capabilities of the local CPU to improve performance. To test against the raw software implementation set the environment variable GNUTLS_CPUID_OVERRIDE to 0x1.

-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 corresponding 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=string

Offer SRTP profiles.

--alpn=string

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.

-b, --heartbeat

Activate heartbeat support.

--recordsize=number

The maximum record size to advertize. This option takes an integer number as its argument. The value of number is constrained to being:

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 priority 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 expected 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=string

Change the default delimiter for inline commands..

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 /etc/gnutls/pkcs11.conf

--fips140-mode

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

--logfile=string

Redirect informational messages to a specific file..

--keymatexport=string

Label used for exporting keying material.

--keymatexportsize=number

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

-h, --help

Display usage information and exit.

-!, --more-help

Pass the extended usage information through a pager.

-v [{v|c|n --version [{v|c|n}]}]

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.

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 parameter, it will query only for the password during the handshake.

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.

70  (EX_SOFTWARE)

libopts had an internal operational error.  Please report it to autogen-users@lists.sourceforge.net.  Thank you.

See Also

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

Authors

Nikos Mavrogiannopoulos, Simon Josefsson and others; see /usr/share/doc/gnutls/AUTHORS for a complete list.

Copyright

Copyright (C) 2000-2019 Free Software Foundation, and others all rights reserved. This program is released under the terms of the GNU General Public License, version 3 or later.

Bugs

Please send bug reports to: bugs@gnutls.org

Notes

This manual page was AutoGen-erated from the gnutls-cli option definitions.

Referenced By

gnutls-cli-debug(1), gnutls-serv(1), ldap.conf(5), slapd.conf(5), slapd-config(5).