Next: gnutls-serv Invocation, Up: Other included programs [Contents][Index]
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.
The text printed is the same whether selected with the help option
(--help) or the more-help option (--more-help). more-help will print
the usage text by passing it through a pager program.
more-help is disabled on platforms without a working
fork(2) function. The PAGER environment variable is
used to select the program, defaulting to more. Both will exit
with a status code of 0.
gnutls-cli - GnuTLS client
Usage: gnutls-cli [ -<flag> [<val>] | --<name>[{=| }<val>] ]... [hostname]
None:
-d, --debug=num Enable debugging
- it must be in the range:
0 to 9999
-V, --verbose More verbose output
--tofu Enable trust on first use authentication
--strict-tofu Fail to connect if a certificate is unknown or a known certificate has changed
--dane Enable DANE certificate verification (DNSSEC)
--local-dns Use the local DNS server for DNSSEC resolving
--ca-verification Enable CA certificate verification
- enabled by default
- disabled as '--no-ca-verification'
--ocsp Enable OCSP certificate verification
-r, --resume Establish a session and resume
--earlydata=str Send early data on resumption from the specified file
-e, --rehandshake Establish a session and rehandshake
--sni-hostname=str Server's hostname for server name indication extension
--verify-hostname=str Server's hostname to use for validation
-s, --starttls Connect, establish a plain session and start TLS
--app-proto 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)
- prohibits the option 'starttls'
--starttls-name=str The hostname presented to the application protocol for STARTTLS (for smtp, xmpp, lmtp)
- prohibits the option 'starttls'
- requires the option 'starttls-proto'
-u, --udp Use DTLS (datagram TLS) over UDP
--mtu=num Set MTU for datagram TLS
- it must be in the range:
0 to 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
- prohibits the option 'save-ocsp-multi'
--save-ocsp-multi=str Save all OCSP responses provided by the peer in this file
- prohibits the option 'save-ocsp'
--save-server-trace=str Save the server-side TLS message trace in the provided file
--save-client-trace=str Save the client-side TLS message trace in the provided file
--dh-bits=num The minimum number of bits allowed for DH
--priority=str Priorities string
--x509cafile=str Certificate file or PKCS #11 URL to use
--x509crlfile=file CRL file to use
- file must pre-exist
--x509keyfile=str X.509 key file or PKCS #11 URL to use
--x509certfile=str X.509 Certificate file or PKCS #11 URL to use
- requires the option 'x509keyfile'
--rawpkkeyfile=str Private key file (PKCS #8 or PKCS #12) or PKCS #11 URL to use
--rawpkfile=str Raw public-key file to use
- requires the option 'rawpkkeyfile'
--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, --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
--benchmark-ciphers Benchmark individual ciphers
--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
- prohibits the option 'port'
--priority-list Print a list of the supported priority strings
--noticket Don't allow session tickets
--srtp-profiles=str Offer SRTP profiles
--alpn=str Application layer protocol
--compress-cert=str Compress certificate
-b, --heartbeat Activate heartbeat support
--recordsize=num The maximum record size to advertise
- it must be in the range:
0 to 4096
--disable-sni Do not send a Server Name Indication (SNI)
--single-key-share Send a single key share under TLS1.3
--post-handshake-auth Enable post-handshake authentication under TLS1.3
--inline-commands Inline commands of the form ^<cmd>^
--inline-commands-prefix=str Change the default delimiter for inline commands
--provider=file Specify the PKCS #11 provider library
- file must pre-exist
--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
--keymatexport=str Label used for exporting keying material
--keymatexportsize=num Size of the exported keying material
--waitresumption Block waiting for the resumption data under TLS1.3
--ca-auto-retrieve Enable automatic retrieval of missing CA certificates
--attime=str Perform validation at the timestamp instead of the system time
Version, usage and configuration options:
-v, --version[=arg] output version information and exit
-h, --help display extended usage information and exit
-!, --more-help extended usage information passed thru pager
Options are specified by doubled hyphens and their name or by a single
hyphen and the flag character.
Operands and options may be intermixed. They will be reordered.
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.
Please send bug reports to: <bugs@gnutls.org>
This is the “enable debugging” option. This option takes a ArgumentType.NUMBER argument. Specifies the debug level.
This is the “enable trust on first use authentication” 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.
This is the “fail to connect if a certificate is unknown or a known certificate has changed” 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.
This is the “enable dane certificate verification (dnssec)” 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.
This is the “use the local dns server for dnssec resolving” option. This option will use the local DNS server for DNSSEC. This is disabled by default due to many servers not allowing DNSSEC.
This is the “enable ca certificate verification” option.
This option has some usage constraints. It:
This option can be used to enable or disable CA certificate verification. It is to be used with the –dane or –tofu options.
This is the “enable ocsp certificate verification” option. This option will enable verification of the peer’s certificate using ocsp
This is the “establish a session and resume” option. Connect, establish a session, reconnect and resume.
This is the “establish a session and rehandshake” option. Connect, establish a session and rehandshake immediately.
This is the “server’s hostname for server name indication extension” option. This option takes a ArgumentType.STRING argument. 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.
This is the “server’s hostname to use for validation” option. This option takes a ArgumentType.STRING argument. Set explicitly the server name to be used when validating the server’s certificate.
This is the “connect, establish a plain session and start tls” option. The TLS session will be initiated when EOF or a SIGALRM is received.
This is an alias for the starttls-proto option,
see the starttls-proto option documentation.
This is the “the application protocol to be used to obtain the server’s certificate (https, ftp, smtp, imap, ldap, xmpp, lmtp, pop3, nntp, sieve, postgres)” option. This option takes a ArgumentType.STRING argument.
This option has some usage constraints. It:
Specify the application layer protocol for STARTTLS. If the protocol is supported, gnutls-cli will proceed to the TLS negotiation.
This is the “the hostname presented to the application protocol for starttls (for smtp, xmpp, lmtp)” option. This option takes a ArgumentType.STRING argument.
This option has some usage constraints. It:
Specify the hostname presented to the application protocol for STARTTLS.
This is the “save all ocsp responses provided by the peer in this file” option. This option takes a ArgumentType.STRING argument.
This option has some usage constraints. It:
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 certificate.
This is the “the minimum number of bits allowed for dh” option. This option takes a ArgumentType.NUMBER 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.
This is the “priorities string” option. This option takes a ArgumentType.STRING argument. 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
This is the “private key file (pkcs #8 or pkcs #12) or pkcs #11 url to use” option. This option takes a ArgumentType.STRING argument. 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 information on how to set certificate types.
This is the “raw public-key file to use” option. This option takes a ArgumentType.STRING argument.
This option has some usage constraints. It:
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 information on how to set certificate types.
This is the “use length-hiding padding to prevent traffic analysis” option. When possible (e.g., when using CBC ciphersuites), use length-hiding padding to prevent traffic analysis.
NOTE: THIS OPTION IS DEPRECATED
This is the “benchmark individual ciphers” option. 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.
This is the “benchmark tls ciphers” option. 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.
This is the “print a list of the supported algorithms and modes” option.
This option has some usage constraints. It:
Print a list of the supported algorithms and modes. If a priority string is given then only the enabled ciphersuites are shown.
This is the “print a list of the supported priority strings” option. Print a list of the supported priority strings. The ciphersuites corresponding to each priority string can be examined using -l -p.
This is the “don’t allow session tickets” option. Disable the request of receiving of session tickets under TLS1.2 or earlier
This is the “application layer protocol” option. This option takes a ArgumentType.STRING argument. This option will set and enable the Application Layer Protocol Negotiation (ALPN) in the TLS protocol.
This is the “compress certificate” option. This option takes a ArgumentType.STRING argument. This option sets a supported compression method for certificate compression.
This is the “disable all the tls extensions” option. This option disables all TLS extensions. Deprecated option. Use the priority string.
NOTE: THIS OPTION IS DEPRECATED
This is the “send a single key share under tls1.3” option. This option switches the default mode of sending multiple key shares, to send a single one (the top one).
This is the “enable post-handshake authentication under tls1.3” option. This option enables post-handshake authentication when under TLS1.3.
This is the “inline commands of the form ^<cmd>^” option. 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.
This is the “change the default delimiter for inline commands” option. This option takes a ArgumentType.STRING argument. 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
This is the “specify the pkcs #11 provider library” option. This option takes a ArgumentType.FILE argument. This will override the default options in /etc/gnutls/pkcs11.conf
This is the “redirect informational messages to a specific file” option. This option takes a ArgumentType.STRING argument. 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.
This is the “block waiting for the resumption data under tls1.3” option. This option makes the client to block waiting for the resumption data under TLS1.3. The option has effect only when –resume is provided.
This is the “enable automatic retrieval of missing ca certificates” option. This option enables the client to automatically retrieve the missing intermediate CA certificates in the certificate chain, based on the Authority Information Access (AIA) extension.
This is the “perform validation at the timestamp instead of the system time” option. This option takes a ArgumentType.STRING argument timestamp. 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 documentation available at <https://www.gnu.org/software/coreutils/manual/html_node/Date-input-formats.html> or locally via info ’(coreutils) date invocation’.
This is the “output version information and exit” option. This option takes a ArgumentType.KEYWORD argument. 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.
This is the “display extended usage information and exit” option. Display usage information and exit.
This is the “extended usage information passed thru pager” option. Pass the extended usage information through a pager.
One of the following exit values will be returned:
Successful program execution.
The operation failed or the command syntax was not valid.
gnutls-cli-debug(1), gnutls-serv(1)
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.
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:
You could also use the client to connect to services with starttls capability.
$ gnutls-cli --starttls-proto smtp --port 25 localhost
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
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.
Next: gnutls-serv Invocation, Up: Other included programs [Contents][Index]