gnutls-cli - Online in the Cloud

PROGRAM:

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.

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

This option will perform authentication as with option --tofu; however, while
--tofu asks whether to trust a changed public key, this option will fail in case of
public key changes.

--dane, - Fl -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, - Fl -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, - Fl -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, - Fl -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.

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

Connect, establish a session and rehandshake immediately.

-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). 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.

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

-f, --fingerprint
Send the openpgp fingerprint, instead of the key.

--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.

--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.

--pgpkeyfile=file
PGP Key file to use.

--pgpkeyring=file
PGP Key ring file to use.

--pgpcertfile=file
PGP Public Key (certificate) file to use. This option must appear in combination
with the following options: pgpkeyfile.

--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.

--pgpsubkey=string
PGP subkey to use (hex or auto).

--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.

--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.

--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.

--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.

--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 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.

-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.

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-
[email protected]. Thank you.

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