Provided by: gnutls-bin_3.7.3-4ubuntu1.7_amd64 bug

NAME

       gnutls-cli-debug - GnuTLS debug client

SYNOPSIS

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

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

DESCRIPTION

       TLS  debug  client.  It sets up multiple TLS connections to a server and queries its capabilities. It was
       created to assist in debugging GnuTLS, but it might be useful to extract a TLS server's capabilities.  It
       connects to a TLS server, performs tests and print the server's capabilities. If  called  with  the  `-V'
       parameter more checks will be performed.  Can be used to check for servers with special needs or bugs.

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.

       -p number, --port=number The port to connect to.  This option takes an integer number as its argument.
       The value of number is constrained to being:
           in the range 0  through  65536

       --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).

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

       -v keyword, --version=keyword 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
                  $ gnutls-cli-debug localhost
                  GnuTLS debug client 3.5.0
                  Checking localhost:443
                                               for SSL 3.0 (RFC6101) support... yes
                                          whether we need to disable TLS 1.2... no
                                          whether we need to disable TLS 1.1... no
                                          whether we need to disable TLS 1.0... no
                                          whether %NO_EXTENSIONS is required... no
                                                 whether %COMPAT is required... no
                                               for TLS 1.0 (RFC2246) support... yes
                                               for TLS 1.1 (RFC4346) support... yes
                                               for TLS 1.2 (RFC5246) support... yes
                                                    fallback from TLS 1.6 to... TLS1.2
                                          for RFC7507 inappropriate fallback... yes
                                                       for HTTPS server name... Local
                                                 for certificate chain order... sorted
                                    for safe renegotiation (RFC5746) support... yes
                                       for Safe renegotiation support (SCSV)... no
                                      for encrypt-then-MAC (RFC7366) support... no
                                     for ext master secret (RFC7627) support... no
                                             for heartbeat (RFC6520) support... no
                                         for version rollback bug in RSA PMS... dunno
                                    for version rollback bug in Client Hello... no
                              whether the server ignores the RSA PMS version... yes
                  whether small records (512 bytes) are tolerated on handshake... yes
                      whether cipher suites not in SSL 3.0 spec are accepted... yes
                  whether a bogus TLS record version in the client hello is accepted... yes
                           whether the server understands TLS closure alerts... partially
                              whether the server supports session resumption... yes
                                        for anonymous authentication support... no
                                        for ephemeral Diffie-Hellman support... no
                                     for ephemeral EC Diffie-Hellman support... yes
                                      ephemeral EC Diffie-Hellman group info... SECP256R1
                                    for AES-128-GCM cipher (RFC5288) support... yes
                                    for AES-128-CCM cipher (RFC6655) support... no
                                  for AES-128-CCM-8 cipher (RFC6655) support... no
                                    for AES-128-CBC cipher (RFC3268) support... yes
                               for CAMELLIA-128-GCM cipher (RFC6367) support... no
                               for CAMELLIA-128-CBC cipher (RFC5932) support... no
                                       for 3DES-CBC cipher (RFC2246) support... yes
                                    for ARCFOUR 128 cipher (RFC2246) support... yes
                                                         for MD5 MAC support... yes
                                                        for SHA1 MAC support... yes
                                                      for SHA256 MAC support... yes
                                                for ZLIB compression support... no
                                       for max record size (RFC6066) support... no
                                  for OCSP status response (RFC6066) support... no
                                for OpenPGP authentication (RFC6091) support... no

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

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(1), gnutls-serv(1)

AUTHORS

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

COPYRIGHT

       Copyright (C) 2020-2021 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

3.7.3                                              18 Jan 2022                               gnutls-cli-debug(1)