@node gnutls-cli-debug Invocation @heading Invoking gnutls-cli-debug @pindex gnutls-cli-debug 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. @anchor{gnutls-cli-debug usage} @subheading gnutls-cli-debug help/usage (@option{-?}) @cindex gnutls-cli-debug help The text printed is the same whether selected with the @code{help} option (@option{--help}) or the @code{more-help} option (@option{--more-help}). @code{more-help} will print the usage text by passing it through a pager program. @code{more-help} is disabled on platforms without a working @code{fork(2)} function. The @code{PAGER} environment variable is used to select the program, defaulting to @file{more}. Both will exit with a status code of 0. @exampleindent 0 @example gnutls-cli-debug - GnuTLS debug client Usage: gnutls-cli-debug [ - [] | --[@{=| @}] ]... [hostname] None: -d, --debug=num Enable debugging - it must be in the range: 0 to 9999 -V, --verbose More verbose output -p, --port=num The port to connect to - it must be in the range: 0 to 65536 --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) 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. 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. Please send bug reports to: @end example @exampleindent 4 @subheading debug option (-d). @anchor{gnutls-cli-debug debug} This is the ``enable debugging'' option. This option takes a ArgumentType.NUMBER argument. Specifies the debug level. @subheading app-proto option. @anchor{gnutls-cli-debug app-proto} This is an alias for the @code{starttls-proto} option, @pxref{gnutls-cli-debug starttls-proto, the starttls-proto option documentation}. @subheading starttls-proto option. @anchor{gnutls-cli-debug starttls-proto} 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. Specify the application layer protocol for STARTTLS. If the protocol is supported, gnutls-cli will proceed to the TLS negotiation. @subheading version option (-v). @anchor{gnutls-cli-debug version} 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. @subheading help option (-h). @anchor{gnutls-cli-debug help} This is the ``display extended usage information and exit'' option. Display usage information and exit. @subheading more-help option (-!). @anchor{gnutls-cli-debug more-help} This is the ``extended usage information passed thru pager'' option. Pass the extended usage information through a pager. @anchor{gnutls-cli-debug exit status} @subheading gnutls-cli-debug exit status One of the following exit values will be returned: @table @samp @item 0 (EXIT_SUCCESS) Successful program execution. @item 1 (EXIT_FAILURE) The operation failed or the command syntax was not valid. @end table @anchor{gnutls-cli-debug See Also} @subsubheading gnutls-cli-debug See Also gnutls-cli(1), gnutls-serv(1) @anchor{gnutls-cli-debug Examples} @subsubheading gnutls-cli-debug Examples @example $ 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 @end example You could also use the client to debug services with starttls capability. @example $ gnutls-cli-debug --starttls-proto smtp --port 25 localhost @end example