2000-01-09 03:05:47 +08:00
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=pod
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=head1 NAME
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s_client - SSL/TLS client program
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=head1 SYNOPSIS
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B<openssl> B<s_client>
|
2004-01-05 02:59:14 +08:00
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[B<-connect host:port>]
|
2015-05-09 03:34:07 +08:00
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[B<-proxy host:port>]
|
2014-07-03 10:42:40 +08:00
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[B<-servername name>]
|
2000-01-15 06:43:11 +08:00
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[B<-verify depth>]
|
2014-04-07 20:02:10 +08:00
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[B<-verify_return_error>]
|
2000-01-09 03:05:47 +08:00
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[B<-cert filename>]
|
2004-11-17 01:30:59 +08:00
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[B<-certform DER|PEM>]
|
2000-01-09 03:05:47 +08:00
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[B<-key filename>]
|
2004-11-17 01:30:59 +08:00
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[B<-keyform DER|PEM>]
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[B<-pass arg>]
|
2000-01-09 03:05:47 +08:00
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[B<-CApath directory>]
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[B<-CAfile filename>]
|
2015-09-23 02:43:59 +08:00
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[B<-no-CAfile>]
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[B<-no-CApath>]
|
2015-12-30 03:25:50 +08:00
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[B<-dane_tlsa_domain domain>]
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[B<-dane_tlsa_rrdata rrdata>]
|
2014-06-19 21:34:49 +08:00
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[B<-attime timestamp>]
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[B<-check_ss_sig>]
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[B<-crl_check>]
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[B<-crl_check_all>]
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[B<-explicit_policy>]
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[B<-extended_crl>]
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[B<-ignore_critical>]
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[B<-inhibit_any>]
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[B<-inhibit_map>]
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[B<-issuer_checks>]
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[B<-partial_chain>]
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[B<-policy arg>]
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[B<-policy_check>]
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[B<-policy_print>]
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[B<-purpose purpose>]
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[B<-suiteB_128>]
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[B<-suiteB_128_only>]
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[B<-suiteB_192>]
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[B<-trusted_first>]
|
2015-01-27 19:15:15 +08:00
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[B<-no_alt_chains>]
|
2014-06-19 21:34:49 +08:00
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[B<-use_deltas>]
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[B<-verify_depth num>]
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[B<-verify_email email>]
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[B<-verify_hostname hostname>]
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[B<-verify_ip ip>]
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[B<-verify_name name>]
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[B<-x509_strict>]
|
2000-01-09 03:05:47 +08:00
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[B<-reconnect>]
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[B<-showcerts>]
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[B<-debug>]
|
2001-11-10 10:12:09 +08:00
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[B<-msg>]
|
2000-01-09 03:05:47 +08:00
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[B<-nbio_test>]
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[B<-state>]
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[B<-nbio>]
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[B<-crlf>]
|
2000-03-10 20:18:28 +08:00
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[B<-ign_eof>]
|
2014-07-03 10:42:40 +08:00
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[B<-no_ign_eof>]
|
2000-01-09 03:05:47 +08:00
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[B<-quiet>]
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[B<-ssl3>]
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[B<-tls1>]
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[B<-no_ssl3>]
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[B<-no_tls1>]
|
2014-10-15 16:43:50 +08:00
|
|
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[B<-no_tls1_1>]
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[B<-no_tls1_2>]
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[B<-fallback_scsv>]
|
2015-10-06 20:48:43 +08:00
|
|
|
[B<-async>]
|
2000-01-09 03:05:47 +08:00
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[B<-bugs>]
|
2016-02-04 05:45:39 +08:00
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|
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[B<-comp>]
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[B<-no_comp>]
|
2000-01-09 03:05:47 +08:00
|
|
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[B<-cipher cipherlist>]
|
2014-07-03 10:42:40 +08:00
|
|
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[B<-serverpref>]
|
2003-03-21 00:34:27 +08:00
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[B<-starttls protocol>]
|
2012-08-06 08:24:51 +08:00
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[B<-xmpphost hostname>]
|
2000-10-27 05:07:28 +08:00
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[B<-engine id>]
|
2007-08-23 19:34:48 +08:00
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[B<-tlsextdebug>]
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[B<-no_ticket>]
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[B<-sess_out filename>]
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[B<-sess_in filename>]
|
2001-02-15 18:22:07 +08:00
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|
[B<-rand file(s)>]
|
2013-06-14 13:36:45 +08:00
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[B<-serverinfo types>]
|
2014-07-07 05:16:21 +08:00
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[B<-status>]
|
2014-06-06 22:48:43 +08:00
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|
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[B<-nextprotoneg protocols>]
|
2000-01-09 03:05:47 +08:00
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=head1 DESCRIPTION
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The B<s_client> command implements a generic SSL/TLS client which connects
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to a remote host using SSL/TLS. It is a I<very> useful diagnostic tool for
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SSL servers.
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=head1 OPTIONS
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|
2012-11-20 00:07:53 +08:00
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In addition to the options below the B<s_client> utility also supports the
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common and client only options documented in the
|
2012-11-20 09:01:33 +08:00
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|
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in the L<SSL_CONF_cmd(3)|SSL_CONF_cmd(3)/SUPPORTED COMMAND LINE COMMANDS>
|
|
|
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manual page.
|
2012-11-20 00:07:53 +08:00
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|
2000-01-09 03:05:47 +08:00
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|
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=over 4
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=item B<-connect host:port>
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This specifies the host and optional port to connect to. If not specified
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then an attempt is made to connect to the local host on port 4433.
|
|
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|
|
2015-05-09 03:34:07 +08:00
|
|
|
=item B<-proxy host:port>
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When used with the B<-connect> flag, the program uses the host and port
|
|
|
|
specified with this flag and issues an HTTP CONNECT command to connect
|
|
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to the desired server.
|
|
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|
|
2014-07-03 10:42:40 +08:00
|
|
|
=item B<-servername name>
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Set the TLS SNI (Server Name Indication) extension in the ClientHello message.
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|
2000-01-09 03:05:47 +08:00
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|
|
=item B<-cert certname>
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The certificate to use, if one is requested by the server. The default is
|
|
|
|
not to use a certificate.
|
|
|
|
|
2004-11-17 01:30:59 +08:00
|
|
|
=item B<-certform format>
|
|
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|
|
The certificate format to use: DER or PEM. PEM is the default.
|
|
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|
2000-01-09 03:05:47 +08:00
|
|
|
=item B<-key keyfile>
|
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|
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The private key to use. If not specified then the certificate file will
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|
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|
be used.
|
|
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|
|
2004-11-17 01:30:59 +08:00
|
|
|
=item B<-keyform format>
|
|
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|
The private format to use: DER or PEM. PEM is the default.
|
|
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|
|
=item B<-pass arg>
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|
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|
|
the private key password source. For more information about the format of B<arg>
|
2015-08-18 03:21:33 +08:00
|
|
|
see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
|
2004-11-17 01:30:59 +08:00
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|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=item B<-verify depth>
|
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|
|
The verify depth to use. This specifies the maximum length of the
|
|
|
|
server certificate chain and turns on server certificate verification.
|
|
|
|
Currently the verify operation continues after errors so all the problems
|
|
|
|
with a certificate chain can be seen. As a side effect the connection
|
|
|
|
will never fail due to a server certificate verify failure.
|
|
|
|
|
2014-04-07 20:02:10 +08:00
|
|
|
=item B<-verify_return_error>
|
|
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|
Return verification errors instead of continuing. This will typically
|
|
|
|
abort the handshake with a fatal error.
|
|
|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=item B<-CApath directory>
|
|
|
|
|
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|
|
The directory to use for server certificate verification. This directory
|
|
|
|
must be in "hash format", see B<verify> for more information. These are
|
|
|
|
also used when building the client certificate chain.
|
|
|
|
|
|
|
|
=item B<-CAfile file>
|
|
|
|
|
|
|
|
A file containing trusted certificates to use during server authentication
|
|
|
|
and to use when attempting to build the client certificate chain.
|
|
|
|
|
2015-09-23 02:43:59 +08:00
|
|
|
=item B<-no-CAfile>
|
|
|
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|
|
Do not load the trusted CA certificates from the default file location
|
|
|
|
|
|
|
|
=item B<-no-CApath>
|
|
|
|
|
|
|
|
Do not load the trusted CA certificates from the default directory location
|
|
|
|
|
2015-12-30 03:25:50 +08:00
|
|
|
=item B<-dane_tlsa_domain domain>
|
|
|
|
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|
|
Enable RFC6698/RFC7671 DANE TLSA authentication and specify the
|
|
|
|
TLSA base domain which becomes the default SNI hint and the primary
|
|
|
|
reference identifier for hostname checks. This must be used in
|
|
|
|
combination with at least one instance of the B<-dane_tlsa_rrdata>
|
|
|
|
option below.
|
|
|
|
|
|
|
|
When DANE authentication succeeds, the diagnostic output will include
|
|
|
|
the lowest (closest to 0) depth at which a TLSA record authenticated
|
|
|
|
a chain certificate. When that TLSA record is a "2 1 0" trust
|
|
|
|
anchor public key that signed (rather than matched) the top-most
|
|
|
|
certificate of the chain, the result is reported as "TA public key
|
|
|
|
verified". Otherwise, either the TLSA record "matched TA certificate"
|
|
|
|
at a positive depth or else "matched EE certificate" at depth 0.
|
|
|
|
|
|
|
|
=item B<-dane_tlsa_rrdata rrdata>
|
|
|
|
|
|
|
|
Use one or more times to specify the RRDATA fields of the DANE TLSA
|
|
|
|
RRset associated with the target service. The B<rrdata> value is
|
|
|
|
specied in "presentation form", that is four whitespace separated
|
|
|
|
fields that specify the usage, selector, matching type and associated
|
|
|
|
data, with the last of these encoded in hexadecimal. Optional
|
|
|
|
whitespace is ignored in the associated data field. For example:
|
|
|
|
|
|
|
|
$ openssl s_client -starttls smtp -connect smtp.example.com:25 \
|
|
|
|
-dane_tlsa_domain smtp.example.com \
|
|
|
|
-dane_tlsa_rrdata "2 1 1
|
|
|
|
B111DD8A1C2091A89BD4FD60C57F0716CCE50FEEFF8137CDBEE0326E 02CF362B" \
|
|
|
|
-dane_tlsa_rrdata "2 1 1
|
|
|
|
60B87575447DCBA2A36B7D11AC09FB24A9DB406FEE12D2CC90180517 616E8A18"
|
|
|
|
CONNECTED(00000003)
|
|
|
|
...
|
|
|
|
DANE TLSA 2 1 1 matched TA certificate at depth 1
|
|
|
|
Verified peername: smtp.example.com
|
|
|
|
...
|
|
|
|
Verify return code: 0 (ok)
|
|
|
|
...
|
|
|
|
|
2014-06-19 21:34:49 +08:00
|
|
|
=item B<-attime>, B<-check_ss_sig>, B<-crl_check>, B<-crl_check_all>,
|
|
|
|
B<explicit_policy>, B<-extended_crl>, B<-ignore_critical>, B<-inhibit_any>,
|
|
|
|
B<-inhibit_map>, B<-issuer_checks>, B<-partial_chain>, B<-policy>,
|
|
|
|
B<-policy_check>, B<-policy_print>, B<-purpose>, B<-suiteB_128>,
|
2015-01-27 19:15:15 +08:00
|
|
|
B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>, B<-no_alt_chains>,
|
|
|
|
B<-use_deltas>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
|
|
|
|
B<-verify_ip>, B<-verify_name>, B<-x509_strict>
|
2009-04-15 23:27:03 +08:00
|
|
|
|
2015-01-27 19:15:15 +08:00
|
|
|
Set various certificate chain validation options. See the
|
2015-08-18 03:21:33 +08:00
|
|
|
L<verify(1)> manual page for details.
|
2009-04-15 23:27:03 +08:00
|
|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=item B<-reconnect>
|
|
|
|
|
|
|
|
reconnects to the same server 5 times using the same session ID, this can
|
|
|
|
be used as a test that session caching is working.
|
|
|
|
|
|
|
|
=item B<-showcerts>
|
|
|
|
|
|
|
|
display the whole server certificate chain: normally only the server
|
|
|
|
certificate itself is displayed.
|
|
|
|
|
|
|
|
=item B<-prexit>
|
|
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|
|
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|
|
print session information when the program exits. This will always attempt
|
|
|
|
to print out information even if the connection fails. Normally information
|
|
|
|
will only be printed out once if the connection succeeds. This option is useful
|
|
|
|
because the cipher in use may be renegotiated or the connection may fail
|
|
|
|
because a client certificate is required or is requested only after an
|
|
|
|
attempt is made to access a certain URL. Note: the output produced by this
|
|
|
|
option is not always accurate because a connection might never have been
|
|
|
|
established.
|
|
|
|
|
|
|
|
=item B<-state>
|
|
|
|
|
|
|
|
prints out the SSL session states.
|
|
|
|
|
|
|
|
=item B<-debug>
|
|
|
|
|
|
|
|
print extensive debugging information including a hex dump of all traffic.
|
|
|
|
|
2001-11-10 10:12:09 +08:00
|
|
|
=item B<-msg>
|
|
|
|
|
|
|
|
show all protocol messages with hex dump.
|
|
|
|
|
2012-11-20 00:37:18 +08:00
|
|
|
=item B<-trace>
|
|
|
|
|
|
|
|
show verbose trace output of protocol messages. OpenSSL needs to be compiled
|
|
|
|
with B<enable-ssl-trace> for this option to work.
|
|
|
|
|
|
|
|
=item B<-msgfile>
|
|
|
|
|
|
|
|
file to send output of B<-msg> or B<-trace> to, default standard output.
|
|
|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=item B<-nbio_test>
|
|
|
|
|
2000-02-04 07:23:24 +08:00
|
|
|
tests non-blocking I/O
|
2000-01-09 03:05:47 +08:00
|
|
|
|
|
|
|
=item B<-nbio>
|
|
|
|
|
2000-02-04 07:23:24 +08:00
|
|
|
turns on non-blocking I/O
|
2000-01-09 03:05:47 +08:00
|
|
|
|
|
|
|
=item B<-crlf>
|
|
|
|
|
|
|
|
this option translated a line feed from the terminal into CR+LF as required
|
|
|
|
by some servers.
|
|
|
|
|
2000-03-10 20:18:28 +08:00
|
|
|
=item B<-ign_eof>
|
|
|
|
|
|
|
|
inhibit shutting down the connection when end of file is reached in the
|
|
|
|
input.
|
|
|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=item B<-quiet>
|
|
|
|
|
2001-09-07 14:13:40 +08:00
|
|
|
inhibit printing of session and certificate information. This implicitly
|
2000-03-10 20:18:28 +08:00
|
|
|
turns on B<-ign_eof> as well.
|
2000-01-09 03:05:47 +08:00
|
|
|
|
2014-07-03 10:42:40 +08:00
|
|
|
=item B<-no_ign_eof>
|
|
|
|
|
|
|
|
shut down the connection when end of file is reached in the input.
|
|
|
|
Can be used to override the implicit B<-ign_eof> after B<-quiet>.
|
|
|
|
|
2006-03-11 07:06:27 +08:00
|
|
|
=item B<-psk_identity identity>
|
|
|
|
|
|
|
|
Use the PSK identity B<identity> when using a PSK cipher suite.
|
|
|
|
|
|
|
|
=item B<-psk key>
|
|
|
|
|
|
|
|
Use the PSK key B<key> when using a PSK cipher suite. The key is
|
|
|
|
given as a hexadecimal number without leading 0x, for example -psk
|
|
|
|
1a2b3c4d.
|
|
|
|
|
2014-11-30 22:35:22 +08:00
|
|
|
=item B<-ssl3>, B<-tls1>, B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>
|
2000-01-09 03:05:47 +08:00
|
|
|
|
|
|
|
these options disable the use of certain SSL or TLS protocols. By default
|
|
|
|
the initial handshake uses a method which should be compatible with all
|
2014-11-30 22:35:22 +08:00
|
|
|
servers and permit them to use SSL v3 or TLS as appropriate.
|
2000-01-09 03:05:47 +08:00
|
|
|
|
2014-10-15 16:43:50 +08:00
|
|
|
Unfortunately there are still ancient and broken servers in use which
|
2000-01-09 03:05:47 +08:00
|
|
|
cannot handle this technique and will fail to connect. Some servers only
|
2014-10-15 16:43:50 +08:00
|
|
|
work if TLS is turned off.
|
|
|
|
|
|
|
|
=item B<-fallback_scsv>
|
|
|
|
|
|
|
|
Send TLS_FALLBACK_SCSV in the ClientHello.
|
2000-01-09 03:05:47 +08:00
|
|
|
|
2015-10-06 20:48:43 +08:00
|
|
|
=item B<-async>
|
|
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|
switch on asynchronous mode. Cryptographic operations will be performed
|
|
|
|
asynchronously. This will only have an effect if an asynchronous capable engine
|
|
|
|
is also used via the B<-engine> option. For test purposes the dummy async engine
|
|
|
|
(dasync) can be used (if available).
|
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|
|
2000-01-09 03:05:47 +08:00
|
|
|
=item B<-bugs>
|
|
|
|
|
|
|
|
there are several known bug in SSL and TLS implementations. Adding this
|
|
|
|
option enables various workarounds.
|
|
|
|
|
2016-02-04 05:45:39 +08:00
|
|
|
=item B<-comp>
|
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|
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|
|
Enables support for SSL/TLS compression.
|
|
|
|
This option was introduced in OpenSSL 1.1.0.
|
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|
|
TLS compression is not recommended and is off by default as of
|
|
|
|
OpenSSL 1.1.0.
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|
|
=item B<-no_comp>
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|
|
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|
|
Disables support for SSL/TLS compression.
|
|
|
|
TLS compression is not recommended and is off by default as of
|
|
|
|
OpenSSL 1.1.0.
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|
2012-11-20 00:07:53 +08:00
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|
|
=item B<-brief>
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|
|
only provide a brief summary of connection parameters instead of the
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|
|
|
normal verbose output.
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|
2000-01-09 03:05:47 +08:00
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|
|
=item B<-cipher cipherlist>
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|
2000-01-23 10:28:08 +08:00
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|
|
this allows the cipher list sent by the client to be modified. Although
|
|
|
|
the server determines which cipher suite is used it should take the first
|
|
|
|
supported cipher in the list sent by the client. See the B<ciphers>
|
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|
|
command for more information.
|
2000-01-09 03:05:47 +08:00
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|
2003-03-21 00:34:27 +08:00
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|
|
=item B<-starttls protocol>
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|
|
send the protocol-specific message(s) to switch to TLS for communication.
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|
|
B<protocol> is a keyword for the intended protocol. Currently, the only
|
2015-05-14 04:00:21 +08:00
|
|
|
supported keywords are "smtp", "pop3", "imap", "ftp", "xmpp", "xmpp-server",
|
|
|
|
and "irc."
|
2003-03-21 00:34:27 +08:00
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|
|
2012-08-06 08:24:51 +08:00
|
|
|
=item B<-xmpphost hostname>
|
|
|
|
|
2015-07-30 05:41:00 +08:00
|
|
|
This option, when used with "-starttls xmpp" or "-starttls xmpp-server",
|
|
|
|
specifies the host for the "to" attribute of the stream element.
|
2012-08-06 08:24:51 +08:00
|
|
|
If this option is not specified, then the host specified with "-connect"
|
|
|
|
will be used.
|
|
|
|
|
2007-08-23 19:34:48 +08:00
|
|
|
=item B<-tlsextdebug>
|
|
|
|
|
|
|
|
print out a hex dump of any TLS extensions received from the server.
|
|
|
|
|
|
|
|
=item B<-no_ticket>
|
|
|
|
|
|
|
|
disable RFC4507bis session ticket support.
|
|
|
|
|
|
|
|
=item B<-sess_out filename>
|
|
|
|
|
|
|
|
output SSL session to B<filename>
|
|
|
|
|
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|
|
=item B<-sess_in sess.pem>
|
|
|
|
|
|
|
|
load SSL session from B<filename>. The client will attempt to resume a
|
|
|
|
connection from this session.
|
|
|
|
|
2000-10-27 05:07:28 +08:00
|
|
|
=item B<-engine id>
|
|
|
|
|
2009-04-15 23:27:03 +08:00
|
|
|
specifying an engine (by its unique B<id> string) will cause B<s_client>
|
2000-10-27 05:07:28 +08:00
|
|
|
to attempt to obtain a functional reference to the specified engine,
|
|
|
|
thus initialising it if needed. The engine will then be set as the default
|
|
|
|
for all available algorithms.
|
|
|
|
|
2001-02-15 18:22:07 +08:00
|
|
|
=item B<-rand file(s)>
|
|
|
|
|
|
|
|
a file or files containing random data used to seed the random number
|
2015-08-18 03:21:33 +08:00
|
|
|
generator, or an EGD socket (see L<RAND_egd(3)>).
|
2001-02-15 18:22:07 +08:00
|
|
|
Multiple files can be specified separated by a OS-dependent character.
|
|
|
|
The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
|
|
|
|
all others.
|
|
|
|
|
2013-06-14 13:36:45 +08:00
|
|
|
=item B<-serverinfo types>
|
|
|
|
|
|
|
|
a list of comma-separated TLS Extension Types (numbers between 0 and
|
|
|
|
65535). Each type will be sent as an empty ClientHello TLS Extension.
|
|
|
|
The server's response (if any) will be encoded and displayed as a PEM
|
|
|
|
file.
|
|
|
|
|
2014-07-07 05:16:21 +08:00
|
|
|
=item B<-status>
|
|
|
|
|
|
|
|
sends a certificate status request to the server (OCSP stapling). The server
|
|
|
|
response (if any) is printed out.
|
|
|
|
|
2014-06-06 22:48:43 +08:00
|
|
|
=item B<-nextprotoneg protocols>
|
|
|
|
|
|
|
|
enable Next Protocol Negotiation TLS extension and provide a list of
|
|
|
|
comma-separated protocol names that the client should advertise
|
|
|
|
support for. The list should contain most wanted protocols first.
|
|
|
|
Protocol names are printable ASCII strings, for example "http/1.1" or
|
|
|
|
"spdy/3".
|
|
|
|
Empty list of protocols is treated specially and will cause the client to
|
|
|
|
advertise support for the TLS extension but disconnect just after
|
2015-04-14 00:29:52 +08:00
|
|
|
receiving ServerHello with a list of server supported protocols.
|
2014-06-06 22:48:43 +08:00
|
|
|
|
2000-01-11 08:06:40 +08:00
|
|
|
=back
|
|
|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=head1 CONNECTED COMMANDS
|
|
|
|
|
|
|
|
If a connection is established with an SSL server then any data received
|
|
|
|
from the server is displayed and any key presses will be sent to the
|
2000-03-10 20:18:28 +08:00
|
|
|
server. When used interactively (which means neither B<-quiet> nor B<-ign_eof>
|
2001-09-07 14:13:40 +08:00
|
|
|
have been given), the session will be renegotiated if the line begins with an
|
2000-03-10 20:18:28 +08:00
|
|
|
B<R>, and if the line begins with a B<Q> or if end of file is reached, the
|
|
|
|
connection will be closed down.
|
2000-01-09 03:05:47 +08:00
|
|
|
|
|
|
|
=head1 NOTES
|
|
|
|
|
|
|
|
B<s_client> can be used to debug SSL servers. To connect to an SSL HTTP
|
|
|
|
server the command:
|
|
|
|
|
|
|
|
openssl s_client -connect servername:443
|
|
|
|
|
|
|
|
would typically be used (https uses port 443). If the connection succeeds
|
|
|
|
then an HTTP command can be given such as "GET /" to retrieve a web page.
|
|
|
|
|
|
|
|
If the handshake fails then there are several possible causes, if it is
|
2014-11-30 22:35:22 +08:00
|
|
|
nothing obvious like no client certificate then the B<-bugs>,
|
|
|
|
B<-ssl3>, B<-tls1>, B<-no_ssl3>, B<-no_tls1> options can be tried
|
2000-01-09 03:05:47 +08:00
|
|
|
in case it is a buggy server. In particular you should play with these
|
|
|
|
options B<before> submitting a bug report to an OpenSSL mailing list.
|
|
|
|
|
|
|
|
A frequent problem when attempting to get client certificates working
|
|
|
|
is that a web client complains it has no certificates or gives an empty
|
|
|
|
list to choose from. This is normally because the server is not sending
|
|
|
|
the clients certificate authority in its "acceptable CA list" when it
|
|
|
|
requests a certificate. By using B<s_client> the CA list can be viewed
|
|
|
|
and checked. However some servers only request client authentication
|
|
|
|
after a specific URL is requested. To obtain the list in this case it
|
2004-01-05 02:59:14 +08:00
|
|
|
is necessary to use the B<-prexit> option and send an HTTP request
|
2000-01-09 03:05:47 +08:00
|
|
|
for an appropriate page.
|
|
|
|
|
|
|
|
If a certificate is specified on the command line using the B<-cert>
|
|
|
|
option it will not be used unless the server specifically requests
|
|
|
|
a client certificate. Therefor merely including a client certificate
|
|
|
|
on the command line is no guarantee that the certificate works.
|
|
|
|
|
|
|
|
If there are problems verifying a server certificate then the
|
|
|
|
B<-showcerts> option can be used to show the whole chain.
|
|
|
|
|
2014-04-07 20:02:10 +08:00
|
|
|
The B<s_client> utility is a test tool and is designed to continue the
|
|
|
|
handshake after any certificate verification errors. As a result it will
|
|
|
|
accept any certificate chain (trusted or not) sent by the peer. None test
|
|
|
|
applications should B<not> do this as it makes them vulnerable to a MITM
|
|
|
|
attack. This behaviour can be changed by with the B<-verify_return_error>
|
|
|
|
option: any verify errors are then returned aborting the handshake.
|
|
|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=head1 BUGS
|
|
|
|
|
|
|
|
Because this program has a lot of options and also because some of
|
2000-01-09 09:26:43 +08:00
|
|
|
the techniques used are rather old, the C source of s_client is rather
|
2000-01-09 03:05:47 +08:00
|
|
|
hard to read and not a model of how things should be done. A typical
|
|
|
|
SSL client program would be much simpler.
|
|
|
|
|
|
|
|
The B<-prexit> option is a bit of a hack. We should really report
|
|
|
|
information whenever a session is renegotiated.
|
|
|
|
|
|
|
|
=head1 SEE ALSO
|
|
|
|
|
2015-08-18 03:21:33 +08:00
|
|
|
L<sess_id(1)>, L<s_server(1)>, L<ciphers(1)>
|
2000-01-09 03:05:47 +08:00
|
|
|
|
2015-01-27 19:15:15 +08:00
|
|
|
=head1 HISTORY
|
|
|
|
|
|
|
|
The -no_alt_chains options was first added to OpenSSL 1.1.0.
|
|
|
|
|
2000-01-09 03:05:47 +08:00
|
|
|
=cut
|