s_server - SSL/TLS server program


SYNOPSIS

       openssl s_server [-accept port] [-context id] [-verify
       depth] [-Verify depth] [-cert filename] [-key keyfile]
       [-dcert filename] [-dkey keyfile] [-dhparam filename]
       [-nbio] [-nbio_test] [-crlf] [-debug] [-state] [-CApath
       directory] [-CAfile filename] [-nocert] [-cipher
       cipherlist] [-quiet] [-no_tmp_rsa] [-ssl2] [-ssl3] [-tls1]
       [-no_ssl2] [-no_ssl3] [-no_tls1] [-no_dhe] [-bugs] [-hack]
       [-www] [-WWW] [-rand file(s)] [-engine id]


DESCRIPTION

       The s_server command implements a generic SSL/TLS server
       which listens for connections on a given port using
       SSL/TLS.


OPTIONS

       -accept port
           the TCP port to listen on for connections. If not
           specified 4433 is used.

       -context id
           sets the SSL context id. It can be given any string
           value. If this option is not present a default value
           will be used.

       -cert certname
           The certificate to use, most servers cipher suites
           require the use of a certificate and some require a
           certificate with a certain public key type: for
           example the DSS cipher suites require a certificate
           containing a DSS (DSA) key. If not specified then the
           filename "server.pem" will be used.

       -key keyfile
           The private key to use. If not specified then the
           certificate file will be used.

       -dcert filename, -dkey keyname
           specify an additional certificate and private key,
           these behave in the same manner as the -cert and -key
           options except there is no default if they are not
           specified (no additional certificate and key is used).
           As noted above some cipher suites require a
           certificate containing a key of a certain type. Some
           cipher suites need a certificate carrying an RSA key
           and some a DSS (DSA) key. By using RSA and DSS
           certificates and keys a server can support clients
           which only support RSA or DSS cipher suites by using
           an appropriate certificate.

           if this option is set then no certificate is used.
           This restricts the cipher suites available to the
           anonymous ones (currently just anonymous DH).

       -dhparam filename
           the DH parameter file to use. The ephemeral DH cipher
           suites generate keys using a set of DH parameters. If
           not specified then an attempt is made to load the
           parameters from the server certificate file. If this
           fails then a static set of parameters hard coded into
           the s_server program will be used.

       -no_dhe
           if this option is set then no DH parameters will be
           loaded effectively disabling the ephemeral DH cipher
           suites.

       -no_tmp_rsa
           certain export cipher suites sometimes use a temporary
           RSA key, this option disables temporary RSA key
           generation.

       -verify depth, -Verify depth
           The verify depth to use. This specifies the maximum
           length of the client certificate chain and makes the
           server request a certificate from the client. With the
           -verify option a certificate is requested but the
           client does not have to send one, with the -Verify
           option the client must supply a certificate or an
           error occurs.

       -CApath directory
           The directory to use for client certificate
           verification. This directory must be in "hash format",
           see verify for more information. These are also used
           when building the server certificate chain.

       -CAfile file
           A file containing trusted certificates to use during
           client authentication and to use when attempting to
           build the server certificate chain. The list is also
           used in the list of acceptable client CAs passed to
           the client when a certificate is requested.

       -state
           prints out the SSL session states.

       -debug
           print extensive debugging information including a hex
           dump of all traffic.

       -nbio_test
           tests non blocking I/O

           turns on non blocking I/O

       -crlf
           this option translated a line feed from the terminal
           into CR+LF.

       -quiet
           inhibit printing of session and certificate
           information.

       -ssl2, -ssl3, -tls1, -no_ssl2, -no_ssl3, -no_tls1
           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 servers and
           permit them to use SSL v3, SSL v2 or TLS as
           appropriate.

       -bugs
           there are several known bug in SSL and TLS
           implementations. Adding this option enables various
           workarounds.

       -hack
           this option enables a further workaround for some some
           early Netscape SSL code (?).

       -cipher cipherlist
           this allows the cipher list used by the server to be
           modified.  When the client sends a list of supported
           ciphers the first client cipher also included in the
           server list is used. Because the client specifies the
           preference order, the order of the server cipherlist
           irrelevant. See the ciphers command for more
           information.

       -www
           sends a status message back to the client when it
           connects. This includes lots of information about the
           ciphers used and various session parameters.  The
           output is in HTML format so this option will normally
           be used with a web browser.

       -WWW
           emulates a simple web server. Pages will be resolved
           relative to the current directory, for example if the
           URL https://myhost/page.html is requested the file
           ./page.html will be loaded.

       -rand file(s)
           a file or files containing random data used to seed
           the random number generator, or an EGD socket (see
           RAND_egd(3)).  Multiple files can be specified
           separated by a OS-dependent character.  The separator

           others.

       -engine id
           specifying an engine (by it's unique id string) will
           cause s_server 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.


CONNECTED COMMANDS

       If a connection request is established with an SSL client
       and neither the -www nor the -WWW option has been used
       then normally any data received from the client is
       displayed and any key presses will be sent to the client.

       Certain single letter commands are also recognized which
       perform special operations: these are listed below.

       q   end the current SSL connection but still accept new
           connections.

       Q   end the current SSL connection and exit.

       r   renegotiate the SSL session.

       R   renegotiate the SSL session and request a client
           certificate.

       P   send some plain text down the underlying TCP
           connection: this should cause the client to disconnect
           due to a protocol violation.

       S   print out some session cache status information.


NOTES

       s_server can be used to debug SSL clients. To accept
       connections from a web browser the command:

        openssl s_server -accept 443 -www

       can be used for example.

       Most web browsers (in particular Netscape and MSIE) only
       support RSA cipher suites, so they cannot connect to
       servers which don't use a certificate carrying an RSA key
       or a version of OpenSSL with RSA disabled.

       Although specifying an empty list of CAs when requesting a
       client certificate is strictly speaking a protocol
       violation, some SSL clients interpret this to mean any CA
       is acceptable. This is useful for debugging purposes.

       The session parameters can printed out using the sess_id



BUGS

       Because this program has a lot of options and also because
       some of the techniques used are rather old, the C source
       of s_server is rather hard to read and not a model of how
       things should be done. A typical SSL server program would
       be much simpler.

       The output of common ciphers is wrong: it just gives the
       list of ciphers that OpenSSL recognizes and the client
       supports.

       There should be a way for the s_server program to print
       out details of any unknown cipher suites a client says it
       supports.


SEE ALSO

       sess_id(1), s_client(1), ciphers(1)



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