S_SERVER(1)                 OpenSSL                 S_SERVER(1)





NAME
       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] [-msg] [-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] [-HTTP] [-engine
       id] [-id_prefix arg] [-rand file(s)]

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 cer-
           tificates and keys a server can support clients
           which only support RSA or DSS cipher suites by using
           an appropriate certificate.

       -nocert
           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 param-
           eters. 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 tempo-
           rary 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 -Ver-
           ify option the client must supply a certificate or
           an error occurs.

       -CApath directory
           The directory to use for client certificate verifi-
           cation. 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.

       -msg
           show all protocol messages with hex dump.

       -nbio_test
           tests non blocking I/O

       -nbio
           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 informa-
           tion.

       -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 implemen-
           tations. Adding this option enables various work-
           arounds.

       -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.

       -HTTP
           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. The files loaded
           are assumed to contain a complete and correct HTTP
           response (lines that are part of the HTTP response
           line and headers must end with CRLF).

       -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.

       -id_prefix arg
           generate SSL/TLS session IDs prefixed by arg. This
           is mostly useful for testing any SSL/TLS code (eg.
           proxies) that wish to deal with multiple servers,
           when each of which might be generating a unique
           range of session IDs (eg. with a certain prefix).

       -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 sepa-
           rated by a OS-dependent character.  The separator is
           ; for MS-Windows, , for OpenVMS, and : for all oth-
           ers.

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 connec-
           tion: 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
       program.

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)



0.9.7c                     2003-03-20               S_SERVER(1)
