S_SERVER(1)                         OpenSSL                        S_SERVER(1)



NAME
       s_server - SSL/TLS server program

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
       openssl s_server [-accept port] [-context id] [-verify depth] [-Verify
       depth] [-crl_check] [-crl_check_all] [-cert filename] [-certform
       DER|PEM] [-key keyfile] [-keyform DER|PEM] [-pass arg] [-dcert
       filename] [-dcertform DER|PEM] [-dkey keyfile] [-dkeyform DER|PEM]
       [-dpass arg] [-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] [-no_ecdhe] [-bugs] [-hack]
       [-www] [-WWW] [-HTTP] [-engine id] [-tlsextdebug] [-no_ticket]
       [-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.

       -certform format
           The certificate format to use: DER or PEM. PEM is the default.

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

       -keyform format
           The private format to use: DER or PEM. PEM is the default.

       -pass arg
           the private key password source. For more information about the
           format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).

       -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.

       -dcertform format, -dkeyform format, -dpass arg
           additional certificate and private key format and passphrase
           respectively.

       -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 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_ecdhe
           if this option is set then no ECDH parameters will be loaded
           effectively disabling the ephemeral ECDH 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.

       -crl_check, -crl_check_all
           Check the peer certificate has not been revoked by its CA.  The
           CRL(s) are appended to the certificate file. With the
           -crl_check_all option all CRLs of all CAs in the chain are checked.

       -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.

       -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 information.

       -psk_hint hint
           Use the PSK identity hint hint when using a PSK cipher suite.

       -psk key
           Use the PSK key key when using a PSK cipher suite. The key is given
           as a hexadecimal number without leading 0x, for example -psk
           1a2b3c4d.

       -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.

       -tlsextdebug
           print out a hex dump of any TLS extensions received from the
           server.

       -no_ticket
           disable RFC4507bis session ticket support.

       -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 its 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 separated by a OS-dependent character.  The
           separator is ; for MS-Windows, , for OpenVMS, and : for all others.

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 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
       openssl_sess_id(1), openssl_s_client(1), openssl_ciphers(1)



1.0.1h                            2014-06-05                       S_SERVER(1)

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