S_SERVER 1 2008-05-09 0.9.9-dev OpenSSL

NAME

s_server - SSL/TLS server program

LIBRARY

libcrypto, -lcrypto

SYNOPSIS

ooppeennssssll ss__sseerrvveerr [--aacccceepptt ppoorrtt] [--ccoonntteexxtt iidd] [--vveerriiffyy ddeepptthh] [--VVeerriiffyy ddeepptthh] [--cceerrtt ffiilleennaammee] [--cceerrttffoorrmm DDEERR||PPEEMM] [--kkeeyy kkeeyyffiillee] [--kkeeyyffoorrmm DDEERR||PPEEMM] [--ppaassss aarrgg] [--ddcceerrtt ffiilleennaammee] [--ddcceerrttffoorrmm DDEERR||PPEEMM] [--ddkkeeyy kkeeyyffiillee] [--ddkkeeyyffoorrmm DDEERR||PPEEMM] [--ddppaassss aarrgg] [--ddhhppaarraamm ffiilleennaammee] [--nnbbiioo] [--nnbbiioo__tteesstt] [--ccrrllff] [--ddeebbuugg] [--mmssgg] [--ssttaattee] [--CCAAppaatthh ddiirreeccttoorryy] [--CCAAffiillee ffiilleennaammee] [--nnoocceerrtt] [--cciipphheerr cciipphheerrlliisstt] [--qquuiieett] [--nnoo__ttmmpp__rrssaa] [--ssssll22] [--ssssll33] [--ttllss11] [--nnoo__ssssll22] [--nnoo__ssssll33] [--nnoo__ttllss11] [--nnoo__ddhhee] [--bbuuggss] [--hhaacckk] [--wwwwww] [--WWWWWW] [--HHTTTTPP] [--eennggiinnee iidd] [--ttllsseexxttddeebbuugg] [--nnoo__ttiicckkeett] [--iidd__pprreeffiixx aarrgg] [--rraanndd ffiillee((ss))]

DESCRIPTION

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

OPTIONS

--aacccceepptt ppoorrtt the TCP port to listen on for connections. If not specified 4433 is used.
--ccoonntteexxtt iidd sets the SSL context id. It can be given any string value. If this option
is not present a default value will be used.
--cceerrtt cceerrttnnaammee 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.
--cceerrttffoorrmm ffoorrmmaatt The certificate format to use: DER or PEM. PEM is the default.
--kkeeyy kkeeyyffiillee The private key to use. If not specified then the certificate file will
be used.
--kkeeyyffoorrmm ffoorrmmaatt The private format to use: DER or PEM. PEM is the default.
--ppaassss aarrgg the private key password source. For more information about the format of aarrgg
see the PPAASSSS PPHHRRAASSEE AARRGGUUMMEENNTTSS section in _o_p_e_n_s_s_l(1).
--ddcceerrtt ffiilleennaammee, --ddkkeeyy kkeeyynnaammee specify an additional certificate and private key, these behave in the
same manner as the --cceerrtt and --kkeeyy 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.
--ddcceerrttffoorrmm ffoorrmmaatt, --ddkkeeyyffoorrmm ffoorrmmaatt, --ddppaassss aarrgg addtional certificate and private key format and passphrase respectively.
--nnoocceerrtt if this option is set then no certificate is used. This restricts the
cipher suites available to the anonymous ones (currently just anonymous DH).
--ddhhppaarraamm ffiilleennaammee 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.
--nnoo__ddhhee if this option is set then no DH parameters will be loaded effectively
disabling the ephemeral DH cipher suites.
--nnoo__ttmmpp__rrssaa certain export cipher suites sometimes use a temporary RSA key, this option
disables temporary RSA key generation.
--vveerriiffyy ddeepptthh, --VVeerriiffyy ddeepptthh 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 --vveerriiffyy option a certificate is requested but the client does not have to send one, with the --VVeerriiffyy option the client must supply a certificate or an error occurs.
--CCAAppaatthh ddiirreeccttoorryy The directory to use for client certificate verification. This directory
must be in "hash format", see vveerriiffyy for more information. These are also used when building the server certificate chain.
--CCAAffiillee ffiillee 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.
--ssttaattee prints out the SSL session states.
--ddeebbuugg print extensive debugging information including a hex dump of all traffic.
--mmssgg show all protocol messages with hex dump.
--nnbbiioo__tteesstt tests non blocking I/O
--nnbbiioo turns on non blocking I/O
--ccrrllff this option translated a line feed from the terminal into CR+LF.
--qquuiieett inhibit printing of session and certificate information.
--ppsskk__hhiinntt hhiinntt Use the PSK identity hint hhiinntt when using a PSK cipher suite.
--ppsskk kkeeyy Use the PSK key kkeeyy when using a PSK cipher suite. The key is
given as a hexadecimal number without leading 0x, for example -psk 1a2b3c4d.
--ssssll22, --ssssll33, --ttllss11, --nnoo__ssssll22, --nnoo__ssssll33, --nnoo__ttllss11 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.
--bbuuggss there are several known bug in SSL and TLS implementations. Adding this
option enables various workarounds.
--hhaacckk this option enables a further workaround for some some early Netscape
SSL code (?).
--cciipphheerr cciipphheerrlliisstt 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 cciipphheerrss command for more information.
--ttllsseexxttddeebbuugg print out a hex dump of any TLS extensions received from the server.
--nnoo__ttiicckkeett disable RFC4507bis session ticket support.
--wwwwww 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.
--WWWWWW 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.
--HHTTTTPP 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).
--eennggiinnee iidd specifying an engine (by it's unique iidd string) will cause ss__sseerrvveerr
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.
--iidd__pprreeffiixx aarrgg generate SSL/TLS session IDs prefixed by aarrgg. 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).
--rraanndd ffiillee((ss)) a file or files containing random data used to seed the random number
generator, or an EGD socket (see _R_A_N_D___e_g_d(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 --wwwwww nor the --WWWWWW 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.

qq end the current SSL connection but still accept new connections.
QQ end the current SSL connection and exit.
rr renegotiate the SSL session.
RR renegotiate the SSL session and request a client certificate.
PP send some plain text down the underlying TCP connection: this should
cause the client to disconnect due to a protocol violation.
SS print out some session cache status information.

NOTES

ss__sseerrvveerr 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 sseessss__iidd 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 ss__sseerrvveerr program to print out details of any unknown cipher suites a client says it supports.

SEE ALSO

_o_p_e_n_s_s_l___s_e_s_s___i_d(1), _o_p_e_n_s_s_l___s___c_l_i_e_n_t(1), _o_p_e_n_s_s_l___c_i_p_h_e_r_s(1)