6 s_server - SSL/TLS server program
10 B<openssl> B<s_server>
18 [B<-certform DER|PEM>]
23 [B<-dcertform DER|PEM>]
25 [B<-dkeyform DER|PEM>]
27 [B<-dhparam filename>]
34 [B<-CApath directory>]
37 [B<-cipher cipherlist>]
61 The B<s_server> command implements a generic SSL/TLS server which listens
62 for connections on a given port using SSL/TLS.
70 the TCP port to listen on for connections. If not specified 4433 is used.
74 sets the SSL context id. It can be given any string value. If this option
75 is not present a default value will be used.
77 =item B<-cert certname>
79 The certificate to use, most servers cipher suites require the use of a
80 certificate and some require a certificate with a certain public key type:
81 for example the DSS cipher suites require a certificate containing a DSS
82 (DSA) key. If not specified then the filename "server.pem" will be used.
84 =item B<-certform format>
86 The certificate format to use: DER or PEM. PEM is the default.
90 The private key to use. If not specified then the certificate file will
93 =item B<-keyform format>
95 The private format to use: DER or PEM. PEM is the default.
99 the private key password source. For more information about the format of B<arg>
100 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
102 =item B<-dcert filename>, B<-dkey keyname>
104 specify an additional certificate and private key, these behave in the
105 same manner as the B<-cert> and B<-key> options except there is no default
106 if they are not specified (no additional certificate and key is used). As
107 noted above some cipher suites require a certificate containing a key of
108 a certain type. Some cipher suites need a certificate carrying an RSA key
109 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
110 a server can support clients which only support RSA or DSS cipher suites
111 by using an appropriate certificate.
113 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
115 addtional certificate and private key format and passphrase respectively.
119 if this option is set then no certificate is used. This restricts the
120 cipher suites available to the anonymous ones (currently just anonymous
123 =item B<-dhparam filename>
125 the DH parameter file to use. The ephemeral DH cipher suites generate keys
126 using a set of DH parameters. If not specified then an attempt is made to
127 load the parameters from the server certificate file. If this fails then
128 a static set of parameters hard coded into the s_server program will be used.
132 if this option is set then no DH parameters will be loaded effectively
133 disabling the ephemeral DH cipher suites.
137 certain export cipher suites sometimes use a temporary RSA key, this option
138 disables temporary RSA key generation.
140 =item B<-verify depth>, B<-Verify depth>
142 The verify depth to use. This specifies the maximum length of the
143 client certificate chain and makes the server request a certificate from
144 the client. With the B<-verify> option a certificate is requested but the
145 client does not have to send one, with the B<-Verify> option the client
146 must supply a certificate or an error occurs.
148 If the ciphersuite cannot request a client certificate (for example an
149 anonymous ciphersuite or PSK) this option has no effect.
151 =item B<-crl_check>, B<-crl_check_all>
153 Check the peer certificate has not been revoked by its CA.
154 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
155 option all CRLs of all CAs in the chain are checked.
157 =item B<-CApath directory>
159 The directory to use for client certificate verification. This directory
160 must be in "hash format", see B<verify> for more information. These are
161 also used when building the server certificate chain.
163 =item B<-CAfile file>
165 A file containing trusted certificates to use during client authentication
166 and to use when attempting to build the server certificate chain. The list
167 is also used in the list of acceptable client CAs passed to the client when
168 a certificate is requested.
172 prints out the SSL session states.
176 print extensive debugging information including a hex dump of all traffic.
180 show all protocol messages with hex dump.
184 tests non blocking I/O
188 turns on non blocking I/O
192 this option translated a line feed from the terminal into CR+LF.
196 inhibit printing of session and certificate information.
198 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
200 these options disable the use of certain SSL or TLS protocols. By default
201 the initial handshake uses a method which should be compatible with all
202 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
206 there are several known bug in SSL and TLS implementations. Adding this
207 option enables various workarounds.
211 this option enables a further workaround for some some early Netscape
214 =item B<-cipher cipherlist>
216 this allows the cipher list used by the server to be modified. When
217 the client sends a list of supported ciphers the first client cipher
218 also included in the server list is used. Because the client specifies
219 the preference order, the order of the server cipherlist irrelevant. See
220 the B<ciphers> command for more information.
224 use the server's cipher preferences, rather than the client's preferences.
226 =item B<-tlsextdebug>
228 print out a hex dump of any TLS extensions received from the server.
232 disable RFC4507bis session ticket support.
236 sends a status message back to the client when it connects. This includes
237 lots of information about the ciphers used and various session parameters.
238 The output is in HTML format so this option will normally be used with a
243 emulates a simple web server. Pages will be resolved relative to the
244 current directory, for example if the URL https://myhost/page.html is
245 requested the file ./page.html will be loaded.
249 emulates a simple web server. Pages will be resolved relative to the
250 current directory, for example if the URL https://myhost/page.html is
251 requested the file ./page.html will be loaded. The files loaded are
252 assumed to contain a complete and correct HTTP response (lines that
253 are part of the HTTP response line and headers must end with CRLF).
257 specifying an engine (by it's unique B<id> string) will cause B<s_server>
258 to attempt to obtain a functional reference to the specified engine,
259 thus initialising it if needed. The engine will then be set as the default
260 for all available algorithms.
262 =item B<-id_prefix arg>
264 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
265 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
266 servers, when each of which might be generating a unique range of session
267 IDs (eg. with a certain prefix).
269 =item B<-rand file(s)>
271 a file or files containing random data used to seed the random number
272 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
273 Multiple files can be specified separated by a OS-dependent character.
274 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
279 =head1 CONNECTED COMMANDS
281 If a connection request is established with an SSL client and neither the
282 B<-www> nor the B<-WWW> option has been used then normally any data received
283 from the client is displayed and any key presses will be sent to the client.
285 Certain single letter commands are also recognized which perform special
286 operations: these are listed below.
292 end the current SSL connection but still accept new connections.
296 end the current SSL connection and exit.
300 renegotiate the SSL session.
304 renegotiate the SSL session and request a client certificate.
308 send some plain text down the underlying TCP connection: this should
309 cause the client to disconnect due to a protocol violation.
313 print out some session cache status information.
319 B<s_server> can be used to debug SSL clients. To accept connections from
320 a web browser the command:
322 openssl s_server -accept 443 -www
324 can be used for example.
326 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
327 suites, so they cannot connect to servers which don't use a certificate
328 carrying an RSA key or a version of OpenSSL with RSA disabled.
330 Although specifying an empty list of CAs when requesting a client certificate
331 is strictly speaking a protocol violation, some SSL clients interpret this to
332 mean any CA is acceptable. This is useful for debugging purposes.
334 The session parameters can printed out using the B<sess_id> program.
336 TLS extensions are only supported in OpenSSL 0.9.8 if they are explictly
337 enabled at compile time using for example the B<enable-tlsext> switch.
341 Because this program has a lot of options and also because some of
342 the techniques used are rather old, the C source of s_server is rather
343 hard to read and not a model of how things should be done. A typical
344 SSL server program would be much simpler.
346 The output of common ciphers is wrong: it just gives the list of ciphers that
347 OpenSSL recognizes and the client supports.
349 There should be a way for the B<s_server> program to print out details of any
350 unknown cipher suites a client says it supports.
354 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>