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 [B<-status_timeout nsec>]
66 The B<s_server> command implements a generic SSL/TLS server which listens
67 for connections on a given port using SSL/TLS.
75 the TCP port to listen on for connections. If not specified 4433 is used.
79 sets the SSL context id. It can be given any string value. If this option
80 is not present a default value will be used.
82 =item B<-cert certname>
84 The certificate to use, most servers cipher suites require the use of a
85 certificate and some require a certificate with a certain public key type:
86 for example the DSS cipher suites require a certificate containing a DSS
87 (DSA) key. If not specified then the filename "server.pem" will be used.
89 =item B<-certform format>
91 The certificate format to use: DER or PEM. PEM is the default.
95 The private key to use. If not specified then the certificate file will
98 =item B<-keyform format>
100 The private format to use: DER or PEM. PEM is the default.
104 the private key password source. For more information about the format of B<arg>
105 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
107 =item B<-dcert filename>, B<-dkey keyname>
109 specify an additional certificate and private key, these behave in the
110 same manner as the B<-cert> and B<-key> options except there is no default
111 if they are not specified (no additional certificate and key is used). As
112 noted above some cipher suites require a certificate containing a key of
113 a certain type. Some cipher suites need a certificate carrying an RSA key
114 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
115 a server can support clients which only support RSA or DSS cipher suites
116 by using an appropriate certificate.
118 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
120 additional certificate and private key format and passphrase respectively.
124 if this option is set then no certificate is used. This restricts the
125 cipher suites available to the anonymous ones (currently just anonymous
128 =item B<-dhparam filename>
130 the DH parameter file to use. The ephemeral DH cipher suites generate keys
131 using a set of DH parameters. If not specified then an attempt is made to
132 load the parameters from the server certificate file. If this fails then
133 a static set of parameters hard coded into the s_server program will be used.
137 if this option is set then no DH parameters will be loaded effectively
138 disabling the ephemeral DH cipher suites.
142 if this option is set then no ECDH parameters will be loaded effectively
143 disabling the ephemeral ECDH cipher suites.
147 certain export cipher suites sometimes use a temporary RSA key, this option
148 disables temporary RSA key generation.
150 =item B<-verify depth>, B<-Verify depth>
152 The verify depth to use. This specifies the maximum length of the
153 client certificate chain and makes the server request a certificate from
154 the client. With the B<-verify> option a certificate is requested but the
155 client does not have to send one, with the B<-Verify> option the client
156 must supply a certificate or an error occurs.
158 If the ciphersuite cannot request a client certificate (for example an
159 anonymous ciphersuite or PSK) this option has no effect.
161 =item B<-crl_check>, B<-crl_check_all>
163 Check the peer certificate has not been revoked by its CA.
164 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
165 option all CRLs of all CAs in the chain are checked.
167 =item B<-CApath directory>
169 The directory to use for client certificate verification. This directory
170 must be in "hash format", see B<verify> for more information. These are
171 also used when building the server certificate chain.
173 =item B<-CAfile file>
175 A file containing trusted certificates to use during client authentication
176 and to use when attempting to build the server certificate chain. The list
177 is also used in the list of acceptable client CAs passed to the client when
178 a certificate is requested.
182 prints out the SSL session states.
186 print extensive debugging information including a hex dump of all traffic.
190 show all protocol messages with hex dump.
194 tests non blocking I/O
198 turns on non blocking I/O
202 this option translated a line feed from the terminal into CR+LF.
206 inhibit printing of session and certificate information.
208 =item B<-psk_hint hint>
210 Use the PSK identity hint B<hint> when using a PSK cipher suite.
214 Use the PSK key B<key> when using a PSK cipher suite. The key is
215 given as a hexadecimal number without leading 0x, for example -psk
218 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
220 these options disable the use of certain SSL or TLS protocols. By default
221 the initial handshake uses a method which should be compatible with all
222 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
226 there are several known bug in SSL and TLS implementations. Adding this
227 option enables various workarounds.
231 this option enables a further workaround for some some early Netscape
234 =item B<-cipher cipherlist>
236 this allows the cipher list used by the server to be modified. When
237 the client sends a list of supported ciphers the first client cipher
238 also included in the server list is used. Because the client specifies
239 the preference order, the order of the server cipherlist irrelevant. See
240 the B<ciphers> command for more information.
244 use the server's cipher preferences, rather than the client's preferences.
246 =item B<-tlsextdebug>
248 print out a hex dump of any TLS extensions received from the server.
252 disable RFC4507bis session ticket support.
256 sends a status message back to the client when it connects. This includes
257 lots of information about the ciphers used and various session parameters.
258 The output is in HTML format so this option will normally be used with a
263 emulates a simple web server. Pages will be resolved relative to the
264 current directory, for example if the URL https://myhost/page.html is
265 requested the file ./page.html will be loaded.
269 emulates a simple web server. Pages will be resolved relative to the
270 current directory, for example if the URL https://myhost/page.html is
271 requested the file ./page.html will be loaded. The files loaded are
272 assumed to contain a complete and correct HTTP response (lines that
273 are part of the HTTP response line and headers must end with CRLF).
277 specifying an engine (by its unique B<id> string) will cause B<s_server>
278 to attempt to obtain a functional reference to the specified engine,
279 thus initialising it if needed. The engine will then be set as the default
280 for all available algorithms.
282 =item B<-id_prefix arg>
284 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
285 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
286 servers, when each of which might be generating a unique range of session
287 IDs (eg. with a certain prefix).
289 =item B<-rand file(s)>
291 a file or files containing random data used to seed the random number
292 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
293 Multiple files can be specified separated by a OS-dependent character.
294 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
299 enables certificate status request support (aka OCSP stapling).
301 =item B<-status_verbose>
303 enables certificate status request support (aka OCSP stapling) and gives
304 a verbose printout of the OCSP response.
306 =item B<-status_timeout nsec>
308 sets the timeout for OCSP response to B<nsec> seconds.
310 =item B<-status_url url>
312 sets a fallback responder URL to use if no responder URL is present in the
313 server certificate. Without this option an error is returned if the server
314 certificate does not contain a responder address.
318 =head1 CONNECTED COMMANDS
320 If a connection request is established with an SSL client and neither the
321 B<-www> nor the B<-WWW> option has been used then normally any data received
322 from the client is displayed and any key presses will be sent to the client.
324 Certain single letter commands are also recognized which perform special
325 operations: these are listed below.
331 end the current SSL connection but still accept new connections.
335 end the current SSL connection and exit.
339 renegotiate the SSL session.
343 renegotiate the SSL session and request a client certificate.
347 send some plain text down the underlying TCP connection: this should
348 cause the client to disconnect due to a protocol violation.
352 print out some session cache status information.
358 B<s_server> can be used to debug SSL clients. To accept connections from
359 a web browser the command:
361 openssl s_server -accept 443 -www
363 can be used for example.
365 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
366 suites, so they cannot connect to servers which don't use a certificate
367 carrying an RSA key or a version of OpenSSL with RSA disabled.
369 Although specifying an empty list of CAs when requesting a client certificate
370 is strictly speaking a protocol violation, some SSL clients interpret this to
371 mean any CA is acceptable. This is useful for debugging purposes.
373 The session parameters can printed out using the B<sess_id> program.
377 Because this program has a lot of options and also because some of
378 the techniques used are rather old, the C source of s_server is rather
379 hard to read and not a model of how things should be done. A typical
380 SSL server program would be much simpler.
382 The output of common ciphers is wrong: it just gives the list of ciphers that
383 OpenSSL recognizes and the client supports.
385 There should be a way for the B<s_server> program to print out details of any
386 unknown cipher suites a client says it supports.
390 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>