6 s_server - SSL/TLS server program
10 B<openssl> B<s_server>
19 [B<-certform DER|PEM>]
24 [B<-dcertform DER|PEM>]
26 [B<-dkeyform DER|PEM>]
28 [B<-dhparam filename>]
35 [B<-CApath directory>]
37 [B<-attime timestamp>]
55 [B<-verify_depth num>]
56 [B<-verify_email email>]
57 [B<-verify_hostname hostname>]
59 [B<-verify_name name>]
62 [B<-cipher cipherlist>]
87 [B<-auth_require_reneg>]
88 [B<-no_resumption_on_reneg>]
91 The B<s_server> command implements a generic SSL/TLS server which listens
92 for connections on a given port using SSL/TLS.
96 In addition to the options below the B<s_server> utility also supports the
97 common and server only options documented in the
98 L<SSL_CONF_cmd(3)|SSL_CONF_cmd(3)/SUPPORTED COMMAND LINE COMMANDS> manual
103 =item B<-accept port>
105 the TCP port to listen on for connections. If not specified 4433 is used.
107 =item B<-naccept count>
109 The server will exit after receiving B<number> connections, default unlimited.
113 sets the SSL context id. It can be given any string value. If this option
114 is not present a default value will be used.
116 =item B<-cert certname>
118 The certificate to use, most servers cipher suites require the use of a
119 certificate and some require a certificate with a certain public key type:
120 for example the DSS cipher suites require a certificate containing a DSS
121 (DSA) key. If not specified then the filename "server.pem" will be used.
123 =item B<-certform format>
125 The certificate format to use: DER or PEM. PEM is the default.
127 =item B<-key keyfile>
129 The private key to use. If not specified then the certificate file will
132 =item B<-keyform format>
134 The private format to use: DER or PEM. PEM is the default.
138 the private key password source. For more information about the format of B<arg>
139 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
141 =item B<-dcert filename>, B<-dkey keyname>
143 specify an additional certificate and private key, these behave in the
144 same manner as the B<-cert> and B<-key> options except there is no default
145 if they are not specified (no additional certificate and key is used). As
146 noted above some cipher suites require a certificate containing a key of
147 a certain type. Some cipher suites need a certificate carrying an RSA key
148 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
149 a server can support clients which only support RSA or DSS cipher suites
150 by using an appropriate certificate.
152 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
154 additional certificate and private key format and passphrase respectively.
158 if this option is set then no certificate is used. This restricts the
159 cipher suites available to the anonymous ones (currently just anonymous
162 =item B<-dhparam filename>
164 the DH parameter file to use. The ephemeral DH cipher suites generate keys
165 using a set of DH parameters. If not specified then an attempt is made to
166 load the parameters from the server certificate file. If this fails then
167 a static set of parameters hard coded into the s_server program will be used.
171 if this option is set then no DH parameters will be loaded effectively
172 disabling the ephemeral DH cipher suites.
176 if this option is set then no ECDH parameters will be loaded effectively
177 disabling the ephemeral ECDH cipher suites.
181 certain export cipher suites sometimes use a temporary RSA key, this option
182 disables temporary RSA key generation.
184 =item B<-verify depth>, B<-Verify depth>
186 The verify depth to use. This specifies the maximum length of the
187 client certificate chain and makes the server request a certificate from
188 the client. With the B<-verify> option a certificate is requested but the
189 client does not have to send one, with the B<-Verify> option the client
190 must supply a certificate or an error occurs.
192 =item B<-crl_check>, B<-crl_check_all>
194 Check the peer certificate has not been revoked by its CA.
195 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
196 option all CRLs of all CAs in the chain are checked.
198 =item B<-CApath directory>
200 The directory to use for client certificate verification. This directory
201 must be in "hash format", see B<verify> for more information. These are
202 also used when building the server certificate chain.
204 =item B<-CAfile file>
206 A file containing trusted certificates to use during client authentication
207 and to use when attempting to build the server certificate chain. The list
208 is also used in the list of acceptable client CAs passed to the client when
209 a certificate is requested.
211 =item B<-attime>, B<-check_ss_sig>, B<explicit_policy>, B<-extended_crl>,
212 B<-ignore_critical>, B<-inhibit_any>, B<-inhibit_map>, B<-issuer_checks>,
213 B<-partial_chain>, B<-policy>, B<-policy_check>, B<-policy_print>, B<-purpose>,
214 B<-suiteB_128>, B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>,
215 B<-use_deltas>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
216 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
218 Set different peer certificate verification options.
219 See the L<B<verify>|verify(1)> manual page for details.
223 prints out the SSL session states.
227 print extensive debugging information including a hex dump of all traffic.
231 show all protocol messages with hex dump.
235 show verbose trace output of protocol messages. OpenSSL needs to be compiled
236 with B<enable-ssl-trace> for this option to work.
240 file to send output of B<-msg> or B<-trace> to, default standard output.
244 tests non blocking I/O
248 turns on non blocking I/O
252 this option translated a line feed from the terminal into CR+LF.
256 inhibit printing of session and certificate information.
258 =item B<-psk_hint hint>
260 Use the PSK identity hint B<hint> when using a PSK cipher suite.
264 Use the PSK key B<key> when using a PSK cipher suite. The key is
265 given as a hexadecimal number without leading 0x, for example -psk
268 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
270 these options disable the use of certain SSL or TLS protocols. By default
271 the initial handshake uses a method which should be compatible with all
272 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
276 there are several known bug in SSL and TLS implementations. Adding this
277 option enables various workarounds.
281 only provide a brief summary of connection parameters instead of the
282 normal verbose output.
286 this option enables a further workaround for some some early Netscape
289 =item B<-cipher cipherlist>
291 this allows the cipher list used by the server to be modified. When
292 the client sends a list of supported ciphers the first client cipher
293 also included in the server list is used. Because the client specifies
294 the preference order, the order of the server cipherlist irrelevant. See
295 the B<ciphers> command for more information.
299 use the server's cipher preferences, rather than the client's preferences.
301 =item B<-tlsextdebug>
303 print out a hex dump of any TLS extensions received from the server.
307 disable RFC4507bis session ticket support.
311 sends a status message back to the client when it connects. This includes
312 lots of information about the ciphers used and various session parameters.
313 The output is in HTML format so this option will normally be used with a
318 emulates a simple web server. Pages will be resolved relative to the
319 current directory, for example if the URL https://myhost/page.html is
320 requested the file ./page.html will be loaded.
324 emulates a simple web server. Pages will be resolved relative to the
325 current directory, for example if the URL https://myhost/page.html is
326 requested the file ./page.html will be loaded. The files loaded are
327 assumed to contain a complete and correct HTTP response (lines that
328 are part of the HTTP response line and headers must end with CRLF).
332 simple test server which just reverses the text received from the client
333 and sends it back to the server. Also sets B<-brief>.
337 specifying an engine (by its unique B<id> string) will cause B<s_server>
338 to attempt to obtain a functional reference to the specified engine,
339 thus initialising it if needed. The engine will then be set as the default
340 for all available algorithms.
342 =item B<-id_prefix arg>
344 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
345 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
346 servers, when each of which might be generating a unique range of session
347 IDs (eg. with a certain prefix).
349 =item B<-rand file(s)>
351 a file or files containing random data used to seed the random number
352 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
353 Multiple files can be specified separated by a OS-dependent character.
354 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
357 =item B<-serverinfo file>
359 a file containing one or more blocks of PEM data. Each PEM block
360 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
361 followed by "length" bytes of extension data). If the client sends
362 an empty TLS ClientHello extension matching the type, the corresponding
363 ServerHello extension will be returned.
367 send RFC 5878 client and server authorization extensions in the Client Hello as well as
368 supplemental data if the server also sent the authorization extensions in the Server Hello.
370 =item B<-auth_require_reneg>
372 only send RFC 5878 client and server authorization extensions during renegotiation.
374 =item B<-no_resumption_on_reneg>
376 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Required in order to receive supplemental data
377 during renegotiation if auth and auth_require_reneg are set.
381 =head1 CONNECTED COMMANDS
383 If a connection request is established with an SSL client and neither the
384 B<-www> nor the B<-WWW> option has been used then normally any data received
385 from the client is displayed and any key presses will be sent to the client.
387 Certain single letter commands are also recognized which perform special
388 operations: these are listed below.
394 end the current SSL connection but still accept new connections.
398 end the current SSL connection and exit.
402 renegotiate the SSL session.
406 renegotiate the SSL session and request a client certificate.
410 send some plain text down the underlying TCP connection: this should
411 cause the client to disconnect due to a protocol violation.
415 print out some session cache status information.
421 B<s_server> can be used to debug SSL clients. To accept connections from
422 a web browser the command:
424 openssl s_server -accept 443 -www
426 can be used for example.
428 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
429 suites, so they cannot connect to servers which don't use a certificate
430 carrying an RSA key or a version of OpenSSL with RSA disabled.
432 Although specifying an empty list of CAs when requesting a client certificate
433 is strictly speaking a protocol violation, some SSL clients interpret this to
434 mean any CA is acceptable. This is useful for debugging purposes.
436 The session parameters can printed out using the B<sess_id> program.
440 Because this program has a lot of options and also because some of
441 the techniques used are rather old, the C source of s_server is rather
442 hard to read and not a model of how things should be done. A typical
443 SSL server program would be much simpler.
445 The output of common ciphers is wrong: it just gives the list of ciphers that
446 OpenSSL recognizes and the client supports.
448 There should be a way for the B<s_server> program to print out details of any
449 unknown cipher suites a client says it supports.
453 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>