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>]
86 [B<-no_resumption_on_reneg>]
89 [B<-status_timeout nsec>]
93 The B<s_server> command implements a generic SSL/TLS server which listens
94 for connections on a given port using SSL/TLS.
98 In addition to the options below the B<s_server> utility also supports the
99 common and server only options documented in the
100 L<SSL_CONF_cmd(3)|SSL_CONF_cmd(3)/SUPPORTED COMMAND LINE COMMANDS> manual
105 =item B<-accept port>
107 the TCP port to listen on for connections. If not specified 4433 is used.
109 =item B<-naccept count>
111 The server will exit after receiving B<number> connections, default unlimited.
115 sets the SSL context id. It can be given any string value. If this option
116 is not present a default value will be used.
118 =item B<-cert certname>
120 The certificate to use, most servers cipher suites require the use of a
121 certificate and some require a certificate with a certain public key type:
122 for example the DSS cipher suites require a certificate containing a DSS
123 (DSA) key. If not specified then the filename "server.pem" will be used.
125 =item B<-certform format>
127 The certificate format to use: DER or PEM. PEM is the default.
129 =item B<-key keyfile>
131 The private key to use. If not specified then the certificate file will
134 =item B<-keyform format>
136 The private format to use: DER or PEM. PEM is the default.
140 the private key password source. For more information about the format of B<arg>
141 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
143 =item B<-dcert filename>, B<-dkey keyname>
145 specify an additional certificate and private key, these behave in the
146 same manner as the B<-cert> and B<-key> options except there is no default
147 if they are not specified (no additional certificate and key is used). As
148 noted above some cipher suites require a certificate containing a key of
149 a certain type. Some cipher suites need a certificate carrying an RSA key
150 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
151 a server can support clients which only support RSA or DSS cipher suites
152 by using an appropriate certificate.
154 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
156 additional certificate and private key format and passphrase respectively.
160 if this option is set then no certificate is used. This restricts the
161 cipher suites available to the anonymous ones (currently just anonymous
164 =item B<-dhparam filename>
166 the DH parameter file to use. The ephemeral DH cipher suites generate keys
167 using a set of DH parameters. If not specified then an attempt is made to
168 load the parameters from the server certificate file. If this fails then
169 a static set of parameters hard coded into the s_server program will be used.
173 if this option is set then no DH parameters will be loaded effectively
174 disabling the ephemeral DH cipher suites.
178 if this option is set then no ECDH parameters will be loaded effectively
179 disabling the ephemeral ECDH cipher suites.
183 certain export cipher suites sometimes use a temporary RSA key, this option
184 disables temporary RSA key generation.
186 =item B<-verify depth>, B<-Verify depth>
188 The verify depth to use. This specifies the maximum length of the
189 client certificate chain and makes the server request a certificate from
190 the client. With the B<-verify> option a certificate is requested but the
191 client does not have to send one, with the B<-Verify> option the client
192 must supply a certificate or an error occurs.
194 =item B<-crl_check>, B<-crl_check_all>
196 Check the peer certificate has not been revoked by its CA.
197 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
198 option all CRLs of all CAs in the chain are checked.
200 =item B<-CApath directory>
202 The directory to use for client certificate verification. This directory
203 must be in "hash format", see B<verify> for more information. These are
204 also used when building the server certificate chain.
206 =item B<-CAfile file>
208 A file containing trusted certificates to use during client authentication
209 and to use when attempting to build the server certificate chain. The list
210 is also used in the list of acceptable client CAs passed to the client when
211 a certificate is requested.
213 =item B<-attime>, B<-check_ss_sig>, B<explicit_policy>, B<-extended_crl>,
214 B<-ignore_critical>, B<-inhibit_any>, B<-inhibit_map>, B<-issuer_checks>,
215 B<-partial_chain>, B<-policy>, B<-policy_check>, B<-policy_print>, B<-purpose>,
216 B<-suiteB_128>, B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>,
217 B<-use_deltas>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
218 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
220 Set different peer certificate verification options.
221 See the L<B<verify>|verify(1)> manual page for details.
225 prints out the SSL session states.
229 print extensive debugging information including a hex dump of all traffic.
233 show all protocol messages with hex dump.
237 show verbose trace output of protocol messages. OpenSSL needs to be compiled
238 with B<enable-ssl-trace> for this option to work.
242 file to send output of B<-msg> or B<-trace> to, default standard output.
246 tests non blocking I/O
250 turns on non blocking I/O
254 this option translated a line feed from the terminal into CR+LF.
258 inhibit printing of session and certificate information.
260 =item B<-psk_hint hint>
262 Use the PSK identity hint B<hint> when using a PSK cipher suite.
266 Use the PSK key B<key> when using a PSK cipher suite. The key is
267 given as a hexadecimal number without leading 0x, for example -psk
270 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
272 these options disable the use of certain SSL or TLS protocols. By default
273 the initial handshake uses a method which should be compatible with all
274 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
278 there are several known bug in SSL and TLS implementations. Adding this
279 option enables various workarounds.
283 only provide a brief summary of connection parameters instead of the
284 normal verbose output.
288 this option enables a further workaround for some some early Netscape
291 =item B<-cipher cipherlist>
293 this allows the cipher list used by the server to be modified. When
294 the client sends a list of supported ciphers the first client cipher
295 also included in the server list is used. Because the client specifies
296 the preference order, the order of the server cipherlist irrelevant. See
297 the B<ciphers> command for more information.
301 use the server's cipher preferences, rather than the client's preferences.
303 =item B<-tlsextdebug>
305 print out a hex dump of any TLS extensions received from the server.
309 disable RFC4507bis session ticket support.
313 sends a status message back to the client when it connects. This includes
314 lots of information about the ciphers used and various session parameters.
315 The output is in HTML format so this option will normally be used with a
320 emulates a simple web server. Pages will be resolved relative to the
321 current directory, for example if the URL https://myhost/page.html is
322 requested the file ./page.html will be loaded.
326 emulates a simple web server. Pages will be resolved relative to the
327 current directory, for example if the URL https://myhost/page.html is
328 requested the file ./page.html will be loaded. The files loaded are
329 assumed to contain a complete and correct HTTP response (lines that
330 are part of the HTTP response line and headers must end with CRLF).
334 simple test server which just reverses the text received from the client
335 and sends it back to the server. Also sets B<-brief>.
339 specifying an engine (by its unique B<id> string) will cause B<s_server>
340 to attempt to obtain a functional reference to the specified engine,
341 thus initialising it if needed. The engine will then be set as the default
342 for all available algorithms.
344 =item B<-id_prefix arg>
346 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
347 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
348 servers, when each of which might be generating a unique range of session
349 IDs (eg. with a certain prefix).
351 =item B<-rand file(s)>
353 a file or files containing random data used to seed the random number
354 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
355 Multiple files can be specified separated by a OS-dependent character.
356 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
359 =item B<-serverinfo file>
361 a file containing one or more blocks of PEM data. Each PEM block
362 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
363 followed by "length" bytes of extension data). If the client sends
364 an empty TLS ClientHello extension matching the type, the corresponding
365 ServerHello extension will be returned.
367 =item B<-no_resumption_on_reneg>
369 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag.
373 enables certificate status request support (aka OCSP stapling).
375 =item B<-status_verbose>
377 enables certificate status request support (aka OCSP stapling) and gives
378 a verbose printout of the OCSP response.
380 =item B<-status_timeout nsec>
382 sets the timeout for OCSP response to B<nsec> seconds.
384 =item B<-status_url url>
386 sets a fallback responder URL to use if no responder URL is present in the
387 server certificate. Without this option an error is returned if the server
388 certificate does not contain a responder address.
392 =head1 CONNECTED COMMANDS
394 If a connection request is established with an SSL client and neither the
395 B<-www> nor the B<-WWW> option has been used then normally any data received
396 from the client is displayed and any key presses will be sent to the client.
398 Certain single letter commands are also recognized which perform special
399 operations: these are listed below.
405 end the current SSL connection but still accept new connections.
409 end the current SSL connection and exit.
413 renegotiate the SSL session.
417 renegotiate the SSL session and request a client certificate.
421 send some plain text down the underlying TCP connection: this should
422 cause the client to disconnect due to a protocol violation.
426 print out some session cache status information.
432 B<s_server> can be used to debug SSL clients. To accept connections from
433 a web browser the command:
435 openssl s_server -accept 443 -www
437 can be used for example.
439 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
440 suites, so they cannot connect to servers which don't use a certificate
441 carrying an RSA key or a version of OpenSSL with RSA disabled.
443 Although specifying an empty list of CAs when requesting a client certificate
444 is strictly speaking a protocol violation, some SSL clients interpret this to
445 mean any CA is acceptable. This is useful for debugging purposes.
447 The session parameters can printed out using the B<sess_id> program.
451 Because this program has a lot of options and also because some of
452 the techniques used are rather old, the C source of s_server is rather
453 hard to read and not a model of how things should be done. A typical
454 SSL server program would be much simpler.
456 The output of common ciphers is wrong: it just gives the list of ciphers that
457 OpenSSL recognizes and the client supports.
459 There should be a way for the B<s_server> program to print out details of any
460 unknown cipher suites a client says it supports.
464 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>