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_return_error>]
57 [B<-verify_email email>]
58 [B<-verify_hostname hostname>]
60 [B<-verify_name name>]
63 [B<-cipher cipherlist>]
87 [B<-no_resumption_on_reneg>]
90 [B<-status_timeout nsec>]
92 [B<-nextprotoneg protocols>]
96 The B<s_server> command implements a generic SSL/TLS server which listens
97 for connections on a given port using SSL/TLS.
101 In addition to the options below the B<s_server> utility also supports the
102 common and server only options documented in the
103 L<SSL_CONF_cmd(3)|SSL_CONF_cmd(3)/SUPPORTED COMMAND LINE COMMANDS> manual
108 =item B<-accept port>
110 the TCP port to listen on for connections. If not specified 4433 is used.
112 =item B<-naccept count>
114 The server will exit after receiving B<number> connections, default unlimited.
118 sets the SSL context id. It can be given any string value. If this option
119 is not present a default value will be used.
121 =item B<-cert certname>
123 The certificate to use, most servers cipher suites require the use of a
124 certificate and some require a certificate with a certain public key type:
125 for example the DSS cipher suites require a certificate containing a DSS
126 (DSA) key. If not specified then the filename "server.pem" will be used.
128 =item B<-certform format>
130 The certificate format to use: DER or PEM. PEM is the default.
132 =item B<-key keyfile>
134 The private key to use. If not specified then the certificate file will
137 =item B<-keyform format>
139 The private format to use: DER or PEM. PEM is the default.
143 the private key password source. For more information about the format of B<arg>
144 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
146 =item B<-dcert filename>, B<-dkey keyname>
148 specify an additional certificate and private key, these behave in the
149 same manner as the B<-cert> and B<-key> options except there is no default
150 if they are not specified (no additional certificate and key is used). As
151 noted above some cipher suites require a certificate containing a key of
152 a certain type. Some cipher suites need a certificate carrying an RSA key
153 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
154 a server can support clients which only support RSA or DSS cipher suites
155 by using an appropriate certificate.
157 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
159 additional certificate and private key format and passphrase respectively.
163 if this option is set then no certificate is used. This restricts the
164 cipher suites available to the anonymous ones (currently just anonymous
167 =item B<-dhparam filename>
169 the DH parameter file to use. The ephemeral DH cipher suites generate keys
170 using a set of DH parameters. If not specified then an attempt is made to
171 load the parameters from the server certificate file. If this fails then
172 a static set of parameters hard coded into the s_server program will be used.
176 if this option is set then no DH parameters will be loaded effectively
177 disabling the ephemeral DH cipher suites.
181 if this option is set then no ECDH parameters will be loaded effectively
182 disabling the ephemeral ECDH cipher suites.
186 certain export cipher suites sometimes use a temporary RSA key, this option
187 disables temporary RSA key generation.
189 =item B<-crl_check>, B<-crl_check_all>
191 Check the peer certificate has not been revoked by its CA.
192 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
193 option all CRLs of all CAs in the chain are checked.
195 =item B<-CApath directory>
197 The directory to use for client certificate verification. This directory
198 must be in "hash format", see B<verify> for more information. These are
199 also used when building the server certificate chain.
201 =item B<-CAfile file>
203 A file containing trusted certificates to use during client authentication
204 and to use when attempting to build the server certificate chain. The list
205 is also used in the list of acceptable client CAs passed to the client when
206 a certificate is requested.
208 =item B<-verify depth>, B<-Verify depth>
210 The verify depth to use. This specifies the maximum length of the
211 client certificate chain and makes the server request a certificate from
212 the client. With the B<-verify> option a certificate is requested but the
213 client does not have to send one, with the B<-Verify> option the client
214 must supply a certificate or an error occurs.
216 If the ciphersuite cannot request a client certificate (for example an
217 anonymous ciphersuite or PSK) this option has no effect.
219 =item B<-attime>, B<-check_ss_sig>, B<explicit_policy>, B<-extended_crl>,
220 B<-ignore_critical>, B<-inhibit_any>, B<-inhibit_map>, B<-issuer_checks>,
221 B<-partial_chain>, B<-policy>, B<-policy_check>, B<-policy_print>, B<-purpose>,
222 B<-suiteB_128>, B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>,
223 B<-use_deltas>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
224 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
226 Set different peer certificate verification options.
227 See the L<B<verify>|verify(1)> manual page for details.
229 =item B<-verify_return_error>
231 Verification errors normally just print a message but allow the
232 connection to continue, for debugging purposes.
233 If this option is used, then verification errors close the connection.
237 prints out the SSL session states.
241 print extensive debugging information including a hex dump of all traffic.
245 show all protocol messages with hex dump.
249 show verbose trace output of protocol messages. OpenSSL needs to be compiled
250 with B<enable-ssl-trace> for this option to work.
254 file to send output of B<-msg> or B<-trace> to, default standard output.
258 tests non blocking I/O
262 turns on non blocking I/O
266 this option translated a line feed from the terminal into CR+LF.
270 inhibit printing of session and certificate information.
272 =item B<-psk_hint hint>
274 Use the PSK identity hint B<hint> when using a PSK cipher suite.
278 Use the PSK key B<key> when using a PSK cipher suite. The key is
279 given as a hexadecimal number without leading 0x, for example -psk
282 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
284 these options disable the use of certain SSL or TLS protocols. By default
285 the initial handshake uses a method which should be compatible with all
286 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
290 there are several known bug in SSL and TLS implementations. Adding this
291 option enables various workarounds.
295 only provide a brief summary of connection parameters instead of the
296 normal verbose output.
300 this option enables a further workaround for some some early Netscape
303 =item B<-cipher cipherlist>
305 this allows the cipher list used by the server to be modified. When
306 the client sends a list of supported ciphers the first client cipher
307 also included in the server list is used. Because the client specifies
308 the preference order, the order of the server cipherlist irrelevant. See
309 the B<ciphers> command for more information.
313 use the server's cipher preferences, rather than the client's preferences.
315 =item B<-tlsextdebug>
317 print out a hex dump of any TLS extensions received from the server.
321 disable RFC4507bis session ticket support.
325 sends a status message back to the client when it connects. This includes
326 lots of information about the ciphers used and various session parameters.
327 The output is in HTML format so this option will normally be used with a
332 emulates a simple web server. Pages will be resolved relative to the
333 current directory, for example if the URL https://myhost/page.html is
334 requested the file ./page.html will be loaded.
338 emulates a simple web server. Pages will be resolved relative to the
339 current directory, for example if the URL https://myhost/page.html is
340 requested the file ./page.html will be loaded. The files loaded are
341 assumed to contain a complete and correct HTTP response (lines that
342 are part of the HTTP response line and headers must end with CRLF).
346 simple test server which just reverses the text received from the client
347 and sends it back to the server. Also sets B<-brief>.
351 specifying an engine (by its unique B<id> string) will cause B<s_server>
352 to attempt to obtain a functional reference to the specified engine,
353 thus initialising it if needed. The engine will then be set as the default
354 for all available algorithms.
356 =item B<-id_prefix arg>
358 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
359 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
360 servers, when each of which might be generating a unique range of session
361 IDs (eg. with a certain prefix).
363 =item B<-rand file(s)>
365 a file or files containing random data used to seed the random number
366 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
367 Multiple files can be specified separated by a OS-dependent character.
368 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
371 =item B<-serverinfo file>
373 a file containing one or more blocks of PEM data. Each PEM block
374 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
375 followed by "length" bytes of extension data). If the client sends
376 an empty TLS ClientHello extension matching the type, the corresponding
377 ServerHello extension will be returned.
379 =item B<-no_resumption_on_reneg>
381 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag.
385 enables certificate status request support (aka OCSP stapling).
387 =item B<-status_verbose>
389 enables certificate status request support (aka OCSP stapling) and gives
390 a verbose printout of the OCSP response.
392 =item B<-status_timeout nsec>
394 sets the timeout for OCSP response to B<nsec> seconds.
396 =item B<-status_url url>
398 sets a fallback responder URL to use if no responder URL is present in the
399 server certificate. Without this option an error is returned if the server
400 certificate does not contain a responder address.
402 =item B<-nextprotoneg protocols>
404 enable Next Protocol Negotiation TLS extension and provide a
405 comma-separated list of supported protocol names.
406 The list should contain most wanted protocols first.
407 Protocol names are printable ASCII strings, for example "http/1.1" or
412 =head1 CONNECTED COMMANDS
414 If a connection request is established with an SSL client and neither the
415 B<-www> nor the B<-WWW> option has been used then normally any data received
416 from the client is displayed and any key presses will be sent to the client.
418 Certain single letter commands are also recognized which perform special
419 operations: these are listed below.
425 end the current SSL connection but still accept new connections.
429 end the current SSL connection and exit.
433 renegotiate the SSL session.
437 renegotiate the SSL session and request a client certificate.
441 send some plain text down the underlying TCP connection: this should
442 cause the client to disconnect due to a protocol violation.
446 print out some session cache status information.
452 B<s_server> can be used to debug SSL clients. To accept connections from
453 a web browser the command:
455 openssl s_server -accept 443 -www
457 can be used for example.
459 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
460 suites, so they cannot connect to servers which don't use a certificate
461 carrying an RSA key or a version of OpenSSL with RSA disabled.
463 Although specifying an empty list of CAs when requesting a client certificate
464 is strictly speaking a protocol violation, some SSL clients interpret this to
465 mean any CA is acceptable. This is useful for debugging purposes.
467 The session parameters can printed out using the B<sess_id> program.
471 Because this program has a lot of options and also because some of
472 the techniques used are rather old, the C source of s_server is rather
473 hard to read and not a model of how things should be done. A typical
474 SSL server program would be much simpler.
476 The output of common ciphers is wrong: it just gives the list of ciphers that
477 OpenSSL recognizes and the client supports.
479 There should be a way for the B<s_server> program to print out details of any
480 unknown cipher suites a client says it supports.
484 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>