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>]
91 [B<-nextprotoneg protocols>]
95 The B<s_server> command implements a generic SSL/TLS server which listens
96 for connections on a given port using SSL/TLS.
100 In addition to the options below the B<s_server> utility also supports the
101 common and server only options documented in the
102 L<SSL_CONF_cmd(3)|SSL_CONF_cmd(3)/SUPPORTED COMMAND LINE COMMANDS> manual
107 =item B<-accept port>
109 the TCP port to listen on for connections. If not specified 4433 is used.
111 =item B<-naccept count>
113 The server will exit after receiving B<number> connections, default unlimited.
117 sets the SSL context id. It can be given any string value. If this option
118 is not present a default value will be used.
120 =item B<-cert certname>
122 The certificate to use, most servers cipher suites require the use of a
123 certificate and some require a certificate with a certain public key type:
124 for example the DSS cipher suites require a certificate containing a DSS
125 (DSA) key. If not specified then the filename "server.pem" will be used.
127 =item B<-certform format>
129 The certificate format to use: DER or PEM. PEM is the default.
131 =item B<-key keyfile>
133 The private key to use. If not specified then the certificate file will
136 =item B<-keyform format>
138 The private format to use: DER or PEM. PEM is the default.
142 the private key password source. For more information about the format of B<arg>
143 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
145 =item B<-dcert filename>, B<-dkey keyname>
147 specify an additional certificate and private key, these behave in the
148 same manner as the B<-cert> and B<-key> options except there is no default
149 if they are not specified (no additional certificate and key is used). As
150 noted above some cipher suites require a certificate containing a key of
151 a certain type. Some cipher suites need a certificate carrying an RSA key
152 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
153 a server can support clients which only support RSA or DSS cipher suites
154 by using an appropriate certificate.
156 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
158 additional certificate and private key format and passphrase respectively.
162 if this option is set then no certificate is used. This restricts the
163 cipher suites available to the anonymous ones (currently just anonymous
166 =item B<-dhparam filename>
168 the DH parameter file to use. The ephemeral DH cipher suites generate keys
169 using a set of DH parameters. If not specified then an attempt is made to
170 load the parameters from the server certificate file. If this fails then
171 a static set of parameters hard coded into the s_server program will be used.
175 if this option is set then no DH parameters will be loaded effectively
176 disabling the ephemeral DH cipher suites.
180 if this option is set then no ECDH parameters will be loaded effectively
181 disabling the ephemeral ECDH cipher suites.
185 certain export cipher suites sometimes use a temporary RSA key, this option
186 disables temporary RSA key generation.
188 =item B<-verify depth>, B<-Verify depth>
190 The verify depth to use. This specifies the maximum length of the
191 client certificate chain and makes the server request a certificate from
192 the client. With the B<-verify> option a certificate is requested but the
193 client does not have to send one, with the B<-Verify> option the client
194 must supply a certificate or an error occurs.
196 =item B<-crl_check>, B<-crl_check_all>
198 Check the peer certificate has not been revoked by its CA.
199 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
200 option all CRLs of all CAs in the chain are checked.
202 =item B<-CApath directory>
204 The directory to use for client certificate verification. This directory
205 must be in "hash format", see B<verify> for more information. These are
206 also used when building the server certificate chain.
208 =item B<-CAfile file>
210 A file containing trusted certificates to use during client authentication
211 and to use when attempting to build the server certificate chain. The list
212 is also used in the list of acceptable client CAs passed to the client when
213 a certificate is requested.
215 =item B<-attime>, B<-check_ss_sig>, B<explicit_policy>, B<-extended_crl>,
216 B<-ignore_critical>, B<-inhibit_any>, B<-inhibit_map>, B<-issuer_checks>,
217 B<-partial_chain>, B<-policy>, B<-policy_check>, B<-policy_print>, B<-purpose>,
218 B<-suiteB_128>, B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>,
219 B<-use_deltas>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
220 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
222 Set different peer certificate verification options.
223 See the L<B<verify>|verify(1)> manual page for details.
227 prints out the SSL session states.
231 print extensive debugging information including a hex dump of all traffic.
235 show all protocol messages with hex dump.
239 show verbose trace output of protocol messages. OpenSSL needs to be compiled
240 with B<enable-ssl-trace> for this option to work.
244 file to send output of B<-msg> or B<-trace> to, default standard output.
248 tests non blocking I/O
252 turns on non blocking I/O
256 this option translated a line feed from the terminal into CR+LF.
260 inhibit printing of session and certificate information.
262 =item B<-psk_hint hint>
264 Use the PSK identity hint B<hint> when using a PSK cipher suite.
268 Use the PSK key B<key> when using a PSK cipher suite. The key is
269 given as a hexadecimal number without leading 0x, for example -psk
272 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
274 these options disable the use of certain SSL or TLS protocols. By default
275 the initial handshake uses a method which should be compatible with all
276 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
280 there are several known bug in SSL and TLS implementations. Adding this
281 option enables various workarounds.
285 only provide a brief summary of connection parameters instead of the
286 normal verbose output.
290 this option enables a further workaround for some some early Netscape
293 =item B<-cipher cipherlist>
295 this allows the cipher list used by the server to be modified. When
296 the client sends a list of supported ciphers the first client cipher
297 also included in the server list is used. Because the client specifies
298 the preference order, the order of the server cipherlist irrelevant. See
299 the B<ciphers> command for more information.
303 use the server's cipher preferences, rather than the client's preferences.
305 =item B<-tlsextdebug>
307 print out a hex dump of any TLS extensions received from the server.
311 disable RFC4507bis session ticket support.
315 sends a status message back to the client when it connects. This includes
316 lots of information about the ciphers used and various session parameters.
317 The output is in HTML format so this option will normally be used with a
322 emulates a simple web server. Pages will be resolved relative to the
323 current directory, for example if the URL https://myhost/page.html is
324 requested the file ./page.html will be loaded.
328 emulates a simple web server. Pages will be resolved relative to the
329 current directory, for example if the URL https://myhost/page.html is
330 requested the file ./page.html will be loaded. The files loaded are
331 assumed to contain a complete and correct HTTP response (lines that
332 are part of the HTTP response line and headers must end with CRLF).
336 simple test server which just reverses the text received from the client
337 and sends it back to the server. Also sets B<-brief>.
341 specifying an engine (by its unique B<id> string) will cause B<s_server>
342 to attempt to obtain a functional reference to the specified engine,
343 thus initialising it if needed. The engine will then be set as the default
344 for all available algorithms.
346 =item B<-id_prefix arg>
348 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
349 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
350 servers, when each of which might be generating a unique range of session
351 IDs (eg. with a certain prefix).
353 =item B<-rand file(s)>
355 a file or files containing random data used to seed the random number
356 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
357 Multiple files can be specified separated by a OS-dependent character.
358 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
361 =item B<-serverinfo file>
363 a file containing one or more blocks of PEM data. Each PEM block
364 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
365 followed by "length" bytes of extension data). If the client sends
366 an empty TLS ClientHello extension matching the type, the corresponding
367 ServerHello extension will be returned.
369 =item B<-no_resumption_on_reneg>
371 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag.
375 enables certificate status request support (aka OCSP stapling).
377 =item B<-status_verbose>
379 enables certificate status request support (aka OCSP stapling) and gives
380 a verbose printout of the OCSP response.
382 =item B<-status_timeout nsec>
384 sets the timeout for OCSP response to B<nsec> seconds.
386 =item B<-status_url url>
388 sets a fallback responder URL to use if no responder URL is present in the
389 server certificate. Without this option an error is returned if the server
390 certificate does not contain a responder address.
392 =item B<-nextprotoneg protocols>
394 enable Next Protocol Negotiation TLS extension and provide a
395 comma-separated list of supported protocol names.
396 The list should contain most wanted protocols first.
397 Protocol names are printable ASCII strings, for example "http/1.1" or
402 =head1 CONNECTED COMMANDS
404 If a connection request is established with an SSL client and neither the
405 B<-www> nor the B<-WWW> option has been used then normally any data received
406 from the client is displayed and any key presses will be sent to the client.
408 Certain single letter commands are also recognized which perform special
409 operations: these are listed below.
415 end the current SSL connection but still accept new connections.
419 end the current SSL connection and exit.
423 renegotiate the SSL session.
427 renegotiate the SSL session and request a client certificate.
431 send some plain text down the underlying TCP connection: this should
432 cause the client to disconnect due to a protocol violation.
436 print out some session cache status information.
442 B<s_server> can be used to debug SSL clients. To accept connections from
443 a web browser the command:
445 openssl s_server -accept 443 -www
447 can be used for example.
449 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
450 suites, so they cannot connect to servers which don't use a certificate
451 carrying an RSA key or a version of OpenSSL with RSA disabled.
453 Although specifying an empty list of CAs when requesting a client certificate
454 is strictly speaking a protocol violation, some SSL clients interpret this to
455 mean any CA is acceptable. This is useful for debugging purposes.
457 The session parameters can printed out using the B<sess_id> program.
461 Because this program has a lot of options and also because some of
462 the techniques used are rather old, the C source of s_server is rather
463 hard to read and not a model of how things should be done. A typical
464 SSL server program would be much simpler.
466 The output of common ciphers is wrong: it just gives the list of ciphers that
467 OpenSSL recognizes and the client supports.
469 There should be a way for the B<s_server> program to print out details of any
470 unknown cipher suites a client says it supports.
474 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>