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>]
56 [B<-verify_depth num>]
57 [B<-verify_return_error>]
58 [B<-verify_email email>]
59 [B<-verify_hostname hostname>]
61 [B<-verify_name name>]
64 [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<-crl_check>, B<-crl_check_all>
190 Check the peer certificate has not been revoked by its CA.
191 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
192 option all CRLs of all CAs in the chain are checked.
194 =item B<-CApath directory>
196 The directory to use for client certificate verification. This directory
197 must be in "hash format", see B<verify> for more information. These are
198 also used when building the server certificate chain.
200 =item B<-CAfile file>
202 A file containing trusted certificates to use during client authentication
203 and to use when attempting to build the server certificate chain. The list
204 is also used in the list of acceptable client CAs passed to the client when
205 a certificate is requested.
207 =item B<-verify depth>, B<-Verify depth>
209 The verify depth to use. This specifies the maximum length of the
210 client certificate chain and makes the server request a certificate from
211 the client. With the B<-verify> option a certificate is requested but the
212 client does not have to send one, with the B<-Verify> option the client
213 must supply a certificate or an error occurs.
215 If the ciphersuite cannot request a client certificate (for example an
216 anonymous ciphersuite or PSK) this option has no effect.
218 =item B<-attime>, B<-check_ss_sig>, B<explicit_policy>, B<-extended_crl>,
219 B<-ignore_critical>, B<-inhibit_any>, B<-inhibit_map>, B<-issuer_checks>,
220 B<-partial_chain>, B<-policy>, B<-policy_check>, B<-policy_print>, B<-purpose>,
221 B<-suiteB_128>, B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>,
222 B<-no_alt_chains>, B<-use_deltas>, B<-verify_depth>, B<-verify_email>,
223 B<-verify_hostname>, B<-verify_ip>, B<-verify_name>, B<-x509_strict>
225 Set different peer certificate verification options.
226 See the L<B<verify>|verify(1)> manual page for details.
228 =item B<-verify_return_error>
230 Verification errors normally just print a message but allow the
231 connection to continue, for debugging purposes.
232 If this option is used, then verification errors close the connection.
236 prints out the SSL session states.
240 print extensive debugging information including a hex dump of all traffic.
244 show all protocol messages with hex dump.
248 show verbose trace output of protocol messages. OpenSSL needs to be compiled
249 with B<enable-ssl-trace> for this option to work.
253 file to send output of B<-msg> or B<-trace> to, default standard output.
257 tests non blocking I/O
261 turns on non blocking I/O
265 this option translated a line feed from the terminal into CR+LF.
269 inhibit printing of session and certificate information.
271 =item B<-psk_hint hint>
273 Use the PSK identity hint B<hint> when using a PSK cipher suite.
277 Use the PSK key B<key> when using a PSK cipher suite. The key is
278 given as a hexadecimal number without leading 0x, for example -psk
281 =item B<-ssl3>, B<-tls1>, B<-no_ssl3>, B<-no_tls1>
283 these options disable the use of certain SSL or TLS protocols. By default
284 the initial handshake uses a method which should be compatible with all
285 servers and permit them to use SSL v3 or TLS as appropriate.
289 there are several known bug in SSL and TLS implementations. Adding this
290 option enables various workarounds.
294 only provide a brief summary of connection parameters instead of the
295 normal verbose output.
299 this option enables a further workaround for some some early Netscape
302 =item B<-cipher cipherlist>
304 this allows the cipher list used by the server to be modified. When
305 the client sends a list of supported ciphers the first client cipher
306 also included in the server list is used. Because the client specifies
307 the preference order, the order of the server cipherlist irrelevant. See
308 the B<ciphers> command for more information.
312 use the server's cipher preferences, rather than the client's preferences.
314 =item B<-tlsextdebug>
316 print out a hex dump of any TLS extensions received from the server.
320 disable RFC4507bis session ticket support.
324 sends a status message back to the client when it connects. This includes
325 lots of information about the ciphers used and various session parameters.
326 The output is in HTML format so this option will normally be used with a
331 emulates a simple web server. Pages will be resolved relative to the
332 current directory, for example if the URL https://myhost/page.html is
333 requested the file ./page.html will be loaded.
337 emulates a simple web server. Pages will be resolved relative to the
338 current directory, for example if the URL https://myhost/page.html is
339 requested the file ./page.html will be loaded. The files loaded are
340 assumed to contain a complete and correct HTTP response (lines that
341 are part of the HTTP response line and headers must end with CRLF).
345 simple test server which just reverses the text received from the client
346 and sends it back to the server. Also sets B<-brief>.
350 specifying an engine (by its unique B<id> string) will cause B<s_server>
351 to attempt to obtain a functional reference to the specified engine,
352 thus initialising it if needed. The engine will then be set as the default
353 for all available algorithms.
355 =item B<-id_prefix arg>
357 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
358 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
359 servers, when each of which might be generating a unique range of session
360 IDs (eg. with a certain prefix).
362 =item B<-rand file(s)>
364 a file or files containing random data used to seed the random number
365 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
366 Multiple files can be specified separated by a OS-dependent character.
367 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
370 =item B<-serverinfo file>
372 a file containing one or more blocks of PEM data. Each PEM block
373 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
374 followed by "length" bytes of extension data). If the client sends
375 an empty TLS ClientHello extension matching the type, the corresponding
376 ServerHello extension will be returned.
378 =item B<-no_resumption_on_reneg>
380 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag.
384 enables certificate status request support (aka OCSP stapling).
386 =item B<-status_verbose>
388 enables certificate status request support (aka OCSP stapling) and gives
389 a verbose printout of the OCSP response.
391 =item B<-status_timeout nsec>
393 sets the timeout for OCSP response to B<nsec> seconds.
395 =item B<-status_url url>
397 sets a fallback responder URL to use if no responder URL is present in the
398 server certificate. Without this option an error is returned if the server
399 certificate does not contain a responder address.
401 =item B<-nextprotoneg protocols>
403 enable Next Protocol Negotiation TLS extension and provide a
404 comma-separated list of supported protocol names.
405 The list should contain most wanted protocols first.
406 Protocol names are printable ASCII strings, for example "http/1.1" or
411 =head1 CONNECTED COMMANDS
413 If a connection request is established with an SSL client and neither the
414 B<-www> nor the B<-WWW> option has been used then normally any data received
415 from the client is displayed and any key presses will be sent to the client.
417 Certain single letter commands are also recognized which perform special
418 operations: these are listed below.
424 end the current SSL connection but still accept new connections.
428 end the current SSL connection and exit.
432 renegotiate the SSL session.
436 renegotiate the SSL session and request a client certificate.
440 send some plain text down the underlying TCP connection: this should
441 cause the client to disconnect due to a protocol violation.
445 print out some session cache status information.
451 B<s_server> can be used to debug SSL clients. To accept connections from
452 a web browser the command:
454 openssl s_server -accept 443 -www
456 can be used for example.
458 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
459 suites, so they cannot connect to servers which don't use a certificate
460 carrying an RSA key or a version of OpenSSL with RSA disabled.
462 Although specifying an empty list of CAs when requesting a client certificate
463 is strictly speaking a protocol violation, some SSL clients interpret this to
464 mean any CA is acceptable. This is useful for debugging purposes.
466 The session parameters can printed out using the B<sess_id> program.
470 Because this program has a lot of options and also because some of
471 the techniques used are rather old, the C source of s_server is rather
472 hard to read and not a model of how things should be done. A typical
473 SSL server program would be much simpler.
475 The output of common ciphers is wrong: it just gives the list of ciphers that
476 OpenSSL recognizes and the client supports.
478 There should be a way for the B<s_server> program to print out details of any
479 unknown cipher suites a client says it supports.
483 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>
487 The -no_alt_chains options was first added to OpenSSL 1.1.0.