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 The B<s_server> command implements a generic SSL/TLS server which listens
90 for connections on a given port using SSL/TLS.
94 In addition to the options below the B<s_server> utility also supports the
95 common and server only options documented in the
96 L<SSL_CONF_cmd(3)|SSL_CONF_cmd(3)/SUPPORTED COMMAND LINE COMMANDS> manual
101 =item B<-accept port>
103 the TCP port to listen on for connections. If not specified 4433 is used.
105 =item B<-naccept count>
107 The server will exit after receiving B<number> connections, default unlimited.
111 sets the SSL context id. It can be given any string value. If this option
112 is not present a default value will be used.
114 =item B<-cert certname>
116 The certificate to use, most servers cipher suites require the use of a
117 certificate and some require a certificate with a certain public key type:
118 for example the DSS cipher suites require a certificate containing a DSS
119 (DSA) key. If not specified then the filename "server.pem" will be used.
121 =item B<-certform format>
123 The certificate format to use: DER or PEM. PEM is the default.
125 =item B<-key keyfile>
127 The private key to use. If not specified then the certificate file will
130 =item B<-keyform format>
132 The private format to use: DER or PEM. PEM is the default.
136 the private key password source. For more information about the format of B<arg>
137 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
139 =item B<-dcert filename>, B<-dkey keyname>
141 specify an additional certificate and private key, these behave in the
142 same manner as the B<-cert> and B<-key> options except there is no default
143 if they are not specified (no additional certificate and key is used). As
144 noted above some cipher suites require a certificate containing a key of
145 a certain type. Some cipher suites need a certificate carrying an RSA key
146 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
147 a server can support clients which only support RSA or DSS cipher suites
148 by using an appropriate certificate.
150 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
152 additional certificate and private key format and passphrase respectively.
156 if this option is set then no certificate is used. This restricts the
157 cipher suites available to the anonymous ones (currently just anonymous
160 =item B<-dhparam filename>
162 the DH parameter file to use. The ephemeral DH cipher suites generate keys
163 using a set of DH parameters. If not specified then an attempt is made to
164 load the parameters from the server certificate file. If this fails then
165 a static set of parameters hard coded into the s_server program will be used.
169 if this option is set then no DH parameters will be loaded effectively
170 disabling the ephemeral DH cipher suites.
174 if this option is set then no ECDH parameters will be loaded effectively
175 disabling the ephemeral ECDH cipher suites.
179 certain export cipher suites sometimes use a temporary RSA key, this option
180 disables temporary RSA key generation.
182 =item B<-verify depth>, B<-Verify depth>
184 The verify depth to use. This specifies the maximum length of the
185 client certificate chain and makes the server request a certificate from
186 the client. With the B<-verify> option a certificate is requested but the
187 client does not have to send one, with the B<-Verify> option the client
188 must supply a certificate or an error occurs.
190 =item B<-crl_check>, B<-crl_check_all>
192 Check the peer certificate has not been revoked by its CA.
193 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
194 option all CRLs of all CAs in the chain are checked.
196 =item B<-CApath directory>
198 The directory to use for client certificate verification. This directory
199 must be in "hash format", see B<verify> for more information. These are
200 also used when building the server certificate chain.
202 =item B<-CAfile file>
204 A file containing trusted certificates to use during client authentication
205 and to use when attempting to build the server certificate chain. The list
206 is also used in the list of acceptable client CAs passed to the client when
207 a certificate is requested.
209 =item B<-attime>, B<-check_ss_sig>, B<explicit_policy>, B<-extended_crl>,
210 B<-ignore_critical>, B<-inhibit_any>, B<-inhibit_map>, B<-issuer_checks>,
211 B<-partial_chain>, B<-policy>, B<-policy_check>, B<-policy_print>, B<-purpose>,
212 B<-suiteB_128>, B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>,
213 B<-use_deltas>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
214 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
216 Set different peer certificate verification options.
217 See the L<B<verify>|verify(1)> manual page for details.
221 prints out the SSL session states.
225 print extensive debugging information including a hex dump of all traffic.
229 show all protocol messages with hex dump.
233 show verbose trace output of protocol messages. OpenSSL needs to be compiled
234 with B<enable-ssl-trace> for this option to work.
238 file to send output of B<-msg> or B<-trace> to, default standard output.
242 tests non blocking I/O
246 turns on non blocking I/O
250 this option translated a line feed from the terminal into CR+LF.
254 inhibit printing of session and certificate information.
256 =item B<-psk_hint hint>
258 Use the PSK identity hint B<hint> when using a PSK cipher suite.
262 Use the PSK key B<key> when using a PSK cipher suite. The key is
263 given as a hexadecimal number without leading 0x, for example -psk
266 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
268 these options disable the use of certain SSL or TLS protocols. By default
269 the initial handshake uses a method which should be compatible with all
270 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
274 there are several known bug in SSL and TLS implementations. Adding this
275 option enables various workarounds.
279 only provide a brief summary of connection parameters instead of the
280 normal verbose output.
284 this option enables a further workaround for some some early Netscape
287 =item B<-cipher cipherlist>
289 this allows the cipher list used by the server to be modified. When
290 the client sends a list of supported ciphers the first client cipher
291 also included in the server list is used. Because the client specifies
292 the preference order, the order of the server cipherlist irrelevant. See
293 the B<ciphers> command for more information.
297 use the server's cipher preferences, rather than the client's preferences.
299 =item B<-tlsextdebug>
301 print out a hex dump of any TLS extensions received from the server.
305 disable RFC4507bis session ticket support.
309 sends a status message back to the client when it connects. This includes
310 lots of information about the ciphers used and various session parameters.
311 The output is in HTML format so this option will normally be used with a
316 emulates a simple web server. Pages will be resolved relative to the
317 current directory, for example if the URL https://myhost/page.html is
318 requested the file ./page.html will be loaded.
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. The files loaded are
325 assumed to contain a complete and correct HTTP response (lines that
326 are part of the HTTP response line and headers must end with CRLF).
330 simple test server which just reverses the text received from the client
331 and sends it back to the server. Also sets B<-brief>.
335 specifying an engine (by its unique B<id> string) will cause B<s_server>
336 to attempt to obtain a functional reference to the specified engine,
337 thus initialising it if needed. The engine will then be set as the default
338 for all available algorithms.
340 =item B<-id_prefix arg>
342 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
343 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
344 servers, when each of which might be generating a unique range of session
345 IDs (eg. with a certain prefix).
347 =item B<-rand file(s)>
349 a file or files containing random data used to seed the random number
350 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
351 Multiple files can be specified separated by a OS-dependent character.
352 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
355 =item B<-serverinfo file>
357 a file containing one or more blocks of PEM data. Each PEM block
358 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
359 followed by "length" bytes of extension data). If the client sends
360 an empty TLS ClientHello extension matching the type, the corresponding
361 ServerHello extension will be returned.
363 =item B<-no_resumption_on_reneg>
365 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag.
369 =head1 CONNECTED COMMANDS
371 If a connection request is established with an SSL client and neither the
372 B<-www> nor the B<-WWW> option has been used then normally any data received
373 from the client is displayed and any key presses will be sent to the client.
375 Certain single letter commands are also recognized which perform special
376 operations: these are listed below.
382 end the current SSL connection but still accept new connections.
386 end the current SSL connection and exit.
390 renegotiate the SSL session.
394 renegotiate the SSL session and request a client certificate.
398 send some plain text down the underlying TCP connection: this should
399 cause the client to disconnect due to a protocol violation.
403 print out some session cache status information.
409 B<s_server> can be used to debug SSL clients. To accept connections from
410 a web browser the command:
412 openssl s_server -accept 443 -www
414 can be used for example.
416 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
417 suites, so they cannot connect to servers which don't use a certificate
418 carrying an RSA key or a version of OpenSSL with RSA disabled.
420 Although specifying an empty list of CAs when requesting a client certificate
421 is strictly speaking a protocol violation, some SSL clients interpret this to
422 mean any CA is acceptable. This is useful for debugging purposes.
424 The session parameters can printed out using the B<sess_id> program.
428 Because this program has a lot of options and also because some of
429 the techniques used are rather old, the C source of s_server is rather
430 hard to read and not a model of how things should be done. A typical
431 SSL server program would be much simpler.
433 The output of common ciphers is wrong: it just gives the list of ciphers that
434 OpenSSL recognizes and the client supports.
436 There should be a way for the B<s_server> program to print out details of any
437 unknown cipher suites a client says it supports.
441 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>