6 s_server - SSL/TLS server program
10 B<openssl> B<s_server>
18 [B<-certform DER|PEM>]
23 [B<-dcertform DER|PEM>]
25 [B<-dkeyform DER|PEM>]
27 [B<-dhparam filename>]
34 [B<-CApath directory>]
38 [B<-cipher cipherlist>]
62 [B<-status_timeout nsec>]
64 [B<-nextprotoneg protocols>]
68 The B<s_server> command implements a generic SSL/TLS server which listens
69 for connections on a given port using SSL/TLS.
77 the TCP port to listen on for connections. If not specified 4433 is used.
81 sets the SSL context id. It can be given any string value. If this option
82 is not present a default value will be used.
84 =item B<-cert certname>
86 The certificate to use, most servers cipher suites require the use of a
87 certificate and some require a certificate with a certain public key type:
88 for example the DSS cipher suites require a certificate containing a DSS
89 (DSA) key. If not specified then the filename "server.pem" will be used.
91 =item B<-certform format>
93 The certificate format to use: DER or PEM. PEM is the default.
97 The private key to use. If not specified then the certificate file will
100 =item B<-keyform format>
102 The private format to use: DER or PEM. PEM is the default.
106 the private key password source. For more information about the format of B<arg>
107 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
109 =item B<-dcert filename>, B<-dkey keyname>
111 specify an additional certificate and private key, these behave in the
112 same manner as the B<-cert> and B<-key> options except there is no default
113 if they are not specified (no additional certificate and key is used). As
114 noted above some cipher suites require a certificate containing a key of
115 a certain type. Some cipher suites need a certificate carrying an RSA key
116 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
117 a server can support clients which only support RSA or DSS cipher suites
118 by using an appropriate certificate.
120 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
122 additional certificate and private key format and passphrase respectively.
126 if this option is set then no certificate is used. This restricts the
127 cipher suites available to the anonymous ones (currently just anonymous
130 =item B<-dhparam filename>
132 the DH parameter file to use. The ephemeral DH cipher suites generate keys
133 using a set of DH parameters. If not specified then an attempt is made to
134 load the parameters from the server certificate file. If this fails then
135 a static set of parameters hard coded into the s_server program will be used.
139 if this option is set then no DH parameters will be loaded effectively
140 disabling the ephemeral DH cipher suites.
144 if this option is set then no ECDH parameters will be loaded effectively
145 disabling the ephemeral ECDH cipher suites.
149 certain export cipher suites sometimes use a temporary RSA key, this option
150 disables temporary RSA key generation.
152 =item B<-verify depth>, B<-Verify depth>
154 The verify depth to use. This specifies the maximum length of the
155 client certificate chain and makes the server request a certificate from
156 the client. With the B<-verify> option a certificate is requested but the
157 client does not have to send one, with the B<-Verify> option the client
158 must supply a certificate or an error occurs.
160 If the ciphersuite cannot request a client certificate (for example an
161 anonymous ciphersuite or PSK) this option has no effect.
163 =item B<-crl_check>, B<-crl_check_all>
165 Check the peer certificate has not been revoked by its CA.
166 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
167 option all CRLs of all CAs in the chain are checked.
169 =item B<-CApath directory>
171 The directory to use for client certificate verification. This directory
172 must be in "hash format", see B<verify> for more information. These are
173 also used when building the server certificate chain.
175 =item B<-CAfile file>
177 A file containing trusted certificates to use during client authentication
178 and to use when attempting to build the server certificate chain. The list
179 is also used in the list of acceptable client CAs passed to the client when
180 a certificate is requested.
182 =item B<-no_alt_chains>
184 See the L<B<verify>|verify(1)> manual page for details.
188 prints out the SSL session states.
192 print extensive debugging information including a hex dump of all traffic.
196 show all protocol messages with hex dump.
200 tests non blocking I/O
204 turns on non blocking I/O
208 this option translated a line feed from the terminal into CR+LF.
212 inhibit printing of session and certificate information.
214 =item B<-psk_hint hint>
216 Use the PSK identity hint B<hint> when using a PSK cipher suite.
220 Use the PSK key B<key> when using a PSK cipher suite. The key is
221 given as a hexadecimal number without leading 0x, for example -psk
224 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
226 these options disable the use of certain SSL or TLS protocols. By default
227 the initial handshake uses a method which should be compatible with all
228 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
232 there are several known bug in SSL and TLS implementations. Adding this
233 option enables various workarounds.
237 this option enables a further workaround for some some early Netscape
240 =item B<-cipher cipherlist>
242 this allows the cipher list used by the server to be modified. When
243 the client sends a list of supported ciphers the first client cipher
244 also included in the server list is used. Because the client specifies
245 the preference order, the order of the server cipherlist irrelevant. See
246 the B<ciphers> command for more information.
250 use the server's cipher preferences, rather than the client's preferences.
252 =item B<-tlsextdebug>
254 print out a hex dump of any TLS extensions received from the server.
258 disable RFC4507bis session ticket support.
262 sends a status message back to the client when it connects. This includes
263 lots of information about the ciphers used and various session parameters.
264 The output is in HTML format so this option will normally be used with a
269 emulates a simple web server. Pages will be resolved relative to the
270 current directory, for example if the URL https://myhost/page.html is
271 requested the file ./page.html will be loaded.
275 emulates a simple web server. Pages will be resolved relative to the
276 current directory, for example if the URL https://myhost/page.html is
277 requested the file ./page.html will be loaded. The files loaded are
278 assumed to contain a complete and correct HTTP response (lines that
279 are part of the HTTP response line and headers must end with CRLF).
283 specifying an engine (by its unique B<id> string) will cause B<s_server>
284 to attempt to obtain a functional reference to the specified engine,
285 thus initialising it if needed. The engine will then be set as the default
286 for all available algorithms.
288 =item B<-id_prefix arg>
290 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
291 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
292 servers, when each of which might be generating a unique range of session
293 IDs (eg. with a certain prefix).
295 =item B<-rand file(s)>
297 a file or files containing random data used to seed the random number
298 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
299 Multiple files can be specified separated by a OS-dependent character.
300 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
305 enables certificate status request support (aka OCSP stapling).
307 =item B<-status_verbose>
309 enables certificate status request support (aka OCSP stapling) and gives
310 a verbose printout of the OCSP response.
312 =item B<-status_timeout nsec>
314 sets the timeout for OCSP response to B<nsec> seconds.
316 =item B<-status_url url>
318 sets a fallback responder URL to use if no responder URL is present in the
319 server certificate. Without this option an error is returned if the server
320 certificate does not contain a responder address.
322 =item B<-nextprotoneg protocols>
324 enable Next Protocol Negotiation TLS extension and provide a
325 comma-separated list of supported protocol names.
326 The list should contain most wanted protocols first.
327 Protocol names are printable ASCII strings, for example "http/1.1" or
332 =head1 CONNECTED COMMANDS
334 If a connection request is established with an SSL client and neither the
335 B<-www> nor the B<-WWW> option has been used then normally any data received
336 from the client is displayed and any key presses will be sent to the client.
338 Certain single letter commands are also recognized which perform special
339 operations: these are listed below.
345 end the current SSL connection but still accept new connections.
349 end the current SSL connection and exit.
353 renegotiate the SSL session.
357 renegotiate the SSL session and request a client certificate.
361 send some plain text down the underlying TCP connection: this should
362 cause the client to disconnect due to a protocol violation.
366 print out some session cache status information.
372 B<s_server> can be used to debug SSL clients. To accept connections from
373 a web browser the command:
375 openssl s_server -accept 443 -www
377 can be used for example.
379 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
380 suites, so they cannot connect to servers which don't use a certificate
381 carrying an RSA key or a version of OpenSSL with RSA disabled.
383 Although specifying an empty list of CAs when requesting a client certificate
384 is strictly speaking a protocol violation, some SSL clients interpret this to
385 mean any CA is acceptable. This is useful for debugging purposes.
387 The session parameters can printed out using the B<sess_id> program.
391 Because this program has a lot of options and also because some of
392 the techniques used are rather old, the C source of s_server is rather
393 hard to read and not a model of how things should be done. A typical
394 SSL server program would be much simpler.
396 The output of common ciphers is wrong: it just gives the list of ciphers that
397 OpenSSL recognizes and the client supports.
399 There should be a way for the B<s_server> program to print out details of any
400 unknown cipher suites a client says it supports.
404 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>
408 The -no_alt_chains options was first added to OpenSSL 1.0.1n and 1.0.2b.