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>]
37 [B<-cipher cipherlist>]
62 The B<s_server> command implements a generic SSL/TLS server which listens
63 for connections on a given port using SSL/TLS.
71 the TCP port to listen on for connections. If not specified 4433 is used.
75 sets the SSL context id. It can be given any string value. If this option
76 is not present a default value will be used.
78 =item B<-cert certname>
80 The certificate to use, most servers cipher suites require the use of a
81 certificate and some require a certificate with a certain public key type:
82 for example the DSS cipher suites require a certificate containing a DSS
83 (DSA) key. If not specified then the filename "server.pem" will be used.
85 =item B<-certform format>
87 The certificate format to use: DER or PEM. PEM is the default.
91 The private key to use. If not specified then the certificate file will
94 =item B<-keyform format>
96 The private format to use: DER or PEM. PEM is the default.
100 the private key password source. For more information about the format of B<arg>
101 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
103 =item B<-dcert filename>, B<-dkey keyname>
105 specify an additional certificate and private key, these behave in the
106 same manner as the B<-cert> and B<-key> options except there is no default
107 if they are not specified (no additional certificate and key is used). As
108 noted above some cipher suites require a certificate containing a key of
109 a certain type. Some cipher suites need a certificate carrying an RSA key
110 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
111 a server can support clients which only support RSA or DSS cipher suites
112 by using an appropriate certificate.
114 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
116 additional certificate and private key format and passphrase respectively.
120 if this option is set then no certificate is used. This restricts the
121 cipher suites available to the anonymous ones (currently just anonymous
124 =item B<-dhparam filename>
126 the DH parameter file to use. The ephemeral DH cipher suites generate keys
127 using a set of DH parameters. If not specified then an attempt is made to
128 load the parameters from the server certificate file. If this fails then
129 a static set of parameters hard coded into the s_server program will be used.
133 if this option is set then no DH parameters will be loaded effectively
134 disabling the ephemeral DH cipher suites.
138 if this option is set then no ECDH parameters will be loaded effectively
139 disabling the ephemeral ECDH cipher suites.
143 certain export cipher suites sometimes use a temporary RSA key, this option
144 disables temporary RSA key generation.
146 =item B<-verify depth>, B<-Verify depth>
148 The verify depth to use. This specifies the maximum length of the
149 client certificate chain and makes the server request a certificate from
150 the client. With the B<-verify> option a certificate is requested but the
151 client does not have to send one, with the B<-Verify> option the client
152 must supply a certificate or an error occurs.
154 =item B<-crl_check>, B<-crl_check_all>
156 Check the peer certificate has not been revoked by its CA.
157 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
158 option all CRLs of all CAs in the chain are checked.
160 =item B<-CApath directory>
162 The directory to use for client certificate verification. This directory
163 must be in "hash format", see B<verify> for more information. These are
164 also used when building the server certificate chain.
166 =item B<-CAfile file>
168 A file containing trusted certificates to use during client authentication
169 and to use when attempting to build the server certificate chain. The list
170 is also used in the list of acceptable client CAs passed to the client when
171 a certificate is requested.
175 prints out the SSL session states.
179 print extensive debugging information including a hex dump of all traffic.
183 show all protocol messages with hex dump.
187 tests non blocking I/O
191 turns on non blocking I/O
195 this option translated a line feed from the terminal into CR+LF.
199 inhibit printing of session and certificate information.
201 =item B<-psk_hint hint>
203 Use the PSK identity hint B<hint> when using a PSK cipher suite.
207 Use the PSK key B<key> when using a PSK cipher suite. The key is
208 given as a hexadecimal number without leading 0x, for example -psk
211 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
213 these options disable the use of certain SSL or TLS protocols. By default
214 the initial handshake uses a method which should be compatible with all
215 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
219 there are several known bug in SSL and TLS implementations. Adding this
220 option enables various workarounds.
224 this option enables a further workaround for some some early Netscape
227 =item B<-cipher cipherlist>
229 this allows the cipher list used by the server to be modified. When
230 the client sends a list of supported ciphers the first client cipher
231 also included in the server list is used. Because the client specifies
232 the preference order, the order of the server cipherlist irrelevant. See
233 the B<ciphers> command for more information.
237 use the server's cipher preferences, rather than the client's preferences.
239 =item B<-tlsextdebug>
241 print out a hex dump of any TLS extensions received from the server.
245 disable RFC4507bis session ticket support.
249 sends a status message back to the client when it connects. This includes
250 lots of information about the ciphers used and various session parameters.
251 The output is in HTML format so this option will normally be used with a
256 emulates a simple web server. Pages will be resolved relative to the
257 current directory, for example if the URL https://myhost/page.html is
258 requested the file ./page.html will be loaded.
262 emulates a simple web server. Pages will be resolved relative to the
263 current directory, for example if the URL https://myhost/page.html is
264 requested the file ./page.html will be loaded. The files loaded are
265 assumed to contain a complete and correct HTTP response (lines that
266 are part of the HTTP response line and headers must end with CRLF).
270 specifying an engine (by its unique B<id> string) will cause B<s_server>
271 to attempt to obtain a functional reference to the specified engine,
272 thus initialising it if needed. The engine will then be set as the default
273 for all available algorithms.
275 =item B<-id_prefix arg>
277 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
278 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
279 servers, when each of which might be generating a unique range of session
280 IDs (eg. with a certain prefix).
282 =item B<-rand file(s)>
284 a file or files containing random data used to seed the random number
285 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
286 Multiple files can be specified separated by a OS-dependent character.
287 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
292 =head1 CONNECTED COMMANDS
294 If a connection request is established with an SSL client and neither the
295 B<-www> nor the B<-WWW> option has been used then normally any data received
296 from the client is displayed and any key presses will be sent to the client.
298 Certain single letter commands are also recognized which perform special
299 operations: these are listed below.
305 end the current SSL connection but still accept new connections.
309 end the current SSL connection and exit.
313 renegotiate the SSL session.
317 renegotiate the SSL session and request a client certificate.
321 send some plain text down the underlying TCP connection: this should
322 cause the client to disconnect due to a protocol violation.
326 print out some session cache status information.
332 B<s_server> can be used to debug SSL clients. To accept connections from
333 a web browser the command:
335 openssl s_server -accept 443 -www
337 can be used for example.
339 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
340 suites, so they cannot connect to servers which don't use a certificate
341 carrying an RSA key or a version of OpenSSL with RSA disabled.
343 Although specifying an empty list of CAs when requesting a client certificate
344 is strictly speaking a protocol violation, some SSL clients interpret this to
345 mean any CA is acceptable. This is useful for debugging purposes.
347 The session parameters can printed out using the B<sess_id> program.
351 Because this program has a lot of options and also because some of
352 the techniques used are rather old, the C source of s_server is rather
353 hard to read and not a model of how things should be done. A typical
354 SSL server program would be much simpler.
356 The output of common ciphers is wrong: it just gives the list of ciphers that
357 OpenSSL recognizes and the client supports.
359 There should be a way for the B<s_server> program to print out details of any
360 unknown cipher suites a client says it supports.
364 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>