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>]
59 [B<-auth_require_reneg>]
60 [B<-no_resumption_on_reneg>]
63 The B<s_server> command implements a generic SSL/TLS server which listens
64 for connections on a given port using SSL/TLS.
72 the TCP port to listen on for connections. If not specified 4433 is used.
76 sets the SSL context id. It can be given any string value. If this option
77 is not present a default value will be used.
79 =item B<-cert certname>
81 The certificate to use, most servers cipher suites require the use of a
82 certificate and some require a certificate with a certain public key type:
83 for example the DSS cipher suites require a certificate containing a DSS
84 (DSA) key. If not specified then the filename "server.pem" will be used.
86 =item B<-certform format>
88 The certificate format to use: DER or PEM. PEM is the default.
92 The private key to use. If not specified then the certificate file will
95 =item B<-keyform format>
97 The private format to use: DER or PEM. PEM is the default.
101 the private key password source. For more information about the format of B<arg>
102 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
104 =item B<-dcert filename>, B<-dkey keyname>
106 specify an additional certificate and private key, these behave in the
107 same manner as the B<-cert> and B<-key> options except there is no default
108 if they are not specified (no additional certificate and key is used). As
109 noted above some cipher suites require a certificate containing a key of
110 a certain type. Some cipher suites need a certificate carrying an RSA key
111 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
112 a server can support clients which only support RSA or DSS cipher suites
113 by using an appropriate certificate.
115 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
117 addtional certificate and private key format and passphrase respectively.
121 if this option is set then no certificate is used. This restricts the
122 cipher suites available to the anonymous ones (currently just anonymous
125 =item B<-dhparam filename>
127 the DH parameter file to use. The ephemeral DH cipher suites generate keys
128 using a set of DH parameters. If not specified then an attempt is made to
129 load the parameters from the server certificate file. If this fails then
130 a static set of parameters hard coded into the s_server program will be used.
134 if this option is set then no DH parameters will be loaded effectively
135 disabling the ephemeral DH cipher suites.
139 certain export cipher suites sometimes use a temporary RSA key, this option
140 disables temporary RSA key generation.
142 =item B<-verify depth>, B<-Verify depth>
144 The verify depth to use. This specifies the maximum length of the
145 client certificate chain and makes the server request a certificate from
146 the client. With the B<-verify> option a certificate is requested but the
147 client does not have to send one, with the B<-Verify> option the client
148 must supply a certificate or an error occurs.
150 =item B<-crl_check>, B<-crl_check_all>
152 Check the peer certificate has not been revoked by its CA.
153 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
154 option all CRLs of all CAs in the chain are checked.
156 =item B<-CApath directory>
158 The directory to use for client certificate verification. This directory
159 must be in "hash format", see B<verify> for more information. These are
160 also used when building the server certificate chain.
162 =item B<-CAfile file>
164 A file containing trusted certificates to use during client authentication
165 and to use when attempting to build the server certificate chain. The list
166 is also used in the list of acceptable client CAs passed to the client when
167 a certificate is requested.
171 prints out the SSL session states.
175 print extensive debugging information including a hex dump of all traffic.
179 show all protocol messages with hex dump.
183 tests non blocking I/O
187 turns on non blocking I/O
191 this option translated a line feed from the terminal into CR+LF.
195 inhibit printing of session and certificate information.
197 =item B<-psk_hint hint>
199 Use the PSK identity hint B<hint> when using a PSK cipher suite.
203 Use the PSK key B<key> when using a PSK cipher suite. The key is
204 given as a hexadecimal number without leading 0x, for example -psk
207 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
209 these options disable the use of certain SSL or TLS protocols. By default
210 the initial handshake uses a method which should be compatible with all
211 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
215 there are several known bug in SSL and TLS implementations. Adding this
216 option enables various workarounds.
220 this option enables a further workaround for some some early Netscape
223 =item B<-cipher cipherlist>
225 this allows the cipher list used by the server to be modified. When
226 the client sends a list of supported ciphers the first client cipher
227 also included in the server list is used. Because the client specifies
228 the preference order, the order of the server cipherlist irrelevant. See
229 the B<ciphers> command for more information.
231 =item B<-tlsextdebug>
233 print out a hex dump of any TLS extensions received from the server.
237 disable RFC4507bis session ticket support.
241 sends a status message back to the client when it connects. This includes
242 lots of information about the ciphers used and various session parameters.
243 The output is in HTML format so this option will normally be used with a
248 emulates a simple web server. Pages will be resolved relative to the
249 current directory, for example if the URL https://myhost/page.html is
250 requested the file ./page.html will be loaded.
254 emulates a simple web server. Pages will be resolved relative to the
255 current directory, for example if the URL https://myhost/page.html is
256 requested the file ./page.html will be loaded. The files loaded are
257 assumed to contain a complete and correct HTTP response (lines that
258 are part of the HTTP response line and headers must end with CRLF).
262 specifying an engine (by its unique B<id> string) will cause B<s_server>
263 to attempt to obtain a functional reference to the specified engine,
264 thus initialising it if needed. The engine will then be set as the default
265 for all available algorithms.
267 =item B<-id_prefix arg>
269 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
270 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
271 servers, when each of which might be generating a unique range of session
272 IDs (eg. with a certain prefix).
274 =item B<-rand file(s)>
276 a file or files containing random data used to seed the random number
277 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
278 Multiple files can be specified separated by a OS-dependent character.
279 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
282 =item B<-serverinfo file>
284 a file containing one or more blocks of PEM data. Each PEM block
285 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
286 followed by "length" bytes of extension data). If the client sends
287 an empty TLS ClientHello extension matching the type, the corresponding
288 ServerHello extension will be returned.
292 send RFC 5878 client and server authorization extensions in the Client Hello as well as
293 supplemental data if the server also sent the authorization extensions in the Server Hello.
295 =item B<-auth_require_reneg>
297 only send RFC 5878 client and server authorization extensions during renegotiation.
299 =item B<-no_resumption_on_reneg>
301 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. Required in order to receive supplemental data
302 during renegotiation if auth and auth_require_reneg are set.
306 =head1 CONNECTED COMMANDS
308 If a connection request is established with an SSL client and neither the
309 B<-www> nor the B<-WWW> option has been used then normally any data received
310 from the client is displayed and any key presses will be sent to the client.
312 Certain single letter commands are also recognized which perform special
313 operations: these are listed below.
319 end the current SSL connection but still accept new connections.
323 end the current SSL connection and exit.
327 renegotiate the SSL session.
331 renegotiate the SSL session and request a client certificate.
335 send some plain text down the underlying TCP connection: this should
336 cause the client to disconnect due to a protocol violation.
340 print out some session cache status information.
346 B<s_server> can be used to debug SSL clients. To accept connections from
347 a web browser the command:
349 openssl s_server -accept 443 -www
351 can be used for example.
353 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
354 suites, so they cannot connect to servers which don't use a certificate
355 carrying an RSA key or a version of OpenSSL with RSA disabled.
357 Although specifying an empty list of CAs when requesting a client certificate
358 is strictly speaking a protocol violation, some SSL clients interpret this to
359 mean any CA is acceptable. This is useful for debugging purposes.
361 The session parameters can printed out using the B<sess_id> program.
365 Because this program has a lot of options and also because some of
366 the techniques used are rather old, the C source of s_server is rather
367 hard to read and not a model of how things should be done. A typical
368 SSL server program would be much simpler.
370 The output of common ciphers is wrong: it just gives the list of ciphers that
371 OpenSSL recognizes and the client supports.
373 There should be a way for the B<s_server> program to print out details of any
374 unknown cipher suites a client says it supports.
378 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>