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>]
61 The B<s_server> command implements a generic SSL/TLS server which listens
62 for connections on a given port using SSL/TLS.
70 the TCP port to listen on for connections. If not specified 4433 is used.
74 sets the SSL context id. It can be given any string value. If this option
75 is not present a default value will be used.
77 =item B<-cert certname>
79 The certificate to use, most servers cipher suites require the use of a
80 certificate and some require a certificate with a certain public key type:
81 for example the DSS cipher suites require a certificate containing a DSS
82 (DSA) key. If not specified then the filename "server.pem" will be used.
84 =item B<-certform format>
86 The certificate format to use: DER or PEM. PEM is the default.
90 The private key to use. If not specified then the certificate file will
93 =item B<-keyform format>
95 The private format to use: DER or PEM. PEM is the default.
99 the private key password source. For more information about the format of B<arg>
100 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
102 =item B<-dcert filename>, B<-dkey keyname>
104 specify an additional certificate and private key, these behave in the
105 same manner as the B<-cert> and B<-key> options except there is no default
106 if they are not specified (no additional certificate and key is used). As
107 noted above some cipher suites require a certificate containing a key of
108 a certain type. Some cipher suites need a certificate carrying an RSA key
109 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
110 a server can support clients which only support RSA or DSS cipher suites
111 by using an appropriate certificate.
113 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
115 additional certificate and private key format and passphrase respectively.
119 if this option is set then no certificate is used. This restricts the
120 cipher suites available to the anonymous ones (currently just anonymous
123 =item B<-dhparam filename>
125 the DH parameter file to use. The ephemeral DH cipher suites generate keys
126 using a set of DH parameters. If not specified then an attempt is made to
127 load the parameters from the server certificate file. If this fails then
128 a static set of parameters hard coded into the s_server program will be used.
132 if this option is set then no DH parameters will be loaded effectively
133 disabling the ephemeral DH cipher suites.
137 if this option is set then no ECDH parameters will be loaded effectively
138 disabling the ephemeral ECDH cipher suites.
142 certain export cipher suites sometimes use a temporary RSA key, this option
143 disables temporary RSA key generation.
145 =item B<-verify depth>, B<-Verify depth>
147 The verify depth to use. This specifies the maximum length of the
148 client certificate chain and makes the server request a certificate from
149 the client. With the B<-verify> option a certificate is requested but the
150 client does not have to send one, with the B<-Verify> option the client
151 must supply a certificate or an error occurs.
153 =item B<-crl_check>, B<-crl_check_all>
155 Check the peer certificate has not been revoked by its CA.
156 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
157 option all CRLs of all CAs in the chain are checked.
159 =item B<-CApath directory>
161 The directory to use for client certificate verification. This directory
162 must be in "hash format", see B<verify> for more information. These are
163 also used when building the server certificate chain.
165 =item B<-CAfile file>
167 A file containing trusted certificates to use during client authentication
168 and to use when attempting to build the server certificate chain. The list
169 is also used in the list of acceptable client CAs passed to the client when
170 a certificate is requested.
174 prints out the SSL session states.
178 print extensive debugging information including a hex dump of all traffic.
182 show all protocol messages with hex dump.
186 tests non blocking I/O
190 turns on non blocking I/O
194 this option translated a line feed from the terminal into CR+LF.
198 inhibit printing of session and certificate information.
200 =item B<-psk_hint hint>
202 Use the PSK identity hint B<hint> when using a PSK cipher suite.
206 Use the PSK key B<key> when using a PSK cipher suite. The key is
207 given as a hexadecimal number without leading 0x, for example -psk
210 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
212 these options disable the use of certain SSL or TLS protocols. By default
213 the initial handshake uses a method which should be compatible with all
214 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
218 there are several known bug in SSL and TLS implementations. Adding this
219 option enables various workarounds.
223 this option enables a further workaround for some some early Netscape
226 =item B<-cipher cipherlist>
228 this allows the cipher list used by the server to be modified. When
229 the client sends a list of supported ciphers the first client cipher
230 also included in the server list is used. Because the client specifies
231 the preference order, the order of the server cipherlist irrelevant. See
232 the B<ciphers> command for more information.
234 =item B<-tlsextdebug>
236 print out a hex dump of any TLS extensions received from the server.
240 disable RFC4507bis session ticket support.
244 sends a status message back to the client when it connects. This includes
245 lots of information about the ciphers used and various session parameters.
246 The output is in HTML format so this option will normally be used with a
251 emulates a simple web server. Pages will be resolved relative to the
252 current directory, for example if the URL https://myhost/page.html is
253 requested the file ./page.html will be loaded.
257 emulates a simple web server. Pages will be resolved relative to the
258 current directory, for example if the URL https://myhost/page.html is
259 requested the file ./page.html will be loaded. The files loaded are
260 assumed to contain a complete and correct HTTP response (lines that
261 are part of the HTTP response line and headers must end with CRLF).
265 specifying an engine (by its unique B<id> string) will cause B<s_server>
266 to attempt to obtain a functional reference to the specified engine,
267 thus initialising it if needed. The engine will then be set as the default
268 for all available algorithms.
270 =item B<-id_prefix arg>
272 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
273 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
274 servers, when each of which might be generating a unique range of session
275 IDs (eg. with a certain prefix).
277 =item B<-rand file(s)>
279 a file or files containing random data used to seed the random number
280 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
281 Multiple files can be specified separated by a OS-dependent character.
282 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
287 =head1 CONNECTED COMMANDS
289 If a connection request is established with an SSL client and neither the
290 B<-www> nor the B<-WWW> option has been used then normally any data received
291 from the client is displayed and any key presses will be sent to the client.
293 Certain single letter commands are also recognized which perform special
294 operations: these are listed below.
300 end the current SSL connection but still accept new connections.
304 end the current SSL connection and exit.
308 renegotiate the SSL session.
312 renegotiate the SSL session and request a client certificate.
316 send some plain text down the underlying TCP connection: this should
317 cause the client to disconnect due to a protocol violation.
321 print out some session cache status information.
327 B<s_server> can be used to debug SSL clients. To accept connections from
328 a web browser the command:
330 openssl s_server -accept 443 -www
332 can be used for example.
334 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
335 suites, so they cannot connect to servers which don't use a certificate
336 carrying an RSA key or a version of OpenSSL with RSA disabled.
338 Although specifying an empty list of CAs when requesting a client certificate
339 is strictly speaking a protocol violation, some SSL clients interpret this to
340 mean any CA is acceptable. This is useful for debugging purposes.
342 The session parameters can printed out using the B<sess_id> program.
346 Because this program has a lot of options and also because some of
347 the techniques used are rather old, the C source of s_server is rather
348 hard to read and not a model of how things should be done. A typical
349 SSL server program would be much simpler.
351 The output of common ciphers is wrong: it just gives the list of ciphers that
352 OpenSSL recognizes and the client supports.
354 There should be a way for the B<s_server> program to print out details of any
355 unknown cipher suites a client says it supports.
359 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>