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<-no_resumption_on_reneg>]
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 certain export cipher suites sometimes use a temporary RSA key, this option
139 disables temporary RSA key generation.
141 =item B<-verify depth>, B<-Verify depth>
143 The verify depth to use. This specifies the maximum length of the
144 client certificate chain and makes the server request a certificate from
145 the client. With the B<-verify> option a certificate is requested but the
146 client does not have to send one, with the B<-Verify> option the client
147 must supply a certificate or an error occurs.
149 =item B<-crl_check>, B<-crl_check_all>
151 Check the peer certificate has not been revoked by its CA.
152 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
153 option all CRLs of all CAs in the chain are checked.
155 =item B<-CApath directory>
157 The directory to use for client certificate verification. This directory
158 must be in "hash format", see B<verify> for more information. These are
159 also used when building the server certificate chain.
161 =item B<-CAfile file>
163 A file containing trusted certificates to use during client authentication
164 and to use when attempting to build the server certificate chain. The list
165 is also used in the list of acceptable client CAs passed to the client when
166 a certificate is requested.
170 prints out the SSL session states.
174 print extensive debugging information including a hex dump of all traffic.
178 show all protocol messages with hex dump.
182 tests non blocking I/O
186 turns on non blocking I/O
190 this option translated a line feed from the terminal into CR+LF.
194 inhibit printing of session and certificate information.
196 =item B<-psk_hint hint>
198 Use the PSK identity hint B<hint> when using a PSK cipher suite.
202 Use the PSK key B<key> when using a PSK cipher suite. The key is
203 given as a hexadecimal number without leading 0x, for example -psk
206 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
208 these options disable the use of certain SSL or TLS protocols. By default
209 the initial handshake uses a method which should be compatible with all
210 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
214 there are several known bug in SSL and TLS implementations. Adding this
215 option enables various workarounds.
219 this option enables a further workaround for some some early Netscape
222 =item B<-cipher cipherlist>
224 this allows the cipher list used by the server to be modified. When
225 the client sends a list of supported ciphers the first client cipher
226 also included in the server list is used. Because the client specifies
227 the preference order, the order of the server cipherlist irrelevant. See
228 the B<ciphers> command for more information.
232 use the server's cipher preferences, rather than the client's preferences.
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
285 =item B<-serverinfo file>
287 a file containing one or more blocks of PEM data. Each PEM block
288 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
289 followed by "length" bytes of extension data). If the client sends
290 an empty TLS ClientHello extension matching the type, the corresponding
291 ServerHello extension will be returned.
293 =item B<-no_resumption_on_reneg>
295 set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag.
299 =head1 CONNECTED COMMANDS
301 If a connection request is established with an SSL client and neither the
302 B<-www> nor the B<-WWW> option has been used then normally any data received
303 from the client is displayed and any key presses will be sent to the client.
305 Certain single letter commands are also recognized which perform special
306 operations: these are listed below.
312 end the current SSL connection but still accept new connections.
316 end the current SSL connection and exit.
320 renegotiate the SSL session.
324 renegotiate the SSL session and request a client certificate.
328 send some plain text down the underlying TCP connection: this should
329 cause the client to disconnect due to a protocol violation.
333 print out some session cache status information.
339 B<s_server> can be used to debug SSL clients. To accept connections from
340 a web browser the command:
342 openssl s_server -accept 443 -www
344 can be used for example.
346 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
347 suites, so they cannot connect to servers which don't use a certificate
348 carrying an RSA key or a version of OpenSSL with RSA disabled.
350 Although specifying an empty list of CAs when requesting a client certificate
351 is strictly speaking a protocol violation, some SSL clients interpret this to
352 mean any CA is acceptable. This is useful for debugging purposes.
354 The session parameters can printed out using the B<sess_id> program.
358 Because this program has a lot of options and also because some of
359 the techniques used are rather old, the C source of s_server is rather
360 hard to read and not a model of how things should be done. A typical
361 SSL server program would be much simpler.
363 The output of common ciphers is wrong: it just gives the list of ciphers that
364 OpenSSL recognizes and the client supports.
366 There should be a way for the B<s_server> program to print out details of any
367 unknown cipher suites a client says it supports.
371 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>