6 s_server - SSL/TLS server program
10 B<openssl> B<s_server>
16 [B<-certform DER|PEM>]
21 [B<-dcertform DER|PEM>]
23 [B<-dkeyform DER|PEM>]
25 [B<-dhparam filename>]
32 [B<-CApath directory>]
35 [B<-cipher cipherlist>]
56 The B<s_server> command implements a generic SSL/TLS server which listens
57 for connections on a given port using SSL/TLS.
65 the TCP port to listen on for connections. If not specified 4433 is used.
69 sets the SSL context id. It can be given any string value. If this option
70 is not present a default value will be used.
72 =item B<-cert certname>
74 The certificate to use, most servers cipher suites require the use of a
75 certificate and some require a certificate with a certain public key type:
76 for example the DSS cipher suites require a certificate containing a DSS
77 (DSA) key. If not specified then the filename "server.pem" will be used.
79 =item B<-certform format>
81 The certificate format to use: DER or PEM. PEM is the default.
85 The private key to use. If not specified then the certificate file will
88 =item B<-keyform format>
90 The private format to use: DER or PEM. PEM is the default.
94 the private key password source. For more information about the format of B<arg>
95 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
97 =item B<-dcert filename>, B<-dkey keyname>
99 specify an additional certificate and private key, these behave in the
100 same manner as the B<-cert> and B<-key> options except there is no default
101 if they are not specified (no additional certificate and key is used). As
102 noted above some cipher suites require a certificate containing a key of
103 a certain type. Some cipher suites need a certificate carrying an RSA key
104 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
105 a server can support clients which only support RSA or DSS cipher suites
106 by using an appropriate certificate.
108 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
110 addtional certificate and private key format and passphrase respectively.
114 if this option is set then no certificate is used. This restricts the
115 cipher suites available to the anonymous ones (currently just anonymous
118 =item B<-dhparam filename>
120 the DH parameter file to use. The ephemeral DH cipher suites generate keys
121 using a set of DH parameters. If not specified then an attempt is made to
122 load the parameters from the server certificate file. If this fails then
123 a static set of parameters hard coded into the s_server program will be used.
127 if this option is set then no DH parameters will be loaded effectively
128 disabling the ephemeral DH cipher suites.
132 certain export cipher suites sometimes use a temporary RSA key, this option
133 disables temporary RSA key generation.
135 =item B<-verify depth>, B<-Verify depth>
137 The verify depth to use. This specifies the maximum length of the
138 client certificate chain and makes the server request a certificate from
139 the client. With the B<-verify> option a certificate is requested but the
140 client does not have to send one, with the B<-Verify> option the client
141 must supply a certificate or an error occurs.
143 =item B<-CApath directory>
145 The directory to use for client certificate verification. This directory
146 must be in "hash format", see B<verify> for more information. These are
147 also used when building the server certificate chain.
149 =item B<-CAfile file>
151 A file containing trusted certificates to use during client authentication
152 and to use when attempting to build the server certificate chain. The list
153 is also used in the list of acceptable client CAs passed to the client when
154 a certificate is requested.
158 prints out the SSL session states.
162 print extensive debugging information including a hex dump of all traffic.
166 show all protocol messages with hex dump.
170 tests non blocking I/O
174 turns on non blocking I/O
178 this option translated a line feed from the terminal into CR+LF.
182 inhibit printing of session and certificate information.
184 =item B<-psk_hint hint>
186 Use the PSK identity hint B<hint> when using a PSK cipher suite.
190 Use the PSK key B<key> when using a PSK cipher suite. The key is
191 given as a hexadecimal number without leading 0x, for example -psk
194 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>
196 these options disable the use of certain SSL or TLS protocols. By default
197 the initial handshake uses a method which should be compatible with all
198 servers and permit them to use SSL v3, SSL v2 or TLS as appropriate.
202 there are several known bug in SSL and TLS implementations. Adding this
203 option enables various workarounds.
207 this option enables a further workaround for some some early Netscape
210 =item B<-cipher cipherlist>
212 this allows the cipher list used by the server to be modified. When
213 the client sends a list of supported ciphers the first client cipher
214 also included in the server list is used. Because the client specifies
215 the preference order, the order of the server cipherlist irrelevant. See
216 the B<ciphers> command for more information.
220 sends a status message back to the client when it connects. This includes
221 lots of information about the ciphers used and various session parameters.
222 The output is in HTML format so this option will normally be used with a
227 emulates a simple web server. Pages will be resolved relative to the
228 current directory, for example if the URL https://myhost/page.html is
229 requested the file ./page.html will be loaded.
233 emulates a simple web server. Pages will be resolved relative to the
234 current directory, for example if the URL https://myhost/page.html is
235 requested the file ./page.html will be loaded. The files loaded are
236 assumed to contain a complete and correct HTTP response (lines that
237 are part of the HTTP response line and headers must end with CRLF).
241 specifying an engine (by it's unique B<id> string) will cause B<s_server>
242 to attempt to obtain a functional reference to the specified engine,
243 thus initialising it if needed. The engine will then be set as the default
244 for all available algorithms.
246 =item B<-id_prefix arg>
248 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
249 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
250 servers, when each of which might be generating a unique range of session
251 IDs (eg. with a certain prefix).
253 =item B<-rand file(s)>
255 a file or files containing random data used to seed the random number
256 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
257 Multiple files can be specified separated by a OS-dependent character.
258 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
263 =head1 CONNECTED COMMANDS
265 If a connection request is established with an SSL client and neither the
266 B<-www> nor the B<-WWW> option has been used then normally any data received
267 from the client is displayed and any key presses will be sent to the client.
269 Certain single letter commands are also recognized which perform special
270 operations: these are listed below.
276 end the current SSL connection but still accept new connections.
280 end the current SSL connection and exit.
284 renegotiate the SSL session.
288 renegotiate the SSL session and request a client certificate.
292 send some plain text down the underlying TCP connection: this should
293 cause the client to disconnect due to a protocol violation.
297 print out some session cache status information.
303 B<s_server> can be used to debug SSL clients. To accept connections from
304 a web browser the command:
306 openssl s_server -accept 443 -www
308 can be used for example.
310 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
311 suites, so they cannot connect to servers which don't use a certificate
312 carrying an RSA key or a version of OpenSSL with RSA disabled.
314 Although specifying an empty list of CAs when requesting a client certificate
315 is strictly speaking a protocol violation, some SSL clients interpret this to
316 mean any CA is acceptable. This is useful for debugging purposes.
318 The session parameters can printed out using the B<sess_id> program.
322 Because this program has a lot of options and also because some of
323 the techniques used are rather old, the C source of s_server is rather
324 hard to read and not a model of how things should be done. A typical
325 SSL server program would be much simpler.
327 The output of common ciphers is wrong: it just gives the list of ciphers that
328 OpenSSL recognizes and the client supports.
330 There should be a way for the B<s_server> program to print out details of any
331 unknown cipher suites a client says it supports.
335 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>