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>]
60 The B<s_server> command implements a generic SSL/TLS server which listens
61 for connections on a given port using SSL/TLS.
69 the TCP port to listen on for connections. If not specified 4433 is used.
73 sets the SSL context id. It can be given any string value. If this option
74 is not present a default value will be used.
76 =item B<-cert certname>
78 The certificate to use, most servers cipher suites require the use of a
79 certificate and some require a certificate with a certain public key type:
80 for example the DSS cipher suites require a certificate containing a DSS
81 (DSA) key. If not specified then the filename "server.pem" will be used.
83 =item B<-certform format>
85 The certificate format to use: DER or PEM. PEM is the default.
89 The private key to use. If not specified then the certificate file will
92 =item B<-keyform format>
94 The private format to use: DER or PEM. PEM is the default.
98 the private key password source. For more information about the format of B<arg>
99 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
101 =item B<-dcert filename>, B<-dkey keyname>
103 specify an additional certificate and private key, these behave in the
104 same manner as the B<-cert> and B<-key> options except there is no default
105 if they are not specified (no additional certificate and key is used). As
106 noted above some cipher suites require a certificate containing a key of
107 a certain type. Some cipher suites need a certificate carrying an RSA key
108 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
109 a server can support clients which only support RSA or DSS cipher suites
110 by using an appropriate certificate.
112 =item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg>
114 addtional certificate and private key format and passphrase respectively.
118 if this option is set then no certificate is used. This restricts the
119 cipher suites available to the anonymous ones (currently just anonymous
122 =item B<-dhparam filename>
124 the DH parameter file to use. The ephemeral DH cipher suites generate keys
125 using a set of DH parameters. If not specified then an attempt is made to
126 load the parameters from the server certificate file. If this fails then
127 a static set of parameters hard coded into the s_server program will be used.
131 if this option is set then no DH parameters will be loaded effectively
132 disabling the ephemeral DH cipher suites.
136 certain export cipher suites sometimes use a temporary RSA key, this option
137 disables temporary RSA key generation.
139 =item B<-verify depth>, B<-Verify depth>
141 The verify depth to use. This specifies the maximum length of the
142 client certificate chain and makes the server request a certificate from
143 the client. With the B<-verify> option a certificate is requested but the
144 client does not have to send one, with the B<-Verify> option the client
145 must supply a certificate or an error occurs.
147 =item B<-crl_check>, B<-crl_check_all>
149 Check the peer certificate has not been revoked by its CA.
150 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
151 option all CRLs of all CAs in the chain are checked.
153 =item B<-CApath directory>
155 The directory to use for client certificate verification. This directory
156 must be in "hash format", see B<verify> for more information. These are
157 also used when building the server certificate chain.
159 =item B<-CAfile file>
161 A file containing trusted certificates to use during client authentication
162 and to use when attempting to build the server certificate chain. The list
163 is also used in the list of acceptable client CAs passed to the client when
164 a certificate is requested.
168 prints out the SSL session states.
172 print extensive debugging information including a hex dump of all traffic.
176 show all protocol messages with hex dump.
180 tests non blocking I/O
184 turns on non blocking I/O
188 this option translated a line feed from the terminal into CR+LF.
192 inhibit printing of session and certificate information.
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.
218 =item B<-tlsextdebug>
220 print out a hex dump of any TLS extensions received from the server.
224 disable RFC4507bis session ticket support.
228 sends a status message back to the client when it connects. This includes
229 lots of information about the ciphers used and various session parameters.
230 The output is in HTML format so this option will normally be used with a
235 emulates a simple web server. Pages will be resolved relative to the
236 current directory, for example if the URL https://myhost/page.html is
237 requested the file ./page.html will be loaded.
241 emulates a simple web server. Pages will be resolved relative to the
242 current directory, for example if the URL https://myhost/page.html is
243 requested the file ./page.html will be loaded. The files loaded are
244 assumed to contain a complete and correct HTTP response (lines that
245 are part of the HTTP response line and headers must end with CRLF).
249 specifying an engine (by it's unique B<id> string) will cause B<s_server>
250 to attempt to obtain a functional reference to the specified engine,
251 thus initialising it if needed. The engine will then be set as the default
252 for all available algorithms.
254 =item B<-id_prefix arg>
256 generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful
257 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
258 servers, when each of which might be generating a unique range of session
259 IDs (eg. with a certain prefix).
261 =item B<-rand file(s)>
263 a file or files containing random data used to seed the random number
264 generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>).
265 Multiple files can be specified separated by a OS-dependent character.
266 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
271 =head1 CONNECTED COMMANDS
273 If a connection request is established with an SSL client and neither the
274 B<-www> nor the B<-WWW> option has been used then normally any data received
275 from the client is displayed and any key presses will be sent to the client.
277 Certain single letter commands are also recognized which perform special
278 operations: these are listed below.
284 end the current SSL connection but still accept new connections.
288 end the current SSL connection and exit.
292 renegotiate the SSL session.
296 renegotiate the SSL session and request a client certificate.
300 send some plain text down the underlying TCP connection: this should
301 cause the client to disconnect due to a protocol violation.
305 print out some session cache status information.
311 B<s_server> can be used to debug SSL clients. To accept connections from
312 a web browser the command:
314 openssl s_server -accept 443 -www
316 can be used for example.
318 Most web browsers (in particular Netscape and MSIE) only support RSA cipher
319 suites, so they cannot connect to servers which don't use a certificate
320 carrying an RSA key or a version of OpenSSL with RSA disabled.
322 Although specifying an empty list of CAs when requesting a client certificate
323 is strictly speaking a protocol violation, some SSL clients interpret this to
324 mean any CA is acceptable. This is useful for debugging purposes.
326 The session parameters can printed out using the B<sess_id> program.
328 TLS extensions are only supported in OpenSSL 0.9.8 if they are explictly
329 enabled at compile time using for example the B<enable-tlsext> switch.
333 Because this program has a lot of options and also because some of
334 the techniques used are rather old, the C source of s_server is rather
335 hard to read and not a model of how things should be done. A typical
336 SSL server program would be much simpler.
338 The output of common ciphers is wrong: it just gives the list of ciphers that
339 OpenSSL recognizes and the client supports.
341 There should be a way for the B<s_server> program to print out details of any
342 unknown cipher suites a client says it supports.
346 L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)>