s_server.pod revision 267258
1 2=pod 3 4=head1 NAME 5 6s_server - SSL/TLS server program 7 8=head1 SYNOPSIS 9 10B<openssl> B<s_server> 11[B<-accept port>] 12[B<-context id>] 13[B<-verify depth>] 14[B<-Verify depth>] 15[B<-crl_check>] 16[B<-crl_check_all>] 17[B<-cert filename>] 18[B<-certform DER|PEM>] 19[B<-key keyfile>] 20[B<-keyform DER|PEM>] 21[B<-pass arg>] 22[B<-dcert filename>] 23[B<-dcertform DER|PEM>] 24[B<-dkey keyfile>] 25[B<-dkeyform DER|PEM>] 26[B<-dpass arg>] 27[B<-dhparam filename>] 28[B<-nbio>] 29[B<-nbio_test>] 30[B<-crlf>] 31[B<-debug>] 32[B<-msg>] 33[B<-state>] 34[B<-CApath directory>] 35[B<-CAfile filename>] 36[B<-nocert>] 37[B<-cipher cipherlist>] 38[B<-quiet>] 39[B<-no_tmp_rsa>] 40[B<-ssl2>] 41[B<-ssl3>] 42[B<-tls1>] 43[B<-no_ssl2>] 44[B<-no_ssl3>] 45[B<-no_tls1>] 46[B<-no_dhe>] 47[B<-no_ecdhe>] 48[B<-bugs>] 49[B<-hack>] 50[B<-www>] 51[B<-WWW>] 52[B<-HTTP>] 53[B<-engine id>] 54[B<-tlsextdebug>] 55[B<-no_ticket>] 56[B<-id_prefix arg>] 57[B<-rand file(s)>] 58 59=head1 DESCRIPTION 60 61The B<s_server> command implements a generic SSL/TLS server which listens 62for connections on a given port using SSL/TLS. 63 64=head1 OPTIONS 65 66=over 4 67 68=item B<-accept port> 69 70the TCP port to listen on for connections. If not specified 4433 is used. 71 72=item B<-context id> 73 74sets the SSL context id. It can be given any string value. If this option 75is not present a default value will be used. 76 77=item B<-cert certname> 78 79The certificate to use, most servers cipher suites require the use of a 80certificate and some require a certificate with a certain public key type: 81for 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. 83 84=item B<-certform format> 85 86The certificate format to use: DER or PEM. PEM is the default. 87 88=item B<-key keyfile> 89 90The private key to use. If not specified then the certificate file will 91be used. 92 93=item B<-keyform format> 94 95The private format to use: DER or PEM. PEM is the default. 96 97=item B<-pass arg> 98 99the private key password source. For more information about the format of B<arg> 100see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 101 102=item B<-dcert filename>, B<-dkey keyname> 103 104specify an additional certificate and private key, these behave in the 105same manner as the B<-cert> and B<-key> options except there is no default 106if they are not specified (no additional certificate and key is used). As 107noted above some cipher suites require a certificate containing a key of 108a certain type. Some cipher suites need a certificate carrying an RSA key 109and some a DSS (DSA) key. By using RSA and DSS certificates and keys 110a server can support clients which only support RSA or DSS cipher suites 111by using an appropriate certificate. 112 113=item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg> 114 115additional certificate and private key format and passphrase respectively. 116 117=item B<-nocert> 118 119if this option is set then no certificate is used. This restricts the 120cipher suites available to the anonymous ones (currently just anonymous 121DH). 122 123=item B<-dhparam filename> 124 125the DH parameter file to use. The ephemeral DH cipher suites generate keys 126using a set of DH parameters. If not specified then an attempt is made to 127load the parameters from the server certificate file. If this fails then 128a static set of parameters hard coded into the s_server program will be used. 129 130=item B<-no_dhe> 131 132if this option is set then no DH parameters will be loaded effectively 133disabling the ephemeral DH cipher suites. 134 135=item B<-no_ecdhe> 136 137if this option is set then no ECDH parameters will be loaded effectively 138disabling the ephemeral ECDH cipher suites. 139 140=item B<-no_tmp_rsa> 141 142certain export cipher suites sometimes use a temporary RSA key, this option 143disables temporary RSA key generation. 144 145=item B<-verify depth>, B<-Verify depth> 146 147The verify depth to use. This specifies the maximum length of the 148client certificate chain and makes the server request a certificate from 149the client. With the B<-verify> option a certificate is requested but the 150client does not have to send one, with the B<-Verify> option the client 151must supply a certificate or an error occurs. 152 153=item B<-crl_check>, B<-crl_check_all> 154 155Check the peer certificate has not been revoked by its CA. 156The CRL(s) are appended to the certificate file. With the B<-crl_check_all> 157option all CRLs of all CAs in the chain are checked. 158 159=item B<-CApath directory> 160 161The directory to use for client certificate verification. This directory 162must be in "hash format", see B<verify> for more information. These are 163also used when building the server certificate chain. 164 165=item B<-CAfile file> 166 167A file containing trusted certificates to use during client authentication 168and to use when attempting to build the server certificate chain. The list 169is also used in the list of acceptable client CAs passed to the client when 170a certificate is requested. 171 172=item B<-state> 173 174prints out the SSL session states. 175 176=item B<-debug> 177 178print extensive debugging information including a hex dump of all traffic. 179 180=item B<-msg> 181 182show all protocol messages with hex dump. 183 184=item B<-nbio_test> 185 186tests non blocking I/O 187 188=item B<-nbio> 189 190turns on non blocking I/O 191 192=item B<-crlf> 193 194this option translated a line feed from the terminal into CR+LF. 195 196=item B<-quiet> 197 198inhibit printing of session and certificate information. 199 200=item B<-psk_hint hint> 201 202Use the PSK identity hint B<hint> when using a PSK cipher suite. 203 204=item B<-psk key> 205 206Use the PSK key B<key> when using a PSK cipher suite. The key is 207given as a hexadecimal number without leading 0x, for example -psk 2081a2b3c4d. 209 210=item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1> 211 212these options disable the use of certain SSL or TLS protocols. By default 213the initial handshake uses a method which should be compatible with all 214servers and permit them to use SSL v3, SSL v2 or TLS as appropriate. 215 216=item B<-bugs> 217 218there are several known bug in SSL and TLS implementations. Adding this 219option enables various workarounds. 220 221=item B<-hack> 222 223this option enables a further workaround for some some early Netscape 224SSL code (?). 225 226=item B<-cipher cipherlist> 227 228this allows the cipher list used by the server to be modified. When 229the client sends a list of supported ciphers the first client cipher 230also included in the server list is used. Because the client specifies 231the preference order, the order of the server cipherlist irrelevant. See 232the B<ciphers> command for more information. 233 234=item B<-tlsextdebug> 235 236print out a hex dump of any TLS extensions received from the server. 237 238=item B<-no_ticket> 239 240disable RFC4507bis session ticket support. 241 242=item B<-www> 243 244sends a status message back to the client when it connects. This includes 245lots of information about the ciphers used and various session parameters. 246The output is in HTML format so this option will normally be used with a 247web browser. 248 249=item B<-WWW> 250 251emulates a simple web server. Pages will be resolved relative to the 252current directory, for example if the URL https://myhost/page.html is 253requested the file ./page.html will be loaded. 254 255=item B<-HTTP> 256 257emulates a simple web server. Pages will be resolved relative to the 258current directory, for example if the URL https://myhost/page.html is 259requested the file ./page.html will be loaded. The files loaded are 260assumed to contain a complete and correct HTTP response (lines that 261are part of the HTTP response line and headers must end with CRLF). 262 263=item B<-engine id> 264 265specifying an engine (by its unique B<id> string) will cause B<s_server> 266to attempt to obtain a functional reference to the specified engine, 267thus initialising it if needed. The engine will then be set as the default 268for all available algorithms. 269 270=item B<-id_prefix arg> 271 272generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful 273for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple 274servers, when each of which might be generating a unique range of session 275IDs (eg. with a certain prefix). 276 277=item B<-rand file(s)> 278 279a file or files containing random data used to seed the random number 280generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 281Multiple files can be specified separated by a OS-dependent character. 282The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 283all others. 284 285=back 286 287=head1 CONNECTED COMMANDS 288 289If a connection request is established with an SSL client and neither the 290B<-www> nor the B<-WWW> option has been used then normally any data received 291from the client is displayed and any key presses will be sent to the client. 292 293Certain single letter commands are also recognized which perform special 294operations: these are listed below. 295 296=over 4 297 298=item B<q> 299 300end the current SSL connection but still accept new connections. 301 302=item B<Q> 303 304end the current SSL connection and exit. 305 306=item B<r> 307 308renegotiate the SSL session. 309 310=item B<R> 311 312renegotiate the SSL session and request a client certificate. 313 314=item B<P> 315 316send some plain text down the underlying TCP connection: this should 317cause the client to disconnect due to a protocol violation. 318 319=item B<S> 320 321print out some session cache status information. 322 323=back 324 325=head1 NOTES 326 327B<s_server> can be used to debug SSL clients. To accept connections from 328a web browser the command: 329 330 openssl s_server -accept 443 -www 331 332can be used for example. 333 334Most web browsers (in particular Netscape and MSIE) only support RSA cipher 335suites, so they cannot connect to servers which don't use a certificate 336carrying an RSA key or a version of OpenSSL with RSA disabled. 337 338Although specifying an empty list of CAs when requesting a client certificate 339is strictly speaking a protocol violation, some SSL clients interpret this to 340mean any CA is acceptable. This is useful for debugging purposes. 341 342The session parameters can printed out using the B<sess_id> program. 343 344=head1 BUGS 345 346Because this program has a lot of options and also because some of 347the techniques used are rather old, the C source of s_server is rather 348hard to read and not a model of how things should be done. A typical 349SSL server program would be much simpler. 350 351The output of common ciphers is wrong: it just gives the list of ciphers that 352OpenSSL recognizes and the client supports. 353 354There should be a way for the B<s_server> program to print out details of any 355unknown cipher suites a client says it supports. 356 357=head1 SEE ALSO 358 359L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)> 360 361=cut 362