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<-no_alt_chains>] 37[B<-nocert>] 38[B<-cipher cipherlist>] 39[B<-serverpref>] 40[B<-quiet>] 41[B<-no_tmp_rsa>] 42[B<-ssl2>] 43[B<-ssl3>] 44[B<-tls1>] 45[B<-no_ssl2>] 46[B<-no_ssl3>] 47[B<-no_tls1>] 48[B<-no_dhe>] 49[B<-bugs>] 50[B<-hack>] 51[B<-www>] 52[B<-WWW>] 53[B<-HTTP>] 54[B<-engine id>] 55[B<-tlsextdebug>] 56[B<-no_ticket>] 57[B<-id_prefix arg>] 58[B<-rand file(s)>] 59[B<-serverinfo file>] 60[B<-no_resumption_on_reneg>] 61[B<-status>] 62[B<-status_verbose>] 63[B<-status_timeout nsec>] 64[B<-status_url url>] 65[B<-nextprotoneg protocols>] 66 67=head1 DESCRIPTION 68 69The B<s_server> command implements a generic SSL/TLS server which listens 70for connections on a given port using SSL/TLS. 71 72=head1 OPTIONS 73 74=over 4 75 76=item B<-accept port> 77 78the TCP port to listen on for connections. If not specified 4433 is used. 79 80=item B<-context id> 81 82sets the SSL context id. It can be given any string value. If this option 83is not present a default value will be used. 84 85=item B<-cert certname> 86 87The certificate to use, most servers cipher suites require the use of a 88certificate and some require a certificate with a certain public key type: 89for example the DSS cipher suites require a certificate containing a DSS 90(DSA) key. If not specified then the filename "server.pem" will be used. 91 92=item B<-certform format> 93 94The certificate format to use: DER or PEM. PEM is the default. 95 96=item B<-key keyfile> 97 98The private key to use. If not specified then the certificate file will 99be used. 100 101=item B<-keyform format> 102 103The private format to use: DER or PEM. PEM is the default. 104 105=item B<-pass arg> 106 107the private key password source. For more information about the format of B<arg> 108see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 109 110=item B<-dcert filename>, B<-dkey keyname> 111 112specify an additional certificate and private key, these behave in the 113same manner as the B<-cert> and B<-key> options except there is no default 114if they are not specified (no additional certificate and key is used). As 115noted above some cipher suites require a certificate containing a key of 116a certain type. Some cipher suites need a certificate carrying an RSA key 117and some a DSS (DSA) key. By using RSA and DSS certificates and keys 118a server can support clients which only support RSA or DSS cipher suites 119by using an appropriate certificate. 120 121=item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg> 122 123additional certificate and private key format and passphrase respectively. 124 125=item B<-nocert> 126 127if this option is set then no certificate is used. This restricts the 128cipher suites available to the anonymous ones (currently just anonymous 129DH). 130 131=item B<-dhparam filename> 132 133the DH parameter file to use. The ephemeral DH cipher suites generate keys 134using a set of DH parameters. If not specified then an attempt is made to 135load the parameters from the server certificate file. If this fails then 136a static set of parameters hard coded into the s_server program will be used. 137 138=item B<-no_dhe> 139 140if this option is set then no DH parameters will be loaded effectively 141disabling the ephemeral DH cipher suites. 142 143=item B<-no_tmp_rsa> 144 145certain export cipher suites sometimes use a temporary RSA key, this option 146disables temporary RSA key generation. 147 148=item B<-verify depth>, B<-Verify depth> 149 150The verify depth to use. This specifies the maximum length of the 151client certificate chain and makes the server request a certificate from 152the client. With the B<-verify> option a certificate is requested but the 153client does not have to send one, with the B<-Verify> option the client 154must supply a certificate or an error occurs. 155 156If the ciphersuite cannot request a client certificate (for example an 157anonymous ciphersuite or PSK) this option has no effect. 158 159=item B<-crl_check>, B<-crl_check_all> 160 161Check the peer certificate has not been revoked by its CA. 162The CRL(s) are appended to the certificate file. With the B<-crl_check_all> 163option all CRLs of all CAs in the chain are checked. 164 165=item B<-CApath directory> 166 167The directory to use for client certificate verification. This directory 168must be in "hash format", see B<verify> for more information. These are 169also used when building the server certificate chain. 170 171=item B<-CAfile file> 172 173A file containing trusted certificates to use during client authentication 174and to use when attempting to build the server certificate chain. The list 175is also used in the list of acceptable client CAs passed to the client when 176a certificate is requested. 177 178=item B<-no_alt_chains> 179 180See the L<B<verify>|verify(1)> manual page for details. 181 182=item B<-state> 183 184prints out the SSL session states. 185 186=item B<-debug> 187 188print extensive debugging information including a hex dump of all traffic. 189 190=item B<-msg> 191 192show all protocol messages with hex dump. 193 194=item B<-nbio_test> 195 196tests non blocking I/O 197 198=item B<-nbio> 199 200turns on non blocking I/O 201 202=item B<-crlf> 203 204this option translated a line feed from the terminal into CR+LF. 205 206=item B<-quiet> 207 208inhibit printing of session and certificate information. 209 210=item B<-psk_hint hint> 211 212Use the PSK identity hint B<hint> when using a PSK cipher suite. 213 214=item B<-psk key> 215 216Use the PSK key B<key> when using a PSK cipher suite. The key is 217given as a hexadecimal number without leading 0x, for example -psk 2181a2b3c4d. 219 220=item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-tls1_1>, B<-tls1_2>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2> 221 222These options require or disable the use of the specified SSL or TLS protocols. 223By default the initial handshake uses a I<version-flexible> method which will 224negotiate the highest mutually supported protocol version. 225 226=item B<-bugs> 227 228there are several known bug in SSL and TLS implementations. Adding this 229option enables various workarounds. 230 231=item B<-hack> 232 233this option enables a further workaround for some some early Netscape 234SSL code (?). 235 236=item B<-cipher cipherlist> 237 238this allows the cipher list used by the server to be modified. When 239the client sends a list of supported ciphers the first client cipher 240also included in the server list is used. Because the client specifies 241the preference order, the order of the server cipherlist irrelevant. See 242the B<ciphers> command for more information. 243 244=item B<-serverpref> 245 246use the server's cipher preferences, rather than the client's preferences. 247 248=item B<-tlsextdebug> 249 250print out a hex dump of any TLS extensions received from the server. 251 252=item B<-no_ticket> 253 254disable RFC4507bis session ticket support. 255 256=item B<-www> 257 258sends a status message back to the client when it connects. This includes 259lots of information about the ciphers used and various session parameters. 260The output is in HTML format so this option will normally be used with a 261web browser. 262 263=item B<-WWW> 264 265emulates a simple web server. Pages will be resolved relative to the 266current directory, for example if the URL https://myhost/page.html is 267requested the file ./page.html will be loaded. 268 269=item B<-HTTP> 270 271emulates a simple web server. Pages will be resolved relative to the 272current directory, for example if the URL https://myhost/page.html is 273requested the file ./page.html will be loaded. The files loaded are 274assumed to contain a complete and correct HTTP response (lines that 275are part of the HTTP response line and headers must end with CRLF). 276 277=item B<-engine id> 278 279specifying an engine (by its unique B<id> string) will cause B<s_server> 280to attempt to obtain a functional reference to the specified engine, 281thus initialising it if needed. The engine will then be set as the default 282for all available algorithms. 283 284=item B<-id_prefix arg> 285 286generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful 287for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple 288servers, when each of which might be generating a unique range of session 289IDs (eg. with a certain prefix). 290 291=item B<-rand file(s)> 292 293a file or files containing random data used to seed the random number 294generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 295Multiple files can be specified separated by a OS-dependent character. 296The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 297all others. 298 299=item B<-serverinfo file> 300 301a file containing one or more blocks of PEM data. Each PEM block 302must encode a TLS ServerHello extension (2 bytes type, 2 bytes length, 303followed by "length" bytes of extension data). If the client sends 304an empty TLS ClientHello extension matching the type, the corresponding 305ServerHello extension will be returned. 306 307=item B<-no_resumption_on_reneg> 308 309set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. 310 311=item B<-status> 312 313enables certificate status request support (aka OCSP stapling). 314 315=item B<-status_verbose> 316 317enables certificate status request support (aka OCSP stapling) and gives 318a verbose printout of the OCSP response. 319 320=item B<-status_timeout nsec> 321 322sets the timeout for OCSP response to B<nsec> seconds. 323 324=item B<-status_url url> 325 326sets a fallback responder URL to use if no responder URL is present in the 327server certificate. Without this option an error is returned if the server 328certificate does not contain a responder address. 329 330=item B<-nextprotoneg protocols> 331 332enable Next Protocol Negotiation TLS extension and provide a 333comma-separated list of supported protocol names. 334The list should contain most wanted protocols first. 335Protocol names are printable ASCII strings, for example "http/1.1" or 336"spdy/3". 337 338=back 339 340=head1 CONNECTED COMMANDS 341 342If a connection request is established with an SSL client and neither the 343B<-www> nor the B<-WWW> option has been used then normally any data received 344from the client is displayed and any key presses will be sent to the client. 345 346Certain single letter commands are also recognized which perform special 347operations: these are listed below. 348 349=over 4 350 351=item B<q> 352 353end the current SSL connection but still accept new connections. 354 355=item B<Q> 356 357end the current SSL connection and exit. 358 359=item B<r> 360 361renegotiate the SSL session. 362 363=item B<R> 364 365renegotiate the SSL session and request a client certificate. 366 367=item B<P> 368 369send some plain text down the underlying TCP connection: this should 370cause the client to disconnect due to a protocol violation. 371 372=item B<S> 373 374print out some session cache status information. 375 376=back 377 378=head1 NOTES 379 380B<s_server> can be used to debug SSL clients. To accept connections from 381a web browser the command: 382 383 openssl s_server -accept 443 -www 384 385can be used for example. 386 387Most web browsers (in particular Netscape and MSIE) only support RSA cipher 388suites, so they cannot connect to servers which don't use a certificate 389carrying an RSA key or a version of OpenSSL with RSA disabled. 390 391Although specifying an empty list of CAs when requesting a client certificate 392is strictly speaking a protocol violation, some SSL clients interpret this to 393mean any CA is acceptable. This is useful for debugging purposes. 394 395The session parameters can printed out using the B<sess_id> program. 396 397=head1 BUGS 398 399Because this program has a lot of options and also because some of 400the techniques used are rather old, the C source of s_server is rather 401hard to read and not a model of how things should be done. A typical 402SSL server program would be much simpler. 403 404The output of common ciphers is wrong: it just gives the list of ciphers that 405OpenSSL recognizes and the client supports. 406 407There should be a way for the B<s_server> program to print out details of any 408unknown cipher suites a client says it supports. 409 410=head1 SEE ALSO 411 412L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)> 413 414=head1 HISTORY 415 416The -no_alt_chains options was first added to OpenSSL 1.0.2b. 417 418=cut 419