s_server.pod revision 325335
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<-client_sigalgs sigalglist>] 39[B<-named_curve curve>] 40[B<-cipher cipherlist>] 41[B<-serverpref>] 42[B<-quiet>] 43[B<-no_tmp_rsa>] 44[B<-ssl2>] 45[B<-ssl3>] 46[B<-tls1>] 47[B<-no_ssl2>] 48[B<-no_ssl3>] 49[B<-no_tls1>] 50[B<-no_dhe>] 51[B<-bugs>] 52[B<-hack>] 53[B<-www>] 54[B<-WWW>] 55[B<-HTTP>] 56[B<-engine id>] 57[B<-tlsextdebug>] 58[B<-no_ticket>] 59[B<-id_prefix arg>] 60[B<-rand file(s)>] 61[B<-serverinfo file>] 62[B<-no_resumption_on_reneg>] 63[B<-status>] 64[B<-status_verbose>] 65[B<-status_timeout nsec>] 66[B<-status_url url>] 67[B<-alpn protocols>] 68[B<-nextprotoneg protocols>] 69 70=head1 DESCRIPTION 71 72The B<s_server> command implements a generic SSL/TLS server which listens 73for connections on a given port using SSL/TLS. 74 75=head1 OPTIONS 76 77=over 4 78 79=item B<-accept port> 80 81the TCP port to listen on for connections. If not specified 4433 is used. 82 83=item B<-context id> 84 85sets the SSL context id. It can be given any string value. If this option 86is not present a default value will be used. 87 88=item B<-cert certname> 89 90The certificate to use, most servers cipher suites require the use of a 91certificate and some require a certificate with a certain public key type: 92for example the DSS cipher suites require a certificate containing a DSS 93(DSA) key. If not specified then the filename "server.pem" will be used. 94 95=item B<-certform format> 96 97The certificate format to use: DER or PEM. PEM is the default. 98 99=item B<-key keyfile> 100 101The private key to use. If not specified then the certificate file will 102be used. 103 104=item B<-keyform format> 105 106The private format to use: DER or PEM. PEM is the default. 107 108=item B<-pass arg> 109 110the private key password source. For more information about the format of B<arg> 111see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 112 113=item B<-dcert filename>, B<-dkey keyname> 114 115specify an additional certificate and private key, these behave in the 116same manner as the B<-cert> and B<-key> options except there is no default 117if they are not specified (no additional certificate and key is used). As 118noted above some cipher suites require a certificate containing a key of 119a certain type. Some cipher suites need a certificate carrying an RSA key 120and some a DSS (DSA) key. By using RSA and DSS certificates and keys 121a server can support clients which only support RSA or DSS cipher suites 122by using an appropriate certificate. 123 124=item B<-dcertform format>, B<-dkeyform format>, B<-dpass arg> 125 126additional certificate and private key format and passphrase respectively. 127 128=item B<-nocert> 129 130if this option is set then no certificate is used. This restricts the 131cipher suites available to the anonymous ones (currently just anonymous 132DH). 133 134=item B<-dhparam filename> 135 136the DH parameter file to use. The ephemeral DH cipher suites generate keys 137using a set of DH parameters. If not specified then an attempt is made to 138load the parameters from the server certificate file. If this fails then 139a static set of parameters hard coded into the s_server program will be used. 140 141=item B<-no_dhe> 142 143if this option is set then no DH parameters will be loaded effectively 144disabling the ephemeral DH cipher suites. 145 146=item B<-no_tmp_rsa> 147 148certain export cipher suites sometimes use a temporary RSA key, this option 149disables temporary RSA key generation. 150 151=item B<-verify depth>, B<-Verify depth> 152 153The verify depth to use. This specifies the maximum length of the 154client certificate chain and makes the server request a certificate from 155the client. With the B<-verify> option a certificate is requested but the 156client does not have to send one, with the B<-Verify> option the client 157must supply a certificate or an error occurs. 158 159If the ciphersuite cannot request a client certificate (for example an 160anonymous ciphersuite or PSK) this option has no effect. 161 162=item B<-crl_check>, B<-crl_check_all> 163 164Check the peer certificate has not been revoked by its CA. 165The CRL(s) are appended to the certificate file. With the B<-crl_check_all> 166option all CRLs of all CAs in the chain are checked. 167 168=item B<-CApath directory> 169 170The directory to use for client certificate verification. This directory 171must be in "hash format", see B<verify> for more information. These are 172also used when building the server certificate chain. 173 174=item B<-CAfile file> 175 176A file containing trusted certificates to use during client authentication 177and to use when attempting to build the server certificate chain. The list 178is also used in the list of acceptable client CAs passed to the client when 179a certificate is requested. 180 181=item B<-no_alt_chains> 182 183See the L<B<verify>|verify(1)> manual page for details. 184 185=item B<-state> 186 187prints out the SSL session states. 188 189=item B<-debug> 190 191print extensive debugging information including a hex dump of all traffic. 192 193=item B<-msg> 194 195show all protocol messages with hex dump. 196 197=item B<-nbio_test> 198 199tests non blocking I/O 200 201=item B<-nbio> 202 203turns on non blocking I/O 204 205=item B<-crlf> 206 207this option translated a line feed from the terminal into CR+LF. 208 209=item B<-quiet> 210 211inhibit printing of session and certificate information. 212 213=item B<-psk_hint hint> 214 215Use the PSK identity hint B<hint> when using a PSK cipher suite. 216 217=item B<-psk key> 218 219Use the PSK key B<key> when using a PSK cipher suite. The key is 220given as a hexadecimal number without leading 0x, for example -psk 2211a2b3c4d. 222 223=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> 224 225These options require or disable the use of the specified SSL or TLS protocols. 226By default the initial handshake uses a I<version-flexible> method which will 227negotiate the highest mutually supported protocol version. 228 229=item B<-bugs> 230 231there are several known bug in SSL and TLS implementations. Adding this 232option enables various workarounds. 233 234=item B<-hack> 235 236this option enables a further workaround for some some early Netscape 237SSL code (?). 238 239=item B<-client_sigalgs sigalglist> 240 241Signature algorithms to support for client certificate authentication 242(colon-separated list) 243 244=item B<-named_curve curve> 245 246Specifies the elliptic curve to use. NOTE: this is single curve, not a list. 247For a list of all possible curves, use: 248 249 $ openssl ecparam -list_curves 250 251=item B<-cipher cipherlist> 252 253this allows the cipher list used by the server to be modified. When 254the client sends a list of supported ciphers the first client cipher 255also included in the server list is used. Because the client specifies 256the preference order, the order of the server cipherlist irrelevant. See 257the B<ciphers> command for more information. 258 259=item B<-serverpref> 260 261use the server's cipher preferences, rather than the client's preferences. 262 263=item B<-tlsextdebug> 264 265print out a hex dump of any TLS extensions received from the server. 266 267=item B<-no_ticket> 268 269disable RFC4507bis session ticket support. 270 271=item B<-www> 272 273sends a status message back to the client when it connects. This includes 274lots of information about the ciphers used and various session parameters. 275The output is in HTML format so this option will normally be used with a 276web browser. 277 278=item B<-WWW> 279 280emulates a simple web server. Pages will be resolved relative to the 281current directory, for example if the URL https://myhost/page.html is 282requested the file ./page.html will be loaded. 283 284=item B<-HTTP> 285 286emulates a simple web server. Pages will be resolved relative to the 287current directory, for example if the URL https://myhost/page.html is 288requested the file ./page.html will be loaded. The files loaded are 289assumed to contain a complete and correct HTTP response (lines that 290are part of the HTTP response line and headers must end with CRLF). 291 292=item B<-engine id> 293 294specifying an engine (by its unique B<id> string) will cause B<s_server> 295to attempt to obtain a functional reference to the specified engine, 296thus initialising it if needed. The engine will then be set as the default 297for all available algorithms. 298 299=item B<-id_prefix arg> 300 301generate SSL/TLS session IDs prefixed by B<arg>. This is mostly useful 302for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple 303servers, when each of which might be generating a unique range of session 304IDs (eg. with a certain prefix). 305 306=item B<-rand file(s)> 307 308a file or files containing random data used to seed the random number 309generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 310Multiple files can be specified separated by a OS-dependent character. 311The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 312all others. 313 314=item B<-serverinfo file> 315 316a file containing one or more blocks of PEM data. Each PEM block 317must encode a TLS ServerHello extension (2 bytes type, 2 bytes length, 318followed by "length" bytes of extension data). If the client sends 319an empty TLS ClientHello extension matching the type, the corresponding 320ServerHello extension will be returned. 321 322=item B<-no_resumption_on_reneg> 323 324set SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION flag. 325 326=item B<-status> 327 328enables certificate status request support (aka OCSP stapling). 329 330=item B<-status_verbose> 331 332enables certificate status request support (aka OCSP stapling) and gives 333a verbose printout of the OCSP response. 334 335=item B<-status_timeout nsec> 336 337sets the timeout for OCSP response to B<nsec> seconds. 338 339=item B<-status_url url> 340 341sets a fallback responder URL to use if no responder URL is present in the 342server certificate. Without this option an error is returned if the server 343certificate does not contain a responder address. 344 345=item B<-alpn protocols>, B<-nextprotoneg protocols> 346 347these flags enable the 348Enable the Application-Layer Protocol Negotiation or Next Protocol 349Negotiation extension, respectively. ALPN is the IETF standard and 350replaces NPN. 351The B<protocols> list is a 352comma-separated list of supported protocol names. 353The list should contain most wanted protocols first. 354Protocol names are printable ASCII strings, for example "http/1.1" or 355"spdy/3". 356 357=back 358 359=head1 CONNECTED COMMANDS 360 361If a connection request is established with an SSL client and neither the 362B<-www> nor the B<-WWW> option has been used then normally any data received 363from the client is displayed and any key presses will be sent to the client. 364 365Certain single letter commands are also recognized which perform special 366operations: these are listed below. 367 368=over 4 369 370=item B<q> 371 372end the current SSL connection but still accept new connections. 373 374=item B<Q> 375 376end the current SSL connection and exit. 377 378=item B<r> 379 380renegotiate the SSL session. 381 382=item B<R> 383 384renegotiate the SSL session and request a client certificate. 385 386=item B<P> 387 388send some plain text down the underlying TCP connection: this should 389cause the client to disconnect due to a protocol violation. 390 391=item B<S> 392 393print out some session cache status information. 394 395=back 396 397=head1 NOTES 398 399B<s_server> can be used to debug SSL clients. To accept connections from 400a web browser the command: 401 402 openssl s_server -accept 443 -www 403 404can be used for example. 405 406Most web browsers (in particular Netscape and MSIE) only support RSA cipher 407suites, so they cannot connect to servers which don't use a certificate 408carrying an RSA key or a version of OpenSSL with RSA disabled. 409 410Although specifying an empty list of CAs when requesting a client certificate 411is strictly speaking a protocol violation, some SSL clients interpret this to 412mean any CA is acceptable. This is useful for debugging purposes. 413 414The session parameters can printed out using the B<sess_id> program. 415 416=head1 BUGS 417 418Because this program has a lot of options and also because some of 419the techniques used are rather old, the C source of s_server is rather 420hard to read and not a model of how things should be done. A typical 421SSL server program would be much simpler. 422 423The output of common ciphers is wrong: it just gives the list of ciphers that 424OpenSSL recognizes and the client supports. 425 426There should be a way for the B<s_server> program to print out details of any 427unknown cipher suites a client says it supports. 428 429=head1 SEE ALSO 430 431L<sess_id(1)|sess_id(1)>, L<s_client(1)|s_client(1)>, L<ciphers(1)|ciphers(1)> 432 433=head1 HISTORY 434 435The -no_alt_chains options was first added to OpenSSL 1.0.2b. 436 437=cut 438