2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
6 openssl-s_server - SSL/TLS server program
10 B<openssl> B<s_server>
23 [B<-serverinfo> I<val>]
24 [B<-certform> B<DER>|B<PEM>]
26 [B<-keyform> B<DER>|B<PEM>]
29 [B<-dcertform> B<DER>|B<PEM>]
31 [B<-dkeyform> B<DER>|B<PEM>]
37 [B<-msgfile> I<outfile>]
41 [B<-no_resume_ephemeral>]
45 [B<-servername_fatal>]
50 [B<-id_prefix> I<val>]
51 [B<-keymatexport> I<val>]
52 [B<-keymatexportlen> I<+int>]
53 [B<-CRLform> B<DER>|B<PEM>]
56 [B<-cert_chain> I<infile>]
57 [B<-dcert_chain> I<infile>]
58 [B<-chainCApath> I<dir>]
59 [B<-verifyCApath> I<dir>]
60 [B<-chainCAstore> I<uri>]
61 [B<-verifyCAstore> I<uri>]
64 [B<-verify_return_error>]
67 [B<-chainCAfile> I<infile>]
68 [B<-verifyCAfile> I<infile>]
73 [B<-status_timeout> I<int>]
74 [B<-status_url> I<val>]
75 [B<-status_file> I<infile>]
78 [B<-security_debug_verbose>]
82 [B<-ssl_config> I<val>]
83 [B<-max_send_frag> I<+int>]
84 [B<-split_send_frag> I<+int>]
85 [B<-max_pipelines> I<+int>]
86 [B<-read_buf> I<+int>]
93 [B<-legacy_renegotiation>]
94 [B<-no_renegotiation>]
95 [B<-legacy_server_connect>]
96 [B<-no_resumption_on_reneg>]
97 [B<-no_legacy_server_connect>]
98 [B<-allow_no_dhe_kex>]
99 [B<-prioritize_chacha>]
102 [B<-client_sigalgs> I<val>]
105 [B<-named_curve> I<val>]
107 [B<-ciphersuites> I<val>]
108 [B<-dhparam> I<infile>]
109 [B<-record_padding> I<val>]
110 [B<-debug_broken_protocol>]
112 [B<-psk_identity> I<val>]
113 [B<-psk_hint> I<val>]
115 [B<-psk_session> I<file>]
116 [B<-srpvfile> I<infile>]
117 [B<-srpuserseed> I<val>]
124 [B<-nextprotoneg> I<val>]
125 [B<-use_srtp> I<val>]
127 [B<-keylogfile> I<outfile>]
128 [B<-max_early_data> I<int>]
129 [B<-recv_max_early_data> I<int>]
134 [B<-http_server_binmode>]
135 {- $OpenSSL::safe::opt_name_synopsis -}
136 {- $OpenSSL::safe::opt_version_synopsis -}
137 {- $OpenSSL::safe::opt_v_synopsis -}
138 {- $OpenSSL::safe::opt_x_synopsis -}
139 {- $OpenSSL::safe::opt_trust_synopsis -}
140 {- $OpenSSL::safe::opt_r_synopsis -}
141 {- $OpenSSL::safe::opt_engine_synopsis -}
143 =for openssl ifdef unix 4 6 unlink no_dhe nextprotoneg use_srtp engine
145 =for openssl ifdef status status_verbose status_timeout status_url status_file
147 =for openssl ifdef psk_hint srpvfile srpuserseed sctp sctp_label_bug
149 =for openssl ifdef sctp sctp_label_bug trace mtu timeout listen
151 =for openssl ifdef ssl3 tls1 tls1_1 tls1_2 tls1_3 dtls mtu dtls1 dtls1_2
155 This command implements a generic SSL/TLS server which
156 listens for connections on a given port using SSL/TLS.
160 In addition to the options below, this command also supports
161 the common and server only options documented
162 L<SSL_CONF_cmd(3)/Supported Command Line Commands>
168 Print out a usage message.
170 =item B<-port> I<+int>
172 The TCP port to listen on for connections. If not specified 4433 is used.
174 =item B<-accept> I<val>
176 The optional TCP host and port to listen on for connections. If not specified, *:4433 is used.
178 =item B<-unix> I<val>
180 Unix domain socket to accept on.
192 For -unix, unlink any existing socket first.
194 =item B<-context> I<val>
196 Sets the SSL context id. It can be given any string value. If this option
197 is not present a default value will be used.
199 =item B<-verify> I<int>, B<-Verify> I<int>
201 The verify depth to use. This specifies the maximum length of the
202 client certificate chain and makes the server request a certificate from
203 the client. With the B<-verify> option a certificate is requested but the
204 client does not have to send one, with the B<-Verify> option the client
205 must supply a certificate or an error occurs.
207 If the cipher suite cannot request a client certificate (for example an
208 anonymous cipher suite or PSK) this option has no effect.
210 =item B<-cert> I<infile>
212 The certificate to use, most servers cipher suites require the use of a
213 certificate and some require a certificate with a certain public key type:
214 for example the DSS cipher suites require a certificate containing a DSS
215 (DSA) key. If not specified then the filename F<server.pem> will be used.
219 A file containing trusted certificates to use when attempting to build the
220 client/server certificate chain related to the certificate specified via the
223 =item B<-build_chain>
225 Specify whether the application should build the certificate chain to be
226 provided to the client.
228 =item B<-naccept> I<+int>
230 The server will exit after receiving the specified number of connections,
233 =item B<-serverinfo> I<val>
235 A file containing one or more blocks of PEM data. Each PEM block
236 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
237 followed by "length" bytes of extension data). If the client sends
238 an empty TLS ClientHello extension matching the type, the corresponding
239 ServerHello extension will be returned.
241 =item B<-certform> B<DER>|B<PEM>, B<-CRLForm> B<DER>|B<PEM>
243 The certificate and CRL format; the default is PEM.
244 See L<openssl(1)/Format Options> for details.
246 =item B<-key> I<infile>
248 The private key to use. If not specified then the certificate file will
251 =item B<-keyform> B<DER>|B<PEM>
253 The key format; the default is B<PEM>.
254 See L<openssl(1)/Format Options> for details.
256 =item B<-pass> I<val>
258 The private key password source.
259 For more information about the format of I<val>,
260 see L<openssl(1)/Pass Phrase Options>.
262 =item B<-dcert> I<infile>, B<-dkey> I<infile>
264 Specify an additional certificate and private key, these behave in the
265 same manner as the B<-cert> and B<-key> options except there is no default
266 if they are not specified (no additional certificate and key is used). As
267 noted above some cipher suites require a certificate containing a key of
268 a certain type. Some cipher suites need a certificate carrying an RSA key
269 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
270 a server can support clients which only support RSA or DSS cipher suites
271 by using an appropriate certificate.
273 =item B<-dcert_chain>
275 A file containing trusted certificates to use when attempting to build the
276 server certificate chain when a certificate specified via the B<-dcert> option
279 =item B<-dcertform> B<DER>|B<PEM>, B<-dkeyform> B<DER>|B<PEM>
281 The format of the certificate and private key; the default is B<PEM>
282 see L<openssl(1)/Format Options>.
284 =item B<-dpass> I<val>
286 The passphrase for the additional private key.
287 For more information about the format of I<val>,
288 see L<openssl(1)/Pass Phrase Options>.
292 Tests non blocking I/O.
296 This option translated a line feed from the terminal into CR+LF.
300 Print extensive debugging information including a hex dump of all traffic.
304 Show all protocol messages with hex dump.
306 =item B<-msgfile> I<outfile>
308 File to send output of B<-msg> or B<-trace> to, default standard output.
312 Prints the SSL session states.
314 =item B<-chainCApath> I<dir>
316 The directory to use for building the chain provided to the client. This
317 directory must be in "hash format", see L<openssl-verify(1)> for more
320 =item B<-chainCAfile> I<file>
322 A file containing trusted certificates to use when attempting to build the
323 server certificate chain.
325 =item B<-chainCAstore> I<uri>
327 The URI to a store to use for building the chain provided to the client.
328 The URI may indicate a single certificate, as well as a collection of
330 With URIs in the C<file:> scheme, this acts as B<-chainCAfile> or
331 B<-chainCApath>, depending on if the URI indicates a directory or a
333 See L<ossl_store-file(7)> for more information on the C<file:> scheme.
337 If this option is set then no certificate is used. This restricts the
338 cipher suites available to the anonymous ones (currently just anonymous
343 Inhibit printing of session and certificate information.
345 =item B<-tlsextdebug>
347 Print a hex dump of any TLS extensions received from the server.
351 Sends a status message back to the client when it connects. This includes
352 information about the ciphers used and various session parameters.
353 The output is in HTML format so this option can be used with a web browser.
354 The special URL C</renegcert> turns on client cert validation, and C</reneg>
355 tells the server to request renegotiation.
356 The B<-early_data> option cannot be used with this option.
358 =item B<-WWW>, B<-HTTP>
360 Emulates a simple web server. Pages will be resolved relative to the
361 current directory, for example if the URL C<https://myhost/page.html> is
362 requested the file F<./page.html> will be sent.
363 If the B<-HTTP> flag is used, the files are sent directly, and should contain
364 any HTTP response headers (including status response line).
365 If the B<-WWW> option is used,
366 the response headers are generated by the server, and the file extension is
367 examined to determine the B<Content-Type> header.
368 Extensions of C<html>, C<htm>, and C<php> are C<text/html> and all others are
370 In addition, the special URL C</stats> will return status
371 information like the B<-www> option.
372 Neither of these options can be used in conjunction with B<-early_data>.
374 =item B<-id_prefix> I<val>
376 Generate SSL/TLS session IDs prefixed by I<val>. This is mostly useful
377 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
378 servers, when each of which might be generating a unique range of session
379 IDs (eg. with a certain prefix).
381 =item B<-verify_return_error>
383 Verification errors normally just print a message but allow the
384 connection to continue, for debugging purposes.
385 If this option is used, then verification errors close the connection.
389 Enables certificate status request support (aka OCSP stapling).
391 =item B<-status_verbose>
393 Enables certificate status request support (aka OCSP stapling) and gives
394 a verbose printout of the OCSP response.
396 =item B<-status_timeout> I<int>
398 Sets the timeout for OCSP response to I<int> seconds.
400 =item B<-status_url> I<val>
402 Sets a fallback responder URL to use if no responder URL is present in the
403 server certificate. Without this option an error is returned if the server
404 certificate does not contain a responder address.
406 =item B<-status_file> I<infile>
408 Overrides any OCSP responder URLs from the certificate and always provides the
409 OCSP Response stored in the file. The file must be in DER format.
413 Show verbose trace output of protocol messages. OpenSSL needs to be compiled
414 with B<enable-ssl-trace> for this option to work.
418 Provide a brief summary of connection parameters instead of the normal verbose
423 Simple test server which just reverses the text received from the client
424 and sends it back to the server. Also sets B<-brief>. Cannot be used in
425 conjunction with B<-early_data>.
429 Switch on asynchronous mode. Cryptographic operations will be performed
430 asynchronously. This will only have an effect if an asynchronous capable engine
431 is also used via the B<-engine> option. For test purposes the dummy async engine
432 (dasync) can be used (if available).
434 =item B<-max_send_frag> I<+int>
436 The maximum size of data fragment to send.
437 See L<SSL_CTX_set_max_send_fragment(3)> for further information.
439 =item B<-split_send_frag> I<+int>
441 The size used to split data for encrypt pipelines. If more data is written in
442 one go than this value then it will be split into multiple pipelines, up to the
443 maximum number of pipelines defined by max_pipelines. This only has an effect if
444 a suitable cipher suite has been negotiated, an engine that supports pipelining
445 has been loaded, and max_pipelines is greater than 1. See
446 L<SSL_CTX_set_split_send_fragment(3)> for further information.
448 =item B<-max_pipelines> I<+int>
450 The maximum number of encrypt/decrypt pipelines to be used. This will only have
451 an effect if an engine has been loaded that supports pipelining (e.g. the dasync
452 engine) and a suitable cipher suite has been negotiated. The default value is 1.
453 See L<SSL_CTX_set_max_pipelines(3)> for further information.
455 =item B<-read_buf> I<+int>
457 The default read buffer size to be used for connections. This will only have an
458 effect if the buffer size is larger than the size that would otherwise be used
459 and pipelining is in use (see L<SSL_CTX_set_default_read_buffer_len(3)> for
460 further information).
464 There are several known bugs in SSL and TLS implementations. Adding this
465 option enables various workarounds.
469 Disable negotiation of TLS compression.
470 TLS compression is not recommended and is off by default as of
475 Enable negotiation of TLS compression.
476 This option was introduced in OpenSSL 1.1.0.
477 TLS compression is not recommended and is off by default as of
482 Disable RFC4507bis session ticket support. This option has no effect if TLSv1.3
483 is negotiated. See B<-num_tickets>.
485 =item B<-num_tickets>
487 Control the number of tickets that will be sent to the client after a full
488 handshake in TLSv1.3. The default number of tickets is 2. This option does not
489 affect the number of tickets sent after a resumption handshake.
493 Use the server's cipher preferences, rather than the client's preferences.
495 =item B<-prioritize_chacha>
497 Prioritize ChaCha ciphers when preferred by clients. Requires B<-serverpref>.
499 =item B<-no_resumption_on_reneg>
501 Set the B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> option.
503 =item B<-client_sigalgs> I<val>
505 Signature algorithms to support for client certificate authentication
506 (colon-separated list).
508 =item B<-named_curve> I<val>
510 Specifies the elliptic curve to use. NOTE: this is single curve, not a list.
511 For a list of all possible curves, use:
513 $ openssl ecparam -list_curves
515 =item B<-cipher> I<val>
517 This allows the list of TLSv1.2 and below ciphersuites used by the server to be
518 modified. This list is combined with any TLSv1.3 ciphersuites that have been
519 configured. When the client sends a list of supported ciphers the first client
520 cipher also included in the server list is used. Because the client specifies
521 the preference order, the order of the server cipherlist is irrelevant. See
522 L<openssl-ciphers(1)> for more information.
524 =item B<-ciphersuites> I<val>
526 This allows the list of TLSv1.3 ciphersuites used by the server to be modified.
527 This list is combined with any TLSv1.2 and below ciphersuites that have been
528 configured. When the client sends a list of supported ciphers the first client
529 cipher also included in the server list is used. Because the client specifies
530 the preference order, the order of the server cipherlist is irrelevant. See
531 L<openssl-ciphers(1)> command for more information. The format for this list is
532 a simple colon (":") separated list of TLSv1.3 ciphersuite names.
534 =item B<-dhparam> I<infile>
536 The DH parameter file to use. The ephemeral DH cipher suites generate keys
537 using a set of DH parameters. If not specified then an attempt is made to
538 load the parameters from the server certificate file.
539 If this fails then a static set of parameters hard coded into this command
544 Turns on non blocking I/O.
546 =item B<-psk_identity> I<val>
548 Expect the client to send PSK identity I<val> when using a PSK
549 cipher suite, and warn if they do not. By default, the expected PSK
550 identity is the string "Client_identity".
552 =item B<-psk_hint> I<val>
554 Use the PSK identity hint I<val> when using a PSK cipher suite.
558 Use the PSK key I<val> when using a PSK cipher suite. The key is
559 given as a hexadecimal number without leading 0x, for example -psk
561 This option must be provided in order to use a PSK cipher.
563 =item B<-psk_session> I<file>
565 Use the pem encoded SSL_SESSION data stored in I<file> as the basis of a PSK.
566 Note that this will only work if TLSv1.3 is negotiated.
570 This option can only be used in conjunction with one of the DTLS options above.
571 With this option, this command will listen on a UDP port for incoming
573 Any ClientHellos that arrive will be checked to see if they have a cookie in
575 Any without a cookie will be responded to with a HelloVerifyRequest.
576 If a ClientHello with a cookie is received then this command will
577 connect to that peer and complete the handshake.
581 Use SCTP for the transport protocol instead of UDP in DTLS. Must be used in
582 conjunction with B<-dtls>, B<-dtls1> or B<-dtls1_2>. This option is only
583 available where OpenSSL has support for SCTP enabled.
585 =item B<-sctp_label_bug>
587 Use the incorrect behaviour of older OpenSSL implementations when computing
588 endpoint-pair shared secrets for DTLS/SCTP. This allows communication with
589 older broken implementations but breaks interoperability with correct
590 implementations. Must be used in conjunction with B<-sctp>. This option is only
591 available where OpenSSL has support for SCTP enabled.
595 If this option is set then no DH parameters will be loaded effectively
596 disabling the ephemeral DH cipher suites.
598 =item B<-alpn> I<val>, B<-nextprotoneg> I<val>
600 These flags enable the Enable the Application-Layer Protocol Negotiation
601 or Next Protocol Negotiation (NPN) extension, respectively. ALPN is the
602 IETF standard and replaces NPN.
603 The I<val> list is a comma-separated list of supported protocol
604 names. The list should contain the most desirable protocols first.
605 Protocol names are printable ASCII strings, for example "http/1.1" or
607 The flag B<-nextprotoneg> cannot be specified if B<-tls1_3> is used.
609 =item B<-keylogfile> I<outfile>
611 Appends TLS secrets to the specified keylog file such that external programs
612 (like Wireshark) can decrypt TLS connections.
614 =item B<-max_early_data> I<int>
616 Change the default maximum early data bytes that are specified for new sessions
617 and any incoming early data (when used in conjunction with the B<-early_data>
618 flag). The default value is approximately 16k. The argument must be an integer
619 greater than or equal to 0.
621 =item B<-recv_max_early_data> I<int>
623 Specify the hard limit on the maximum number of early data bytes that will
628 Accept early data where possible. Cannot be used in conjunction with B<-www>,
629 B<-WWW>, B<-HTTP> or B<-rev>.
633 Require TLSv1.3 cookies.
635 =item B<-anti_replay>, B<-no_anti_replay>
637 Switches replay protection on or off, respectively. Replay protection is on by
638 default unless overridden by a configuration file. When it is on, OpenSSL will
639 automatically detect if a session ticket has been used more than once, TLSv1.3
640 has been negotiated, and early data is enabled on the server. A full handshake
641 is forced if a session ticket is used a second or subsequent time. Any early
642 data that was sent will be rejected.
644 =item B<-http_server_binmode>
646 When acting as web-server (using option B<-WWW> or B<-HTTP>) open files requested
647 by the client in binary mode.
649 {- $OpenSSL::safe::opt_name_item -}
651 {- $OpenSSL::safe::opt_version_item -}
653 {- $OpenSSL::safe::opt_x_item -}
655 {- $OpenSSL::safe::opt_trust_item -}
657 {- $OpenSSL::safe::opt_r_item -}
659 {- $OpenSSL::safe::opt_engine_item -}
661 {- $OpenSSL::safe::opt_v_item -}
663 If the server requests a client certificate, then
664 verification errors are displayed, for debugging, but the command will
665 proceed unless the B<-verify_return_error> option is used.
669 =head1 CONNECTED COMMANDS
671 If a connection request is established with an SSL client and neither the
672 B<-www> nor the B<-WWW> option has been used then normally any data received
673 from the client is displayed and any key presses will be sent to the client.
675 Certain commands are also recognized which perform special operations. These
676 commands are a letter which must appear at the start of a line. They are listed
683 End the current SSL connection but still accept new connections.
687 End the current SSL connection and exit.
691 Renegotiate the SSL session (TLSv1.2 and below only).
695 Renegotiate the SSL session and request a client certificate (TLSv1.2 and below
700 Send some plain text down the underlying TCP connection: this should
701 cause the client to disconnect due to a protocol violation.
705 Print out some session cache status information.
709 Send a key update message to the client (TLSv1.3 only)
713 Send a key update message to the client and request one back (TLSv1.3 only)
717 Send a certificate request to the client (TLSv1.3 only)
723 This command can be used to debug SSL clients. To accept connections
724 from a web browser the command:
726 openssl s_server -accept 443 -www
728 can be used for example.
730 Although specifying an empty list of CAs when requesting a client certificate
731 is strictly speaking a protocol violation, some SSL clients interpret this to
732 mean any CA is acceptable. This is useful for debugging purposes.
734 The session parameters can printed out using the L<openssl-sess_id(1)> command.
738 Because this program has a lot of options and also because some of the
739 techniques used are rather old, the C source for this command is rather
740 hard to read and not a model of how things should be done.
741 A typical SSL server program would be much simpler.
743 The output of common ciphers is wrong: it just gives the list of ciphers that
744 OpenSSL recognizes and the client supports.
746 There should be a way for this command to print out details
747 of any unknown cipher suites a client says it supports.
752 L<openssl-sess_id(1)>,
753 L<openssl-s_client(1)>,
754 L<openssl-ciphers(1)>,
756 L<SSL_CTX_set_max_send_fragment(3)>,
757 L<SSL_CTX_set_split_send_fragment(3)>,
758 L<SSL_CTX_set_max_pipelines(3)>,
759 L<ossl_store-file(7)>
763 The -no_alt_chains option was added in OpenSSL 1.1.0.
766 -allow-no-dhe-kex and -prioritize_chacha options were added in OpenSSL 1.1.1.
770 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
772 Licensed under the Apache License 2.0 (the "License"). You may not use
773 this file except in compliance with the License. You can obtain a copy
774 in the file LICENSE in the source distribution or at
775 L<https://www.openssl.org/source/license.html>.