2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
6 openssl-s_server - SSL/TLS server program
10 B<openssl> B<s_server>
23 [B<-certform> B<DER>|B<PEM>|B<P12>]
24 [B<-cert_chain> I<infile>]
26 [B<-serverinfo> I<val>]
29 [B<-keyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>]
32 [B<-dcertform> B<DER>|B<PEM>|B<P12>]
33 [B<-dcert_chain> I<infile>]
35 [B<-dkeyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>]
41 [B<-msgfile> I<outfile>]
45 [B<-no_resume_ephemeral>]
48 [B<-http_server_binmode>]
50 [B<-ignore_unexpected_eof>]
52 [B<-servername_fatal>]
55 [B<-id_prefix> I<val>]
56 [B<-keymatexport> I<val>]
57 [B<-keymatexportlen> I<+int>]
59 [B<-CRLform> B<DER>|B<PEM>]
61 [B<-chainCAfile> I<infile>]
62 [B<-chainCApath> I<dir>]
63 [B<-chainCAstore> I<uri>]
64 [B<-verifyCAfile> I<infile>]
65 [B<-verifyCApath> I<dir>]
66 [B<-verifyCAstore> I<uri>]
69 [B<-verify_return_error>]
75 [B<-status_timeout> I<int>]
76 [B<-status_url> I<val>]
77 [B<-status_file> I<infile>]
80 [B<-security_debug_verbose>]
84 [B<-ssl_config> I<val>]
85 [B<-max_send_frag> I<+int>]
86 [B<-split_send_frag> I<+int>]
87 [B<-max_pipelines> I<+int>]
89 [B<-read_buf> I<+int>]
95 [B<-legacy_renegotiation>]
96 [B<-no_renegotiation>]
97 [B<-legacy_server_connect>]
98 [B<-no_resumption_on_reneg>]
99 [B<-no_legacy_server_connect>]
100 [B<-allow_no_dhe_kex>]
101 [B<-prioritize_chacha>]
104 [B<-client_sigalgs> I<val>]
107 [B<-named_curve> I<val>]
109 [B<-ciphersuites> I<val>]
110 [B<-dhparam> I<infile>]
111 [B<-record_padding> I<val>]
112 [B<-debug_broken_protocol>]
114 [B<-psk_identity> I<val>]
115 [B<-psk_hint> I<val>]
117 [B<-psk_session> I<file>]
118 [B<-srpvfile> I<infile>]
119 [B<-srpuserseed> I<val>]
126 [B<-nextprotoneg> I<val>]
127 [B<-use_srtp> I<val>]
130 [B<-keylogfile> I<outfile>]
131 [B<-recv_max_early_data> I<int>]
132 [B<-max_early_data> I<int>]
138 {- $OpenSSL::safe::opt_name_synopsis -}
139 {- $OpenSSL::safe::opt_version_synopsis -}
140 {- $OpenSSL::safe::opt_v_synopsis -}
141 {- $OpenSSL::safe::opt_s_synopsis -}
142 {- $OpenSSL::safe::opt_x_synopsis -}
143 {- $OpenSSL::safe::opt_trust_synopsis -}
144 {- $OpenSSL::safe::opt_r_synopsis -}
145 {- $OpenSSL::safe::opt_engine_synopsis -}
146 {- $OpenSSL::safe::opt_provider_synopsis -}
148 =for openssl ifdef unix 4 6 unlink no_dhe nextprotoneg use_srtp engine
150 =for openssl ifdef status status_verbose status_timeout status_url status_file
152 =for openssl ifdef psk_hint srpvfile srpuserseed sctp sctp_label_bug
154 =for openssl ifdef sctp sctp_label_bug trace mtu timeout listen
156 =for openssl ifdef ssl3 tls1 tls1_1 tls1_2 tls1_3 dtls mtu dtls1 dtls1_2
158 =for openssl ifdef sendfile
162 This command implements a generic SSL/TLS server which
163 listens for connections on a given port using SSL/TLS.
167 In addition to the options below, this command also supports
168 the common and server only options documented
169 L<SSL_CONF_cmd(3)/Supported Command Line Commands>
175 Print out a usage message.
177 =item B<-port> I<+int>
179 The TCP port to listen on for connections. If not specified 4433 is used.
181 =item B<-accept> I<val>
183 The optional TCP host and port to listen on for connections. If not specified, *:4433 is used.
185 =item B<-unix> I<val>
187 Unix domain socket to accept on.
199 For -unix, unlink any existing socket first.
201 =item B<-context> I<val>
203 Sets the SSL context id. It can be given any string value. If this option
204 is not present a default value will be used.
206 =item B<-verify> I<int>, B<-Verify> I<int>
208 The verify depth to use. This specifies the maximum length of the
209 client certificate chain and makes the server request a certificate from
210 the client. With the B<-verify> option a certificate is requested but the
211 client does not have to send one, with the B<-Verify> option the client
212 must supply a certificate or an error occurs.
214 If the cipher suite cannot request a client certificate (for example an
215 anonymous cipher suite or PSK) this option has no effect.
217 =item B<-cert> I<infile>
219 The certificate to use, most servers cipher suites require the use of a
220 certificate and some require a certificate with a certain public key type:
221 for example the DSS cipher suites require a certificate containing a DSS
222 (DSA) key. If not specified then the filename F<server.pem> will be used.
224 =item B<-certform> B<DER>|B<PEM>|B<P12>
226 The server certificate file format.
227 This option has no effect and is retained for backward compatibility only.
231 A file or URI of untrusted certificates to use when attempting to build the
232 certificate chain related to the certificate specified via the B<-cert> option.
233 The input can be in PEM, DER, or PKCS#12 format.
235 =item B<-build_chain>
237 Specify whether the application should build the server certificate chain to be
238 provided to the client.
240 =item B<-serverinfo> I<val>
242 A file containing one or more blocks of PEM data. Each PEM block
243 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
244 followed by "length" bytes of extension data). If the client sends
245 an empty TLS ClientHello extension matching the type, the corresponding
246 ServerHello extension will be returned.
248 =item B<-key> I<infile>
250 The private key to use. If not specified then the certificate file will
253 =item B<-keyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
255 The key format; the default is B<PEM>.
256 The only value with effect is B<ENGINE>; all others have become obsolete.
257 See L<openssl(1)/Format Options> for details.
259 =item B<-pass> I<val>
261 The private key and certificate file password source.
262 For more information about the format of I<val>,
263 see L<openssl(1)/Pass Phrase Options>.
265 =item B<-dcert> I<infile>, B<-dkey> I<infile>
267 Specify an additional certificate and private key, these behave in the
268 same manner as the B<-cert> and B<-key> options except there is no default
269 if they are not specified (no additional certificate and key is used). As
270 noted above some cipher suites require a certificate containing a key of
271 a certain type. Some cipher suites need a certificate carrying an RSA key
272 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
273 a server can support clients which only support RSA or DSS cipher suites
274 by using an appropriate certificate.
276 =item B<-dcert_chain>
278 A file or URI of untrusted certificates to use when attempting to build the
279 server certificate chain when a certificate specified via the B<-dcert> option
281 The input can be in PEM, DER, or PKCS#12 format.
283 =item B<-dcertform> B<DER>|B<PEM>|B<P12>
285 The format of the additional certificate file.
286 This option has no effect and is retained for backward compatibility only.
288 =item B<-dkeyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
290 The format of the additional private key; the default is B<PEM>.
291 The only value with effect is B<ENGINE>; all others have become obsolete.
292 See L<openssl(1)/Format Options>.
294 =item B<-dpass> I<val>
296 The passphrase for the additional private key and certificate.
297 For more information about the format of I<val>,
298 see L<openssl(1)/Pass Phrase Options>.
302 Tests non blocking I/O.
306 This option translated a line feed from the terminal into CR+LF.
310 Print extensive debugging information including a hex dump of all traffic.
314 Show all protocol messages with hex dump.
316 =item B<-msgfile> I<outfile>
318 File to send output of B<-msg> or B<-trace> to, default standard output.
322 Prints the SSL session states.
324 =item B<-CRL> I<infile>
328 =item B<-CRLform> B<DER>|B<PEM>
330 The CRL file format; the default is B<PEM>.
331 See L<openssl(1)/Format Options> for details.
333 =item B<-crl_download>
335 Download CRLs from distribution points given in CDP extensions of certificates
337 =item B<-verifyCAfile> I<filename>
339 A file in PEM format CA containing trusted certificates to use
340 for verifying client certificates.
342 =item B<-verifyCApath> I<dir>
344 A directory containing trusted certificates to use
345 for verifying client certificates.
346 This directory must be in "hash format",
347 see L<openssl-verify(1)> for more information.
349 =item B<-verifyCAstore> I<uri>
351 The URI of a store containing trusted certificates to use
352 for verifying client certificates.
354 =item B<-chainCAfile> I<file>
356 A file in PEM format containing trusted certificates to use
357 when attempting to build the server certificate chain.
359 =item B<-chainCApath> I<dir>
361 A directory containing trusted certificates to use
362 for building the server certificate chain provided to the client.
363 This directory must be in "hash format",
364 see L<openssl-verify(1)> for more information.
366 =item B<-chainCAstore> I<uri>
368 The URI of a store containing trusted certificates to use
369 for building the server certificate chain provided to the client.
370 The URI may indicate a single certificate, as well as a collection of them.
371 With URIs in the C<file:> scheme, this acts as B<-chainCAfile> or
372 B<-chainCApath>, depending on if the URI indicates a directory or a
374 See L<ossl_store-file(7)> for more information on the C<file:> scheme.
378 If this option is set then no certificate is used. This restricts the
379 cipher suites available to the anonymous ones (currently just anonymous
384 Inhibit printing of session and certificate information.
386 =item B<-tlsextdebug>
388 Print a hex dump of any TLS extensions received from the server.
392 Sends a status message back to the client when it connects. This includes
393 information about the ciphers used and various session parameters.
394 The output is in HTML format so this option can be used with a web browser.
395 The special URL C</renegcert> turns on client cert validation, and C</reneg>
396 tells the server to request renegotiation.
397 The B<-early_data> option cannot be used with this option.
399 =item B<-WWW>, B<-HTTP>
401 Emulates a simple web server. Pages will be resolved relative to the
402 current directory, for example if the URL C<https://myhost/page.html> is
403 requested the file F<./page.html> will be sent.
404 If the B<-HTTP> flag is used, the files are sent directly, and should contain
405 any HTTP response headers (including status response line).
406 If the B<-WWW> option is used,
407 the response headers are generated by the server, and the file extension is
408 examined to determine the B<Content-Type> header.
409 Extensions of C<html>, C<htm>, and C<php> are C<text/html> and all others are
411 In addition, the special URL C</stats> will return status
412 information like the B<-www> option.
413 Neither of these options can be used in conjunction with B<-early_data>.
415 =item B<-http_server_binmode>
417 When acting as web-server (using option B<-WWW> or B<-HTTP>) open files requested
418 by the client in binary mode.
420 =item B<-no_ca_names>
422 Disable TLS Extension CA Names. You may want to disable it for security reasons
423 or for compatibility with some Windows TLS implementations crashing when this
424 extension is larger than 1024 bytes.
426 =item B<-ignore_unexpected_eof>
428 Some TLS implementations do not send the mandatory close_notify alert on
429 shutdown. If the application tries to wait for the close_notify alert but the
430 peer closes the connection without sending it, an error is generated. When this
431 option is enabled the peer does not need to send the close_notify alert and a
432 closed connection will be treated as if the close_notify alert was received.
433 For more information on shutting down a connection, see L<SSL_shutdown(3)>.
435 =item B<-id_prefix> I<val>
437 Generate SSL/TLS session IDs prefixed by I<val>. This is mostly useful
438 for testing any SSL/TLS code (e.g. proxies) that wish to deal with multiple
439 servers, when each of which might be generating a unique range of session
440 IDs (e.g. with a certain prefix).
442 =item B<-verify_return_error>
444 Verification errors normally just print a message but allow the
445 connection to continue, for debugging purposes.
446 If this option is used, then verification errors close the connection.
450 Enables certificate status request support (aka OCSP stapling).
452 =item B<-status_verbose>
454 Enables certificate status request support (aka OCSP stapling) and gives
455 a verbose printout of the OCSP response.
457 =item B<-status_timeout> I<int>
459 Sets the timeout for OCSP response to I<int> seconds.
461 =item B<-status_url> I<val>
463 Sets a fallback responder URL to use if no responder URL is present in the
464 server certificate. Without this option an error is returned if the server
465 certificate does not contain a responder address.
467 =item B<-status_file> I<infile>
469 Overrides any OCSP responder URLs from the certificate and always provides the
470 OCSP Response stored in the file. The file must be in DER format.
474 Show verbose trace output of protocol messages. OpenSSL needs to be compiled
475 with B<enable-ssl-trace> for this option to work.
479 Provide a brief summary of connection parameters instead of the normal verbose
484 Simple test server which just reverses the text received from the client
485 and sends it back to the server. Also sets B<-brief>. Cannot be used in
486 conjunction with B<-early_data>.
490 Switch on asynchronous mode. Cryptographic operations will be performed
491 asynchronously. This will only have an effect if an asynchronous capable engine
492 is also used via the B<-engine> option. For test purposes the dummy async engine
493 (dasync) can be used (if available).
495 =item B<-max_send_frag> I<+int>
497 The maximum size of data fragment to send.
498 See L<SSL_CTX_set_max_send_fragment(3)> for further information.
500 =item B<-split_send_frag> I<+int>
502 The size used to split data for encrypt pipelines. If more data is written in
503 one go than this value then it will be split into multiple pipelines, up to the
504 maximum number of pipelines defined by max_pipelines. This only has an effect if
505 a suitable cipher suite has been negotiated, an engine that supports pipelining
506 has been loaded, and max_pipelines is greater than 1. See
507 L<SSL_CTX_set_split_send_fragment(3)> for further information.
509 =item B<-max_pipelines> I<+int>
511 The maximum number of encrypt/decrypt pipelines to be used. This will only have
512 an effect if an engine has been loaded that supports pipelining (e.g. the dasync
513 engine) and a suitable cipher suite has been negotiated. The default value is 1.
514 See L<SSL_CTX_set_max_pipelines(3)> for further information.
516 =item B<-naccept> I<+int>
518 The server will exit after receiving the specified number of connections,
521 =item B<-read_buf> I<+int>
523 The default read buffer size to be used for connections. This will only have an
524 effect if the buffer size is larger than the size that would otherwise be used
525 and pipelining is in use (see L<SSL_CTX_set_default_read_buffer_len(3)> for
526 further information).
530 There are several known bugs in SSL and TLS implementations. Adding this
531 option enables various workarounds.
535 Disable negotiation of TLS compression.
536 TLS compression is not recommended and is off by default as of
541 Enable negotiation of TLS compression.
542 This option was introduced in OpenSSL 1.1.0.
543 TLS compression is not recommended and is off by default as of
548 Disable RFC4507bis session ticket support. This option has no effect if TLSv1.3
549 is negotiated. See B<-num_tickets>.
551 =item B<-num_tickets>
553 Control the number of tickets that will be sent to the client after a full
554 handshake in TLSv1.3. The default number of tickets is 2. This option does not
555 affect the number of tickets sent after a resumption handshake.
559 Use the server's cipher preferences, rather than the client's preferences.
561 =item B<-prioritize_chacha>
563 Prioritize ChaCha ciphers when preferred by clients. Requires B<-serverpref>.
565 =item B<-no_resumption_on_reneg>
567 Set the B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> option.
569 =item B<-client_sigalgs> I<val>
571 Signature algorithms to support for client certificate authentication
572 (colon-separated list).
574 =item B<-named_curve> I<val>
576 Specifies the elliptic curve to use. NOTE: this is single curve, not a list.
577 For a list of all possible curves, use:
579 $ openssl ecparam -list_curves
581 =item B<-cipher> I<val>
583 This allows the list of TLSv1.2 and below ciphersuites used by the server to be
584 modified. This list is combined with any TLSv1.3 ciphersuites that have been
585 configured. When the client sends a list of supported ciphers the first client
586 cipher also included in the server list is used. Because the client specifies
587 the preference order, the order of the server cipherlist is irrelevant. See
588 L<openssl-ciphers(1)> for more information.
590 =item B<-ciphersuites> I<val>
592 This allows the list of TLSv1.3 ciphersuites used by the server to be modified.
593 This list is combined with any TLSv1.2 and below ciphersuites that have been
594 configured. When the client sends a list of supported ciphers the first client
595 cipher also included in the server list is used. Because the client specifies
596 the preference order, the order of the server cipherlist is irrelevant. See
597 L<openssl-ciphers(1)> command for more information. The format for this list is
598 a simple colon (":") separated list of TLSv1.3 ciphersuite names.
600 =item B<-dhparam> I<infile>
602 The DH parameter file to use. The ephemeral DH cipher suites generate keys
603 using a set of DH parameters. If not specified then an attempt is made to
604 load the parameters from the server certificate file.
605 If this fails then a static set of parameters hard coded into this command
610 Turns on non blocking I/O.
612 =item B<-psk_identity> I<val>
614 Expect the client to send PSK identity I<val> when using a PSK
615 cipher suite, and warn if they do not. By default, the expected PSK
616 identity is the string "Client_identity".
618 =item B<-psk_hint> I<val>
620 Use the PSK identity hint I<val> when using a PSK cipher suite.
624 Use the PSK key I<val> when using a PSK cipher suite. The key is
625 given as a hexadecimal number without leading 0x, for example -psk
627 This option must be provided in order to use a PSK cipher.
629 =item B<-psk_session> I<file>
631 Use the pem encoded SSL_SESSION data stored in I<file> as the basis of a PSK.
632 Note that this will only work if TLSv1.3 is negotiated.
636 This option can only be used in conjunction with one of the DTLS options above.
637 With this option, this command will listen on a UDP port for incoming
639 Any ClientHellos that arrive will be checked to see if they have a cookie in
641 Any without a cookie will be responded to with a HelloVerifyRequest.
642 If a ClientHello with a cookie is received then this command will
643 connect to that peer and complete the handshake.
647 Use SCTP for the transport protocol instead of UDP in DTLS. Must be used in
648 conjunction with B<-dtls>, B<-dtls1> or B<-dtls1_2>. This option is only
649 available where OpenSSL has support for SCTP enabled.
651 =item B<-sctp_label_bug>
653 Use the incorrect behaviour of older OpenSSL implementations when computing
654 endpoint-pair shared secrets for DTLS/SCTP. This allows communication with
655 older broken implementations but breaks interoperability with correct
656 implementations. Must be used in conjunction with B<-sctp>. This option is only
657 available where OpenSSL has support for SCTP enabled.
661 If this option is set then no DH parameters will be loaded effectively
662 disabling the ephemeral DH cipher suites.
664 =item B<-alpn> I<val>, B<-nextprotoneg> I<val>
666 These flags enable the Enable the Application-Layer Protocol Negotiation
667 or Next Protocol Negotiation (NPN) extension, respectively. ALPN is the
668 IETF standard and replaces NPN.
669 The I<val> list is a comma-separated list of supported protocol
670 names. The list should contain the most desirable protocols first.
671 Protocol names are printable ASCII strings, for example "http/1.1" or
673 The flag B<-nextprotoneg> cannot be specified if B<-tls1_3> is used.
677 If this option is set and KTLS is enabled, SSL_sendfile() will be used
678 instead of BIO_write() to send the HTTP response requested by a client.
679 This option is only valid if B<-WWW> or B<-HTTP> is specified.
681 =item B<-keylogfile> I<outfile>
683 Appends TLS secrets to the specified keylog file such that external programs
684 (like Wireshark) can decrypt TLS connections.
686 =item B<-max_early_data> I<int>
688 Change the default maximum early data bytes that are specified for new sessions
689 and any incoming early data (when used in conjunction with the B<-early_data>
690 flag). The default value is approximately 16k. The argument must be an integer
691 greater than or equal to 0.
693 =item B<-recv_max_early_data> I<int>
695 Specify the hard limit on the maximum number of early data bytes that will
700 Accept early data where possible. Cannot be used in conjunction with B<-www>,
701 B<-WWW>, B<-HTTP> or B<-rev>.
705 Require TLSv1.3 cookies.
707 =item B<-anti_replay>, B<-no_anti_replay>
709 Switches replay protection on or off, respectively. Replay protection is on by
710 default unless overridden by a configuration file. When it is on, OpenSSL will
711 automatically detect if a session ticket has been used more than once, TLSv1.3
712 has been negotiated, and early data is enabled on the server. A full handshake
713 is forced if a session ticket is used a second or subsequent time. Any early
714 data that was sent will be rejected.
716 {- $OpenSSL::safe::opt_name_item -}
718 {- $OpenSSL::safe::opt_version_item -}
720 {- $OpenSSL::safe::opt_s_item -}
722 {- $OpenSSL::safe::opt_x_item -}
724 {- $OpenSSL::safe::opt_trust_item -}
726 {- $OpenSSL::safe::opt_r_item -}
728 {- $OpenSSL::safe::opt_engine_item -}
730 {- $OpenSSL::safe::opt_provider_item -}
732 {- $OpenSSL::safe::opt_v_item -}
734 If the server requests a client certificate, then
735 verification errors are displayed, for debugging, but the command will
736 proceed unless the B<-verify_return_error> option is used.
740 =head1 CONNECTED COMMANDS
742 If a connection request is established with an SSL client and neither the
743 B<-www> nor the B<-WWW> option has been used then normally any data received
744 from the client is displayed and any key presses will be sent to the client.
746 Certain commands are also recognized which perform special operations. These
747 commands are a letter which must appear at the start of a line. They are listed
754 End the current SSL connection but still accept new connections.
758 End the current SSL connection and exit.
762 Renegotiate the SSL session (TLSv1.2 and below only).
766 Renegotiate the SSL session and request a client certificate (TLSv1.2 and below
771 Send some plain text down the underlying TCP connection: this should
772 cause the client to disconnect due to a protocol violation.
776 Print out some session cache status information.
780 Send a key update message to the client (TLSv1.3 only)
784 Send a key update message to the client and request one back (TLSv1.3 only)
788 Send a certificate request to the client (TLSv1.3 only)
794 This command can be used to debug SSL clients. To accept connections
795 from a web browser the command:
797 openssl s_server -accept 443 -www
799 can be used for example.
801 Although specifying an empty list of CAs when requesting a client certificate
802 is strictly speaking a protocol violation, some SSL clients interpret this to
803 mean any CA is acceptable. This is useful for debugging purposes.
805 The session parameters can printed out using the L<openssl-sess_id(1)> command.
809 Because this program has a lot of options and also because some of the
810 techniques used are rather old, the C source for this command is rather
811 hard to read and not a model of how things should be done.
812 A typical SSL server program would be much simpler.
814 The output of common ciphers is wrong: it just gives the list of ciphers that
815 OpenSSL recognizes and the client supports.
817 There should be a way for this command to print out details
818 of any unknown cipher suites a client says it supports.
823 L<openssl-sess_id(1)>,
824 L<openssl-s_client(1)>,
825 L<openssl-ciphers(1)>,
827 L<SSL_CTX_set_max_send_fragment(3)>,
828 L<SSL_CTX_set_split_send_fragment(3)>,
829 L<SSL_CTX_set_max_pipelines(3)>,
830 L<ossl_store-file(7)>
834 The -no_alt_chains option was added in OpenSSL 1.1.0.
837 -allow-no-dhe-kex and -prioritize_chacha options were added in OpenSSL 1.1.1.
839 All B<-keyform> and B<-dkeyform> values except B<ENGINE>
840 have become obsolete in OpenSSL 3.0.0 and have no effect.
842 The B<-certform> and B<-dcertform> options have become obsolete in OpenSSL 3.0.0
845 The B<-engine> option was deprecated in OpenSSL 3.0.
849 Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
851 Licensed under the Apache License 2.0 (the "License"). You may not use
852 this file except in compliance with the License. You can obtain a copy
853 in the file LICENSE in the source distribution or at
854 L<https://www.openssl.org/source/license.html>.