5 openssl-s_server - SSL/TLS server program
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>]
39 [B<-CAfile> I<infile>]
45 [B<-no_resume_ephemeral>]
49 [B<-servername_fatal>]
54 [B<-id_prefix> I<val>]
56 [B<-writerand> I<file>]
57 [B<-keymatexport> I<val>]
58 [B<-keymatexportlen> I<+int>]
61 [B<-cert_chain> I<infile>]
62 [B<-dcert_chain> I<infile>]
63 [B<-chainCApath> I<dir>]
64 [B<-verifyCApath> I<dir>]
67 [B<-verify_return_error>]
70 [B<-chainCAfile> I<infile>]
71 [B<-verifyCAfile> I<infile>]
76 [B<-status_timeout> I<int>]
77 [B<-status_url> I<val>]
78 [B<-status_file> I<infile>]
81 [B<-security_debug_verbose>]
85 [B<-ssl_config> I<val>]
86 [B<-max_send_frag> I<+int>]
87 [B<-split_send_frag> I<+int>]
88 [B<-max_pipelines> I<+int>]
89 [B<-read_buf> I<+int>]
101 [B<-legacy_renegotiation>]
102 [B<-no_renegotiation>]
103 [B<-legacy_server_connect>]
104 [B<-no_resumption_on_reneg>]
105 [B<-no_legacy_server_connect>]
106 [B<-allow_no_dhe_kex>]
107 [B<-prioritize_chacha>]
110 [B<-client_sigalgs> I<val>]
113 [B<-named_curve> I<val>]
115 [B<-ciphersuites> I<val>]
116 [B<-dhparam> I<infile>]
117 [B<-record_padding> I<val>]
118 [B<-debug_broken_protocol>]
121 [B<-verify_name> I<val>]
122 [B<-verify_depth> I<int>]
123 [B<-auth_level> I<int>]
124 [B<-attime> I<intmax>]
125 [B<-verify_hostname> I<val>]
126 [B<-verify_email> I<val>]
128 [B<-ignore_critical>]
133 [B<-explicit_policy>]
142 [B<-suiteB_128_only>]
148 [B<-allow_proxy_certs>]
153 [B<-CRLform> B<DER>|B<PEM>]
154 [B<-xcertform> B<DER>|B<PEM>]
155 [B<-xkeyform> B<DER>|B<PEM>]
157 [B<-psk_identity> I<val>]
158 [B<-psk_hint> I<val>]
160 [B<-psk_session> I<file>]
161 [B<-srpvfile> I<infile>]
162 [B<-srpuserseed> I<val>]
177 [B<-nextprotoneg> I<val>]
178 [B<-use_srtp> I<val>]
181 [B<-keylogfile> I<outfile>]
182 [B<-max_early_data> I<int>]
186 [B<-http_server_binmode>]
188 =for openssl ifdef unix 4 6 unlink no_dhe nextprotoneg use_srtp engine
190 =for openssl ifdef status status_verbose status_timeout status_url status_file
192 =for openssl ifdef psk_hint srpvfile srpuserseed sctp sctp_label_bug
194 =for openssl ifdef sctp sctp_label_bug trace mtu timeout listen
196 =for openssl ifdef ssl3 tls1 tls1_1 tls1_2 tls1_3 dtls mtu dtls1 dtls1_2
200 This command implements a generic SSL/TLS server which
201 listens for connections on a given port using SSL/TLS.
205 In addition to the options below, this command also supports
206 the common and server only options documented
207 L<SSL_CONF_cmd(3)/Supported Command Line Commands>
213 Print out a usage message.
215 =item B<-port> I<+int>
217 The TCP port to listen on for connections. If not specified 4433 is used.
219 =item B<-accept> I<val>
221 The optional TCP host and port to listen on for connections. If not specified, *:4433 is used.
223 =item B<-unix> I<val>
225 Unix domain socket to accept on.
237 For -unix, unlink any existing socket first.
239 =item B<-context> I<val>
241 Sets the SSL context id. It can be given any string value. If this option
242 is not present a default value will be used.
244 =item B<-verify> I<int>, B<-Verify> I<int>
246 The verify depth to use. This specifies the maximum length of the
247 client certificate chain and makes the server request a certificate from
248 the client. With the B<-verify> option a certificate is requested but the
249 client does not have to send one, with the B<-Verify> option the client
250 must supply a certificate or an error occurs.
252 If the cipher suite cannot request a client certificate (for example an
253 anonymous cipher suite or PSK) this option has no effect.
255 =item B<-cert> I<infile>
257 The certificate to use, most servers cipher suites require the use of a
258 certificate and some require a certificate with a certain public key type:
259 for example the DSS cipher suites require a certificate containing a DSS
260 (DSA) key. If not specified then the filename F<server.pem> will be used.
264 A file containing trusted certificates to use when attempting to build the
265 client/server certificate chain related to the certificate specified via the
268 =item B<-build_chain>
270 Specify whether the application should build the certificate chain to be
271 provided to the client.
273 =item B<-nameopt> I<val>
275 Option which determines how the subject or issuer names are displayed. The
276 I<val> argument can be a single option or multiple options separated by
277 commas. Alternatively the B<-nameopt> switch may be used more than once to
278 set multiple options. See the L<openssl-x509(1)> manual page for details.
280 =item B<-naccept> I<+int>
282 The server will exit after receiving the specified number of connections,
285 =item B<-serverinfo> I<val>
287 A file containing one or more blocks of PEM data. Each PEM block
288 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
289 followed by "length" bytes of extension data). If the client sends
290 an empty TLS ClientHello extension matching the type, the corresponding
291 ServerHello extension will be returned.
293 =item B<-certform> B<DER>|B<PEM>, B<-CRLForm> B<DER>|B<PEM>
295 The certificate and CRL format; the default is PEM.
296 See L<openssl(1)/Format Options> for details.
298 =item B<-key> I<infile>
300 The private key to use. If not specified then the certificate file will
303 =item B<-keyform> B<DER>|B<PEM>]
305 The key format; the default is B<PEM>.
306 See L<openssl(1)/Format Options> for details.
308 =item B<-pass> I<val>
310 The private key password source.
311 For more information about the format of I<val>,
312 see L<openssl(1)/Pass Phrase Options>.
314 =item B<-dcert> I<infile>, B<-dkey> I<infile>
316 Specify an additional certificate and private key, these behave in the
317 same manner as the B<-cert> and B<-key> options except there is no default
318 if they are not specified (no additional certificate and key is used). As
319 noted above some cipher suites require a certificate containing a key of
320 a certain type. Some cipher suites need a certificate carrying an RSA key
321 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
322 a server can support clients which only support RSA or DSS cipher suites
323 by using an appropriate certificate.
325 =item B<-dcert_chain>
327 A file containing trusted certificates to use when attempting to build the
328 server certificate chain when a certificate specified via the B<-dcert> option
331 =item B<-dcertform> B<DER>|B<PEM>, B<-dkeyform> B<DER>|B<PEM>
333 The format of the certificate and private key; the default is B<PEM>
334 see L<openssl(1)/Format Options>.
336 =item B<-dpass> I<val>
338 The passphrase for the additional private key.
339 For more information about the format of I<val>,
340 see L<openssl(1)/Pass Phrase Options>.
342 =item B<-xkey> I<infile>, B<-xcert> I<infile>, B<-xchain>
344 Specify an extra certificate, private key and certificate chain. These behave
345 in the same manner as the B<-cert>, B<-key> and B<-cert_chain> options. When
346 specified, the callback returning the first valid chain will be in use by
349 =item B<-xchain_build>
351 Specify whether the application should build the certificate chain to be
352 provided to the client for the extra certificates provided via B<-xkey> I<infile>,
353 B<-xcert> I<infile>, B<-xchain> options.
355 =item B<-xcertform> B<DER>|B<PEM>, B<-xkeyform> B<DER>|B<PEM>
357 The format for the extra certificate and private key, respectively;
358 the default format is B<PEM>.
359 see L<openssl(1)/Pass Phrase Options>.
363 Tests non blocking I/O.
367 This option translated a line feed from the terminal into CR+LF.
371 Print extensive debugging information including a hex dump of all traffic.
375 Show all protocol messages with hex dump.
377 =item B<-msgfile> I<outfile>
379 File to send output of B<-msg> or B<-trace> to, default standard output.
383 Prints the SSL session states.
385 =item B<-CAfile> I<file>, B<-no-CAfile>, B<-CApath> I<dir>, B<-no-CApath>
387 See L<openssl(1)/Trusted Certificate Options> for more information.
389 =item B<-chainCApath> I<dir>
391 The directory to use for building the chain provided to the client. This
392 directory must be in "hash format", see L<openssl-verify(1)> for more
395 =item B<-chainCAfile> I<file>
397 A file containing trusted certificates to use when attempting to build the
398 server certificate chain.
402 If this option is set then no certificate is used. This restricts the
403 cipher suites available to the anonymous ones (currently just anonymous
408 Inhibit printing of session and certificate information.
412 Sends a status message back to the client when it connects. This includes
413 information about the ciphers used and various session parameters.
414 The output is in HTML format so this option will normally be used with a
415 web browser. Cannot be used in conjunction with B<-early_data>.
419 Emulates a simple web server. Pages will be resolved relative to the
420 current directory, for example if the URL https://myhost/page.html is
421 requested the file F<./page.html> will be loaded. Cannot be used in conjunction
424 =item B<-tlsextdebug>
426 Print a hex dump of any TLS extensions received from the server.
430 Emulates a simple web server. Pages will be resolved relative to the
431 current directory, for example if the URL https://myhost/page.html is
432 requested the file F<./page.html> will be loaded. The files loaded are
433 assumed to contain a complete and correct HTTP response (lines that
434 are part of the HTTP response line and headers must end with CRLF). Cannot be
435 used in conjunction with B<-early_data>.
437 =item B<-id_prefix> I<val>
439 Generate SSL/TLS session IDs prefixed by I<val>. This is mostly useful
440 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
441 servers, when each of which might be generating a unique range of session
442 IDs (eg. with a certain prefix).
444 =item B<-rand> I<files>, B<-writerand> I<file>
446 See L<openssl(1)/Random State Options> for more information.
448 =item B<-verify_return_error>
450 Verification errors normally just print a message but allow the
451 connection to continue, for debugging purposes.
452 If this option is used, then verification errors close the connection.
456 Enables certificate status request support (aka OCSP stapling).
458 =item B<-status_verbose>
460 Enables certificate status request support (aka OCSP stapling) and gives
461 a verbose printout of the OCSP response.
463 =item B<-status_timeout> I<int>
465 Sets the timeout for OCSP response to I<int> seconds.
467 =item B<-status_url> I<val>
469 Sets a fallback responder URL to use if no responder URL is present in the
470 server certificate. Without this option an error is returned if the server
471 certificate does not contain a responder address.
473 =item B<-status_file> I<infile>
475 Overrides any OCSP responder URLs from the certificate and always provides the
476 OCSP Response stored in the file. The file must be in DER format.
480 Show verbose trace output of protocol messages. OpenSSL needs to be compiled
481 with B<enable-ssl-trace> for this option to work.
485 Provide a brief summary of connection parameters instead of the normal verbose
490 Simple test server which just reverses the text received from the client
491 and sends it back to the server. Also sets B<-brief>. Cannot be used in
492 conjunction with B<-early_data>.
496 Switch on asynchronous mode. Cryptographic operations will be performed
497 asynchronously. This will only have an effect if an asynchronous capable engine
498 is also used via the B<-engine> option. For test purposes the dummy async engine
499 (dasync) can be used (if available).
501 =item B<-max_send_frag> I<+int>
503 The maximum size of data fragment to send.
504 See L<SSL_CTX_set_max_send_fragment(3)> for further information.
506 =item B<-split_send_frag> I<+int>
508 The size used to split data for encrypt pipelines. If more data is written in
509 one go than this value then it will be split into multiple pipelines, up to the
510 maximum number of pipelines defined by max_pipelines. This only has an effect if
511 a suitable cipher suite has been negotiated, an engine that supports pipelining
512 has been loaded, and max_pipelines is greater than 1. See
513 L<SSL_CTX_set_split_send_fragment(3)> for further information.
515 =item B<-max_pipelines> I<+int>
517 The maximum number of encrypt/decrypt pipelines to be used. This will only have
518 an effect if an engine has been loaded that supports pipelining (e.g. the dasync
519 engine) and a suitable cipher suite has been negotiated. The default value is 1.
520 See L<SSL_CTX_set_max_pipelines(3)> for further information.
522 =item B<-read_buf> I<+int>
524 The default read buffer size to be used for connections. This will only have an
525 effect if the buffer size is larger than the size that would otherwise be used
526 and pipelining is in use (see L<SSL_CTX_set_default_read_buffer_len(3)> for
527 further information).
529 =item B<-ssl2>, B<-ssl3>, B<-tls1>, B<-tls1_1>, B<-tls1_2>, B<-tls1_3>, B<-no_ssl2>, B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
531 These options require or disable the use of the specified SSL or TLS protocols.
532 By default, this command will negotiate the highest mutually supported
534 When a specific TLS version is required, only that version will be accepted
536 Note that not all protocols and flags may be available, depending on how
541 There are several known bugs in SSL and TLS implementations. Adding this
542 option enables various workarounds.
546 Disable negotiation of TLS compression.
547 TLS compression is not recommended and is off by default as of
552 Enable negotiation of TLS compression.
553 This option was introduced in OpenSSL 1.1.0.
554 TLS compression is not recommended and is off by default as of
559 Disable RFC4507bis session ticket support. This option has no effect if TLSv1.3
560 is negotiated. See B<-num_tickets>.
562 =item B<-num_tickets>
564 Control the number of tickets that will be sent to the client after a full
565 handshake in TLSv1.3. The default number of tickets is 2. This option does not
566 affect the number of tickets sent after a resumption handshake.
570 Use the server's cipher preferences, rather than the client's preferences.
572 =item B<-prioritize_chacha>
574 Prioritize ChaCha ciphers when preferred by clients. Requires B<-serverpref>.
576 =item B<-no_resumption_on_reneg>
578 Set the B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> option.
580 =item B<-client_sigalgs> I<val>
582 Signature algorithms to support for client certificate authentication
583 (colon-separated list).
585 =item B<-named_curve> I<val>
587 Specifies the elliptic curve to use. NOTE: this is single curve, not a list.
588 For a list of all possible curves, use:
590 $ openssl ecparam -list_curves
592 =item B<-cipher> I<val>
594 This allows the list of TLSv1.2 and below ciphersuites used by the server to be
595 modified. This list is combined with any TLSv1.3 ciphersuites that have been
596 configured. When the client sends a list of supported ciphers the first client
597 cipher also included in the server list is used. Because the client specifies
598 the preference order, the order of the server cipherlist is irrelevant. See
599 L<openssl-ciphers(1)> for more information.
601 =item B<-ciphersuites> I<val>
603 This allows the list of TLSv1.3 ciphersuites used by the server to be modified.
604 This list is combined with any TLSv1.2 and below ciphersuites that have been
605 configured. When the client sends a list of supported ciphers the first client
606 cipher also included in the server list is used. Because the client specifies
607 the preference order, the order of the server cipherlist is irrelevant. See
608 L<openssl-ciphers(1)> command for more information. The format for this list is
609 a simple colon (":") separated list of TLSv1.3 ciphersuite names.
611 =item B<-dhparam> I<infile>
613 The DH parameter file to use. The ephemeral DH cipher suites generate keys
614 using a set of DH parameters. If not specified then an attempt is made to
615 load the parameters from the server certificate file.
616 If this fails then a static set of parameters hard coded into this command
619 =item B<-attime>, B<-check_ss_sig>, B<-crl_check>, B<-crl_check_all>,
620 B<-explicit_policy>, B<-extended_crl>, B<-ignore_critical>, B<-inhibit_any>,
621 B<-inhibit_map>, B<-no_alt_chains>, B<-no_check_time>, B<-partial_chain>, B<-policy>,
622 B<-policy_check>, B<-policy_print>, B<-purpose>, B<-suiteB_128>,
623 B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>, B<-use_deltas>,
624 B<-auth_level>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
625 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
627 Set different peer certificate verification options.
628 See the L<openssl-verify(1)> manual page for details.
630 =item B<-crl_check>, B<-crl_check_all>
632 Check the peer certificate has not been revoked by its CA.
633 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
634 option all CRLs of all CAs in the chain are checked.
638 Turns on non blocking I/O.
640 =item B<-psk_identity> I<val>
642 Expect the client to send PSK identity I<val> when using a PSK
643 cipher suite, and warn if they do not. By default, the expected PSK
644 identity is the string "Client_identity".
646 =item B<-psk_hint> I<val>
648 Use the PSK identity hint I<val> when using a PSK cipher suite.
652 Use the PSK key I<val> when using a PSK cipher suite. The key is
653 given as a hexadecimal number without leading 0x, for example -psk
655 This option must be provided in order to use a PSK cipher.
657 =item B<-psk_session> I<file>
659 Use the pem encoded SSL_SESSION data stored in I<file> as the basis of a PSK.
660 Note that this will only work if TLSv1.3 is negotiated.
664 This option can only be used in conjunction with one of the DTLS options above.
665 With this option, this command will listen on a UDP port for incoming
667 Any ClientHellos that arrive will be checked to see if they have a cookie in
669 Any without a cookie will be responded to with a HelloVerifyRequest.
670 If a ClientHello with a cookie is received then this command will
671 connect to that peer and complete the handshake.
673 =item B<-dtls>, B<-dtls1>, B<-dtls1_2>
675 These options make this command use DTLS protocols instead of TLS.
676 With B<-dtls>, it will negotiate any supported DTLS protocol
677 version, whilst B<-dtls1> and B<-dtls1_2> will only support DTLSv1.0 and
678 DTLSv1.2 respectively.
682 Use SCTP for the transport protocol instead of UDP in DTLS. Must be used in
683 conjunction with B<-dtls>, B<-dtls1> or B<-dtls1_2>. This option is only
684 available where OpenSSL has support for SCTP enabled.
686 =item B<-sctp_label_bug>
688 Use the incorrect behaviour of older OpenSSL implementations when computing
689 endpoint-pair shared secrets for DTLS/SCTP. This allows communication with
690 older broken implementations but breaks interoperability with correct
691 implementations. Must be used in conjunction with B<-sctp>. This option is only
692 available where OpenSSL has support for SCTP enabled.
696 If this option is set then no DH parameters will be loaded effectively
697 disabling the ephemeral DH cipher suites.
699 =item B<-alpn> I<val>, B<-nextprotoneg> I<val>
701 These flags enable the Enable the Application-Layer Protocol Negotiation
702 or Next Protocol Negotiation (NPN) extension, respectively. ALPN is the
703 IETF standard and replaces NPN.
704 The I<val> list is a comma-separated list of supported protocol
705 names. The list should contain the most desirable protocols first.
706 Protocol names are printable ASCII strings, for example "http/1.1" or
708 The flag B<-nextprotoneg> cannot be specified if B<-tls1_3> is used.
710 =item B<-engine> I<val>
712 Specifying an engine (by its unique id string in I<val>) will cause
713 this command to attempt to obtain a functional reference to the
714 specified engine, thus initialising it if needed. The engine will then be
715 set as the default for all available algorithms.
717 =item B<-keylogfile> I<outfile>
719 Appends TLS secrets to the specified keylog file such that external programs
720 (like Wireshark) can decrypt TLS connections.
722 =item B<-max_early_data> I<int>
724 Change the default maximum early data bytes that are specified for new sessions
725 and any incoming early data (when used in conjunction with the B<-early_data>
726 flag). The default value is approximately 16k. The argument must be an integer
727 greater than or equal to 0.
731 Accept early data where possible. Cannot be used in conjunction with B<-www>,
732 B<-WWW>, B<-HTTP> or B<-rev>.
734 =item B<-anti_replay>, B<-no_anti_replay>
736 Switches replay protection on or off, respectively. Replay protection is on by
737 default unless overridden by a configuration file. When it is on, OpenSSL will
738 automatically detect if a session ticket has been used more than once, TLSv1.3
739 has been negotiated, and early data is enabled on the server. A full handshake
740 is forced if a session ticket is used a second or subsequent time. Any early
741 data that was sent will be rejected.
743 =item B<-http_server_binmode>
745 When acting as web-server (using option B<-WWW> or B<-HTTP>) open files requested
746 by the client in binary mode.
750 =head1 CONNECTED COMMANDS
752 If a connection request is established with an SSL client and neither the
753 B<-www> nor the B<-WWW> option has been used then normally any data received
754 from the client is displayed and any key presses will be sent to the client.
756 Certain commands are also recognized which perform special operations. These
757 commands are a letter which must appear at the start of a line. They are listed
764 End the current SSL connection but still accept new connections.
768 End the current SSL connection and exit.
772 Renegotiate the SSL session (TLSv1.2 and below only).
776 Renegotiate the SSL session and request a client certificate (TLSv1.2 and below
781 Send some plain text down the underlying TCP connection: this should
782 cause the client to disconnect due to a protocol violation.
786 Print out some session cache status information.
790 Send a key update message to the client (TLSv1.3 only)
794 Send a key update message to the client and request one back (TLSv1.3 only)
798 Send a certificate request to the client (TLSv1.3 only)
804 This command can be used to debug SSL clients. To accept connections
805 from a web browser the command:
807 openssl s_server -accept 443 -www
809 can be used for example.
811 Although specifying an empty list of CAs when requesting a client certificate
812 is strictly speaking a protocol violation, some SSL clients interpret this to
813 mean any CA is acceptable. This is useful for debugging purposes.
815 The session parameters can printed out using the L<openssl-sess_id(1)> command.
819 Because this program has a lot of options and also because some of the
820 techniques used are rather old, the C source for this command is rather
821 hard to read and not a model of how things should be done.
822 A typical SSL server program would be much simpler.
824 The output of common ciphers is wrong: it just gives the list of ciphers that
825 OpenSSL recognizes and the client supports.
827 There should be a way for this command to print out details
828 of any unknown cipher suites a client says it supports.
833 L<openssl-sess_id(1)>,
834 L<openssl-s_client(1)>,
835 L<openssl-ciphers(1)>,
837 L<SSL_CTX_set_max_send_fragment(3)>,
838 L<SSL_CTX_set_split_send_fragment(3)>,
839 L<SSL_CTX_set_max_pipelines(3)>
843 The -no_alt_chains option was added in OpenSSL 1.1.0.
846 -allow-no-dhe-kex and -prioritize_chacha options were added in OpenSSL 1.1.1.
850 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
852 Licensed under the Apache License 2.0 (the "License"). You may not use
853 this file except in compliance with the License. You can obtain a copy
854 in the file LICENSE in the source distribution or at
855 L<https://www.openssl.org/source/license.html>.