5 openssl-s_server - SSL/TLS server program
23 [B<-serverinfo> I<val>]
24 [B<-certform> B<DER>|B<PEM>]
26 [B<-keyform> I<format>]
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<-CRLform> B<DER>|B<PEM>]
68 [B<-verify_return_error>]
71 [B<-chainCAfile> I<infile>]
72 [B<-verifyCAfile> I<infile>]
77 [B<-status_timeout> I<int>]
78 [B<-status_url> I<val>]
79 [B<-status_file> I<infile>]
82 [B<-security_debug_verbose>]
86 [B<-ssl_config> I<val>]
87 [B<-max_send_frag> I<+int>]
88 [B<-split_send_frag> I<+int>]
89 [B<-max_pipelines> I<+int>]
90 [B<-read_buf> I<+int>]
102 [B<-legacy_renegotiation>]
103 [B<-no_renegotiation>]
104 [B<-legacy_server_connect>]
105 [B<-no_resumption_on_reneg>]
106 [B<-no_legacy_server_connect>]
107 [B<-allow_no_dhe_kex>]
108 [B<-prioritize_chacha>]
111 [B<-client_sigalgs> I<val>]
114 [B<-named_curve> I<val>]
116 [B<-ciphersuites> I<val>]
117 [B<-dhparam> I<infile>]
118 [B<-record_padding> I<val>]
119 [B<-debug_broken_protocol>]
122 [B<-verify_name> I<val>]
123 [B<-verify_depth> I<int>]
124 [B<-auth_level> I<int>]
125 [B<-attime> I<intmax>]
126 [B<-verify_hostname> I<val>]
127 [B<-verify_email> I<val>]
129 [B<-ignore_critical>]
134 [B<-explicit_policy>]
143 [B<-suiteB_128_only>]
149 [B<-allow_proxy_certs>]
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 comment ifdef unix 4 6 unlink no_dhe nextprotoneg use_srtp engine
190 =for comment ifdef status status_verbose status_timeout status_url status_file
192 =for comment ifdef psk_hint srpvfile srpuserseed sctp sctp_label_bug
194 =for comment ifdef sctp sctp_label_bug trace mtu timeout listen
196 =for comment 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<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>
295 The certificate format to use: DER or PEM. PEM is the default.
297 =item B<-key> I<infile>
299 The private key to use. If not specified then the certificate file will
302 =item B<-keyform> I<format>
304 The private format to use: DER or PEM. PEM is the default.
306 =item B<-pass> I<val>
308 The private key password source. For more information about the format of B<val>
309 see L<openssl(1)/Pass phrase options>.
311 =item B<-dcert> I<infile>, B<-dkey> I<infile>
313 Specify an additional certificate and private key, these behave in the
314 same manner as the B<-cert> and B<-key> options except there is no default
315 if they are not specified (no additional certificate and key is used). As
316 noted above some cipher suites require a certificate containing a key of
317 a certain type. Some cipher suites need a certificate carrying an RSA key
318 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
319 a server can support clients which only support RSA or DSS cipher suites
320 by using an appropriate certificate.
322 =item B<-dcert_chain>
324 A file containing trusted certificates to use when attempting to build the
325 server certificate chain when a certificate specified via the B<-dcert> option
328 =item B<-dcertform> B<DER>|B<PEM>, B<-dkeyform> B<DER>|B<PEM>, B<-dpass> I<val>
330 Additional certificate and private key format and passphrase respectively.
332 =item B<-xkey> I<infile>, B<-xcert> I<infile>, B<-xchain>
334 Specify an extra certificate, private key and certificate chain. These behave
335 in the same manner as the B<-cert>, B<-key> and B<-cert_chain> options. When
336 specified, the callback returning the first valid chain will be in use by
339 =item B<-xchain_build>
341 Specify whether the application should build the certificate chain to be
342 provided to the client for the extra certificates provided via B<-xkey> I<infile>,
343 B<-xcert> I<infile>, B<-xchain> options.
345 =item B<-xcertform> B<DER>|B<PEM>, B<-xkeyform> B<DER>|B<PEM>
347 Extra certificate and private key format respectively.
351 Tests non blocking I/O.
355 This option translated a line feed from the terminal into CR+LF.
359 Print extensive debugging information including a hex dump of all traffic.
363 Show all protocol messages with hex dump.
365 =item B<-msgfile> I<outfile>
367 File to send output of B<-msg> or B<-trace> to, default standard output.
371 Prints the SSL session states.
373 =item B<-CAfile> I<infile>
375 A file containing trusted certificates to use during client authentication
376 and to use when attempting to build the server certificate chain. The list
377 is also used in the list of acceptable client CAs passed to the client when
378 a certificate is requested.
380 =item B<-CApath> I<dir>
382 The directory to use for client certificate verification. This directory
383 must be in "hash format", see L<verify(1)> for more information. These are
384 also used when building the server certificate chain.
386 =item B<-chainCApath> I<dir>
388 The directory to use for building the chain provided to the client. This
389 directory must be in "hash format", see L<verify(1)> for more information.
391 =item B<-chainCAfile> I<file>
393 A file containing trusted certificates to use when attempting to build the
394 server certificate chain.
398 Do not load the trusted CA certificates from the default file location.
402 Do not load the trusted CA certificates from the default directory location.
406 If this option is set then no certificate is used. This restricts the
407 cipher suites available to the anonymous ones (currently just anonymous
412 Inhibit printing of session and certificate information.
416 Sends a status message back to the client when it connects. This includes
417 information about the ciphers used and various session parameters.
418 The output is in HTML format so this option will normally be used with a
419 web browser. Cannot be used in conjunction with B<-early_data>.
423 Emulates a simple web server. Pages will be resolved relative to the
424 current directory, for example if the URL https://myhost/page.html is
425 requested the file F<./page.html> will be loaded. Cannot be used in conjunction
428 =item B<-tlsextdebug>
430 Print a hex dump of any TLS extensions received from the server.
434 Emulates a simple web server. Pages will be resolved relative to the
435 current directory, for example if the URL https://myhost/page.html is
436 requested the file F<./page.html> will be loaded. The files loaded are
437 assumed to contain a complete and correct HTTP response (lines that
438 are part of the HTTP response line and headers must end with CRLF). Cannot be
439 used in conjunction with B<-early_data>.
441 =item B<-id_prefix> I<val>
443 Generate SSL/TLS session IDs prefixed by I<val>. This is mostly useful
444 for testing any SSL/TLS code (eg. proxies) that wish to deal with multiple
445 servers, when each of which might be generating a unique range of session
446 IDs (eg. with a certain prefix).
448 =item B<-rand> I<files>
450 The files containing random data used to seed the random number generator.
451 Multiple files can be specified separated by an OS-dependent character.
452 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
455 =item B<-writerand> I<file>
457 Writes random data to the specified I<file> upon exit.
458 This can be used with a subsequent B<-rand> flag.
460 =item B<-verify_return_error>
462 Verification errors normally just print a message but allow the
463 connection to continue, for debugging purposes.
464 If this option is used, then verification errors close the connection.
468 Enables certificate status request support (aka OCSP stapling).
470 =item B<-status_verbose>
472 Enables certificate status request support (aka OCSP stapling) and gives
473 a verbose printout of the OCSP response.
475 =item B<-status_timeout> I<int>
477 Sets the timeout for OCSP response to I<int> seconds.
479 =item B<-status_url> I<val>
481 Sets a fallback responder URL to use if no responder URL is present in the
482 server certificate. Without this option an error is returned if the server
483 certificate does not contain a responder address.
485 =item B<-status_file> I<infile>
487 Overrides any OCSP responder URLs from the certificate and always provides the
488 OCSP Response stored in the file. The file must be in DER format.
492 Show verbose trace output of protocol messages. OpenSSL needs to be compiled
493 with B<enable-ssl-trace> for this option to work.
497 Provide a brief summary of connection parameters instead of the normal verbose
502 Simple test server which just reverses the text received from the client
503 and sends it back to the server. Also sets B<-brief>. Cannot be used in
504 conjunction with B<-early_data>.
508 Switch on asynchronous mode. Cryptographic operations will be performed
509 asynchronously. This will only have an effect if an asynchronous capable engine
510 is also used via the B<-engine> option. For test purposes the dummy async engine
511 (dasync) can be used (if available).
513 =item B<-max_send_frag> I<+int>
515 The maximum size of data fragment to send.
516 See L<SSL_CTX_set_max_send_fragment(3)> for further information.
518 =item B<-split_send_frag> I<+int>
520 The size used to split data for encrypt pipelines. If more data is written in
521 one go than this value then it will be split into multiple pipelines, up to the
522 maximum number of pipelines defined by max_pipelines. This only has an effect if
523 a suitable cipher suite has been negotiated, an engine that supports pipelining
524 has been loaded, and max_pipelines is greater than 1. See
525 L<SSL_CTX_set_split_send_fragment(3)> for further information.
527 =item B<-max_pipelines> I<+int>
529 The maximum number of encrypt/decrypt pipelines to be used. This will only have
530 an effect if an engine has been loaded that supports pipelining (e.g. the dasync
531 engine) and a suitable cipher suite has been negotiated. The default value is 1.
532 See L<SSL_CTX_set_max_pipelines(3)> for further information.
534 =item B<-read_buf> I<+int>
536 The default read buffer size to be used for connections. This will only have an
537 effect if the buffer size is larger than the size that would otherwise be used
538 and pipelining is in use (see L<SSL_CTX_set_default_read_buffer_len(3)> for
539 further information).
541 =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>
543 These options require or disable the use of the specified SSL or TLS protocols.
544 By default, this command will negotiate the highest mutually supported
546 When a specific TLS version is required, only that version will be accepted
548 Note that not all protocols and flags may be available, depending on how
553 There are several known bugs in SSL and TLS implementations. Adding this
554 option enables various workarounds.
558 Disable negotiation of TLS compression.
559 TLS compression is not recommended and is off by default as of
564 Enable negotiation of TLS compression.
565 This option was introduced in OpenSSL 1.1.0.
566 TLS compression is not recommended and is off by default as of
571 Disable RFC4507bis session ticket support. This option has no effect if TLSv1.3
572 is negotiated. See B<-num_tickets>.
574 =item B<-num_tickets>
576 Control the number of tickets that will be sent to the client after a full
577 handshake in TLSv1.3. The default number of tickets is 2. This option does not
578 affect the number of tickets sent after a resumption handshake.
582 Use the server's cipher preferences, rather than the client's preferences.
584 =item B<-prioritize_chacha>
586 Prioritize ChaCha ciphers when preferred by clients. Requires B<-serverpref>.
588 =item B<-no_resumption_on_reneg>
590 Set the B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> option.
592 =item B<-client_sigalgs> I<val>
594 Signature algorithms to support for client certificate authentication
595 (colon-separated list).
597 =item B<-named_curve> I<val>
599 Specifies the elliptic curve to use. NOTE: this is single curve, not a list.
600 For a list of all possible curves, use:
602 $ openssl ecparam -list_curves
604 =item B<-cipher> I<val>
606 This allows the list of TLSv1.2 and below ciphersuites used by the server to be
607 modified. This list is combined with any TLSv1.3 ciphersuites that have been
608 configured. When the client sends a list of supported ciphers the first client
609 cipher also included in the server list is used. Because the client specifies
610 the preference order, the order of the server cipherlist is irrelevant. See
611 L<openssl-ciphers(1)> for more information.
613 =item B<-ciphersuites> I<val>
615 This allows the list of TLSv1.3 ciphersuites used by the server to be modified.
616 This list is combined with any TLSv1.2 and below ciphersuites that have been
617 configured. When the client sends a list of supported ciphers the first client
618 cipher also included in the server list is used. Because the client specifies
619 the preference order, the order of the server cipherlist is irrelevant. See
620 L<openssl-ciphers(1)> command for more information. The format for this list is
621 a simple colon (":") separated list of TLSv1.3 ciphersuite names.
623 =item B<-dhparam> I<infile>
625 The DH parameter file to use. The ephemeral DH cipher suites generate keys
626 using a set of DH parameters. If not specified then an attempt is made to
627 load the parameters from the server certificate file.
628 If this fails then a static set of parameters hard coded into this command
631 =item B<-attime>, B<-check_ss_sig>, B<-crl_check>, B<-crl_check_all>,
632 B<-explicit_policy>, B<-extended_crl>, B<-ignore_critical>, B<-inhibit_any>,
633 B<-inhibit_map>, B<-no_alt_chains>, B<-no_check_time>, B<-partial_chain>, B<-policy>,
634 B<-policy_check>, B<-policy_print>, B<-purpose>, B<-suiteB_128>,
635 B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>, B<-use_deltas>,
636 B<-auth_level>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>,
637 B<-verify_ip>, B<-verify_name>, B<-x509_strict>
639 Set different peer certificate verification options.
640 See the L<verify(1)> manual page for details.
642 =item B<-crl_check>, B<-crl_check_all>
644 Check the peer certificate has not been revoked by its CA.
645 The CRL(s) are appended to the certificate file. With the B<-crl_check_all>
646 option all CRLs of all CAs in the chain are checked.
650 Turns on non blocking I/O.
652 =item B<-psk_identity> I<val>
654 Expect the client to send PSK identity I<val> when using a PSK
655 cipher suite, and warn if they do not. By default, the expected PSK
656 identity is the string "Client_identity".
658 =item B<-psk_hint> I<val>
660 Use the PSK identity hint I<val> when using a PSK cipher suite.
664 Use the PSK key I<val> when using a PSK cipher suite. The key is
665 given as a hexadecimal number without leading 0x, for example -psk
667 This option must be provided in order to use a PSK cipher.
669 =item B<-psk_session> I<file>
671 Use the pem encoded SSL_SESSION data stored in I<file> as the basis of a PSK.
672 Note that this will only work if TLSv1.3 is negotiated.
676 This option can only be used in conjunction with one of the DTLS options above.
677 With this option, this command will listen on a UDP port for incoming
679 Any ClientHellos that arrive will be checked to see if they have a cookie in
681 Any without a cookie will be responded to with a HelloVerifyRequest.
682 If a ClientHello with a cookie is received then this command will
683 connect to that peer and complete the handshake.
685 =item B<-dtls>, B<-dtls1>, B<-dtls1_2>
687 These options make this command use DTLS protocols instead of TLS.
688 With B<-dtls>, it will negotiate any supported DTLS protocol
689 version, whilst B<-dtls1> and B<-dtls1_2> will only support DTLSv1.0 and
690 DTLSv1.2 respectively.
694 Use SCTP for the transport protocol instead of UDP in DTLS. Must be used in
695 conjunction with B<-dtls>, B<-dtls1> or B<-dtls1_2>. This option is only
696 available where OpenSSL has support for SCTP enabled.
698 =item B<-sctp_label_bug>
700 Use the incorrect behaviour of older OpenSSL implementations when computing
701 endpoint-pair shared secrets for DTLS/SCTP. This allows communication with
702 older broken implementations but breaks interoperability with correct
703 implementations. Must be used in conjunction with B<-sctp>. This option is only
704 available where OpenSSL has support for SCTP enabled.
708 If this option is set then no DH parameters will be loaded effectively
709 disabling the ephemeral DH cipher suites.
711 =item B<-alpn> I<val>, B<-nextprotoneg> I<val>
713 These flags enable the Enable the Application-Layer Protocol Negotiation
714 or Next Protocol Negotiation (NPN) extension, respectively. ALPN is the
715 IETF standard and replaces NPN.
716 The I<val> list is a comma-separated list of supported protocol
717 names. The list should contain the most desirable protocols first.
718 Protocol names are printable ASCII strings, for example "http/1.1" or
720 The flag B<-nextprotoneg> cannot be specified if B<-tls1_3> is used.
722 =item B<-engine> I<val>
724 Specifying an engine (by its unique id string in I<val>) will cause
725 this command to attempt to obtain a functional reference to the
726 specified engine, thus initialising it if needed. The engine will then be
727 set as the default for all available algorithms.
729 =item B<-keylogfile> I<outfile>
731 Appends TLS secrets to the specified keylog file such that external programs
732 (like Wireshark) can decrypt TLS connections.
734 =item B<-max_early_data> I<int>
736 Change the default maximum early data bytes that are specified for new sessions
737 and any incoming early data (when used in conjunction with the B<-early_data>
738 flag). The default value is approximately 16k. The argument must be an integer
739 greater than or equal to 0.
743 Accept early data where possible. Cannot be used in conjunction with B<-www>,
744 B<-WWW>, B<-HTTP> or B<-rev>.
746 =item B<-anti_replay>, B<-no_anti_replay>
748 Switches replay protection on or off, respectively. Replay protection is on by
749 default unless overridden by a configuration file. When it is on, OpenSSL will
750 automatically detect if a session ticket has been used more than once, TLSv1.3
751 has been negotiated, and early data is enabled on the server. A full handshake
752 is forced if a session ticket is used a second or subsequent time. Any early
753 data that was sent will be rejected.
755 =item B<-http_server_binmode>
757 When acting as web-server (using option B<-WWW> or B<-HTTP>) open files requested
758 by the client in binary mode.
762 =head1 CONNECTED COMMANDS
764 If a connection request is established with an SSL client and neither the
765 B<-www> nor the B<-WWW> option has been used then normally any data received
766 from the client is displayed and any key presses will be sent to the client.
768 Certain commands are also recognized which perform special operations. These
769 commands are a letter which must appear at the start of a line. They are listed
776 End the current SSL connection but still accept new connections.
780 End the current SSL connection and exit.
784 Renegotiate the SSL session (TLSv1.2 and below only).
788 Renegotiate the SSL session and request a client certificate (TLSv1.2 and below
793 Send some plain text down the underlying TCP connection: this should
794 cause the client to disconnect due to a protocol violation.
798 Print out some session cache status information.
802 Send a key update message to the client (TLSv1.3 only)
806 Send a key update message to the client and request one back (TLSv1.3 only)
810 Send a certificate request to the client (TLSv1.3 only)
816 This command can be used to debug SSL clients. To accept connections
817 from a web browser the command:
819 openssl s_server -accept 443 -www
821 can be used for example.
823 Although specifying an empty list of CAs when requesting a client certificate
824 is strictly speaking a protocol violation, some SSL clients interpret this to
825 mean any CA is acceptable. This is useful for debugging purposes.
827 The session parameters can printed out using the L<openssl-sess_id(1)> command.
831 Because this program has a lot of options and also because some of the
832 techniques used are rather old, the C source for this command is rather
833 hard to read and not a model of how things should be done.
834 A typical SSL server program would be much simpler.
836 The output of common ciphers is wrong: it just gives the list of ciphers that
837 OpenSSL recognizes and the client supports.
839 There should be a way for this command to print out details
840 of any unknown cipher suites a client says it supports.
845 L<openssl-sess_id(1)>,
846 L<openssl-s_client(1)>,
847 L<openssl-ciphers(1)>,
849 L<SSL_CTX_set_max_send_fragment(3)>,
850 L<SSL_CTX_set_split_send_fragment(3)>,
851 L<SSL_CTX_set_max_pipelines(3)>
855 The -no_alt_chains option was added in OpenSSL 1.1.0.
858 -allow-no-dhe-kex and -prioritize_chacha options were added in OpenSSL 1.1.1.
862 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
864 Licensed under the Apache License 2.0 (the "License"). You may not use
865 this file except in compliance with the License. You can obtain a copy
866 in the file LICENSE in the source distribution or at
867 L<https://www.openssl.org/source/license.html>.