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>]
27 [B<-key> I<filename>|I<uri>]
28 [B<-key2> I<filename>|I<uri>]
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>]
34 [B<-dkey> I<filename>|I<uri>]
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>]
77 [B<-status_timeout> I<int>]
78 [B<-proxy> I<[http[s]://][userinfo@]host[:port][/path]>]
79 [B<-no_proxy> I<addresses>]
80 [B<-status_url> I<val>]
81 [B<-status_file> I<infile>]
82 [B<-ssl_config> I<val>]
85 [B<-security_debug_verbose>]
89 [B<-max_send_frag> I<+int>]
90 [B<-split_send_frag> I<+int>]
91 [B<-max_pipelines> I<+int>]
93 [B<-read_buf> I<+int>]
101 [B<-legacy_renegotiation>]
102 [B<-no_renegotiation>]
103 [B<-no_resumption_on_reneg>]
104 [B<-allow_no_dhe_kex>]
105 [B<-prefer_no_dhe_kex>]
106 [B<-prioritize_chacha>]
109 [B<-client_sigalgs> I<val>]
112 [B<-named_curve> I<val>]
114 [B<-ciphersuites> I<val>]
115 [B<-dhparam> I<infile>]
116 [B<-record_padding> I<val>]
117 [B<-debug_broken_protocol>]
119 [B<-psk_identity> I<val>]
120 [B<-psk_hint> I<val>]
122 [B<-psk_session> I<file>]
123 [B<-srpvfile> I<infile>]
124 [B<-srpuserseed> I<val>]
130 [B<-use_srtp> I<val>]
132 [B<-nextprotoneg> I<val>]
136 [B<-zerocopy_sendfile>]
137 [B<-keylogfile> I<outfile>]
138 [B<-recv_max_early_data> I<int>]
139 [B<-max_early_data> I<int>]
147 {- $OpenSSL::safe::opt_name_synopsis -}
148 {- $OpenSSL::safe::opt_version_synopsis -}
149 {- $OpenSSL::safe::opt_v_synopsis -}
150 {- $OpenSSL::safe::opt_s_synopsis -}
151 {- $OpenSSL::safe::opt_x_synopsis -}
152 {- $OpenSSL::safe::opt_trust_synopsis -}
153 {- $OpenSSL::safe::opt_r_synopsis -}
154 {- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_provider_synopsis -}
155 [B<-enable_server_rpk>]
156 [B<-enable_client_rpk>]
160 This command implements a generic SSL/TLS server which
161 listens for connections on a given port using SSL/TLS.
165 In addition to the options below, this command also supports
166 the common and server only options documented
167 L<SSL_CONF_cmd(3)/Supported Command Line Commands>
173 Print out a usage message.
175 =item B<-port> I<+int>
177 The TCP port to listen on for connections. If not specified 4433 is used.
179 =item B<-accept> I<val>
181 The optional TCP host and port to listen on for connections. If not specified, *:4433 is used.
183 =item B<-unix> I<val>
185 Unix domain socket to accept on.
197 For -unix, unlink any existing socket first.
199 =item B<-context> I<val>
201 Sets the SSL context id. It can be given any string value. If this option
202 is not present a default value will be used.
204 =item B<-verify> I<int>, B<-Verify> I<int>
206 The verify depth to use. This specifies the maximum length of the
207 client certificate chain and makes the server request a certificate from
208 the client. With the B<-verify> option a certificate is requested but the
209 client does not have to send one, with the B<-Verify> option the client
210 must supply a certificate or an error occurs.
212 If the cipher suite cannot request a client certificate (for example an
213 anonymous cipher suite or PSK) this option has no effect.
215 =item B<-cert> I<infile>
217 The certificate to use, most servers cipher suites require the use of a
218 certificate and some require a certificate with a certain public key type:
219 for example the DSS cipher suites require a certificate containing a DSS
220 (DSA) key. If not specified then the filename F<server.pem> will be used.
222 =item B<-cert2> I<infile>
224 The certificate file to use for servername; default is C<server2.pem>.
226 =item B<-certform> B<DER>|B<PEM>|B<P12>
228 The server certificate file format; unspecified by default.
229 See L<openssl-format-options(1)> for details.
233 A file or URI of untrusted certificates to use when attempting to build the
234 certificate chain related to the certificate specified via the B<-cert> option.
235 These untrusted certificates are sent to clients and used for generating
236 certificate status (aka OCSP stapling) requests.
237 The input can be in PEM, DER, or PKCS#12 format.
239 =item B<-build_chain>
241 Specify whether the application should build the server certificate chain to be
242 provided to the client.
244 =item B<-serverinfo> I<val>
246 A file containing one or more blocks of PEM data. Each PEM block
247 must encode a TLS ServerHello extension (2 bytes type, 2 bytes length,
248 followed by "length" bytes of extension data). If the client sends
249 an empty TLS ClientHello extension matching the type, the corresponding
250 ServerHello extension will be returned.
252 =item B<-key> I<filename>|I<uri>
254 The private key to use. If not specified then the certificate file will
257 =item B<-key2> I<filename>|I<uri>
259 The private Key file to use for servername if not given via B<-cert2>.
261 =item B<-keyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
263 The key format; unspecified by default.
264 See L<openssl-format-options(1)> for details.
266 =item B<-pass> I<val>
268 The private key and certificate file password source.
269 For more information about the format of I<val>,
270 see L<openssl-passphrase-options(1)>.
272 =item B<-dcert> I<infile>, B<-dkey> I<filename>|I<uri>
274 Specify an additional certificate and private key, these behave in the
275 same manner as the B<-cert> and B<-key> options except there is no default
276 if they are not specified (no additional certificate and key is used). As
277 noted above some cipher suites require a certificate containing a key of
278 a certain type. Some cipher suites need a certificate carrying an RSA key
279 and some a DSS (DSA) key. By using RSA and DSS certificates and keys
280 a server can support clients which only support RSA or DSS cipher suites
281 by using an appropriate certificate.
283 =item B<-dcert_chain>
285 A file or URI of untrusted certificates to use when attempting to build the
286 server certificate chain when a certificate specified via the B<-dcert> option
288 The input can be in PEM, DER, or PKCS#12 format.
290 =item B<-dcertform> B<DER>|B<PEM>|B<P12>
292 The format of the additional certificate file; unspecified by default.
293 See L<openssl-format-options(1)> for details.
295 =item B<-dkeyform> B<DER>|B<PEM>|B<P12>|B<ENGINE>
297 The format of the additional private key; unspecified by default.
298 See L<openssl-format-options(1)> for details.
300 =item B<-dpass> I<val>
302 The passphrase for the additional private key and certificate.
303 For more information about the format of I<val>,
304 see L<openssl-passphrase-options(1)>.
308 Tests non blocking I/O.
312 This option translated a line feed from the terminal into CR+LF.
316 Print extensive debugging information including a hex dump of all traffic.
318 =item B<-security_debug>
320 Print output from SSL/TLS security framework.
322 =item B<-security_debug_verbose>
324 Print more output from SSL/TLS security framework
328 Show all protocol messages with hex dump.
330 =item B<-msgfile> I<outfile>
332 File to send output of B<-msg> or B<-trace> to, default standard output.
336 Prints the SSL session states.
338 =item B<-CRL> I<infile>
342 =item B<-CRLform> B<DER>|B<PEM>
344 The CRL file format; unspecified by default.
345 See L<openssl-format-options(1)> for details.
347 =item B<-crl_download>
349 Download CRLs from distribution points given in CDP extensions of certificates
351 =item B<-verifyCAfile> I<filename>
353 A file in PEM format CA containing trusted certificates to use
354 for verifying client certificates.
356 =item B<-verifyCApath> I<dir>
358 A directory containing trusted certificates to use
359 for verifying client certificates.
360 This directory must be in "hash format",
361 see L<openssl-verify(1)> for more information.
363 =item B<-verifyCAstore> I<uri>
365 The URI of a store containing trusted certificates to use
366 for verifying client certificates.
368 =item B<-chainCAfile> I<file>
370 A file in PEM format containing trusted certificates to use
371 when attempting to build the server certificate chain.
373 =item B<-chainCApath> I<dir>
375 A directory containing trusted certificates to use
376 for building the server certificate chain provided to the client.
377 This directory must be in "hash format",
378 see L<openssl-verify(1)> for more information.
380 =item B<-chainCAstore> I<uri>
382 The URI of a store containing trusted certificates to use
383 for building the server certificate chain provided to the client.
384 The URI may indicate a single certificate, as well as a collection of them.
385 With URIs in the C<file:> scheme, this acts as B<-chainCAfile> or
386 B<-chainCApath>, depending on if the URI indicates a directory or a
388 See L<ossl_store-file(7)> for more information on the C<file:> scheme.
392 If this option is set then no certificate is used. This restricts the
393 cipher suites available to the anonymous ones (currently just anonymous
398 Inhibit printing of session and certificate information.
400 =item B<-no_resume_ephemeral>
402 Disable caching and tickets if ephemeral (EC)DH is used.
404 =item B<-tlsextdebug>
406 Print a hex dump of any TLS extensions received from the server.
410 Sends a status message back to the client when it connects. This includes
411 information about the ciphers used and various session parameters.
412 The output is in HTML format so this option can be used with a web browser.
413 The special URL C</renegcert> turns on client cert validation, and C</reneg>
414 tells the server to request renegotiation.
415 The B<-early_data> option cannot be used with this option.
417 =item B<-WWW>, B<-HTTP>
419 Emulates a simple web server. Pages will be resolved relative to the
420 current directory, for example if the URL C<https://myhost/page.html> is
421 requested the file F<./page.html> will be sent.
422 If the B<-HTTP> flag is used, the files are sent directly, and should contain
423 any HTTP response headers (including status response line).
424 If the B<-WWW> option is used,
425 the response headers are generated by the server, and the file extension is
426 examined to determine the B<Content-Type> header.
427 Extensions of C<html>, C<htm>, and C<php> are C<text/html> and all others are
429 In addition, the special URL C</stats> will return status
430 information like the B<-www> option.
431 Neither of these options can be used in conjunction with B<-early_data>.
433 =item B<-http_server_binmode>
435 When acting as web-server (using option B<-WWW> or B<-HTTP>) open files requested
436 by the client in binary mode.
438 =item B<-no_ca_names>
440 Disable TLS Extension CA Names. You may want to disable it for security reasons
441 or for compatibility with some Windows TLS implementations crashing when this
442 extension is larger than 1024 bytes.
444 =item B<-ignore_unexpected_eof>
446 Some TLS implementations do not send the mandatory close_notify alert on
447 shutdown. If the application tries to wait for the close_notify alert but the
448 peer closes the connection without sending it, an error is generated. When this
449 option is enabled the peer does not need to send the close_notify alert and a
450 closed connection will be treated as if the close_notify alert was received.
451 For more information on shutting down a connection, see L<SSL_shutdown(3)>.
455 Servername for HostName TLS extension.
457 =item B<-servername_fatal>
459 On servername mismatch send fatal alert (default: warning alert).
461 =item B<-id_prefix> I<val>
463 Generate SSL/TLS session IDs prefixed by I<val>. This is mostly useful
464 for testing any SSL/TLS code (e.g. proxies) that wish to deal with multiple
465 servers, when each of which might be generating a unique range of session
466 IDs (e.g. with a certain prefix).
468 =item B<-keymatexport>
470 Export keying material using label.
472 =item B<-keymatexportlen>
474 Export the given number of bytes of keying material; default 20.
478 Disable session cache.
482 Disable internal cache, set up and use external cache.
484 =item B<-verify_return_error>
486 Verification errors normally just print a message but allow the
487 connection to continue, for debugging purposes.
488 If this option is used, then verification errors close the connection.
490 =item B<-verify_quiet>
492 No verify output except verify errors.
496 Ignore input EOF (default: when B<-quiet>).
500 Do not ignore input EOF.
504 Disable Encrypt-then-MAC negotiation.
508 Disable Extended master secret negotiation.
512 Enables certificate status request support (aka OCSP stapling).
514 =item B<-status_verbose>
516 Enables certificate status request support (aka OCSP stapling) and gives
517 a verbose printout of the OCSP response.
518 Use the B<-cert_chain> option to specify the certificate of the server's
519 certificate signer that is required for certificate status requests.
521 =item B<-status_timeout> I<int>
523 Sets the timeout for OCSP response to I<int> seconds.
525 =item B<-proxy> I<[http[s]://][userinfo@]host[:port][/path]>
527 The HTTP(S) proxy server to use for reaching the OCSP server unless B<-no_proxy>
529 The proxy port defaults to 80 or 443 if the scheme is C<https>; apart from that
530 the optional C<http://> or C<https://> prefix is ignored,
531 as well as any userinfo and path components.
532 Defaults to the environment variable C<http_proxy> if set, else C<HTTP_PROXY>
533 in case no TLS is used, otherwise C<https_proxy> if set, else C<HTTPS_PROXY>.
535 =item B<-no_proxy> I<addresses>
537 List of IP addresses and/or DNS names of servers
538 not to use an HTTP(S) proxy for, separated by commas and/or whitespace
539 (where in the latter case the whole argument must be enclosed in "...").
540 Default is from the environment variable C<no_proxy> if set, else C<NO_PROXY>.
542 =item B<-status_url> I<val>
544 Sets a fallback responder URL to use if no responder URL is present in the
545 server certificate. Without this option an error is returned if the server
546 certificate does not contain a responder address.
547 The optional userinfo and fragment URL components are ignored.
548 Any given query component is handled as part of the path component.
550 =item B<-status_file> I<infile>
552 Overrides any OCSP responder URLs from the certificate and always provides the
553 OCSP Response stored in the file. The file must be in DER format.
555 =item B<-ssl_config> I<val>
557 Configure SSL_CTX using the given configuration value.
561 Show verbose trace output of protocol messages.
565 Provide a brief summary of connection parameters instead of the normal verbose
570 Simple echo server that sends back received text reversed. Also sets B<-brief>.
571 Cannot be used in conjunction with B<-early_data>.
575 Switch on asynchronous mode. Cryptographic operations will be performed
576 asynchronously. This will only have an effect if an asynchronous capable engine
577 is also used via the B<-engine> option. For test purposes the dummy async engine
578 (dasync) can be used (if available).
580 =item B<-max_send_frag> I<+int>
582 The maximum size of data fragment to send.
583 See L<SSL_CTX_set_max_send_fragment(3)> for further information.
585 =item B<-split_send_frag> I<+int>
587 The size used to split data for encrypt pipelines. If more data is written in
588 one go than this value then it will be split into multiple pipelines, up to the
589 maximum number of pipelines defined by max_pipelines. This only has an effect if
590 a suitable cipher suite has been negotiated, an engine that supports pipelining
591 has been loaded, and max_pipelines is greater than 1. See
592 L<SSL_CTX_set_split_send_fragment(3)> for further information.
594 =item B<-max_pipelines> I<+int>
596 The maximum number of encrypt/decrypt pipelines to be used. This will only have
597 an effect if an engine has been loaded that supports pipelining (e.g. the dasync
598 engine) and a suitable cipher suite has been negotiated. The default value is 1.
599 See L<SSL_CTX_set_max_pipelines(3)> for further information.
601 =item B<-naccept> I<+int>
603 The server will exit after receiving the specified number of connections,
606 =item B<-read_buf> I<+int>
608 The default read buffer size to be used for connections. This will only have an
609 effect if the buffer size is larger than the size that would otherwise be used
610 and pipelining is in use (see L<SSL_CTX_set_default_read_buffer_len(3)> for
611 further information).
615 There are several known bugs in SSL and TLS implementations. Adding this
616 option enables various workarounds.
618 =item B<-no_tx_cert_comp>
620 Disables support for sending TLSv1.3 compressed certificates.
622 =item B<-no_rx_cert_comp>
624 Disables support for receiving TLSv1.3 compressed certificates.
628 Disable negotiation of TLS compression.
629 TLS compression is not recommended and is off by default as of
634 Enables support for SSL/TLS compression.
635 This option was introduced in OpenSSL 1.1.0.
636 TLS compression is not recommended and is off by default as of
637 OpenSSL 1.1.0. TLS compression can only be used in security level 1 or
638 lower. From OpenSSL 3.2.0 and above the default security level is 2, so this
639 option will have no effect without also changing the security level. Use the
640 B<-cipher> option to change the security level. See L<openssl-ciphers(1)> for
645 Disable RFC4507bis session ticket support. This option has no effect if TLSv1.3
646 is negotiated. See B<-num_tickets>.
648 =item B<-num_tickets>
650 Control the number of tickets that will be sent to the client after a full
651 handshake in TLSv1.3. The default number of tickets is 2. This option does not
652 affect the number of tickets sent after a resumption handshake.
656 Use the server's cipher preferences, rather than the client's preferences.
658 =item B<-prioritize_chacha>
660 Prioritize ChaCha ciphers when preferred by clients. Requires B<-serverpref>.
662 =item B<-no_resumption_on_reneg>
664 Set the B<SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION> option.
666 =item B<-client_sigalgs> I<val>
668 Signature algorithms to support for client certificate authentication
669 (colon-separated list).
671 =item B<-named_curve> I<val>
673 Specifies the elliptic curve to use. NOTE: this is single curve, not a list.
674 For a list of all possible curves, use:
676 $ openssl ecparam -list_curves
678 =item B<-cipher> I<val>
680 This allows the list of TLSv1.2 and below ciphersuites used by the server to be
681 modified. This list is combined with any TLSv1.3 ciphersuites that have been
682 configured. When the client sends a list of supported ciphers the first client
683 cipher also included in the server list is used. Because the client specifies
684 the preference order, the order of the server cipherlist is irrelevant. See
685 L<openssl-ciphers(1)> for more information.
687 =item B<-ciphersuites> I<val>
689 This allows the list of TLSv1.3 ciphersuites used by the server to be modified.
690 This list is combined with any TLSv1.2 and below ciphersuites that have been
691 configured. When the client sends a list of supported ciphers the first client
692 cipher also included in the server list is used. Because the client specifies
693 the preference order, the order of the server cipherlist is irrelevant. See
694 L<openssl-ciphers(1)> command for more information. The format for this list is
695 a simple colon (":") separated list of TLSv1.3 ciphersuite names.
697 =item B<-dhparam> I<infile>
699 The DH parameter file to use. The ephemeral DH cipher suites generate keys
700 using a set of DH parameters. If not specified then an attempt is made to
701 load the parameters from the server certificate file.
702 If this fails then a static set of parameters hard coded into this command
707 Turns on non blocking I/O.
717 =item B<-psk_identity> I<val>
719 Expect the client to send PSK identity I<val> when using a PSK
720 cipher suite, and warn if they do not. By default, the expected PSK
721 identity is the string "Client_identity".
723 =item B<-psk_hint> I<val>
725 Use the PSK identity hint I<val> when using a PSK cipher suite.
729 Use the PSK key I<val> when using a PSK cipher suite. The key is
730 given as a hexadecimal number without leading 0x, for example -psk
732 This option must be provided in order to use a PSK cipher.
734 =item B<-psk_session> I<file>
736 Use the pem encoded SSL_SESSION data stored in I<file> as the basis of a PSK.
737 Note that this will only work if TLSv1.3 is negotiated.
741 The verifier file for SRP.
742 This option is deprecated.
744 =item B<-srpuserseed>
746 A seed string for a default user salt.
747 This option is deprecated.
751 This option can only be used in conjunction with one of the DTLS options above.
752 With this option, this command will listen on a UDP port for incoming
754 Any ClientHellos that arrive will be checked to see if they have a cookie in
756 Any without a cookie will be responded to with a HelloVerifyRequest.
757 If a ClientHello with a cookie is received then this command will
758 connect to that peer and complete the handshake.
762 Use SCTP for the transport protocol instead of UDP in DTLS. Must be used in
763 conjunction with B<-dtls>, B<-dtls1> or B<-dtls1_2>. This option is only
764 available where OpenSSL has support for SCTP enabled.
766 =item B<-sctp_label_bug>
768 Use the incorrect behaviour of older OpenSSL implementations when computing
769 endpoint-pair shared secrets for DTLS/SCTP. This allows communication with
770 older broken implementations but breaks interoperability with correct
771 implementations. Must be used in conjunction with B<-sctp>. This option is only
772 available where OpenSSL has support for SCTP enabled.
776 Offer SRTP key management with a colon-separated profile list.
780 If this option is set then no DH parameters will be loaded effectively
781 disabling the ephemeral DH cipher suites.
783 =item B<-alpn> I<val>, B<-nextprotoneg> I<val>
785 These flags enable the Application-Layer Protocol Negotiation
786 or Next Protocol Negotiation (NPN) extension, respectively. ALPN is the
787 IETF standard and replaces NPN.
788 The I<val> list is a comma-separated list of supported protocol
789 names. The list should contain the most desirable protocols first.
790 Protocol names are printable ASCII strings, for example "http/1.1" or
792 The flag B<-nextprotoneg> cannot be specified if B<-tls1_3> is used.
796 Enable Kernel TLS for sending and receiving.
797 This option was introduced in OpenSSL 3.2.0.
798 Kernel TLS is off by default as of OpenSSL 3.2.0.
802 If this option is set and KTLS is enabled, SSL_sendfile() will be used
803 instead of BIO_write() to send the HTTP response requested by a client.
804 This option is only valid when B<-ktls> along with B<-WWW> or B<-HTTP>
807 =item B<-zerocopy_sendfile>
809 If this option is set, SSL_sendfile() will use the zerocopy TX mode, which gives
810 a performance boost when used with KTLS hardware offload. Note that invalid
811 TLS records might be transmitted if the file is changed while being sent.
812 This option depends on B<-sendfile>; when used alone, B<-sendfile> is implied,
813 and a warning is shown. Note that KTLS sendfile on FreeBSD always runs in the
816 =item B<-keylogfile> I<outfile>
818 Appends TLS secrets to the specified keylog file such that external programs
819 (like Wireshark) can decrypt TLS connections.
821 =item B<-max_early_data> I<int>
823 Change the default maximum early data bytes that are specified for new sessions
824 and any incoming early data (when used in conjunction with the B<-early_data>
825 flag). The default value is approximately 16k. The argument must be an integer
826 greater than or equal to 0.
828 =item B<-recv_max_early_data> I<int>
830 Specify the hard limit on the maximum number of early data bytes that will
835 Accept early data where possible. Cannot be used in conjunction with B<-www>,
836 B<-WWW>, B<-HTTP> or B<-rev>.
840 Require TLSv1.3 cookies.
842 =item B<-anti_replay>, B<-no_anti_replay>
844 Switches replay protection on or off, respectively. Replay protection is on by
845 default unless overridden by a configuration file. When it is on, OpenSSL will
846 automatically detect if a session ticket has been used more than once, TLSv1.3
847 has been negotiated, and early data is enabled on the server. A full handshake
848 is forced if a session ticket is used a second or subsequent time. Any early
849 data that was sent will be rejected.
853 Enable acceptance of TCP Fast Open (RFC7413) connections.
857 Pre-compresses certificates (RFC8879) that will be sent during the handshake.
859 {- $OpenSSL::safe::opt_name_item -}
861 {- $OpenSSL::safe::opt_version_item -}
863 {- $OpenSSL::safe::opt_s_item -}
865 {- $OpenSSL::safe::opt_x_item -}
867 {- $OpenSSL::safe::opt_trust_item -}
869 {- $OpenSSL::safe::opt_r_item -}
871 {- $OpenSSL::safe::opt_engine_item -}
873 {- $OpenSSL::safe::opt_provider_item -}
875 {- $OpenSSL::safe::opt_v_item -}
877 If the server requests a client certificate, then
878 verification errors are displayed, for debugging, but the command will
879 proceed unless the B<-verify_return_error> option is used.
881 =item B<-enable_server_rpk>
883 Enable support for sending raw public keys (RFC7250) to the client.
884 A raw public key will be sent by the server, if solicited by the client,
885 provided a suitable key and public certificate pair is configured.
886 Clients that don't support raw public keys or prefer to use X.509
887 certificates can still elect to receive X.509 certificates as usual.
889 Raw public keys are extracted from the configured certificate/private key.
891 =item B<-enable_client_rpk>
893 Enable support for receiving raw public keys (RFC7250) from the client.
894 Use of X.509 certificates by the client becomes optional, and clients that
895 support raw public keys may elect to use them.
896 Clients that don't support raw public keys or prefer to use X.509
897 certificates can still elect to send X.509 certificates as usual.
899 Raw public keys are extracted from the configured certificate/private key.
903 =head1 CONNECTED COMMANDS
905 If a connection request is established with an SSL client and neither the
906 B<-www> nor the B<-WWW> option has been used then normally any data received
907 from the client is displayed and any key presses will be sent to the client.
909 Certain commands are also recognized which perform special operations. These
910 commands are a letter which must appear at the start of a line. They are listed
917 End the current SSL connection but still accept new connections.
921 End the current SSL connection and exit.
925 Renegotiate the SSL session (TLSv1.2 and below only).
929 Renegotiate the SSL session and request a client certificate (TLSv1.2 and below
934 Send some plain text down the underlying TCP connection: this should
935 cause the client to disconnect due to a protocol violation.
939 Print out some session cache status information.
943 Send a key update message to the client (TLSv1.3 only)
947 Send a key update message to the client and request one back (TLSv1.3 only)
951 Send a certificate request to the client (TLSv1.3 only)
957 This command can be used to debug SSL clients. To accept connections
958 from a web browser the command:
960 openssl s_server -accept 443 -www
962 can be used for example.
964 Although specifying an empty list of CAs when requesting a client certificate
965 is strictly speaking a protocol violation, some SSL clients interpret this to
966 mean any CA is acceptable. This is useful for debugging purposes.
968 The session parameters can printed out using the L<openssl-sess_id(1)> command.
972 Because this program has a lot of options and also because some of the
973 techniques used are rather old, the C source for this command is rather
974 hard to read and not a model of how things should be done.
975 A typical SSL server program would be much simpler.
977 The output of common ciphers is wrong: it just gives the list of ciphers that
978 OpenSSL recognizes and the client supports.
980 There should be a way for this command to print out details
981 of any unknown cipher suites a client says it supports.
986 L<openssl-sess_id(1)>,
987 L<openssl-s_client(1)>,
988 L<openssl-ciphers(1)>,
990 L<SSL_CTX_set_max_send_fragment(3)>,
991 L<SSL_CTX_set_split_send_fragment(3)>,
992 L<SSL_CTX_set_max_pipelines(3)>,
993 L<ossl_store-file(7)>
997 The -no_alt_chains option was added in OpenSSL 1.1.0.
1000 -allow-no-dhe-kex and -prioritize_chacha options were added in OpenSSL 1.1.1.
1002 The B<-srpvfile>, B<-srpuserseed>, and B<-engine>
1003 option were deprecated in OpenSSL 3.0.
1006 B<-enable_client_rpk>,
1007 B<-enable_server_rpk>,
1008 B<-no_rx_cert_comp>,
1009 B<-no_tx_cert_comp>,
1011 options were added in OpenSSL 3.2.
1015 Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved.
1017 Licensed under the Apache License 2.0 (the "License"). You may not use
1018 this file except in compliance with the License. You can obtain a copy
1019 in the file LICENSE in the source distribution or at
1020 L<https://www.openssl.org/source/license.html>.