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133 .\" ========================================================================
135 .IX Title "S_CLIENT 1"
136 .TH S_CLIENT 1 "2020-03-31" "1.1.1f" "OpenSSL"
137 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
138 .\" way too many mistakes in technical documents.
142 openssl\-s_client, s_client \- SSL/TLS client program
144 .IX Header "SYNOPSIS"
145 \&\fBopenssl\fR \fBs_client\fR
147 [\fB\-connect host:port\fR]
148 [\fB\-bind host:port\fR]
149 [\fB\-proxy host:port\fR]
153 [\fB\-servername name\fR]
154 [\fB\-noservername\fR]
155 [\fB\-verify depth\fR]
156 [\fB\-verify_return_error\fR]
157 [\fB\-cert filename\fR]
158 [\fB\-certform DER|PEM\fR]
159 [\fB\-key filename\fR]
160 [\fB\-keyform DER|PEM\fR]
161 [\fB\-cert_chain filename\fR]
162 [\fB\-build_chain\fR]
166 [\fB\-xchain_build\fR]
167 [\fB\-xcertform PEM|DER\fR]
168 [\fB\-xkeyform PEM|DER\fR]
170 [\fB\-CApath directory\fR]
171 [\fB\-CAfile filename\fR]
172 [\fB\-chainCApath directory\fR]
173 [\fB\-chainCAfile filename\fR]
176 [\fB\-requestCAfile filename\fR]
177 [\fB\-dane_tlsa_domain domain\fR]
178 [\fB\-dane_tlsa_rrdata rrdata\fR]
179 [\fB\-dane_ee_no_namechecks\fR]
180 [\fB\-attime timestamp\fR]
181 [\fB\-check_ss_sig\fR]
183 [\fB\-crl_check_all\fR]
184 [\fB\-explicit_policy\fR]
185 [\fB\-extended_crl\fR]
186 [\fB\-ignore_critical\fR]
187 [\fB\-inhibit_any\fR]
188 [\fB\-inhibit_map\fR]
189 [\fB\-no_check_time\fR]
190 [\fB\-partial_chain\fR]
192 [\fB\-policy_check\fR]
193 [\fB\-policy_print\fR]
194 [\fB\-purpose purpose\fR]
196 [\fB\-suiteB_128_only\fR]
198 [\fB\-trusted_first\fR]
199 [\fB\-no_alt_chains\fR]
201 [\fB\-auth_level num\fR]
202 [\fB\-nameopt option\fR]
203 [\fB\-verify_depth num\fR]
204 [\fB\-verify_email email\fR]
205 [\fB\-verify_hostname hostname\fR]
206 [\fB\-verify_ip ip\fR]
207 [\fB\-verify_name name\fR]
208 [\fB\-build_chain\fR]
209 [\fB\-x509_strict\fR]
220 [\fB\-psk_identity identity\fR]
222 [\fB\-psk_session file\fR]
238 [\fB\-sctp_label_bug\fR]
239 [\fB\-fallback_scsv\fR]
241 [\fB\-max_send_frag\fR]
242 [\fB\-split_send_frag\fR]
243 [\fB\-max_pipelines\fR]
248 [\fB\-allow_no_dhe_kex\fR]
249 [\fB\-sigalgs sigalglist\fR]
250 [\fB\-curves curvelist\fR]
251 [\fB\-cipher cipherlist\fR]
252 [\fB\-ciphersuites val\fR]
254 [\fB\-starttls protocol\fR]
255 [\fB\-xmpphost hostname\fR]
256 [\fB\-name hostname\fR]
258 [\fB\-tlsextdebug\fR]
260 [\fB\-sess_out filename\fR]
261 [\fB\-sess_in filename\fR]
262 [\fB\-rand file...\fR]
263 [\fB\-writerand file\fR]
264 [\fB\-serverinfo types\fR]
266 [\fB\-alpn protocols\fR]
267 [\fB\-nextprotoneg protocols\fR]
271 [\fB\-keylogfile file\fR]
272 [\fB\-early_data file\fR]
276 .IX Header "DESCRIPTION"
277 The \fBs_client\fR command implements a generic \s-1SSL/TLS\s0 client which connects
278 to a remote host using \s-1SSL/TLS.\s0 It is a \fIvery\fR useful diagnostic tool for
279 \&\s-1SSL\s0 servers.
282 In addition to the options below the \fBs_client\fR utility also supports the
283 common and client only options documented
284 in the \*(L"Supported Command Line Commands\*(R" section of the \fBSSL_CONF_cmd\fR\|(3)
288 Print out a usage message.
289 .IP "\fB\-connect host:port\fR" 4
290 .IX Item "-connect host:port"
291 This specifies the host and optional port to connect to. It is possible to
292 select the host and port using the optional target positional argument instead.
293 If neither this nor the target positional argument are specified then an attempt
294 is made to connect to the local host on port 4433.
295 .IP "\fB\-bind host:port\fR]" 4
296 .IX Item "-bind host:port]"
297 This specifies the host address and or port to bind as the source for the
298 connection. For Unix-domain sockets the port is ignored and the host is
299 used as the source socket address.
300 .IP "\fB\-proxy host:port\fR" 4
301 .IX Item "-proxy host:port"
302 When used with the \fB\-connect\fR flag, the program uses the host and port
303 specified with this flag and issues an \s-1HTTP CONNECT\s0 command to connect
304 to the desired server.
305 .IP "\fB\-unix path\fR" 4
306 .IX Item "-unix path"
307 Connect over the specified Unix-domain socket.
314 .IP "\fB\-servername name\fR" 4
315 .IX Item "-servername name"
316 Set the \s-1TLS SNI\s0 (Server Name Indication) extension in the ClientHello message to
318 If \fB\-servername\fR is not provided, the \s-1TLS SNI\s0 extension will be populated with
319 the name given to \fB\-connect\fR if it follows a \s-1DNS\s0 name format. If \fB\-connect\fR is
320 not provided either, the \s-1SNI\s0 is set to \*(L"localhost\*(R".
321 This is the default since OpenSSL 1.1.1.
323 Even though \s-1SNI\s0 should normally be a \s-1DNS\s0 name and not an \s-1IP\s0 address, if
324 \&\fB\-servername\fR is provided then that name will be sent, regardless of whether
325 it is a \s-1DNS\s0 name or not.
327 This option cannot be used in conjunction with \fB\-noservername\fR.
328 .IP "\fB\-noservername\fR" 4
329 .IX Item "-noservername"
330 Suppresses sending of the \s-1SNI\s0 (Server Name Indication) extension in the
331 ClientHello message. Cannot be used in conjunction with the \fB\-servername\fR or
332 <\-dane_tlsa_domain> options.
333 .IP "\fB\-cert certname\fR" 4
334 .IX Item "-cert certname"
335 The certificate to use, if one is requested by the server. The default is
336 not to use a certificate.
337 .IP "\fB\-certform format\fR" 4
338 .IX Item "-certform format"
339 The certificate format to use: \s-1DER\s0 or \s-1PEM. PEM\s0 is the default.
340 .IP "\fB\-key keyfile\fR" 4
341 .IX Item "-key keyfile"
342 The private key to use. If not specified then the certificate file will
344 .IP "\fB\-keyform format\fR" 4
345 .IX Item "-keyform format"
346 The private format to use: \s-1DER\s0 or \s-1PEM. PEM\s0 is the default.
347 .IP "\fB\-cert_chain\fR" 4
348 .IX Item "-cert_chain"
349 A file containing trusted certificates to use when attempting to build the
350 client/server certificate chain related to the certificate specified via the
351 \&\fB\-cert\fR option.
352 .IP "\fB\-build_chain\fR" 4
353 .IX Item "-build_chain"
354 Specify whether the application should build the certificate chain to be
355 provided to the server.
356 .IP "\fB\-xkey infile\fR, \fB\-xcert infile\fR, \fB\-xchain\fR" 4
357 .IX Item "-xkey infile, -xcert infile, -xchain"
358 Specify an extra certificate, private key and certificate chain. These behave
359 in the same manner as the \fB\-cert\fR, \fB\-key\fR and \fB\-cert_chain\fR options. When
360 specified, the callback returning the first valid chain will be in use by the
362 .IP "\fB\-xchain_build\fR" 4
363 .IX Item "-xchain_build"
364 Specify whether the application should build the certificate chain to be
365 provided to the server for the extra certificates provided via \fB\-xkey infile\fR,
366 \&\fB\-xcert infile\fR, \fB\-xchain\fR options.
367 .IP "\fB\-xcertform PEM|DER\fR, \fB\-xkeyform PEM|DER\fR" 4
368 .IX Item "-xcertform PEM|DER, -xkeyform PEM|DER"
369 Extra certificate and private key format respectively.
370 .IP "\fB\-pass arg\fR" 4
372 the private key password source. For more information about the format of \fBarg\fR
373 see the \fB\s-1PASS PHRASE ARGUMENTS\s0\fR section in \fBopenssl\fR\|(1).
374 .IP "\fB\-verify depth\fR" 4
375 .IX Item "-verify depth"
376 The verify depth to use. This specifies the maximum length of the
377 server certificate chain and turns on server certificate verification.
378 Currently the verify operation continues after errors so all the problems
379 with a certificate chain can be seen. As a side effect the connection
380 will never fail due to a server certificate verify failure.
381 .IP "\fB\-verify_return_error\fR" 4
382 .IX Item "-verify_return_error"
383 Return verification errors instead of continuing. This will typically
384 abort the handshake with a fatal error.
385 .IP "\fB\-nameopt option\fR" 4
386 .IX Item "-nameopt option"
387 Option which determines how the subject or issuer names are displayed. The
388 \&\fBoption\fR argument can be a single option or multiple options separated by
389 commas. Alternatively the \fB\-nameopt\fR switch may be used more than once to
390 set multiple options. See the \fBx509\fR\|(1) manual page for details.
391 .IP "\fB\-CApath directory\fR" 4
392 .IX Item "-CApath directory"
393 The directory to use for server certificate verification. This directory
394 must be in \*(L"hash format\*(R", see \fBverify\fR\|(1) for more information. These are
395 also used when building the client certificate chain.
396 .IP "\fB\-CAfile file\fR" 4
397 .IX Item "-CAfile file"
398 A file containing trusted certificates to use during server authentication
399 and to use when attempting to build the client certificate chain.
400 .IP "\fB\-chainCApath directory\fR" 4
401 .IX Item "-chainCApath directory"
402 The directory to use for building the chain provided to the server. This
403 directory must be in \*(L"hash format\*(R", see \fBverify\fR\|(1) for more information.
404 .IP "\fB\-chainCAfile file\fR" 4
405 .IX Item "-chainCAfile file"
406 A file containing trusted certificates to use when attempting to build the
407 client certificate chain.
408 .IP "\fB\-no\-CAfile\fR" 4
409 .IX Item "-no-CAfile"
410 Do not load the trusted \s-1CA\s0 certificates from the default file location
411 .IP "\fB\-no\-CApath\fR" 4
412 .IX Item "-no-CApath"
413 Do not load the trusted \s-1CA\s0 certificates from the default directory location
414 .IP "\fB\-requestCAfile file\fR" 4
415 .IX Item "-requestCAfile file"
416 A file containing a list of certificates whose subject names will be sent
417 to the server in the \fBcertificate_authorities\fR extension. Only supported
419 .IP "\fB\-dane_tlsa_domain domain\fR" 4
420 .IX Item "-dane_tlsa_domain domain"
421 Enable \s-1RFC6698/RFC7671 DANE TLSA\s0 authentication and specify the
422 \&\s-1TLSA\s0 base domain which becomes the default \s-1SNI\s0 hint and the primary
423 reference identifier for hostname checks. This must be used in
424 combination with at least one instance of the \fB\-dane_tlsa_rrdata\fR
427 When \s-1DANE\s0 authentication succeeds, the diagnostic output will include
428 the lowest (closest to 0) depth at which a \s-1TLSA\s0 record authenticated
429 a chain certificate. When that \s-1TLSA\s0 record is a \*(L"2 1 0\*(R" trust
430 anchor public key that signed (rather than matched) the top-most
431 certificate of the chain, the result is reported as \*(L"\s-1TA\s0 public key
432 verified\*(R". Otherwise, either the \s-1TLSA\s0 record \*(L"matched \s-1TA\s0 certificate\*(R"
433 at a positive depth or else \*(L"matched \s-1EE\s0 certificate\*(R" at depth 0.
434 .IP "\fB\-dane_tlsa_rrdata rrdata\fR" 4
435 .IX Item "-dane_tlsa_rrdata rrdata"
436 Use one or more times to specify the \s-1RRDATA\s0 fields of the \s-1DANE TLSA\s0
437 RRset associated with the target service. The \fBrrdata\fR value is
438 specified in \*(L"presentation form\*(R", that is four whitespace separated
439 fields that specify the usage, selector, matching type and associated
440 data, with the last of these encoded in hexadecimal. Optional
441 whitespace is ignored in the associated data field. For example:
444 \& $ openssl s_client \-brief \-starttls smtp \e
445 \& \-connect smtp.example.com:25 \e
446 \& \-dane_tlsa_domain smtp.example.com \e
447 \& \-dane_tlsa_rrdata "2 1 1
448 \& B111DD8A1C2091A89BD4FD60C57F0716CCE50FEEFF8137CDBEE0326E 02CF362B" \e
449 \& \-dane_tlsa_rrdata "2 1 1
450 \& 60B87575447DCBA2A36B7D11AC09FB24A9DB406FEE12D2CC90180517 616E8A18"
453 \& Verified peername: smtp.example.com
454 \& DANE TLSA 2 1 1 ...ee12d2cc90180517616e8a18 matched TA certificate at depth 1
457 .IP "\fB\-dane_ee_no_namechecks\fR" 4
458 .IX Item "-dane_ee_no_namechecks"
459 This disables server name checks when authenticating via \s-1\fBDANE\-EE\s0\fR\|(3) \s-1TLSA\s0
461 For some applications, primarily web browsers, it is not safe to disable name
462 checks due to \*(L"unknown key share\*(R" attacks, in which a malicious server can
463 convince a client that a connection to a victim server is instead a secure
464 connection to the malicious server.
465 The malicious server may then be able to violate cross-origin scripting
467 Thus, despite the text of \s-1RFC7671,\s0 name checks are by default enabled for
468 \&\s-1\fBDANE\-EE\s0\fR\|(3) \s-1TLSA\s0 records, and can be disabled in applications where it is safe
470 In particular, \s-1SMTP\s0 and \s-1XMPP\s0 clients should set this option as \s-1SRV\s0 and \s-1MX\s0
471 records already make it possible for a remote domain to redirect client
472 connections to any server of its choice, and in any case \s-1SMTP\s0 and \s-1XMPP\s0 clients
473 do not execute scripts downloaded from remote servers.
474 .IP "\fB\-attime\fR, \fB\-check_ss_sig\fR, \fB\-crl_check\fR, \fB\-crl_check_all\fR, \fB\-explicit_policy\fR, \fB\-extended_crl\fR, \fB\-ignore_critical\fR, \fB\-inhibit_any\fR, \fB\-inhibit_map\fR, \fB\-no_alt_chains\fR, \fB\-no_check_time\fR, \fB\-partial_chain\fR, \fB\-policy\fR, \fB\-policy_check\fR, \fB\-policy_print\fR, \fB\-purpose\fR, \fB\-suiteB_128\fR, \fB\-suiteB_128_only\fR, \fB\-suiteB_192\fR, \fB\-trusted_first\fR, \fB\-use_deltas\fR, \fB\-auth_level\fR, \fB\-verify_depth\fR, \fB\-verify_email\fR, \fB\-verify_hostname\fR, \fB\-verify_ip\fR, \fB\-verify_name\fR, \fB\-x509_strict\fR" 4
475 .IX Item "-attime, -check_ss_sig, -crl_check, -crl_check_all, -explicit_policy, -extended_crl, -ignore_critical, -inhibit_any, -inhibit_map, -no_alt_chains, -no_check_time, -partial_chain, -policy, -policy_check, -policy_print, -purpose, -suiteB_128, -suiteB_128_only, -suiteB_192, -trusted_first, -use_deltas, -auth_level, -verify_depth, -verify_email, -verify_hostname, -verify_ip, -verify_name, -x509_strict"
476 Set various certificate chain validation options. See the
477 \&\fBverify\fR\|(1) manual page for details.
478 .IP "\fB\-reconnect\fR" 4
479 .IX Item "-reconnect"
480 Reconnects to the same server 5 times using the same session \s-1ID,\s0 this can
481 be used as a test that session caching is working.
482 .IP "\fB\-showcerts\fR" 4
483 .IX Item "-showcerts"
484 Displays the server certificate list as sent by the server: it only consists of
485 certificates the server has sent (in the order the server has sent them). It is
486 \&\fBnot\fR a verified chain.
487 .IP "\fB\-prexit\fR" 4
489 Print session information when the program exits. This will always attempt
490 to print out information even if the connection fails. Normally information
491 will only be printed out once if the connection succeeds. This option is useful
492 because the cipher in use may be renegotiated or the connection may fail
493 because a client certificate is required or is requested only after an
494 attempt is made to access a certain \s-1URL.\s0 Note: the output produced by this
495 option is not always accurate because a connection might never have been
497 .IP "\fB\-state\fR" 4
499 Prints out the \s-1SSL\s0 session states.
500 .IP "\fB\-debug\fR" 4
502 Print extensive debugging information including a hex dump of all traffic.
505 Show all protocol messages with hex dump.
506 .IP "\fB\-trace\fR" 4
508 Show verbose trace output of protocol messages. OpenSSL needs to be compiled
509 with \fBenable-ssl-trace\fR for this option to work.
510 .IP "\fB\-msgfile\fR" 4
512 File to send output of \fB\-msg\fR or \fB\-trace\fR to, default standard output.
513 .IP "\fB\-nbio_test\fR" 4
514 .IX Item "-nbio_test"
515 Tests non-blocking I/O
518 Turns on non-blocking I/O
521 This option translated a line feed from the terminal into \s-1CR+LF\s0 as required
523 .IP "\fB\-ign_eof\fR" 4
525 Inhibit shutting down the connection when end of file is reached in the
527 .IP "\fB\-quiet\fR" 4
529 Inhibit printing of session and certificate information. This implicitly
530 turns on \fB\-ign_eof\fR as well.
531 .IP "\fB\-no_ign_eof\fR" 4
532 .IX Item "-no_ign_eof"
533 Shut down the connection when end of file is reached in the input.
534 Can be used to override the implicit \fB\-ign_eof\fR after \fB\-quiet\fR.
535 .IP "\fB\-psk_identity identity\fR" 4
536 .IX Item "-psk_identity identity"
537 Use the \s-1PSK\s0 identity \fBidentity\fR when using a \s-1PSK\s0 cipher suite.
538 The default value is \*(L"Client_identity\*(R" (without the quotes).
539 .IP "\fB\-psk key\fR" 4
541 Use the \s-1PSK\s0 key \fBkey\fR when using a \s-1PSK\s0 cipher suite. The key is
542 given as a hexadecimal number without leading 0x, for example \-psk
544 This option must be provided in order to use a \s-1PSK\s0 cipher.
545 .IP "\fB\-psk_session file\fR" 4
546 .IX Item "-psk_session file"
547 Use the pem encoded \s-1SSL_SESSION\s0 data stored in \fBfile\fR as the basis of a \s-1PSK.\s0
548 Note that this will only work if TLSv1.3 is negotiated.
549 .IP "\fB\-ssl3\fR, \fB\-tls1\fR, \fB\-tls1_1\fR, \fB\-tls1_2\fR, \fB\-tls1_3\fR, \fB\-no_ssl3\fR, \fB\-no_tls1\fR, \fB\-no_tls1_1\fR, \fB\-no_tls1_2\fR, \fB\-no_tls1_3\fR" 4
550 .IX Item "-ssl3, -tls1, -tls1_1, -tls1_2, -tls1_3, -no_ssl3, -no_tls1, -no_tls1_1, -no_tls1_2, -no_tls1_3"
551 These options require or disable the use of the specified \s-1SSL\s0 or \s-1TLS\s0 protocols.
552 By default \fBs_client\fR will negotiate the highest mutually supported protocol
554 When a specific \s-1TLS\s0 version is required, only that version will be offered to
555 and accepted from the server.
556 Note that not all protocols and flags may be available, depending on how
558 .IP "\fB\-dtls\fR, \fB\-dtls1\fR, \fB\-dtls1_2\fR" 4
559 .IX Item "-dtls, -dtls1, -dtls1_2"
560 These options make \fBs_client\fR use \s-1DTLS\s0 protocols instead of \s-1TLS.\s0
561 With \fB\-dtls\fR, \fBs_client\fR will negotiate any supported \s-1DTLS\s0 protocol version,
562 whilst \fB\-dtls1\fR and \fB\-dtls1_2\fR will only support \s-1DTLS1.0\s0 and \s-1DTLS1.2\s0
566 Use \s-1SCTP\s0 for the transport protocol instead of \s-1UDP\s0 in \s-1DTLS.\s0 Must be used in
567 conjunction with \fB\-dtls\fR, \fB\-dtls1\fR or \fB\-dtls1_2\fR. This option is only
568 available where OpenSSL has support for \s-1SCTP\s0 enabled.
569 .IP "\fB\-sctp_label_bug\fR" 4
570 .IX Item "-sctp_label_bug"
571 Use the incorrect behaviour of older OpenSSL implementations when computing
572 endpoint-pair shared secrets for \s-1DTLS/SCTP.\s0 This allows communication with
573 older broken implementations but breaks interoperability with correct
574 implementations. Must be used in conjunction with \fB\-sctp\fR. This option is only
575 available where OpenSSL has support for \s-1SCTP\s0 enabled.
576 .IP "\fB\-fallback_scsv\fR" 4
577 .IX Item "-fallback_scsv"
578 Send \s-1TLS_FALLBACK_SCSV\s0 in the ClientHello.
579 .IP "\fB\-async\fR" 4
581 Switch on asynchronous mode. Cryptographic operations will be performed
582 asynchronously. This will only have an effect if an asynchronous capable engine
583 is also used via the \fB\-engine\fR option. For test purposes the dummy async engine
584 (dasync) can be used (if available).
585 .IP "\fB\-max_send_frag int\fR" 4
586 .IX Item "-max_send_frag int"
587 The maximum size of data fragment to send.
588 See \fBSSL_CTX_set_max_send_fragment\fR\|(3) for further information.
589 .IP "\fB\-split_send_frag int\fR" 4
590 .IX Item "-split_send_frag int"
591 The size used to split data for encrypt pipelines. If more data is written in
592 one go than this value then it will be split into multiple pipelines, up to the
593 maximum number of pipelines defined by max_pipelines. This only has an effect if
594 a suitable cipher suite has been negotiated, an engine that supports pipelining
595 has been loaded, and max_pipelines is greater than 1. See
596 \&\fBSSL_CTX_set_split_send_fragment\fR\|(3) for further information.
597 .IP "\fB\-max_pipelines int\fR" 4
598 .IX Item "-max_pipelines int"
599 The maximum number of encrypt/decrypt pipelines to be used. This will only have
600 an effect if an engine has been loaded that supports pipelining (e.g. the dasync
601 engine) and a suitable cipher suite has been negotiated. The default value is 1.
602 See \fBSSL_CTX_set_max_pipelines\fR\|(3) for further information.
603 .IP "\fB\-read_buf int\fR" 4
604 .IX Item "-read_buf int"
605 The default read buffer size to be used for connections. This will only have an
606 effect if the buffer size is larger than the size that would otherwise be used
607 and pipelining is in use (see \fBSSL_CTX_set_default_read_buffer_len\fR\|(3) for
608 further information).
611 There are several known bugs in \s-1SSL\s0 and \s-1TLS\s0 implementations. Adding this
612 option enables various workarounds.
615 Enables support for \s-1SSL/TLS\s0 compression.
616 This option was introduced in OpenSSL 1.1.0.
617 \&\s-1TLS\s0 compression is not recommended and is off by default as of
619 .IP "\fB\-no_comp\fR" 4
621 Disables support for \s-1SSL/TLS\s0 compression.
622 \&\s-1TLS\s0 compression is not recommended and is off by default as of
624 .IP "\fB\-brief\fR" 4
626 Only provide a brief summary of connection parameters instead of the
627 normal verbose output.
628 .IP "\fB\-sigalgs sigalglist\fR" 4
629 .IX Item "-sigalgs sigalglist"
630 Specifies the list of signature algorithms that are sent by the client.
631 The server selects one entry in the list based on its preferences.
632 For example strings, see \fBSSL_CTX_set1_sigalgs\fR\|(3)
633 .IP "\fB\-curves curvelist\fR" 4
634 .IX Item "-curves curvelist"
635 Specifies the list of supported curves to be sent by the client. The curve is
636 ultimately selected by the server. For a list of all curves, use:
639 \& $ openssl ecparam \-list_curves
641 .IP "\fB\-cipher cipherlist\fR" 4
642 .IX Item "-cipher cipherlist"
643 This allows the TLSv1.2 and below cipher list sent by the client to be modified.
644 This list will be combined with any TLSv1.3 ciphersuites that have been
645 configured. Although the server determines which ciphersuite is used it should
646 take the first supported cipher in the list sent by the client. See the
647 \&\fBciphers\fR command for more information.
648 .IP "\fB\-ciphersuites val\fR" 4
649 .IX Item "-ciphersuites val"
650 This allows the TLSv1.3 ciphersuites sent by the client to be modified. This
651 list will be combined with any TLSv1.2 and below ciphersuites that have been
652 configured. Although the server determines which cipher suite is used it should
653 take the first supported cipher in the list sent by the client. See the
654 \&\fBciphers\fR command for more information. The format for this list is a simple
655 colon (\*(L":\*(R") separated list of TLSv1.3 ciphersuite names.
656 .IP "\fB\-starttls protocol\fR" 4
657 .IX Item "-starttls protocol"
658 Send the protocol-specific message(s) to switch to \s-1TLS\s0 for communication.
659 \&\fBprotocol\fR is a keyword for the intended protocol. Currently, the only
660 supported keywords are \*(L"smtp\*(R", \*(L"pop3\*(R", \*(L"imap\*(R", \*(L"ftp\*(R", \*(L"xmpp\*(R", \*(L"xmpp-server\*(R",
661 \&\*(L"irc\*(R", \*(L"postgres\*(R", \*(L"mysql\*(R", \*(L"lmtp\*(R", \*(L"nntp\*(R", \*(L"sieve\*(R" and \*(L"ldap\*(R".
662 .IP "\fB\-xmpphost hostname\fR" 4
663 .IX Item "-xmpphost hostname"
664 This option, when used with \*(L"\-starttls xmpp\*(R" or \*(L"\-starttls xmpp-server\*(R",
665 specifies the host for the \*(L"to\*(R" attribute of the stream element.
666 If this option is not specified, then the host specified with \*(L"\-connect\*(R"
669 This option is an alias of the \fB\-name\fR option for \*(L"xmpp\*(R" and \*(L"xmpp-server\*(R".
670 .IP "\fB\-name hostname\fR" 4
671 .IX Item "-name hostname"
672 This option is used to specify hostname information for various protocols
673 used with \fB\-starttls\fR option. Currently only \*(L"xmpp\*(R", \*(L"xmpp-server\*(R",
674 \&\*(L"smtp\*(R" and \*(L"lmtp\*(R" can utilize this \fB\-name\fR option.
676 If this option is used with \*(L"\-starttls xmpp\*(R" or \*(L"\-starttls xmpp-server\*(R",
677 if specifies the host for the \*(L"to\*(R" attribute of the stream element. If this
678 option is not specified, then the host specified with \*(L"\-connect\*(R" will be used.
680 If this option is used with \*(L"\-starttls lmtp\*(R" or \*(L"\-starttls smtp\*(R", it specifies
681 the name to use in the \*(L"\s-1LMTP LHLO\*(R"\s0 or \*(L"\s-1SMTP EHLO\*(R"\s0 message, respectively. If
682 this option is not specified, then \*(L"mail.example.com\*(R" will be used.
683 .IP "\fB\-tlsextdebug\fR" 4
684 .IX Item "-tlsextdebug"
685 Print out a hex dump of any \s-1TLS\s0 extensions received from the server.
686 .IP "\fB\-no_ticket\fR" 4
687 .IX Item "-no_ticket"
688 Disable RFC4507bis session ticket support.
689 .IP "\fB\-sess_out filename\fR" 4
690 .IX Item "-sess_out filename"
691 Output \s-1SSL\s0 session to \fBfilename\fR.
692 .IP "\fB\-sess_in sess.pem\fR" 4
693 .IX Item "-sess_in sess.pem"
694 Load \s-1SSL\s0 session from \fBfilename\fR. The client will attempt to resume a
695 connection from this session.
696 .IP "\fB\-engine id\fR" 4
697 .IX Item "-engine id"
698 Specifying an engine (by its unique \fBid\fR string) will cause \fBs_client\fR
699 to attempt to obtain a functional reference to the specified engine,
700 thus initialising it if needed. The engine will then be set as the default
701 for all available algorithms.
702 .IP "\fB\-rand file...\fR" 4
703 .IX Item "-rand file..."
704 A file or files containing random data used to seed the random number
706 Multiple files can be specified separated by an OS-dependent character.
707 The separator is \fB;\fR for MS-Windows, \fB,\fR for OpenVMS, and \fB:\fR for
709 .IP "[\fB\-writerand file\fR]" 4
710 .IX Item "[-writerand file]"
711 Writes random data to the specified \fIfile\fR upon exit.
712 This can be used with a subsequent \fB\-rand\fR flag.
713 .IP "\fB\-serverinfo types\fR" 4
714 .IX Item "-serverinfo types"
715 A list of comma-separated \s-1TLS\s0 Extension Types (numbers between 0 and
716 65535). Each type will be sent as an empty ClientHello \s-1TLS\s0 Extension.
717 The server's response (if any) will be encoded and displayed as a \s-1PEM\s0
719 .IP "\fB\-status\fR" 4
721 Sends a certificate status request to the server (\s-1OCSP\s0 stapling). The server
722 response (if any) is printed out.
723 .IP "\fB\-alpn protocols\fR, \fB\-nextprotoneg protocols\fR" 4
724 .IX Item "-alpn protocols, -nextprotoneg protocols"
725 These flags enable the Enable the Application-Layer Protocol Negotiation
726 or Next Protocol Negotiation (\s-1NPN\s0) extension, respectively. \s-1ALPN\s0 is the
727 \&\s-1IETF\s0 standard and replaces \s-1NPN.\s0
728 The \fBprotocols\fR list is a comma-separated list of protocol names that
729 the client should advertise support for. The list should contain the most
730 desirable protocols first. Protocol names are printable \s-1ASCII\s0 strings,
731 for example \*(L"http/1.1\*(R" or \*(L"spdy/3\*(R".
732 An empty list of protocols is treated specially and will cause the
733 client to advertise support for the \s-1TLS\s0 extension but disconnect just
734 after receiving ServerHello with a list of server supported protocols.
735 The flag \fB\-nextprotoneg\fR cannot be specified if \fB\-tls1_3\fR is used.
736 .IP "\fB\-ct\fR, \fB\-noct\fR" 4
737 .IX Item "-ct, -noct"
738 Use one of these two options to control whether Certificate Transparency (\s-1CT\s0)
739 is enabled (\fB\-ct\fR) or disabled (\fB\-noct\fR).
740 If \s-1CT\s0 is enabled, signed certificate timestamps (SCTs) will be requested from
741 the server and reported at handshake completion.
743 Enabling \s-1CT\s0 also enables \s-1OCSP\s0 stapling, as this is one possible delivery method
745 .IP "\fB\-ctlogfile\fR" 4
746 .IX Item "-ctlogfile"
747 A file containing a list of known Certificate Transparency logs. See
748 \&\fBSSL_CTX_set_ctlog_list_file\fR\|(3) for the expected file format.
749 .IP "\fB\-keylogfile file\fR" 4
750 .IX Item "-keylogfile file"
751 Appends \s-1TLS\s0 secrets to the specified keylog file such that external programs
752 (like Wireshark) can decrypt \s-1TLS\s0 connections.
753 .IP "\fB\-early_data file\fR" 4
754 .IX Item "-early_data file"
755 Reads the contents of the specified file and attempts to send it as early data
756 to the server. This will only work with resumed sessions that support early
757 data and when the server accepts the early data.
758 .IP "\fB\-enable_pha\fR" 4
759 .IX Item "-enable_pha"
760 For TLSv1.3 only, send the Post-Handshake Authentication extension. This will
761 happen whether or not a certificate has been provided via \fB\-cert\fR.
762 .IP "\fB[target]\fR" 4
764 Rather than providing \fB\-connect\fR, the target hostname and optional port may
765 be provided as a single positional argument after all options. If neither this
766 nor \fB\-connect\fR are provided, falls back to attempting to connect to localhost
768 .SH "CONNECTED COMMANDS"
769 .IX Header "CONNECTED COMMANDS"
770 If a connection is established with an \s-1SSL\s0 server then any data received
771 from the server is displayed and any key presses will be sent to the
772 server. If end of file is reached then the connection will be closed down. When
773 used interactively (which means neither \fB\-quiet\fR nor \fB\-ign_eof\fR have been
774 given), then certain commands are also recognized which perform special
775 operations. These commands are a letter which must appear at the start of a
776 line. They are listed below.
779 End the current \s-1SSL\s0 connection and exit.
782 Renegotiate the \s-1SSL\s0 session (TLSv1.2 and below only).
785 Send a heartbeat message to the server (\s-1DTLS\s0 only)
788 Send a key update message to the server (TLSv1.3 only)
791 Send a key update message to the server and request one back (TLSv1.3 only)
794 \&\fBs_client\fR can be used to debug \s-1SSL\s0 servers. To connect to an \s-1SSL HTTP\s0
798 \& openssl s_client \-connect servername:443
801 would typically be used (https uses port 443). If the connection succeeds
802 then an \s-1HTTP\s0 command can be given such as \*(L"\s-1GET /\*(R"\s0 to retrieve a web page.
804 If the handshake fails then there are several possible causes, if it is
805 nothing obvious like no client certificate then the \fB\-bugs\fR,
806 \&\fB\-ssl3\fR, \fB\-tls1\fR, \fB\-no_ssl3\fR, \fB\-no_tls1\fR options can be tried
807 in case it is a buggy server. In particular you should play with these
808 options \fBbefore\fR submitting a bug report to an OpenSSL mailing list.
810 A frequent problem when attempting to get client certificates working
811 is that a web client complains it has no certificates or gives an empty
812 list to choose from. This is normally because the server is not sending
813 the clients certificate authority in its \*(L"acceptable \s-1CA\s0 list\*(R" when it
814 requests a certificate. By using \fBs_client\fR the \s-1CA\s0 list can be viewed
815 and checked. However some servers only request client authentication
816 after a specific \s-1URL\s0 is requested. To obtain the list in this case it
817 is necessary to use the \fB\-prexit\fR option and send an \s-1HTTP\s0 request
818 for an appropriate page.
820 If a certificate is specified on the command line using the \fB\-cert\fR
821 option it will not be used unless the server specifically requests
822 a client certificate. Therefor merely including a client certificate
823 on the command line is no guarantee that the certificate works.
825 If there are problems verifying a server certificate then the
826 \&\fB\-showcerts\fR option can be used to show all the certificates sent by the
829 The \fBs_client\fR utility is a test tool and is designed to continue the
830 handshake after any certificate verification errors. As a result it will
831 accept any certificate chain (trusted or not) sent by the peer. None test
832 applications should \fBnot\fR do this as it makes them vulnerable to a \s-1MITM\s0
833 attack. This behaviour can be changed by with the \fB\-verify_return_error\fR
834 option: any verify errors are then returned aborting the handshake.
836 The \fB\-bind\fR option may be useful if the server or a firewall requires
837 connections to come from some particular address and or port.
840 Because this program has a lot of options and also because some of the
841 techniques used are rather old, the C source of \fBs_client\fR is rather hard to
842 read and not a model of how things should be done.
843 A typical \s-1SSL\s0 client program would be much simpler.
845 The \fB\-prexit\fR option is a bit of a hack. We should really report
846 information whenever a session is renegotiated.
848 .IX Header "SEE ALSO"
849 \&\fBSSL_CONF_cmd\fR\|(3), \fBsess_id\fR\|(1), \fBs_server\fR\|(1), \fBciphers\fR\|(1),
850 \&\fBSSL_CTX_set_max_send_fragment\fR\|(3), \fBSSL_CTX_set_split_send_fragment\fR\|(3),
851 \&\fBSSL_CTX_set_max_pipelines\fR\|(3)
854 The \fB\-no_alt_chains\fR option was added in OpenSSL 1.1.0.
855 The \fB\-name\fR option was added in OpenSSL 1.1.1.
857 .IX Header "COPYRIGHT"
858 Copyright 2000\-2020 The OpenSSL Project Authors. All Rights Reserved.
860 Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use
861 this file except in compliance with the License. You can obtain a copy
862 in the file \s-1LICENSE\s0 in the source distribution or at
863 <https://www.openssl.org/source/license.html>.
projects / FreeBSD / FreeBSD.git / blob