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Commit | Line | Data |
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c3ed3b6e DSH |
1 | =pod |
2 | ||
3 | =head1 NAME | |
4 | ||
5 | s_client - SSL/TLS client program | |
6 | ||
7 | =head1 SYNOPSIS | |
8 | ||
9 | B<openssl> B<s_client> | |
169394d4 | 10 | [B<-help>] |
a32fc687 | 11 | [B<-connect host:port>] |
552bf8ec | 12 | [B<-proxy host:port>] |
a22f9c84 E |
13 | [B<-unix path>] |
14 | [B<-4>] | |
15 | [B<-6>] | |
fc1d88f0 | 16 | [B<-servername name>] |
11ba87f2 | 17 | [B<-noservername>] |
b46c3e9b | 18 | [B<-verify depth>] |
4e6c12f3 | 19 | [B<-verify_return_error>] |
c3ed3b6e | 20 | [B<-cert filename>] |
826a42a0 | 21 | [B<-certform DER|PEM>] |
c3ed3b6e | 22 | [B<-key filename>] |
826a42a0 DSH |
23 | [B<-keyform DER|PEM>] |
24 | [B<-pass arg>] | |
c3ed3b6e DSH |
25 | [B<-CApath directory>] |
26 | [B<-CAfile filename>] | |
40e2d76b MC |
27 | [B<-no-CAfile>] |
28 | [B<-no-CApath>] | |
5a185729 | 29 | [B<-requestCAfile filename>] |
cddd424a VD |
30 | [B<-dane_tlsa_domain domain>] |
31 | [B<-dane_tlsa_rrdata rrdata>] | |
c4fbed6c | 32 | [B<-dane_ee_no_namechecks>] |
e42d84be HK |
33 | [B<-attime timestamp>] |
34 | [B<-check_ss_sig>] | |
35 | [B<-crl_check>] | |
36 | [B<-crl_check_all>] | |
37 | [B<-explicit_policy>] | |
38 | [B<-extended_crl>] | |
39 | [B<-ignore_critical>] | |
40 | [B<-inhibit_any>] | |
41 | [B<-inhibit_map>] | |
5a1f853b | 42 | [B<-no_check_time>] |
e42d84be HK |
43 | [B<-partial_chain>] |
44 | [B<-policy arg>] | |
45 | [B<-policy_check>] | |
46 | [B<-policy_print>] | |
47 | [B<-purpose purpose>] | |
48 | [B<-suiteB_128>] | |
49 | [B<-suiteB_128_only>] | |
50 | [B<-suiteB_192>] | |
51 | [B<-trusted_first>] | |
fa7b0111 | 52 | [B<-no_alt_chains>] |
e42d84be | 53 | [B<-use_deltas>] |
fbb82a60 | 54 | [B<-auth_level num>] |
a7c04f2b | 55 | [B<-nameopt option>] |
e42d84be HK |
56 | [B<-verify_depth num>] |
57 | [B<-verify_email email>] | |
58 | [B<-verify_hostname hostname>] | |
59 | [B<-verify_ip ip>] | |
60 | [B<-verify_name name>] | |
61 | [B<-x509_strict>] | |
c3ed3b6e | 62 | [B<-reconnect>] |
c3ed3b6e DSH |
63 | [B<-showcerts>] |
64 | [B<-debug>] | |
1d8634b1 | 65 | [B<-msg>] |
c3ed3b6e DSH |
66 | [B<-nbio_test>] |
67 | [B<-state>] | |
68 | [B<-nbio>] | |
69 | [B<-crlf>] | |
ce301b6b | 70 | [B<-ign_eof>] |
fc1d88f0 | 71 | [B<-no_ign_eof>] |
c3ed3b6e | 72 | [B<-quiet>] |
c3ed3b6e DSH |
73 | [B<-ssl3>] |
74 | [B<-tls1>] | |
8c73aeb6 VD |
75 | [B<-tls1_1>] |
76 | [B<-tls1_2>] | |
582a17d6 | 77 | [B<-tls1_3>] |
c3ed3b6e DSH |
78 | [B<-no_ssl3>] |
79 | [B<-no_tls1>] | |
fb0e87fb BM |
80 | [B<-no_tls1_1>] |
81 | [B<-no_tls1_2>] | |
582a17d6 | 82 | [B<-no_tls1_3>] |
8c73aeb6 VD |
83 | [B<-dtls>] |
84 | [B<-dtls1>] | |
85 | [B<-dtls1_2>] | |
19044d3c | 86 | [B<-sctp>] |
fb0e87fb | 87 | [B<-fallback_scsv>] |
bc8857bf | 88 | [B<-async>] |
28e5ea88 | 89 | [B<-max_send_frag>] |
0df80881 MC |
90 | [B<-split_send_frag>] |
91 | [B<-max_pipelines>] | |
92 | [B<-read_buf>] | |
c3ed3b6e | 93 | [B<-bugs>] |
cc5a9ba4 VD |
94 | [B<-comp>] |
95 | [B<-no_comp>] | |
254b58fd SC |
96 | [B<-sigalgs sigalglist>] |
97 | [B<-curves curvelist>] | |
c3ed3b6e | 98 | [B<-cipher cipherlist>] |
fc1d88f0 | 99 | [B<-serverpref>] |
e986704d | 100 | [B<-starttls protocol>] |
b98af49d | 101 | [B<-xmpphost hostname>] |
5270e702 | 102 | [B<-engine id>] |
d24a9c8f DSH |
103 | [B<-tlsextdebug>] |
104 | [B<-no_ticket>] | |
105 | [B<-sess_out filename>] | |
106 | [B<-sess_in filename>] | |
52b621db | 107 | [B<-rand file(s)>] |
9cd50f73 | 108 | [B<-serverinfo types>] |
cba3f1c7 | 109 | [B<-status>] |
776e15f9 | 110 | [B<-alpn protocols>] |
7efd0e77 | 111 | [B<-nextprotoneg protocols>] |
43341433 | 112 | [B<-ct|noct>] |
eb64a6c6 | 113 | [B<-ctlogfile>] |
6437b802 MC |
114 | [B<-keylogfile file>] |
115 | [B<-early_data file>] | |
c3ed3b6e DSH |
116 | |
117 | =head1 DESCRIPTION | |
118 | ||
119 | The B<s_client> command implements a generic SSL/TLS client which connects | |
120 | to a remote host using SSL/TLS. It is a I<very> useful diagnostic tool for | |
121 | SSL servers. | |
122 | ||
123 | =head1 OPTIONS | |
124 | ||
765b4137 DSH |
125 | In addition to the options below the B<s_client> utility also supports the |
126 | common and client only options documented in the | |
6f0ac0e2 | 127 | in the "Supported Command Line Commands" section of the L<SSL_CONF_cmd(3)> |
13cfb043 | 128 | manual page. |
765b4137 | 129 | |
c3ed3b6e DSH |
130 | =over 4 |
131 | ||
169394d4 MR |
132 | =item B<-help> |
133 | ||
134 | Print out a usage message. | |
135 | ||
c3ed3b6e DSH |
136 | =item B<-connect host:port> |
137 | ||
138 | This specifies the host and optional port to connect to. If not specified | |
139 | then an attempt is made to connect to the local host on port 4433. | |
140 | ||
552bf8ec MT |
141 | =item B<-proxy host:port> |
142 | ||
143 | When used with the B<-connect> flag, the program uses the host and port | |
144 | specified with this flag and issues an HTTP CONNECT command to connect | |
145 | to the desired server. | |
146 | ||
a22f9c84 E |
147 | =item B<-unix path> |
148 | ||
149 | Connect over the specified Unix-domain socket. | |
150 | ||
151 | =item B<-4> | |
152 | ||
153 | Use IPv4 only. | |
154 | ||
155 | =item B<-6> | |
156 | ||
157 | Use IPv6 only. | |
158 | ||
fc1d88f0 RS |
159 | =item B<-servername name> |
160 | ||
11ba87f2 | 161 | Set the TLS SNI (Server Name Indication) extension in the ClientHello message to |
481afe2a PY |
162 | the given value. If both this option and the B<-noservername> are not given, the |
163 | TLS SNI extension is still set to the hostname provided to the B<-connect> option, | |
164 | or "localhost" if B<-connect> has not been supplied. This is default since OpenSSL | |
165 | 1.1.1. | |
166 | ||
167 | Even though SNI name should normally be a DNS name and not an IP address, this | |
168 | option will not make the distinction when parsing B<-connect> and will send | |
169 | IP address if one passed. | |
11ba87f2 MC |
170 | |
171 | =item B<-noservername> | |
172 | ||
173 | Suppresses sending of the SNI (Server Name Indication) extension in the | |
174 | ClientHello message. Cannot be used in conjunction with the B<-servername> or | |
481afe2a | 175 | <-dane_tlsa_domain> options. |
fc1d88f0 | 176 | |
c3ed3b6e DSH |
177 | =item B<-cert certname> |
178 | ||
179 | The certificate to use, if one is requested by the server. The default is | |
180 | not to use a certificate. | |
181 | ||
826a42a0 DSH |
182 | =item B<-certform format> |
183 | ||
184 | The certificate format to use: DER or PEM. PEM is the default. | |
185 | ||
c3ed3b6e DSH |
186 | =item B<-key keyfile> |
187 | ||
188 | The private key to use. If not specified then the certificate file will | |
189 | be used. | |
190 | ||
826a42a0 DSH |
191 | =item B<-keyform format> |
192 | ||
193 | The private format to use: DER or PEM. PEM is the default. | |
194 | ||
195 | =item B<-pass arg> | |
196 | ||
197 | the private key password source. For more information about the format of B<arg> | |
9b86974e | 198 | see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>. |
826a42a0 | 199 | |
c3ed3b6e DSH |
200 | =item B<-verify depth> |
201 | ||
202 | The verify depth to use. This specifies the maximum length of the | |
203 | server certificate chain and turns on server certificate verification. | |
204 | Currently the verify operation continues after errors so all the problems | |
205 | with a certificate chain can be seen. As a side effect the connection | |
206 | will never fail due to a server certificate verify failure. | |
207 | ||
4e6c12f3 DSH |
208 | =item B<-verify_return_error> |
209 | ||
210 | Return verification errors instead of continuing. This will typically | |
211 | abort the handshake with a fatal error. | |
212 | ||
a7c04f2b DB |
213 | =item B<-nameopt option> |
214 | ||
c4de074e | 215 | Option which determines how the subject or issuer names are displayed. The |
a7c04f2b DB |
216 | B<option> argument can be a single option or multiple options separated by |
217 | commas. Alternatively the B<-nameopt> switch may be used more than once to | |
218 | set multiple options. See the L<x509(1)> manual page for details. | |
219 | ||
c3ed3b6e DSH |
220 | =item B<-CApath directory> |
221 | ||
222 | The directory to use for server certificate verification. This directory | |
223 | must be in "hash format", see B<verify> for more information. These are | |
224 | also used when building the client certificate chain. | |
225 | ||
226 | =item B<-CAfile file> | |
227 | ||
228 | A file containing trusted certificates to use during server authentication | |
229 | and to use when attempting to build the client certificate chain. | |
230 | ||
40e2d76b MC |
231 | =item B<-no-CAfile> |
232 | ||
233 | Do not load the trusted CA certificates from the default file location | |
234 | ||
235 | =item B<-no-CApath> | |
236 | ||
237 | Do not load the trusted CA certificates from the default directory location | |
238 | ||
5a185729 DSH |
239 | =item B<-requestCAfile file> |
240 | ||
241 | A file containing a list of certificates whose subject names will be sent | |
242 | to the server in the B<certificate_authorities> extension. Only supported | |
243 | for TLS 1.3 | |
244 | ||
cddd424a VD |
245 | =item B<-dane_tlsa_domain domain> |
246 | ||
247 | Enable RFC6698/RFC7671 DANE TLSA authentication and specify the | |
248 | TLSA base domain which becomes the default SNI hint and the primary | |
249 | reference identifier for hostname checks. This must be used in | |
250 | combination with at least one instance of the B<-dane_tlsa_rrdata> | |
251 | option below. | |
252 | ||
253 | When DANE authentication succeeds, the diagnostic output will include | |
254 | the lowest (closest to 0) depth at which a TLSA record authenticated | |
255 | a chain certificate. When that TLSA record is a "2 1 0" trust | |
256 | anchor public key that signed (rather than matched) the top-most | |
257 | certificate of the chain, the result is reported as "TA public key | |
258 | verified". Otherwise, either the TLSA record "matched TA certificate" | |
259 | at a positive depth or else "matched EE certificate" at depth 0. | |
260 | ||
261 | =item B<-dane_tlsa_rrdata rrdata> | |
262 | ||
263 | Use one or more times to specify the RRDATA fields of the DANE TLSA | |
264 | RRset associated with the target service. The B<rrdata> value is | |
265 | specied in "presentation form", that is four whitespace separated | |
266 | fields that specify the usage, selector, matching type and associated | |
267 | data, with the last of these encoded in hexadecimal. Optional | |
268 | whitespace is ignored in the associated data field. For example: | |
269 | ||
c0a445a9 VD |
270 | $ openssl s_client -brief -starttls smtp \ |
271 | -connect smtp.example.com:25 \ | |
cddd424a VD |
272 | -dane_tlsa_domain smtp.example.com \ |
273 | -dane_tlsa_rrdata "2 1 1 | |
274 | B111DD8A1C2091A89BD4FD60C57F0716CCE50FEEFF8137CDBEE0326E 02CF362B" \ | |
275 | -dane_tlsa_rrdata "2 1 1 | |
276 | 60B87575447DCBA2A36B7D11AC09FB24A9DB406FEE12D2CC90180517 616E8A18" | |
cddd424a | 277 | ... |
c0a445a9 | 278 | Verification: OK |
cddd424a | 279 | Verified peername: smtp.example.com |
c0a445a9 | 280 | DANE TLSA 2 1 1 ...ee12d2cc90180517616e8a18 matched TA certificate at depth 1 |
cddd424a VD |
281 | ... |
282 | ||
c4fbed6c VD |
283 | =item B<-dane_ee_no_namechecks> |
284 | ||
285 | This disables server name checks when authenticating via DANE-EE(3) TLSA | |
286 | records. | |
287 | For some applications, primarily web browsers, it is not safe to disable name | |
288 | checks due to "unknown key share" attacks, in which a malicious server can | |
289 | convince a client that a connection to a victim server is instead a secure | |
290 | connection to the malicious server. | |
291 | The malicious server may then be able to violate cross-origin scripting | |
292 | restrictions. | |
293 | Thus, despite the text of RFC7671, name checks are by default enabled for | |
294 | DANE-EE(3) TLSA records, and can be disabled in applications where it is safe | |
295 | to do so. | |
296 | In particular, SMTP and XMPP clients should set this option as SRV and MX | |
297 | records already make it possible for a remote domain to redirect client | |
298 | connections to any server of its choice, and in any case SMTP and XMPP clients | |
299 | do not execute scripts downloaded from remote servers. | |
300 | ||
e42d84be | 301 | =item B<-attime>, B<-check_ss_sig>, B<-crl_check>, B<-crl_check_all>, |
d33def66 | 302 | B<-explicit_policy>, B<-extended_crl>, B<-ignore_critical>, B<-inhibit_any>, |
5a1f853b | 303 | B<-inhibit_map>, B<-no_alt_chains>, B<-no_check_time>, B<-partial_chain>, B<-policy>, |
e42d84be | 304 | B<-policy_check>, B<-policy_print>, B<-purpose>, B<-suiteB_128>, |
d33def66 | 305 | B<-suiteB_128_only>, B<-suiteB_192>, B<-trusted_first>, B<-use_deltas>, |
fbb82a60 VD |
306 | B<-auth_level>, B<-verify_depth>, B<-verify_email>, B<-verify_hostname>, |
307 | B<-verify_ip>, B<-verify_name>, B<-x509_strict> | |
e5fa864f | 308 | |
fa7b0111 | 309 | Set various certificate chain validation options. See the |
9b86974e | 310 | L<verify(1)> manual page for details. |
e5fa864f | 311 | |
c3ed3b6e DSH |
312 | =item B<-reconnect> |
313 | ||
c4de074e | 314 | Reconnects to the same server 5 times using the same session ID, this can |
c3ed3b6e DSH |
315 | be used as a test that session caching is working. |
316 | ||
c3ed3b6e DSH |
317 | =item B<-showcerts> |
318 | ||
c4de074e | 319 | Display the whole server certificate chain: normally only the server |
c3ed3b6e DSH |
320 | certificate itself is displayed. |
321 | ||
322 | =item B<-prexit> | |
323 | ||
c4de074e | 324 | Print session information when the program exits. This will always attempt |
c3ed3b6e DSH |
325 | to print out information even if the connection fails. Normally information |
326 | will only be printed out once if the connection succeeds. This option is useful | |
327 | because the cipher in use may be renegotiated or the connection may fail | |
328 | because a client certificate is required or is requested only after an | |
329 | attempt is made to access a certain URL. Note: the output produced by this | |
330 | option is not always accurate because a connection might never have been | |
331 | established. | |
332 | ||
333 | =item B<-state> | |
334 | ||
c4de074e | 335 | Prints out the SSL session states. |
c3ed3b6e DSH |
336 | |
337 | =item B<-debug> | |
338 | ||
c4de074e | 339 | Print extensive debugging information including a hex dump of all traffic. |
c3ed3b6e | 340 | |
1d8634b1 BM |
341 | =item B<-msg> |
342 | ||
c4de074e | 343 | Show all protocol messages with hex dump. |
1d8634b1 | 344 | |
8dbeb110 DSH |
345 | =item B<-trace> |
346 | ||
c4de074e | 347 | Show verbose trace output of protocol messages. OpenSSL needs to be compiled |
8dbeb110 DSH |
348 | with B<enable-ssl-trace> for this option to work. |
349 | ||
350 | =item B<-msgfile> | |
351 | ||
c4de074e | 352 | File to send output of B<-msg> or B<-trace> to, default standard output. |
8dbeb110 | 353 | |
c3ed3b6e DSH |
354 | =item B<-nbio_test> |
355 | ||
c4de074e | 356 | Tests non-blocking I/O |
c3ed3b6e DSH |
357 | |
358 | =item B<-nbio> | |
359 | ||
c4de074e | 360 | Turns on non-blocking I/O |
c3ed3b6e DSH |
361 | |
362 | =item B<-crlf> | |
363 | ||
c4de074e | 364 | This option translated a line feed from the terminal into CR+LF as required |
c3ed3b6e DSH |
365 | by some servers. |
366 | ||
ce301b6b RL |
367 | =item B<-ign_eof> |
368 | ||
c4de074e | 369 | Inhibit shutting down the connection when end of file is reached in the |
ce301b6b RL |
370 | input. |
371 | ||
c3ed3b6e DSH |
372 | =item B<-quiet> |
373 | ||
c4de074e | 374 | Inhibit printing of session and certificate information. This implicitly |
ce301b6b | 375 | turns on B<-ign_eof> as well. |
c3ed3b6e | 376 | |
fc1d88f0 RS |
377 | =item B<-no_ign_eof> |
378 | ||
c4de074e | 379 | Shut down the connection when end of file is reached in the input. |
fc1d88f0 RS |
380 | Can be used to override the implicit B<-ign_eof> after B<-quiet>. |
381 | ||
ddac1974 NL |
382 | =item B<-psk_identity identity> |
383 | ||
384 | Use the PSK identity B<identity> when using a PSK cipher suite. | |
9d772829 | 385 | The default value is "Client_identity" (without the quotes). |
ddac1974 NL |
386 | |
387 | =item B<-psk key> | |
388 | ||
389 | Use the PSK key B<key> when using a PSK cipher suite. The key is | |
390 | given as a hexadecimal number without leading 0x, for example -psk | |
391 | 1a2b3c4d. | |
9d772829 | 392 | This option must be provided in order to use a PSK cipher. |
ddac1974 | 393 | |
582a17d6 | 394 | =item B<-ssl3>, B<-tls1>, B<-tls1_1>, B<-tls1_2>, B<-tls1_3>, B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3> |
c3ed3b6e | 395 | |
8c73aeb6 VD |
396 | These options require or disable the use of the specified SSL or TLS protocols. |
397 | By default B<s_client> will negotiate the highest mutually supported protocol | |
398 | version. | |
399 | When a specific TLS version is required, only that version will be offered to | |
400 | and accepted from the server. | |
c3ed3b6e | 401 | |
8c73aeb6 VD |
402 | =item B<-dtls>, B<-dtls1>, B<-dtls1_2> |
403 | ||
404 | These options make B<s_client> use DTLS protocols instead of TLS. | |
60250017 | 405 | With B<-dtls>, B<s_client> will negotiate any supported DTLS protocol version, |
8c73aeb6 VD |
406 | whilst B<-dtls1> and B<-dtls1_2> will only support DTLS1.0 and DTLS1.2 |
407 | respectively. | |
fb0e87fb | 408 | |
19044d3c MC |
409 | =item B<-sctp> |
410 | ||
411 | Use SCTP for the transport protocol instead of UDP in DTLS. Must be used in | |
412 | conjunction with B<-dtls>, B<-dtls1> or B<-dtls1_2>. This option is only | |
413 | available where OpenSSL has support for SCTP enabled. | |
414 | ||
fb0e87fb BM |
415 | =item B<-fallback_scsv> |
416 | ||
417 | Send TLS_FALLBACK_SCSV in the ClientHello. | |
c3ed3b6e | 418 | |
bc8857bf MC |
419 | =item B<-async> |
420 | ||
c4de074e | 421 | Switch on asynchronous mode. Cryptographic operations will be performed |
bc8857bf MC |
422 | asynchronously. This will only have an effect if an asynchronous capable engine |
423 | is also used via the B<-engine> option. For test purposes the dummy async engine | |
424 | (dasync) can be used (if available). | |
425 | ||
28e5ea88 F |
426 | =item B<-max_send_frag int> |
427 | ||
428 | The maximum size of data fragment to send. | |
429 | See L<SSL_CTX_set_max_send_fragment(3)> for further information. | |
430 | ||
0df80881 MC |
431 | =item B<-split_send_frag int> |
432 | ||
433 | The size used to split data for encrypt pipelines. If more data is written in | |
434 | one go than this value then it will be split into multiple pipelines, up to the | |
435 | maximum number of pipelines defined by max_pipelines. This only has an effect if | |
c4de074e | 436 | a suitable cipher suite has been negotiated, an engine that supports pipelining |
0df80881 MC |
437 | has been loaded, and max_pipelines is greater than 1. See |
438 | L<SSL_CTX_set_split_send_fragment(3)> for further information. | |
439 | ||
440 | =item B<-max_pipelines int> | |
441 | ||
442 | The maximum number of encrypt/decrypt pipelines to be used. This will only have | |
443 | an effect if an engine has been loaded that supports pipelining (e.g. the dasync | |
c4de074e | 444 | engine) and a suitable cipher suite has been negotiated. The default value is 1. |
0df80881 MC |
445 | See L<SSL_CTX_set_max_pipelines(3)> for further information. |
446 | ||
447 | =item B<-read_buf int> | |
448 | ||
449 | The default read buffer size to be used for connections. This will only have an | |
450 | effect if the buffer size is larger than the size that would otherwise be used | |
451 | and pipelining is in use (see L<SSL_CTX_set_default_read_buffer_len(3)> for | |
452 | further information). | |
453 | ||
c3ed3b6e DSH |
454 | =item B<-bugs> |
455 | ||
c4de074e | 456 | There are several known bug in SSL and TLS implementations. Adding this |
c3ed3b6e DSH |
457 | option enables various workarounds. |
458 | ||
cc5a9ba4 VD |
459 | =item B<-comp> |
460 | ||
461 | Enables support for SSL/TLS compression. | |
462 | This option was introduced in OpenSSL 1.1.0. | |
463 | TLS compression is not recommended and is off by default as of | |
464 | OpenSSL 1.1.0. | |
465 | ||
466 | =item B<-no_comp> | |
467 | ||
468 | Disables support for SSL/TLS compression. | |
469 | TLS compression is not recommended and is off by default as of | |
470 | OpenSSL 1.1.0. | |
471 | ||
765b4137 DSH |
472 | =item B<-brief> |
473 | ||
c4de074e | 474 | Only provide a brief summary of connection parameters instead of the |
765b4137 DSH |
475 | normal verbose output. |
476 | ||
254b58fd SC |
477 | =item B<-sigalgs sigalglist> |
478 | ||
479 | Specifies the list of signature algorithms that are sent by the client. | |
480 | The server selects one entry in the list based on its preferences. | |
481 | For example strings, see L<SSL_CTX_set1_sigalgs(3)> | |
482 | ||
483 | =item B<-curves curvelist> | |
484 | ||
485 | Specifies the list of supported curves to be sent by the client. The curve is | |
486 | is ultimately selected by the server. For a list of all curves, use: | |
487 | ||
488 | $ openssl ecparam -list_curves | |
489 | ||
c3ed3b6e DSH |
490 | =item B<-cipher cipherlist> |
491 | ||
c4de074e | 492 | This allows the cipher list sent by the client to be modified. Although |
fabce041 DSH |
493 | the server determines which cipher suite is used it should take the first |
494 | supported cipher in the list sent by the client. See the B<ciphers> | |
495 | command for more information. | |
c3ed3b6e | 496 | |
e986704d RL |
497 | =item B<-starttls protocol> |
498 | ||
c4de074e | 499 | Send the protocol-specific message(s) to switch to TLS for communication. |
e986704d | 500 | B<protocol> is a keyword for the intended protocol. Currently, the only |
cfb4f1ef | 501 | supported keywords are "smtp", "pop3", "imap", "ftp", "xmpp", "xmpp-server", |
a2d9cfba | 502 | "irc", "postgres", "mysql", "lmtp", "nntp", "sieve" and "ldap". |
e986704d | 503 | |
b98af49d CALP |
504 | =item B<-xmpphost hostname> |
505 | ||
898ea7b8 KE |
506 | This option, when used with "-starttls xmpp" or "-starttls xmpp-server", |
507 | specifies the host for the "to" attribute of the stream element. | |
b98af49d CALP |
508 | If this option is not specified, then the host specified with "-connect" |
509 | will be used. | |
510 | ||
d24a9c8f DSH |
511 | =item B<-tlsextdebug> |
512 | ||
c4de074e | 513 | Print out a hex dump of any TLS extensions received from the server. |
d24a9c8f DSH |
514 | |
515 | =item B<-no_ticket> | |
516 | ||
c4de074e | 517 | Disable RFC4507bis session ticket support. |
d24a9c8f DSH |
518 | |
519 | =item B<-sess_out filename> | |
520 | ||
c4de074e | 521 | Output SSL session to B<filename>. |
d24a9c8f DSH |
522 | |
523 | =item B<-sess_in sess.pem> | |
524 | ||
c4de074e | 525 | Load SSL session from B<filename>. The client will attempt to resume a |
d24a9c8f DSH |
526 | connection from this session. |
527 | ||
5270e702 RL |
528 | =item B<-engine id> |
529 | ||
c4de074e | 530 | Specifying an engine (by its unique B<id> string) will cause B<s_client> |
5270e702 RL |
531 | to attempt to obtain a functional reference to the specified engine, |
532 | thus initialising it if needed. The engine will then be set as the default | |
533 | for all available algorithms. | |
534 | ||
52b621db LJ |
535 | =item B<-rand file(s)> |
536 | ||
c4de074e | 537 | A file or files containing random data used to seed the random number |
9b86974e | 538 | generator, or an EGD socket (see L<RAND_egd(3)>). |
35ed393e | 539 | Multiple files can be specified separated by an OS-dependent character. |
52b621db LJ |
540 | The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for |
541 | all others. | |
542 | ||
9cd50f73 T |
543 | =item B<-serverinfo types> |
544 | ||
c4de074e | 545 | A list of comma-separated TLS Extension Types (numbers between 0 and |
9cd50f73 T |
546 | 65535). Each type will be sent as an empty ClientHello TLS Extension. |
547 | The server's response (if any) will be encoded and displayed as a PEM | |
548 | file. | |
549 | ||
cba3f1c7 DSH |
550 | =item B<-status> |
551 | ||
c4de074e | 552 | Sends a certificate status request to the server (OCSP stapling). The server |
cba3f1c7 DSH |
553 | response (if any) is printed out. |
554 | ||
776e15f9 | 555 | =item B<-alpn protocols>, B<-nextprotoneg protocols> |
7efd0e77 | 556 | |
c4de074e P |
557 | These flags enable the Enable the Application-Layer Protocol Negotiation |
558 | or Next Protocol Negotiation (NPN) extension, respectively. ALPN is the | |
559 | IETF standard and replaces NPN. | |
560 | The B<protocols> list is a comma-separated list of protocol names that | |
561 | the client should advertise support for. The list should contain the most | |
562 | desirable protocols first. Protocol names are printable ASCII strings, | |
563 | for example "http/1.1" or "spdy/3". | |
564 | An empty list of protocols is treated specially and will cause the | |
565 | client to advertise support for the TLS extension but disconnect just | |
566 | after receiving ServerHello with a list of server supported protocols. | |
837f87c2 | 567 | The flag B<-nextprotoneg> cannot be specified if B<-tls1_3> is used. |
7efd0e77 | 568 | |
43341433 | 569 | =item B<-ct|noct> |
eb64a6c6 | 570 | |
43341433 VD |
571 | Use one of these two options to control whether Certificate Transparency (CT) |
572 | is enabled (B<-ct>) or disabled (B<-noct>). | |
573 | If CT is enabled, signed certificate timestamps (SCTs) will be requested from | |
574 | the server and reported at handshake completion. | |
eb64a6c6 RP |
575 | |
576 | Enabling CT also enables OCSP stapling, as this is one possible delivery method | |
577 | for SCTs. | |
578 | ||
579 | =item B<-ctlogfile> | |
580 | ||
581 | A file containing a list of known Certificate Transparency logs. See | |
582 | L<SSL_CTX_set_ctlog_list_file(3)> for the expected file format. | |
583 | ||
6437b802 | 584 | =item B<-keylogfile file> |
4bf73e9f PW |
585 | |
586 | Appends TLS secrets to the specified keylog file such that external programs | |
587 | (like Wireshark) can decrypt TLS connections. | |
588 | ||
6437b802 MC |
589 | =item B<-early_data file> |
590 | ||
591 | Reads the contents of the specified file and attempts to send it as early data | |
592 | to the server. This will only work with resumed sessions that support early | |
593 | data and when the server accepts the early data. | |
594 | ||
efeca6aa UM |
595 | =back |
596 | ||
c3ed3b6e DSH |
597 | =head1 CONNECTED COMMANDS |
598 | ||
599 | If a connection is established with an SSL server then any data received | |
600 | from the server is displayed and any key presses will be sent to the | |
ce301b6b | 601 | server. When used interactively (which means neither B<-quiet> nor B<-ign_eof> |
3b80e3aa | 602 | have been given), the session will be renegotiated if the line begins with an |
ce301b6b RL |
603 | B<R>, and if the line begins with a B<Q> or if end of file is reached, the |
604 | connection will be closed down. | |
c3ed3b6e DSH |
605 | |
606 | =head1 NOTES | |
607 | ||
608 | B<s_client> can be used to debug SSL servers. To connect to an SSL HTTP | |
609 | server the command: | |
610 | ||
611 | openssl s_client -connect servername:443 | |
612 | ||
613 | would typically be used (https uses port 443). If the connection succeeds | |
614 | then an HTTP command can be given such as "GET /" to retrieve a web page. | |
615 | ||
616 | If the handshake fails then there are several possible causes, if it is | |
45f55f6a KR |
617 | nothing obvious like no client certificate then the B<-bugs>, |
618 | B<-ssl3>, B<-tls1>, B<-no_ssl3>, B<-no_tls1> options can be tried | |
c3ed3b6e DSH |
619 | in case it is a buggy server. In particular you should play with these |
620 | options B<before> submitting a bug report to an OpenSSL mailing list. | |
621 | ||
622 | A frequent problem when attempting to get client certificates working | |
623 | is that a web client complains it has no certificates or gives an empty | |
624 | list to choose from. This is normally because the server is not sending | |
625 | the clients certificate authority in its "acceptable CA list" when it | |
626 | requests a certificate. By using B<s_client> the CA list can be viewed | |
627 | and checked. However some servers only request client authentication | |
628 | after a specific URL is requested. To obtain the list in this case it | |
a32fc687 | 629 | is necessary to use the B<-prexit> option and send an HTTP request |
c3ed3b6e DSH |
630 | for an appropriate page. |
631 | ||
632 | If a certificate is specified on the command line using the B<-cert> | |
633 | option it will not be used unless the server specifically requests | |
634 | a client certificate. Therefor merely including a client certificate | |
635 | on the command line is no guarantee that the certificate works. | |
636 | ||
637 | If there are problems verifying a server certificate then the | |
638 | B<-showcerts> option can be used to show the whole chain. | |
639 | ||
4e6c12f3 DSH |
640 | The B<s_client> utility is a test tool and is designed to continue the |
641 | handshake after any certificate verification errors. As a result it will | |
642 | accept any certificate chain (trusted or not) sent by the peer. None test | |
643 | applications should B<not> do this as it makes them vulnerable to a MITM | |
644 | attack. This behaviour can be changed by with the B<-verify_return_error> | |
645 | option: any verify errors are then returned aborting the handshake. | |
646 | ||
c3ed3b6e DSH |
647 | =head1 BUGS |
648 | ||
8c73aeb6 VD |
649 | Because this program has a lot of options and also because some of the |
650 | techniques used are rather old, the C source of B<s_client> is rather hard to | |
651 | read and not a model of how things should be done. | |
652 | A typical SSL client program would be much simpler. | |
c3ed3b6e | 653 | |
c3ed3b6e DSH |
654 | The B<-prexit> option is a bit of a hack. We should really report |
655 | information whenever a session is renegotiated. | |
656 | ||
657 | =head1 SEE ALSO | |
658 | ||
28e5ea88 F |
659 | L<SSL_CONF_cmd(3)>, L<sess_id(1)>, L<s_server(1)>, L<ciphers(1)>, |
660 | L<SSL_CTX_set_max_send_fragment(3)>, L<SSL_CTX_set_split_send_fragment(3)> | |
661 | L<SSL_CTX_set_max_pipelines(3)> | |
c3ed3b6e | 662 | |
fa7b0111 MC |
663 | =head1 HISTORY |
664 | ||
665 | The -no_alt_chains options was first added to OpenSSL 1.1.0. | |
666 | ||
e2f92610 RS |
667 | =head1 COPYRIGHT |
668 | ||
c4de074e | 669 | Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved. |
e2f92610 RS |
670 | |
671 | Licensed under the OpenSSL license (the "License"). You may not use | |
672 | this file except in compliance with the License. You can obtain a copy | |
673 | in the file LICENSE in the source distribution or at | |
674 | L<https://www.openssl.org/source/license.html>. | |
675 | ||
676 | =cut |