source: mod_gnutls/doc/mod_gnutls_manual.mdwn @ c6dda6d

debian/masterdebian/stretch-backportsupstream
Last change on this file since c6dda6d was c6dda6d, checked in by Thomas Klute <thomas2.klute@…>, 3 years ago

Rate limit OCSP requests

Retries after failed OCSP requests must be rate limited. If the
responder is overloaded or buggy we don't want to add too much more
load, and if a MITM is messing with requests a repetition loop might
end up being a self-inflicted denial of service.

The minimum time to wait between retries can be configured using the
GnuTLSOCSPFailureTimeout directive.

  • Property mode set to 100644
File size: 25.9 KB
Line 
1% `mod_gnutls` Manual
2
3* * * * *
4
5`mod_gnutls` is a module for the Apache web server that provides HTTPS
6(HTTP over Transport Layer Security (TLS) or the older Secure Sockets
7Layer (SSL)) using the GnuTLS library.  More information about the
8module can be found at [the project's website](https://mod.gnutls.org/).
9
10* * * * *
11
12Compilation & Installation
13==========================
14
15`mod_gnutls` uses the `./configure && make && make install` mechanism
16common to many Open Source programs.  Most of the dirty work is
17handled by either `./configure` or Apache's `apxs` utility. If you have
18built Apache modules before, there shouldn't be any surprises for you.
19
20The interesting options you can pass to configure are:
21
22`--with-apxs=PATH`
23:   This option is used to specify the location of the apxs utility that
24    was installed as part of apache. Specify the location of the
25    binary, not the directory it is located in.
26
27`--with-apu-config=PATH`
28:   Path to APR Utility Library config tool (`apu-1-config`)
29
30`--help`
31:   Provides a list of all available configure options.
32
33It is recommended to run `make check` before installation. If your
34system doesn't have a loopback device with IPv6 and IPv4 support or
35`localhost` does not resolve to at least one of `[::1]` and
36`127.0.0.1`, you may have to set the `TEST_HOST` or `TEST_IP`
37environment variables when running `./configure` to make the test
38suite work correctly.
39
40* * * * *
41
42Integration
43===========
44
45To activate `mod_gnutls` just add the following line to your httpd.conf
46and restart Apache:
47
48    LoadModule gnutls_module modules/mod_gnutls.so
49
50* * * * *
51
52Configuration Directives
53========================
54
55General Options
56---------------
57
58### GnuTLSEnable
59
60Enable GnuTLS for this virtual host
61
62    GnuTLSEnable [on|off]
63
64Default: *off*\
65Context: virtual host
66
67This directive enables SSL/TLS Encryption for a Virtual Host.
68
69### GnuTLSCache
70
71Configure TLS Session Cache
72
73    GnuTLSCache [dbm|gdbm|memcache|none] [PATH|SERVERLIST|-]
74
75Default: `GnuTLSCache none`\
76Context: server config
77
78This directive configures the TLS Session Cache for `mod_gnutls`.
79This could be shared between machines of different architectures. If a
80DBM cache is used, access is serialized using the `gnutls-cache`
81mutex.
82
83`dbm` (Requires Berkeley DBM)
84:   Uses the default Berkeley DB backend of APR DBM to cache TLS
85    Sessions results.  The argument is a relative or absolute path to
86    be used as the DBM Cache file. This is compatible with most
87    operating systems, but needs the Apache Runtime to be compiled
88    with Berkeley DBM support.
89
90`gdbm`
91:   Uses the GDBM backend of APR DBM to cache TLS Sessions results.
92
93    The argument is a relative or absolute path to be used as the DBM Cache
94    file.  This is the recommended option.
95
96`memcache`
97:   Uses a memcached server to cache the TLS Session.
98
99    The argument is a space separated list of servers. If no port
100    number is supplied, the default of 11211 is used.  This can be
101    used to share a session cache between all servers in a cluster.
102
103`none`
104:   Turns off all caching of TLS Sessions.
105
106    This can significantly reduce the performance of `mod_gnutls` since
107    even followup connections by a client must renegotiate parameters
108    instead of reusing old ones.  This is the default, since it
109    requires no configuration.
110
111### GnuTLSCacheTimeout
112
113Timeout for TLS Session Cache expiration
114
115    GnuTLSCacheTimeout SECONDS
116
117Default: `GnuTLSCacheTimeout 300`\
118Context: server config
119
120Sets the timeout for TLS Session Cache entries expiration.  This
121directive is valid even if Session Tickets are used, and indicates the
122expiration time of the ticket in seconds.
123
124### GnuTLSSessionTickets
125
126Enable Session Tickets for the server
127
128    GnuTLSSessionTickets [on|off]
129
130Default: `off`\
131Context: server config, virtual host
132
133To avoid storing data for TLS session resumption it is allowed to
134provide client with a ticket, to use on return. Tickets are an
135alternative to using a session cache, mostly used for busy servers
136with limited storage. For a pool of servers this option is not
137recommended since the tickets are bound to the issuing server only.
138
139If this option is set in the global configuration, virtual hosts
140without a `GnuTLSSessionTickets` setting will use the global setting.
141
142*Warning:* Currently the master key that protects the tickets is
143generated only on server start, and there is no mechanism to roll over
144the key. If session tickets are enabled it is highly recommened to
145restart the server regularly to protect past sessions in case an
146attacker gains access to server memory.
147
148### GnuTLSClientVerify
149
150Enable Client Certificate Verification
151
152    GnuTLSClientVerify [ignore|request|require]
153
154Default: `ignore`\
155Context: server config, virtual host, directory, .htaccess
156
157This directive controls the use of TLS Client Certificate
158Authentication. If used in the .htaccess context, it can force TLS
159re-negotiation.
160
161`ignore`
162:   `mod_gnutls` will ignore the contents of any TLS Client Certificates
163    sent. It will not request that the client sends a certificate.
164
165`request`
166:   The client certificate will be requested, but not required.
167    The Certificate will be validated if sent.  The output of the
168    validation status will be stored in the `SSL_CLIENT_VERIFY`
169    environment variable and can be `SUCCESS`, `FAILED` or `NONE`.
170
171`require`
172:   A Client certificate will be required. Any requests without a valid
173    client certificate will be denied.  The `SSL_CLIENT_VERIFY`
174    environment variable will only be set to `SUCCESS`.
175
176### GnuTLSDHFile
177
178Set to the PKCS \#3 encoded Diffie Hellman parameters
179
180    GnuTLSDHFile FILEPATH
181
182Default: *none*\
183Context: server config, virtual host
184
185Takes an absolute or relative path to a PKCS \#3 encoded DH
186parameters.Those are used when the DHE key exchange method is enabled.
187You can generate this file using `certtool --generate-dh-params --bits
1882048`.  If not set `mod_gnutls` will use the included parameters.
189
190### GnuTLSPriorities
191
192Set the allowed protocol versions, ciphers, key exchange algorithms,
193MACs and compression methods
194
195    GnuTLSPriorities NORMAL:+CIPHER_0:+CIPHER_1:...:+CIPHER_N
196
197Default: *none*\
198Context: server config, virtual host
199
200Takes a colon separated list of protocol version, ciphers, key
201exchange methods message authentication codes, and compression methods
202to enable. The allowed keywords are specified in the
203`gnutls_priority_init()` function of GnuTLS.
204
205Please refer to [the GnuTLS documentation](https://gnutls.org/manual/html_node/Priority-Strings.html#Priority-Strings)
206for details. A few commonly used sets are listed below, note that
207their exact meaning may change with GnuTLS versions.
208
209`PERFORMANCE`
210:   A list with all the secure cipher combinations sorted in terms of
211    performance.
212
213`NORMAL`
214:   A list with all the secure cipher combinations sorted
215    with respect to security margin (subjective term).
216
217`SECURE128`
218:   A list with all the secure cipher suites that offer a security level
219    of 128-bit or more.
220
221`PFS`
222:   Only cipher suites offering perfect forward secrecy (ECDHE and DHE),
223    sorted by security margin.
224
225You can add or remove algorithms using the `+` and `!` prefixes
226respectively. For example, in order to use the `NORMAL` set but
227disable TLS 1.0 and 1.1 you can use the string
228`NORMAL:!VERS-TLS1.0:!VERS-TLS1.1`.
229
230You can find a list of all supported Ciphers, Versions, MACs, etc.  by
231running `gnutls-cli --list`.
232
233### GnuTLSP11Module
234
235Load this PKCS #11 module.
236
237    GnuTLSP11Module PATH_TO_LIBRARY
238
239Default: *none*\
240Context: server config
241
242Load this PKCS #11 provider module, instead of the system
243defaults. May occur multiple times to load multiple modules.
244
245### GnuTLSPIN
246
247Set the PIN to be used to access encrypted key files or PKCS #11 objects.
248
249    GnuTLSPIN XXXXXX
250
251Default: *none*\
252Context: server config, virtual host
253
254Takes a string to be used as a PIN for the protected objects in
255a security module, or as a key to be used to decrypt PKCS #8, PKCS #12,
256or openssl encrypted keys.
257
258### GnuTLSSRKPIN
259
260Set the SRK PIN to be used to access the TPM.
261
262    GnuTLSSRKPIN XXXXXX
263
264Default: *none*\
265Context: server config, virtual host
266
267Takes a string to be used as a PIN for the protected objects in
268the TPM module.
269
270### GnuTLSExportCertificates
271
272Export the PEM encoded certificates to CGIs
273
274    GnuTLSExportCertificates [off|on|SIZE]
275
276Default: `off`\
277Context: server config, virtual host
278
279This directive configures exporting the full certificates of the
280server and the client to CGI scripts via the `SSL_SERVER_CERT` and
281`SSL_CLIENT_CERT` environment variables. The exported certificates
282will be PEM-encoded (if X.509) or ASCII-armored (if OpenPGP) up to the
283size given.  The type of the certificate will be exported in
284`SSL_SERVER_CERT_TYPE` and `SSL_CLIENT_CERT_TYPE`.
285
286SIZE should be an integer number of bytes, or may be written with a
287trailing `K` to indicate kibibytes.  `off` means the same thing as
288`0`, in which case the certificates will not be exported to the
289environment.  `on` is an alias for `16K`.  If a non-zero size is
290specified for this directive, but a certificate is too large to fit in
291the buffer, then the corresponding environment variable will contain
292the fixed string `GNUTLS_CERTIFICATE_SIZE_LIMIT_EXCEEDED`.
293
294With GnuTLSExportCertificates enabled, `mod_gnutls` exports the same
295environment variables to the CGI process as `mod_ssl`.
296
297X.509 Certificate Authentication
298--------------------------------
299
300### GnuTLSCertificateFile
301
302Set to the PEM Encoded Server Certificate
303
304    GnuTLSCertificateFile FILEPATH
305
306Default: *none*\
307Context: server config, virtual host
308
309Takes an absolute or relative path to a PEM-encoded X.509 certificate to
310use as this Server's End Entity (EE) certificate. If you need to supply
311certificates for intermediate Certificate Authorities (iCAs), they
312should be listed in sequence in the file, from EE to the iCA closest to
313the root CA. Optionally, you can also include the root CA's certificate
314as the last certificate in the list.
315
316Since version 0.7 this can be a PKCS #11 URL.
317
318### GnuTLSKeyFile
319
320Set to the PEM Encoded Server Private Key
321
322    GnuTLSKeyFile FILEPATH
323
324Default: *none*\
325Context: server config, virtual host
326
327Takes an absolute or relative path to the Server Private Key. Set
328`GnuTLSPIN` if the key file is encrypted.
329
330Since version 0.7 this can be a PKCS #11 URL.
331
332**Security Warning:**\
333This private key must be protected. It is read while Apache is still
334running as root, and does not need to be readable by the nobody or
335apache user.
336
337### GnuTLSClientCAFile
338
339Set the PEM encoded Certificate Authority list to use for X.509 base
340client authentication
341
342    GnuTLSClientCAFile FILEPATH
343
344Default: *none*
345Context: server config, virtual host
346
347Takes an absolute or relative path to a PEM Encoded Certificate to use
348as a Certificate Authority with Client Certificate Authentication.
349This file may contain a list of trusted authorities.
350
351OpenPGP Certificate Authentication
352----------------------------------
353
354### GnuTLSPGPCertificateFile
355
356Set to a base64 Encoded Server OpenPGP Certificate
357
358    GnuTLSPGPCertificateFile FILEPATH
359
360Default: *none*\
361Context: server config, virtual host
362
363Takes an absolute or relative path to a base64 Encoded OpenPGP
364Certificate to use as this Server's Certificate.
365
366### GnuTLSPGPKeyFile
367
368Set to the Server OpenPGP Secret Key
369
370    GnuTLSPGPKeyFile FILEPATH
371
372Default: *none*\
373Context: server config, virtual host
374
375Takes an absolute or relative path to the Server Private Key. This key
376cannot currently be password protected.
377
378**Security Warning:**\
379 This private key must be protected. It is read while Apache is still
380running as root, and does not need to be readable by the nobody or
381apache user.
382
383### GnuTLSPGPKeyringFile
384
385Set to a base64 Encoded key ring
386
387    GnuTLSPGPKeyringFile FILEPATH
388
389Default: *none*\
390Context: server config, virtual host
391
392Takes an absolute or relative path to a base64 Encoded Certificate
393list (key ring) to use as a means of verification of Client
394Certificates.  This file should contain a list of trusted signers.
395
396SRP Authentication
397------------------
398
399### GnuTLSSRPPasswdFile
400
401Set to the SRP password file for SRP ciphersuites
402
403    GnuTLSSRPPasswdFile FILEPATH
404
405Default: *none*\
406Context: server config, virtual host
407
408Takes an absolute or relative path to an SRP password file. This is
409the same format as used in libsrp.  You can generate such file using
410the command `srptool --passwd /etc/tpasswd --passwd-conf
411/etc/tpasswd.conf -u test` to set a password for user test.  This
412password file holds the username, a password verifier and the
413dependency to the SRP parameters.
414
415### GnuTLSSRPPasswdConfFile
416
417Set to the SRP password.conf file for SRP ciphersuites
418
419    GnuTLSSRPPasswdConfFile FILEPATH
420
421Default: *none*\
422Context: server config, virtual host
423
424Takes an absolute or relative path to an SRP password.conf file. This
425is the same format as used in `libsrp`.  You can generate such file
426using the command `srptool --create-conf /etc/tpasswd.conf`.  This
427file holds the SRP parameters and is associate with the password file
428(the verifiers depends on these parameters).
429
430TLS Proxy Configuration
431-----------------------
432
433### GnuTLSProxyEngine
434
435Enable TLS proxy connections for this virtual host
436
437    GnuTLSProxyEngine [on|off]
438
439Default: *off*\
440Context: virtual host
441
442This directive enables support for TLS proxy connections for a virtual
443host.
444
445### GnuTLSProxyCAFile
446
447Set to the PEM encoded Certificate Authority Certificate
448
449    GnuTLSProxyCAFile FILEPATH
450
451Default: *none*\
452Context: server config, virtual host
453
454Takes an absolute or relative path to a PEM encoded certificate to use
455as a Certificate Authority when verifying certificates provided by
456proxy back end servers. This file may contain a list of trusted
457authorities. If not set, verification of TLS back end servers will
458always fail due to lack of a trusted CA.
459
460### GnuTLSProxyCRLFile
461
462Set to the PEM encoded Certificate Revocation List
463
464    GnuTLSProxyCRLFile FILEPATH
465
466Default: *none*\
467Context: server config, virtual host
468
469Takes an absolute or relative path to a PEM encoded Certificate
470Revocation List to use when verifying certificates provided by proxy
471back end servers. The file may contain a list of CRLs.
472
473### GnuTLSProxyCertificateFile
474
475Set to the PEM encoded Client Certificate
476
477    GnuTLSProxyCertificateFile FILEPATH
478
479Default: *none*\
480Context: server config, virtual host
481
482Takes an absolute or relative path to a PEM encoded X.509 certificate
483to use as this Server's End Entity (EE) client certificate for TLS
484client authentication in proxy TLS connections. If you need to supply
485certificates for intermediate Certificate Authorities (iCAs), they
486should be listed in sequence in the file, from EE to the iCA closest
487to the root CA. Optionally, you can also include the root CA's
488certificate as the last certificate in the list.
489
490If not set, TLS client authentication will be disabled for TLS proxy
491connections. If set, `GnuTLSProxyKeyFile` must be set as well to
492provide the matching private key.
493
494### GnuTLSProxyKeyFile
495
496Set to the PEM encoded Private Key
497
498    GnuTLSProxyKeyFile FILEPATH
499
500Default: *none*\
501Context: server config, virtual host
502
503Takes an absolute or relative path to the Private Key matching the
504certificate configured using the `GnuTLSProxyCertificateFile`
505directive. This key cannot currently be password protected.
506
507**Security Warning:**\
508This private key must be protected. It is read while Apache is still
509running as root, and does not need to be readable by the nobody or
510apache user.
511
512### GnuTLSProxyPriorities
513
514Set the allowed ciphers, key exchange algorithms, MACs and compression
515methods for proxy connections
516
517    GnuTLSProxyPriorities NORMAL:+CIPHER_0:+CIPHER_1:...:+CIPHER_N
518
519Default: *none*\
520Context: server config, virtual host
521
522This option is used to set the allowed ciphers, key exchange
523algorithms, MACs and compression methods for proxy connections. It
524takes the same parameters as `GnuTLSPriorities`. Required if
525`GnuTLSProxyEngine` is `On`.
526
527OCSP Stapling Configuration
528---------------------------
529
530### GnuTLSOCSPStapling
531
532EXPERIMENTAL: Enable OCSP stapling for this (virtual) host.
533
534    GnuTLSOCSPStapling [On|Off]
535
536Default: *off*\
537Context: server config, virtual host
538
539OCSP stapling, formally known as the TLS Certificate Status Request
540extension, allows the server to provide the client with an OCSP
541response for its certificate during the handshake. This way the client
542does not have to send an OCSP request to the CA to check the
543certificate status, which offers privacy and performance advantages.
544
545Using OCSP stapling has a few requirements:
546
547* Caching OCSP responses requires a cache, so `GnuTLSCache` must not
548  be `none`.
549* `GnuTLSCertificateFile` must contain the issuer CA certificate in
550  addition to the server certificate so responses can be verified.
551* The certificate must either contain an OCSP access URI using HTTP,
552  or `GnuTLSOCSPResponseFile` must be set.
553
554OCSP cache updates are serialized using the `gnutls-ocsp` mutex.
555
556### GnuTLSOCSPResponseFile
557
558EXPERIMENTAL: Read the OCSP response for stapling from this file
559instead of sending a request over HTTP
560
561    GnuTLSOCSPResponseFile /path/to/response.der
562
563Default: *empty*\
564Context: server config, virtual host
565
566The response file must be updated externally, for example using a cron
567job. This option is an alternative to the server fetching OCSP
568responses over HTTP. Reasons to use this option include:
569
570* Performing OCSP requests separate from the web server, to prevent slow
571  responses from stalling handshakes.
572* The issuer CA uses an access method other than HTTP.
573* Testing
574
575### GnuTLSOCSPGraceTime
576
577EXPERIMENTAL: Replace cached OCSP responses this many seconds before
578they expire.
579
580    GnuTLSOCSPGraceTime SECONDS
581
582Default: *60*\
583Context: server config, virtual host
584
585A cached OCSP response should be updated a little before it expires to
586account for potential clock skew between server, CA, and client, as
587well as transmission time in corner cases.
588
589### GnuTLSOCSPFailureTimeout
590
591EXPERIMENTAL: Wait this many seconds before retrying a failed OCSP request.
592
593    GnuTLSOCSPFailureTimeout SECONDS
594
595Default: *300*\
596Context: server config, virtual host
597
598Retries of failed OCSP requests must be rate limited to avoid
599overloading both the server using mod_gnutls and the CA's OCSP
600responder. A shorter value increases the load on both sides, a longer
601one means that stapling will remain disabled for longer after a failed
602request.
603
604* * * * *
605
606Configuration Examples
607======================
608
609Simple Standard TLS Example
610---------------------------
611
612The following is an example of simple TLS hosting, using one IP
613Addresses for each virtual host.
614
615     # Load the module into Apache.
616     LoadModule gnutls_module modules/mod_gnutls.so
617     GnuTLSCache gdbm /var/cache/www-tls-cache
618     GnuTLSCacheTimeout 500
619
620     # Without SNI you need one IP Address per-site.
621     Listen 192.0.2.1:443
622     Listen 192.0.2.2:443
623     Listen 192.0.2.3:443
624     Listen 192.0.2.4:443
625
626     <VirtualHost 192.0.2.1:443>
627         GnuTLSEnable on
628         GnuTLSPriorities SECURE128
629         DocumentRoot /www/site1.example.com/html
630         ServerName site1.example.com:443
631         GnuTLSCertificateFile conf/tls/site1.crt
632         GnuTLSKeyFile conf/tls/site1.key
633     </VirtualHost>
634
635     <VirtualHost 192.0.2.2:443>
636         # This virtual host enables SRP authentication
637         GnuTLSEnable on
638         GnuTLSPriorities NORMAL:+SRP
639         DocumentRoot /www/site2.example.com/html
640         ServerName site2.example.com:443
641         GnuTLSSRPPasswdFile conf/tls/tpasswd.site2
642         GnuTLSSRPPasswdConfFile conf/tls/tpasswd.site2.conf
643     </VirtualHost>
644
645     <VirtualHost 192.0.2.3:443>
646         # This server enables SRP, OpenPGP and X.509 authentication.
647         GnuTLSEnable on
648         GnuTLSPriorities NORMAL:+SRP:+SRP-RSA:+SRP-DSS:+CTYPE-OPENPGP
649         DocumentRoot /www/site3.example.com/html
650         ServerName site3.example.com:443
651         GnuTLSCertificateFile conf/tls/site3.crt
652         GnuTLSKeyFile conf/tls/site3.key
653         GnuTLSClientVerify ignore
654         GnuTLSPGPCertificateFile conf/tls/site3.pub.asc
655         GnuTLSPGPKeyFile conf/tls/site3.sec.asc
656         GnuTLSSRPPasswdFile conf/tls/tpasswd.site3
657         GnuTLSSRPPasswdConfFile conf/tls/tpasswd.site3.conf
658     </VirtualHost>
659
660     <VirtualHost 192.0.2.4:443>
661         GnuTLSEnable on
662         # %COMPAT disables some security features to enable maximum
663         # compatibility with clients. Don't use this if you need strong
664         # security.
665         GnuTLSPriorities NORMAL:%COMPAT
666         DocumentRoot /www/site4.example.com/html
667         ServerName site4.example.com:443
668         GnuTLSCertificateFile conf/tls/site4.crt
669         GnuTLSKeyFile conf/tls/site4.key
670     </VirtualHost>
671
672Server Name Indication Example
673------------------------------
674
675`mod_gnutls` supports "Server Name Indication", as specified in
676RFC 3546. This allows hosting many TLS websites with a single IP
677address. All recent browsers support this standard. Here is an
678example using SNI:
679
680     # Load the module into Apache.
681     LoadModule gnutls_module modules/mod_gnutls.so
682
683     # SNI allows hosting multiple sites using one IP address. This
684     # could also be 'Listen *:443', just like '*:80' is common for
685     # non-HTTPS
686     Listen 198.51.100.1:443
687
688     <VirtualHost _default_:443>
689         GnuTLSEnable on
690         GnuTLSSessionTickets on
691         GnuTLSPriorities NORMAL
692         DocumentRoot /www/site1.example.com/html
693         ServerName site1.example.com:443
694         GnuTLSCertificateFile conf/tls/site1.crt
695         GnuTLSKeyFile conf/tls/site1.key
696     </VirtualHost>
697
698     <VirtualHost _default_:443>
699         GnuTLSEnable on
700         GnuTLSPriorities NORMAL
701         DocumentRoot /www/site2.example.com/html
702         ServerName site2.example.com:443
703         GnuTLSCertificateFile conf/tls/site2.crt
704         GnuTLSKeyFile conf/tls/site2.key
705     </VirtualHost>
706
707     <VirtualHost _default_:443>
708         GnuTLSEnable on
709         GnuTLSPriorities NORMAL
710         DocumentRoot /www/site3.example.com/html
711         ServerName site3.example.com:443
712         GnuTLSCertificateFile conf/tls/site3.crt
713         GnuTLSKeyFile conf/tls/site3.key
714     </VirtualHost>
715
716     <VirtualHost _default_:443>
717         GnuTLSEnable on
718         GnuTLSPriorities NORMAL
719         DocumentRoot /www/site4.example.com/html
720         ServerName site4.example.com:443
721         GnuTLSCertificateFile conf/tls/site4.crt
722         GnuTLSKeyFile conf/tls/site4.key
723     </VirtualHost>
724
725OCSP Stapling Example
726---------------------
727
728This example uses an X.509 server certificate. The server will fetch
729OCSP responses from the responder listed in the certificate and store
730them im a memcached cache shared with another server.
731
732     # Load the module into Apache.
733     LoadModule gnutls_module modules/mod_gnutls.so
734     GnuTLSCache memcache "192.0.2.1:11211 192.0.2.2:11211"
735     GnuTLSCacheTimeout 600
736
737     Listen 192.0.2.1:443
738
739     <VirtualHost _default_:443>
740         GnuTLSEnable          On
741         GnuTLSPriorities      NORMAL
742         DocumentRoot          /www/site1.example.com/html
743         ServerName            site1.example.com:443
744         GnuTLSCertificateFile conf/tls/site1.crt
745         GnuTLSKeyFile         conf/tls/site1.key
746         GnuTLSPriorities      NORMAL
747         GnuTLSOCSPStapling    On
748     </VirtualHost>
749
750* * * * *
751
752Environment Variables
753=====================
754
755`mod_gnutls` exports the following environment variables to scripts.
756These are compatible with `mod_ssl`.
757
758`HTTPS`
759-------
760
761Can be `on` or `off`
762
763`SSL_VERSION_LIBRARY`
764---------------------
765
766The version of the GnuTLS library
767
768`SSL_VERSION_INTERFACE`
769-----------------------
770
771The version of this module
772
773`SSL_PROTOCOL`
774--------------
775
776The SSL or TLS protocol name (such as `TLS 1.0` etc.)
777
778`SSL_CIPHER`
779------------
780
781The SSL or TLS cipher suite name
782
783`SSL_COMPRESS_METHOD`
784---------------------
785
786The negotiated compression method (`NULL` or `DEFLATE`)
787
788`SSL_SRP_USER`
789--------------
790
791The SRP username used for authentication (only set when
792`GnuTLSSRPPasswdFile` and `GnuTLSSRPPasswdConfFile` are configured).
793
794`SSL_CIPHER_USEKEYSIZE` & `SSL_CIPHER_ALGKEYSIZE`
795-------------------------------------------------
796
797The number if bits used in the used cipher algorithm.
798
799This does not fully reflect the security level since the size of
800RSA or DHE key exchange parameters affect the security level too.
801
802`SSL_DH_PRIME_BITS`
803-------------------
804
805The number if bits in the modulus for the DH group, if DHE or static
806DH is used.
807
808This will not be set if DH is not used.
809
810`SSL_CIPHER_EXPORT`
811-------------------
812
813`True` or `False`. Whether the cipher suite negotiated is an export one.
814
815`SSL_SESSION_ID`
816----------------
817
818The session ID negotiated in this session. Can be the same during client
819reloads.
820
821`SSL_CLIENT_V_REMAIN`
822---------------------
823
824The number of days until the client's certificate is expired.
825
826`SSL_CLIENT_V_START`
827--------------------
828
829The activation time of client's certificate.
830
831`SSL_CLIENT_V_END`
832------------------
833
834The expiration time of client's certificate.
835
836`SSL_CLIENT_S_DN`
837-----------------
838
839The distinguished name of client's certificate in RFC2253 format.
840
841`SSL_CLIENT_I_DN`
842-----------------
843
844The SSL or TLS cipher suite name
845
846`SSL_CLIENT_S_AN%`
847------------------
848
849These will contain the alternative names of the client certificate (`%` is
850a number starting from zero).
851
852The values will be prepended by `DNSNAME:`, `RFC822NAME:` or `URI:`
853depending on the type.
854
855If it is not supported the value `UNSUPPORTED` will be set.
856
857`SSL_SERVER_M_SERIAL`
858---------------------
859
860The serial number of the server's certificate.
861
862`SSL_SERVER_M_VERSION`
863----------------------
864
865The version of the server's certificate.
866
867`SSL_SERVER_A_SIG`
868------------------
869
870The algorithm used for the signature in server's certificate.
871
872`SSL_SERVER_A_KEY`
873------------------
874
875The public key algorithm in server's certificate.
876
877`SSL_SERVER_CERT`
878------------------
879
880The PEM-encoded (X.509) or ASCII-armored (OpenPGP) server certificate
881(see the `GnuTLSExportCertificates` directive).
882
883`SSL_SERVER_CERT_TYPE`
884----------------------
885
886The certificate type can be `X.509` or `OPENPGP`.
887
888`SSL_CLIENT_CERT`
889------------------
890
891The PEM-encoded (X.509) or ASCII-armored (OpenPGP) client certificate
892(see the `GnuTLSExportCertificates` directive).
893
894`SSL_CLIENT_CERT_TYPE`
895----------------------
896
897The certificate type can be `X.509` or `OPENPGP`.
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