1JAIL.CONF(5) Fail2Ban Configuration JAIL.CONF(5)
2
6 jail.conf - configuration for the fail2ban server
7
9 fail2ban.conf fail2ban.d/*.conf fail2ban.local fail2ban.d/*.local
10 jail.conf jail.d/*.conf jail.local jail.d/*.local
12 action.d/*.conf action.d/*.local action.d/*.py
14 filter.d/*.conf filter.d/*.local
16
19 Fail2ban has four configuration file types:
20 fail2ban.conf
23 Fail2Ban global configuration (such as logging)
24 filter.d/*.conf
26 Filters specifying how to detect authentication failures
27 action.d/*.conf
29 Actions defining the commands for banning and unbanning of IP
30 address
31 jail.conf
33 Jails defining combinations of Filters with Actions.
34
38 *.conf files are distributed by Fail2Ban. It is recommended that
39 *.conf files should remain unchanged to ease upgrades. If needed, cus‐
40 tomizations should be provided in *.local files. For example, if you
41 would like to enable the [ssh-iptables-ipset] jail specified in
42 jail.conf, create jail.local containing
43 jail.local
46 [ssh-iptables-ipset]
47 enabled = true
49 In .local files specify only the settings you would like to change and
52 the rest of the configuration will then come from the corresponding
53 .conf file which is parsed first.
54 jail.d/ and fail2ban.d/
57 In addition to .local, for jail.conf or fail2ban.conf file there
59 can be a corresponding .d/ directory containing additional .conf
60 files. The order e.g. for jail configuration would be:
61 jail.conf
63 jail.d/*.conf (in alphabetical order)
64 jail.local
65 jail.d/*.local (in alphabetical order).
66 i.e. all .local files are parsed after .conf files in the origi‐
68 nal configuration file and files under .d directory. Settings
69 in the file parsed later take precedence over identical entries
70 in previously parsed files. Files are ordered alphabetically,
71 e.g.
72 fail2ban.d/01_custom_log.conf - to use a different log path
74 jail.d/01_enable.conf - to enable a specific jail
75 jail.d/02_custom_port.conf - to change the port(s) of a jail.
76 Configuration files have sections, those specified with [section name],
78 and name = value pairs. For those name items that can accept multiple
79 values, specify the values separated by spaces, or in separate lines
80 space indented at the beginning of the line before the second value.
81 Configuration files can include other (defining common variables) con‐
84 figuration files, which is often used in Filters and Actions. Such
85 inclusions are defined in a section called [INCLUDES]:
86 before indicates that the specified file is to be parsed before the
89 current file.
90 after indicates that the specified file is to be parsed after the cur‐
92 rent file.
93 Using Python "string interpolation" mechanisms, other definitions are
95 allowed and can later be used within other definitions as %(name)s.
96 Fail2ban has more advanced syntax (similar python extended interpola‐
98 tion). This extended interpolation is using %(section/parameter)s to
99 denote a value from a foreign section.
100 Besides cross section interpolation the value of parameter in [DEFAULT]
101 section can be retrieved with %(default/parameter)s.
102 Fail2ban supports also another feature named %(known/parameter)s (means
103 last known option with name parameter). This interpolation makes possi‐
104 ble to extend a stock filter or jail regexp in .local file (opposite to
105 simply set failregex/ignoreregex that overwrites it), e.g.
106 baduseragents = IE|wget|%(my-settings/baduseragents)s
108 failregex = %(known/failregex)s
109 useragent=%(baduseragents)s
110 Additionally to interpolation %(known/parameter)s, that does not works
112 for filter/action init parameters, an interpolation tag <known/parame‐
113 ter> can be used (means last known init definition of filters or
114 actions with name parameter). This interpolation makes possible to
115 extend a parameters of stock filter or action directly in jail inside
116 jail.conf/jail.local file without creating a separately fil‐
117 ter.d/*.local file, e.g.
118 # filter.d/test.conf:
120 [Init]
121 test.method = GET
122 baduseragents = IE|wget
123 [Definition]
124 failregex = ^%(__prefix_line)\s+"<test.method>"\s+test\s+regexp\s+-\s+useragent=(?:<baduseragents>)
125 # jail.local:
127 [test]
128 # use filter "test", overwrite method to "POST" and extend known bad agents with "badagent":
129 filter = test[test.method=POST, baduseragents="badagent|<known/baduseragents>"]
130 Comments: use '#' for comment lines and '; ' (space is important) for
132 inline comments. When using Python2.X, '; ' can only be used on the
133 first line due to an Python library bug.
134
137 The items that can be set in section [Definition] are:
138 loglevel
140 verbosity level of log output: CRITICAL, ERROR, WARNING, NOTICE,
141 INFO, DEBUG, TRACEDEBUG, HEAVYDEBUG or corresponding numeric
142 value (50-5). Default: INFO (equal 20)
143 logtarget
145 log target: filename, SYSLOG, STDERR or STDOUT. Default: STDOUT
146 if not set in fail2ban.conf/fail2ban.local
147 Note. If fail2ban running as systemd-service, for logging to the
148 systemd-journal, the logtarget could be set to STDOUT
149 Only a single log target can be specified. If you change log‐
150 target from the default value and you are using logrotate --
151 also adjust or disable rotation in the corresponding configura‐
152 tion file (e.g. /etc/logrotate.d/fail2ban on Debian systems).
153 socket socket filename. Default: /var/run/fail2ban/fail2ban.sock
155 This is used for communication with the fail2ban server daemon.
156 Do not remove this file when Fail2ban is running. It will not be
157 possible to communicate with the server afterwards.
158 pidfile
160 PID filename. Default: /var/run/fail2ban/fail2ban.pid
161 This is used to store the process ID of the fail2ban server.
162 dbfile Database filename. Default: /var/lib/fail2ban/fail2ban.sqlite3
164 This defines where the persistent data for fail2ban is stored.
165 This persistent data allows bans to be reinstated and continue
166 reading log files from the last read position when fail2ban is
167 restarted. A value of None disables this feature.
168 dbmaxmatches
170 Max number of matches stored in database per ticket. Default: 10
171 This option sets the max number of matched log-lines could be
172 stored per ticket in the database. This also affects values
173 resolvable via tags <ipmatches> and <ipjailmatches> in actions.
174 dbpurgeage
176 Database purge age in seconds. Default: 86400 (24hours)
177 This sets the age at which bans should be purged from the data‐
178 base.
179 The config parameters of section [Thread] are:
181 stacksize
184 Stack size of each thread in fail2ban. Default: 0 (platform or
185 configured default)
186 This specifies the stack size (in KiB) to be used for subse‐
187 quently created threads, and must be 0 or a positive integer
188 value of at least 32.
189
192 The following options are applicable to any jail. They appear in a sec‐
193 tion specifying the jail name or in the [DEFAULT] section which defines
194 default values to be used if not specified in the individual section.
195 filter name of the filter -- filename of the filter in
197 /etc/fail2ban/filter.d/ without the .conf/.local extension.
198 Only one filter can be specified.
199 logpath
201 filename(s) of the log files to be monitored, separated by new
202 lines.
203 Globs -- paths containing * and ? or [0-9] -- can be used how‐
204 ever only the files that exist at start up matching this glob
205 pattern will be considered.
206 Optional space separated option 'tail' can be added to the end
208 of the path to cause the log file to be read from the end, else
209 default 'head' option reads file from the beginning
210 Ensure syslog or the program that generates the log file isn't
212 configured to compress repeated log messages to "*last message
213 repeated 5 time*s" otherwise it will fail to detect. This is
214 called RepeatedMsgReduction in rsyslog and should be Off.
215 logencoding
217 encoding of log files used for decoding. Default value of "auto"
218 uses current system locale.
219 logtimezone
221 Force the time zone for log lines that don't have one.
222 If this option is not specified, log lines from which no
224 explicit time zone has been found are interpreted by fail2ban in
225 its own system time zone, and that may turn to be inappropriate.
226 While the best practice is to configure the monitored applica‐
227 tions to include explicit offsets, this option is meant to han‐
228 dle cases where that is not possible.
229 The supported time zones in this option are those with fixed
231 offset: Z, UTC[+-]hhmm (you can also use GMT as an alias to
232 UTC).
233 This option has no effect on log lines on which an explicit time
235 zone has been found. Examples:
236 logtimezone = UTC
238 logtimezone = UTC+0200
239 logtimezone = GMT-0100
240 banaction
243 banning action (default iptables-multiport) typically specified
244 in the [DEFAULT] section for all jails.
245 This parameter will be used by the standard substitution of
246 action and can be redefined central in the [DEFAULT] section
247 inside jail.local (to apply it to all jails at once) or sepa‐
248 rately in each jail, where this substitution will be used.
249 banaction_allports
251 the same as banaction but for some "allports" jails like "pam-
252 generic" or "recidive" (default iptables-allports).
253 action action(s) from /etc/fail2ban/action.d/ without the .conf/.local
255 extension.
256 Arguments can be passed to actions to override the default val‐
257 ues from the [Init] section in the action file. Arguments are
258 specified by:
259 [name=value,name2=value,name3="values,values"]
261 Values can also be quoted (required when value includes a ",").
263 More that one action can be specified (in separate lines).
264 ignoreself
266 boolean value (default true) indicates the banning of own IP
267 addresses should be prevented
268 ignoreip
270 list of IPs not to ban. They can include a DNS resp. CIDR mask
271 too. The option affects additionally to ignoreself (if true) and
272 don't need to contain own DNS resp. IPs of the running host.
273 ignorecommand
275 command that is executed to determine if the current candidate
276 IP for banning (or failure-ID for raw IDs) should not be banned.
277 The option affects additionally to ignoreself and ignoreip and
278 will be first executed if both don't hit.
279 IP will not be banned if command returns successfully (exit code
280 0). Like ACTION FILES, tags like <ip> are can be included in
281 the ignorecommand value and will be substituted before execu‐
282 tion.
283 ignorecache
285 provide cache parameters (default disabled) for ignore failure
286 check (caching of the result from `ignoreip`, `ignoreself` and
287 `ignorecommand`), syntax:
288 ignorecache = key="<F-USER>@<ip-host>", max-count=100, max-time=5m
290 ignorecommand = if [ "<F-USER>" = "technical" ] && [ "<ip-host>" = "my-host.example.com" ]; then exit 0; fi;
291 exit 1
292 This will cache the result of ignorecommand (does not call it
293 repeatedly) for 5 minutes (cache time) for maximal 100 entries
294 (cache size), using values substituted like "user@host" as
295 cache-keys. Set option ignorecache to empty value disables the
296 cache.
297 bantime
299 effective ban duration (in seconds or time abbreviation format).
300 findtime
302 time interval (in seconds or time abbreviation format) before
303 the current time where failures will count towards a ban.
304 maxretry
306 number of failures that have to occur in the last findtime sec‐
307 onds to ban then IP.
308 backend
310 backend to be used to detect changes in the logpath.
311 It defaults to "auto" which will try "pyinotify", "gamin", "sys‐
312 temd" before "polling". Any of these can be specified. "pyino‐
313 tify" is only valid on Linux systems with the "pyinotify" Python
314 libraries. "gamin" requires the "gamin" libraries.
315 usedns use DNS to resolve HOST names that appear in the logs. By
317 default it is "warn" which will resolve hostnames to IPs however
318 it will also log a warning. If you are using DNS here you could
319 be blocking the wrong IPs due to the asymmetric nature of
320 reverse DNS (that the application used to write the domain name
321 to log) compared to forward DNS that fail2ban uses to resolve
322 this back to an IP (but not necessarily the same one). Ideally
323 you should configure your applications to log a real IP. This
324 can be set to "yes" to prevent warnings in the log or "no" to
325 disable DNS resolution altogether (thus ignoring entries where
326 hostname, not an IP is logged)..
327 prefregex
329 regex (Python regular expression) to parse a common part con‐
330 taining in every message (see prefregex in section FILTER FILES
331 for details).
332 failregex
334 regex (Python regular expression) to be added to the filter's
335 failregexes (see failregex in section FILTER FILES for details).
336 If this is useful for others using your application please share
337 you regular expression with the fail2ban developers by reporting
338 an issue (see REPORTING BUGS below).
339 ignoreregex
341 regex which, if the log line matches, would cause Fail2Ban not
342 consider that line. This line will be ignored even if it
343 matches a failregex of the jail or any of its filters.
344 maxmatches
346 max number of matched log-lines the jail would hold in memory
347 per ticket. By default it is the same value as maxretry of jail
348 (or default). This option also affects values resolvable via
349 tag <matches> in actions.
350 Backends
353 Available options are listed below.
354 pyinotify
356 requires pyinotify (a file alteration monitor) to be installed.
357 If pyinotify is not installed, Fail2ban will use auto.
358 gamin requires Gamin (a file alteration monitor) to be installed. If
360 Gamin is not installed, Fail2ban will use auto.
361 polling
363 uses a polling algorithm which does not require external
364 libraries.
365 systemd
367 uses systemd python library to access the systemd journal. Spec‐
368 ifying logpath is not valid for this backend and instead
369 utilises journalmatch from the jails associated filter config.
370 Multiple systemd-specific flags can be passed to the backend,
371 including journalpath and journalfiles, to explicitly set the
372 path to a directory or set of files. journalflags, which by
373 default is 4 and excludes user session files, can be set to
374 include them with journalflags=1, see the python-systemd docu‐
375 mentation for other settings and further details. Examples:
376 backend = systemd[journalpath=/run/log/journal/machine-1]
378 backend = systemd[journalfiles="/path/to/system.journal, /path/to/user.journal"]
379 backend = systemd[journalflags=1]
380 Actions
383 Each jail can be configured with only a single filter, but may have
384 multiple actions. By default, the name of a action is the action file‐
385 name, and in the case of Python actions, the ".py" file extension is
386 stripped. Where multiple of the same action are to be used, the actname
387 option can be assigned to the action to avoid duplication e.g.:
388 [ssh-iptables-ipset]
390 enabled = true
391 action = smtp.py[dest=chris@example.com, actname=smtp-chris]
392 smtp.py[dest=sally@example.com, actname=smtp-sally]
393
396 The time entries in fail2ban configuration (like findtime or bantime)
397 can be provided as integer in seconds or as string using special abbre‐
398 viation format (e. g. 600 is the same as 10m).
399 Abbreviation tokens:
402 years?, yea?, yy?
404 months?, mon?
405 weeks?, wee?, ww?
406 days?, da, dd?
407 hours?, hou?, hh?
408 minutes?, min?, mm?
409 seconds?, sec?, ss?
410 The question mark (?) means the optional character, so day as well as days can be used.
412 You can combine multiple tokens in format (separated with space resp.
414 without separator), e. g.: 1y 6mo or 1d12h30m.
415 Note that tokens m as well as mm means minutes, for month use abbrevia‐
416 tion mo or mon.
417 The time format can be tested using fail2ban-client:
419 fail2ban-client --str2sec 1d12h
421
424 Action files specify which commands are executed to ban and unban an IP
425 address.
426 Like with jail.conf files, if you desire local changes create an
428 [actionname].local file in the /etc/fail2ban/action.d directory and
429 override the required settings.
430 Action files have two sections, Definition and Init .
432 The [Init] section enables action-specific settings. In
434 jail.conf/jail.local these can be overridden for a particular jail as
435 options of the action's specification in that jail.
436 The following commands can be present in the [Definition] section.
438 actionstart
440 command(s) executed when the jail starts.
441 actionstop
443 command(s) executed when the jail stops.
444 actioncheck
446 command(s) ran before any other action. It aims to verify if the
447 environment is still ok.
448 actionban
450 command(s) that bans the IP address after maxretry log lines
451 matches within last findtime seconds.
452 actionunban
454 command(s) that unbans the IP address after bantime.
455 The [Init] section allows for action-specific settings. In
457 jail.conf/jail.local these can be overwritten for a particular jail as
458 options to the jail. The following are special tags which can be set in
459 the [Init] section:
460 timeout
462 The maximum period of time in seconds that a command can exe‐
463 cuted, before being killed.
464 Commands specified in the [Definition] section are executed through a
466 system shell so shell redirection and process control is allowed. The
467 commands should return 0, otherwise error would be logged. Moreover if
468 actioncheck exits with non-0 status, it is taken as indication that
469 firewall status has changed and fail2ban needs to reinitialize itself
470 (i.e. issue actionstop and actionstart commands). Tags are enclosed in
471 <>. All the elements of [Init] are tags that are replaced in all
472 action commands. Tags can be added by the fail2ban-client using the
473 "set <JAIL> action <ACT>" command. <br> is a tag that is always a new
474 line (\n).
475 More than a single command is allowed to be specified. Each command
477 needs to be on a separate line and indented with whitespace(s) without
478 blank lines. The following example defines two commands to be executed.
479 actionban = iptables -I fail2ban-<name> --source <ip> -j DROP
481 echo ip=<ip>, match=<match>, time=<time> >>
482 /var/log/fail2ban.log
483 Action Tags
486 The following tags are substituted in the actionban, actionunban and
487 actioncheck (when called before actionban/actionunban) commands.
488 ip IPv4 IP address to be banned. e.g. 192.168.0.2
490 failures
492 number of times the failure occurred in the log file. e.g. 3
493 ipfailures
495 As per failures, but total of all failures for that ip address
496 across all jails from the fail2ban persistent database. There‐
497 fore the database must be set for this tag to function.
498 ipjailfailures
500 As per ipfailures, but total based on the IPs failures for the
501 current jail.
502 time UNIX (epoch) time of the ban. e.g. 1357508484
504 matches
506 concatenated string of the log file lines of the matches that
507 generated the ban. Many characters interpreted by shell get
508 escaped to prevent injection, nevertheless use with caution.
509 ipmatches
511 As per matches, but includes all lines for the IP which are con‐
512 tained with the fail2ban persistent database. Therefore the
513 database must be set for this tag to function.
514 ipjailmatches
516 As per ipmatches, but matches are limited for the IP and for the
517 current jail.
518
521 Python based actions can also be used, where the file name must be
522 [actionname].py. The Python file must contain a variable Action which
523 points to Python class. This class must implement a minimum interface
524 as described by fail2ban.server.action.ActionBase, which can be inher‐
525 ited from to ease implementation.
526
529 Filter definitions are those in /etc/fail2ban/filter.d/*.conf and fil‐
530 ter.d/*.local.
531 These are used to identify failed authentication attempts in log files
533 and to extract the host IP address (or hostname if usedns is true).
534 Like action files, filter files are ini files. The main section is the
536 [Definition] section.
537 There are several standard filter definitions used in the [Definition]
539 section:
540 prefregex
542 is the regex (regular expression) to parse a common part con‐
543 taining in every message, which is applied after datepattern
544 found a match, before the search for any failregex or ignor‐
545 eregex would start.
546 If this regex doesn't match the process is starting immediately
547 with next message and search for any failregex does not occur.
548 If prefregex contains <F-CONTENT>...</F-CONTENT>, the part of
549 message enclosed between this tags will be extracted and her‐
550 after used as whole message for search with failregex or ignor‐
551 eregex.
552 For example:
554 prefregex = ^%(__prefix_line)s (?:ERROR|FAILURE) <F-CONTENT>.+</F-CONTENT>$
555 failregex = ^user not found
556 ^authentication failed
557 ^unknown authentication method
558 You can use prefregex in order to:
560 - specify 1 common regex to match some common part
562 present in every messages (do avoid unneeded match in
563 every failregex if you have more as one);
564 - to cut some interesting part of message only (to sim‐
566 plify failregex) enclosed between tags <F-CONTENT> and
567 </F-CONTENT>;
568 - to gather some failure identifier (e. g. some prefix
570 matched by <F-MLFID>...<F-MLFID/> tag) to identify sev‐
571 eral messages belonging to same session, where a connect
572 message containing IP followed by failure message(s) that
573 are not contain IP; this provides a new multi-line pars‐
574 ing method as replacement for old (slow an ugly) multi-
575 line parsing using buffering window (maxlines > 1 and
576 <SKIPLINES>);
577 - to ignore some wrong, too long or even unneeded mes‐
579 sages (a.k.a. parasite log traffic) which can be also
580 present in journal, before failregex search would take
581 place.
582 failregex
585 is the regex (regular expression) that will match failed
586 attempts. The standard replacement tags can be used as part of
587 the regex:
588 <HOST> - common regex for IP addresses and hostnames (if
590 usedns is enabled). Fail2Ban will work out which one of
591 these it actually is.
592 <ADDR> - regex for IP addresses (both families).
594 <IP4> - regex for IPv4 addresses.
596 <IP6> - regex for IPv6 addresses (also IP enclosed in
598 brackets).
599 <DNS> - regex to match hostnames.
601 <CIDR> - helper regex to match CIDR (simple integer form
603 of net-mask).
604 <SUBNET> - regex to match sub-net adresses (in form of
606 IP/CIDR, also single IP is matched, so part /CIDR is
607 optional).
608 NOTE: the failregex will be applied to the remaining part of
610 message after prefregex processing (if specified), which in turn
611 takes place after datepattern processing (whereby the string of
612 timestamp matching the best pattern, cut out from the message).
613 For multiline regexs (parsing with maxlines greater that 1) the
615 tag <SKIPLINES> can be used to separate lines. This allows lines
616 between the matched lines to continue to be searched for other
617 failures. The tag can be used multiple times.
618 This is an obsolete handling and if the lines contain some com‐
619 mon identifier, better would be to use new handling (with tags
620 <F-MLFID>...<F-MLFID/>).
621 ignoreregex
624 is the regex to identify log entries that should be ignored by
625 Fail2Ban, even if they match failregex.
626 maxlines
629 specifies the maximum number of lines to buffer to match multi-
630 line regexs. For some log formats this will not required to be
631 changed. Other logs may require to increase this value if a par‐
632 ticular log file is frequently written to.
633 datepattern
635 specifies a custom date pattern/regex as an alternative to the
636 default date detectors e.g. %%Y-%%m-%%d %%H:%%M(?::%%S)?. For a
637 list of valid format directives, see Python library documenta‐
638 tion for strptime behaviour.
639 NOTE: due to config file string substitution, that %'s must be
640 escaped by an % in config files.
641 Also, special values of Epoch (UNIX Timestamp), TAI64N and
642 ISO8601 can be used as datepattern.
643 Normally the regexp generated for datepattern additionally gets
644 word-start and word-end boundaries to avoid accidental match
645 inside of some word in a message. There are several prefixes
646 and words with special meaning that could be specified with cus‐
647 tom datepattern to control resulting regex:
648 {DEFAULT} - can be used to add default date patterns of
650 fail2ban.
651 {DATE} - can be used as part of regex that will be
653 replaced with default date patterns.
654 {^LN-BEG} - prefix (similar to ^) changing word-start
656 boundary to line-start boundary (ignoring up to 2 charac‐
657 ters). If used as value (not as a prefix), it will also
658 set all default date patterns (similar to {DEFAULT}), but
659 anchored at begin of message line.
660 {UNB} - prefix to disable automatic word boundaries in
662 regex.
663 {NONE} - value would allow to find failures totally with‐
665 out date-time in log message. Filter will use now as a
666 timestamp (or last known timestamp from previous line
667 with timestamp).
668 journalmatch
670 specifies the systemd journal match used to filter the journal
671 entries. See journalctl(1) and systemd.journal-fields(7) for
672 matches syntax and more details on special journal fields. This
673 option is only valid for the systemd backend.
674 Similar to actions, filters may have an [Init] section also (optional
676 since v.0.10). All parameters of both sections [Definition] and [Init]
677 can be overridden (redefined or extended) in jail.conf or jail.local
678 (or in related filter.d/filter-name.local). Every option supplied in
679 the jail to the filter overwrites the value specified in [Init] sec‐
680 tion, which in turm would overwrite the value in [Definition] section.
681 Besides the standard settings of filter both sections can be used to
682 initialize filter-specific options.
683 Filters can also have a section called [INCLUDES]. This is used to read
685 other configuration files.
686 before indicates that this file is read before the [Definition] sec‐
689 tion.
690 after indicates that this file is read after the [Definition] section.
693
696 Fail2ban was originally written by Cyril Jaquier
697 <cyril.jaquier@fail2ban.org>. At the moment it is maintained and fur‐
698 ther developed by Yaroslav O. Halchenko <debian@onerussian.com>, Daniel
699 Black <daniel.subs@internode.on.net> and Steven Hiscocks <steven-
700 fail2ban@hiscocks.me.uk> along with a number of contributors. See
701 THANKS file shipped with Fail2Ban for a full list. Manual page written
702 by Daniel Black and Yaroslav Halchenko.
703
705 Report bugs to https://github.com/fail2ban/fail2ban/issues
706
708 Copyright © 2013 the Fail2Ban Team
709 Copyright of modifications held by their respective authors.
710 Licensed under the GNU General Public License v2 (GPL) or (at your
711 option) any later version.
712
714 fail2ban-server(1)
715Fail2Ban November 2015 JAIL.CONF(5)