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 These files have one section, [Definition].
138 The items that can be set are:
140 loglevel
142 verbosity level of log output: CRITICAL, ERROR, WARNING, NOTICE,
143 INFO, DEBUG, TRACEDEBUG, HEAVYDEBUG or corresponding numeric
144 value (50-5). Default: ERROR (equal 40)
145 logtarget
147 log target: filename, SYSLOG, STDERR or STDOUT. Default: STDOUT
148 if not set in fail2ban.conf/fail2ban.local
149 Note. If fail2ban running as systemd-service, for logging to the
150 systemd-journal, the logtarget could be set to STDOUT
151 Only a single log target can be specified. If you change log‐
152 target from the default value and you are using logrotate --
153 also adjust or disable rotation in the corresponding configura‐
154 tion file (e.g. /etc/logrotate.d/fail2ban on Debian systems).
155 socket socket filename. Default: /var/run/fail2ban/fail2ban.sock
157 This is used for communication with the fail2ban server daemon.
158 Do not remove this file when Fail2ban is running. It will not be
159 possible to communicate with the server afterwards.
160 pidfile
162 PID filename. Default: /var/run/fail2ban/fail2ban.pid
163 This is used to store the process ID of the fail2ban server.
164 dbfile Database filename. Default: /var/lib/fail2ban/fail2ban.sqlite3
166 This defines where the persistent data for fail2ban is stored.
167 This persistent data allows bans to be reinstated and continue
168 reading log files from the last read position when fail2ban is
169 restarted. A value of None disables this feature.
170 dbpurgeage
172 Database purge age in seconds. Default: 86400 (24hours)
173 This sets the age at which bans should be purged from the data‐
174 base.
175
178 The following options are applicable to any jail. They appear in a sec‐
179 tion specifying the jail name or in the [DEFAULT] section which defines
180 default values to be used if not specified in the individual section.
181 filter name of the filter -- filename of the filter in
183 /etc/fail2ban/filter.d/ without the .conf/.local extension.
184 Only one filter can be specified.
185 logpath
187 filename(s) of the log files to be monitored, separated by new
188 lines.
189 Globs -- paths containing * and ? or [0-9] -- can be used how‐
190 ever only the files that exist at start up matching this glob
191 pattern will be considered.
192 Optional space separated option 'tail' can be added to the end
194 of the path to cause the log file to be read from the end, else
195 default 'head' option reads file from the beginning
196 Ensure syslog or the program that generates the log file isn't
198 configured to compress repeated log messages to "*last message
199 repeated 5 time*s" otherwise it will fail to detect. This is
200 called RepeatedMsgReduction in rsyslog and should be Off.
201 logencoding
203 encoding of log files used for decoding. Default value of "auto"
204 uses current system locale.
205 logtimezone
207 Force the time zone for log lines that don't have one.
208 If this option is not specified, log lines from which no
210 explicit time zone has been found are interpreted by fail2ban in
211 its own system time zone, and that may turn to be inappropriate.
212 While the best practice is to configure the monitored applica‐
213 tions to include explicit offsets, this option is meant to han‐
214 dle cases where that is not possible.
215 The supported time zones in this option are those with fixed
217 offset: Z, UTC[+-]hhmm (you can also use GMT as an alias to
218 UTC).
219 This option has no effect on log lines on which an explicit time
221 zone has been found. Examples:
222 logtimezone = UTC
224 logtimezone = UTC+0200
225 logtimezone = GMT-0100
226 banaction
229 banning action (default iptables-multiport) typically specified
230 in the [DEFAULT] section for all jails.
231 This parameter will be used by the standard substitution of
232 action and can be redefined central in the [DEFAULT] section
233 inside jail.local (to apply it to all jails at once) or sepa‐
234 rately in each jail, where this substitution will be used.
235 banaction_allports
237 the same as banaction but for some "allports" jails like "pam-
238 generic" or "recidive" (default iptables-allports).
239 action action(s) from /etc/fail2ban/action.d/ without the .conf/.local
241 extension.
242 Arguments can be passed to actions to override the default val‐
243 ues from the [Init] section in the action file. Arguments are
244 specified by:
245 [name=value,name2=value,name3="values,values"]
247 Values can also be quoted (required when value includes a ",").
249 More that one action can be specified (in separate lines).
250 ignoreself
252 boolean value (default true) indicates the banning of own IP
253 addresses should be prevented
254 ignoreip
256 list of IPs not to ban. They can include a DNS resp. CIDR mask
257 too. The option affects additionally to ignoreself (if true) and
258 don't need to contain own DNS resp. IPs of the running host.
259 ignorecommand
261 command that is executed to determine if the current candidate
262 IP for banning (or failure-ID for raw IDs) should not be banned.
263 The option affects additionally to ignoreself and ignoreip and
264 will be first executed if both don't hit.
265 IP will not be banned if command returns successfully (exit code
266 0). Like ACTION FILES, tags like <ip> are can be included in
267 the ignorecommand value and will be substituted before execu‐
268 tion.
269 ignorecache
271 provide cache parameters (default disabled) for ignore failure
272 check (caching of the result from `ignoreip`, `ignoreself` and
273 `ignorecommand`), syntax:
274 ignorecache = key="<F-USER>@<ip-host>", max-count=100, max-time=5m
276 ignorecommand = if [ "<F-USER>" = "technical" ] && [ "<ip-host>" = "my-host.example.com" ]; then exit 0; fi;
277 exit 1
278 This will cache the result of ignorecommand (does not call it
279 repeatedly) for 5 minutes (cache time) for maximal 100 entries
280 (cache size), using values substituted like "user@host" as
281 cache-keys. Set option ignorecache to empty value disables the
282 cache.
283 bantime
285 effective ban duration (in seconds or time abbreviation format).
286 findtime
288 time interval (in seconds or time abbreviation format) before
289 the current time where failures will count towards a ban.
290 maxretry
292 number of failures that have to occur in the last findtime sec‐
293 onds to ban then IP.
294 backend
296 backend to be used to detect changes in the logpath.
297 It defaults to "auto" which will try "pyinotify", "gamin", "sys‐
298 temd" before "polling". Any of these can be specified. "pyino‐
299 tify" is only valid on Linux systems with the "pyinotify" Python
300 libraries. "gamin" requires the "gamin" libraries.
301 usedns use DNS to resolve HOST names that appear in the logs. By
303 default it is "warn" which will resolve hostnames to IPs however
304 it will also log a warning. If you are using DNS here you could
305 be blocking the wrong IPs due to the asymmetric nature of
306 reverse DNS (that the application used to write the domain name
307 to log) compared to forward DNS that fail2ban uses to resolve
308 this back to an IP (but not necessarily the same one). Ideally
309 you should configure your applications to log a real IP. This
310 can be set to "yes" to prevent warnings in the log or "no" to
311 disable DNS resolution altogether (thus ignoring entries where
312 hostname, not an IP is logged)..
313 failregex
315 regex (Python regular expression) to be added to the filter's
316 failregexes. If this is useful for others using your application
317 please share you regular expression with the fail2ban developers
318 by reporting an issue (see REPORTING BUGS below).
319 ignoreregex
321 regex which, if the log line matches, would cause Fail2Ban not
322 consider that line. This line will be ignored even if it
323 matches a failregex of the jail or any of its filters.
324 Backends
327 Available options are listed below.
328 pyinotify
330 requires pyinotify (a file alteration monitor) to be installed.
331 If pyinotify is not installed, Fail2ban will use auto.
332 gamin requires Gamin (a file alteration monitor) to be installed. If
334 Gamin is not installed, Fail2ban will use auto.
335 polling
337 uses a polling algorithm which does not require external
338 libraries.
339 systemd
341 uses systemd python library to access the systemd journal. Spec‐
342 ifying logpath is not valid for this backend and instead
343 utilises journalmatch from the jails associated filter config.
344 Actions
347 Each jail can be configured with only a single filter, but may have
348 multiple actions. By default, the name of a action is the action file‐
349 name, and in the case of Python actions, the ".py" file extension is
350 stripped. Where multiple of the same action are to be used, the actname
351 option can be assigned to the action to avoid duplication e.g.:
352 [ssh-iptables-ipset]
354 enabled = true
355 action = smtp.py[dest=chris@example.com, actname=smtp-chris]
356 smtp.py[dest=sally@example.com, actname=smtp-sally]
357
360 The time entries in fail2ban configuration (like findtime or bantime)
361 can be provided as integer in seconds or as string using special abbre‐
362 viation format (e. g. 600 is the same as 10m).
363 Abbreviation tokens:
366 years?, yea?, yy?
368 months?, mon?
369 weeks?, wee?, ww?
370 days?, da, dd?
371 hours?, hou?, hh?
372 minutes?, min?, mm?
373 seconds?, sec?, ss?
374 The question mark (?) means the optional character, so day as well as days can be used.
376 You can combine multiple tokens in format (separated with space resp.
378 without separator), e. g.: 1y 6mo or 1d12h30m.
379 Note that tokens m as well as mm means minutes, for month use abbrevia‐
380 tion mo or mon.
381 The time format can be tested using fail2ban-client:
383 fail2ban-client --str2sec 1d12h
385
388 Action files specify which commands are executed to ban and unban an IP
389 address.
390 Like with jail.conf files, if you desire local changes create an
392 [actionname].local file in the /etc/fail2ban/action.d directory and
393 override the required settings.
394 Action files have two sections, Definition and Init .
396 The [Init] section enables action-specific settings. In
398 jail.conf/jail.local these can be overridden for a particular jail as
399 options of the action's specification in that jail.
400 The following commands can be present in the [Definition] section.
402 actionstart
404 command(s) executed when the jail starts.
405 actionstop
407 command(s) executed when the jail stops.
408 actioncheck
410 command(s) ran before any other action. It aims to verify if the
411 environment is still ok.
412 actionban
414 command(s) that bans the IP address after maxretry log lines
415 matches within last findtime seconds.
416 actionunban
418 command(s) that unbans the IP address after bantime.
419 The [Init] section allows for action-specific settings. In
421 jail.conf/jail.local these can be overwritten for a particular jail as
422 options to the jail. The following are special tags which can be set in
423 the [Init] section:
424 timeout
426 The maximum period of time in seconds that a command can exe‐
427 cuted, before being killed.
428 Commands specified in the [Definition] section are executed through a
430 system shell so shell redirection and process control is allowed. The
431 commands should return 0, otherwise error would be logged. Moreover if
432 actioncheck exits with non-0 status, it is taken as indication that
433 firewall status has changed and fail2ban needs to reinitialize itself
434 (i.e. issue actionstop and actionstart commands). Tags are enclosed in
435 <>. All the elements of [Init] are tags that are replaced in all
436 action commands. Tags can be added by the fail2ban-client using the
437 "set <JAIL> action <ACT>" command. <br> is a tag that is always a new
438 line (\n).
439 More than a single command is allowed to be specified. Each command
441 needs to be on a separate line and indented with whitespace(s) without
442 blank lines. The following example defines two commands to be executed.
443 actionban = iptables -I fail2ban-<name> --source <ip> -j DROP
445 echo ip=<ip>, match=<match>, time=<time> >>
446 /var/log/fail2ban.log
447 Action Tags
450 The following tags are substituted in the actionban, actionunban and
451 actioncheck (when called before actionban/actionunban) commands.
452 ip IPv4 IP address to be banned. e.g. 192.168.0.2
454 failures
456 number of times the failure occurred in the log file. e.g. 3
457 ipfailures
459 As per failures, but total of all failures for that ip address
460 across all jails from the fail2ban persistent database. There‐
461 fore the database must be set for this tag to function.
462 ipjailfailures
464 As per ipfailures, but total based on the IPs failures for the
465 current jail.
466 time UNIX (epoch) time of the ban. e.g. 1357508484
468 matches
470 concatenated string of the log file lines of the matches that
471 generated the ban. Many characters interpreted by shell get
472 escaped to prevent injection, nevertheless use with caution.
473 ipmatches
475 As per matches, but includes all lines for the IP which are con‐
476 tained with the fail2ban persistent database. Therefore the
477 database must be set for this tag to function.
478 ipjailmatches
480 As per ipmatches, but matches are limited for the IP and for the
481 current jail.
482
485 Python based actions can also be used, where the file name must be
486 [actionname].py. The Python file must contain a variable Action which
487 points to Python class. This class must implement a minimum interface
488 as described by fail2ban.server.action.ActionBase, which can be inher‐
489 ited from to ease implementation.
490
493 Filter definitions are those in /etc/fail2ban/filter.d/*.conf and fil‐
494 ter.d/*.local.
495 These are used to identify failed authentication attempts in log files
497 and to extract the host IP address (or hostname if usedns is true).
498 Like action files, filter files are ini files. The main section is the
500 [Definition] section.
501 There are two filter definitions used in the [Definition] section:
503 failregex
505 is the regex (regular expression) that will match failed
506 attempts. The tag <HOST> is used as part of the regex and is
507 itself a regex for IPv4 addresses (and hostnames if usedns).
508 Fail2Ban will work out which one of these it actually is. For
509 multiline regexs the tag <SKIPLINES> should be used to separate
510 lines. This allows lines between the matched lines to continue
511 to be searched for other failures. The tag can be used multiple
512 times.
513 ignoreregex
516 is the regex to identify log entries that should be ignored by
517 Fail2Ban, even if they match failregex.
518 Similar to actions, filters have an [Init] section which can be over‐
522 ridden in jail.conf/jail.local. Besides the filter-specific settings,
523 the filter [Init] section can be used to set following standard
524 options:
525 maxlines
527 specifies the maximum number of lines to buffer to match multi-
528 line regexs. For some log formats this will not required to be
529 changed. Other logs may require to increase this value if a par‐
530 ticular log file is frequently written to.
531 datepattern
533 specifies a custom date pattern/regex as an alternative to the
534 default date detectors e.g. %Y-%m-%d %H:%M(?::%S)?. For a list
535 of valid format directives, see Python library documentation for
536 strptime behaviour.
537 Also, special values of Epoch (UNIX Timestamp), TAI64N and
538 ISO8601 can be used.
539 NOTE: due to config file string substitution, that %'s must be
540 escaped by an % in config files.
541 journalmatch
543 specifies the systemd journal match used to filter the journal
544 entries. See journalctl(1) and systemd.journal-fields(7) for
545 matches syntax and more details on special journal fields. This
546 option is only valid for the systemd backend.
547 Similar to actions [Init] section enables filter-specific settings. All
549 parameters specified in [Init] section can be redefined or extended in
550 jail.conf/jail.local.
551 Filters can also have a section called [INCLUDES]. This is used to read
553 other configuration files.
554 before indicates that this file is read before the [Definition] sec‐
557 tion.
558 after indicates that this file is read after the [Definition] section.
561
564 Fail2ban was originally written by Cyril Jaquier
565 <cyril.jaquier@fail2ban.org>. At the moment it is maintained and fur‐
566 ther developed by Yaroslav O. Halchenko <debian@onerussian.com>, Daniel
567 Black <daniel.subs@internode.on.net> and Steven Hiscocks <steven-
568 fail2ban@hiscocks.me.uk> along with a number of contributors. See
569 THANKS file shipped with Fail2Ban for a full list. Manual page written
570 by Daniel Black and Yaroslav Halchenko.
571
573 Report bugs to https://github.com/fail2ban/fail2ban/issues
574
576 Copyright © 2013 the Fail2Ban Team
577 Copyright of modifications held by their respective authors.
578 Licensed under the GNU General Public License v2 (GPL) or (at your
579 option) any later version.
580
582 fail2ban-server(1)
583Fail2Ban November 2015 JAIL.CONF(5)