jail.conf - configuration for the fail2ban server
fail2ban.conf fail2ban.d/*.conf fail2ban.local
fail2ban.d/*.local
jail.conf jail.d/*.conf jail.local jail.d/*.local
action.d/*.conf action.d/*.local action.d/*.py
filter.d/*.conf filter.d/*.local
Fail2ban has four configuration file types:
- fail2ban.conf
- Fail2Ban global configuration (such as logging)
- filter.d/*.conf
- Filters specifying how to detect authentication failures
- action.d/*.conf
- Actions defining the commands for banning and unbanning of IP address
- jail.conf
- Jails defining combinations of Filters with Actions.
*.conf files are distributed by Fail2Ban. It is recommended
that *.conf files should remain unchanged to ease upgrades. If needed,
customizations should be provided in *.local files. For example, if
you would like to enable the [ssh-iptables-ipset] jail specified in
jail.conf, create jail.local containing
- jail.local
- [ssh-iptables-ipset]
enabled = true
In .local files specify only the settings you would like to change
and the rest of the configuration will then come from the corresponding
.conf file which is parsed first.
- jail.d/ and
fail2ban.d/
-
In addition to .local, for jail.conf or fail2ban.conf file
there can be a corresponding .d/ directory containing additional
.conf files. The order e.g. for jail configuration would be:
jail.conf
jail.d/*.conf (in alphabetical order)
jail.local
jail.d/*.local (in alphabetical order).
i.e. all .local files are parsed after .conf files in the original
configuration file and files under .d directory. Settings in the file parsed
later take precedence over identical entries in previously parsed files.
Files are ordered alphabetically, e.g.
fail2ban.d/01_custom_log.conf - to use a different log
path
jail.d/01_enable.conf - to enable a specific
jail
jail.d/02_custom_port.conf - to change the port(s)
of a jail.
Configuration files have sections, those specified with [section
name], and name = value pairs. For those name items that can accept multiple
values, specify the values separated by spaces, or in separate lines space
indented at the beginning of the line before the second value.
Configuration files can include other (defining common variables)
configuration files, which is often used in Filters and Actions. Such
inclusions are defined in a section called [INCLUDES]:
- before
- indicates that the specified file is to be parsed before the current
file.
- after
- indicates that the specified file is to be parsed after the current
file.
Using Python "string interpolation" mechanisms, other
definitions are allowed and can later be used within other definitions as
%(name)s.
Fail2ban has more advanced syntax (similar python extended
interpolation). This extended interpolation is using
%(section/parameter)s to denote a value from a foreign section.
Besides cross section interpolation the value of parameter in [DEFAULT]
section can be retrieved with %(default/parameter)s.
Fail2ban supports also another feature named %(known/parameter)s (means
last known option with name parameter). This interpolation makes
possible to extend a stock filter or jail regexp in .local file (opposite to
simply set failregex/ignoreregex that overwrites it), e.g.
baduseragents = IE|wget|%(my-settings/baduseragents)s
failregex = %(known/failregex)s
useragent=%(baduseragents)s
Additionally to interpolation %(known/parameter)s, that
does not works for filter/action init parameters, an interpolation tag
<known/parameter> can be used (means last known init definition
of filters or actions with name parameter). This interpolation makes
possible to extend a parameters of stock filter or action directly in jail
inside jail.conf/jail.local file without creating a separately
filter.d/*.local file, e.g.
# filter.d/test.conf:
[Init]
test.method = GET
baduseragents = IE|wget
[Definition]
failregex = ^%(__prefix_line)\s+"<test.method>"\s+test\s+regexp\s+-\s+useragent=(?:<baduseragents>)
# jail.local:
[test]
# use filter "test", overwrite method to "POST" and extend known bad agents with "badagent":
filter = test[test.method=POST, baduseragents="badagent|<known/baduseragents>"]
Comments: use '#' for comment lines and '; ' (space is important)
for inline comments. When using Python2.X, '; ' can only be used on the
first line due to an Python library bug.
The items that can be set in section [Definition] are:
- loglevel
- verbosity level of log output: CRITICAL, ERROR, WARNING, NOTICE, INFO,
DEBUG, TRACEDEBUG, HEAVYDEBUG or corresponding numeric value (50-5).
Default: INFO (equal 20)
- logtarget
- log target: filename, SYSLOG, STDERR or STDOUT. Default: STDOUT if not set
in fail2ban.conf/fail2ban.local
Note. If fail2ban running as systemd-service, for logging to the
systemd-journal, the logtarget could be set to STDOUT
Only a single log target can be specified. If you change logtarget from the
default value and you are using logrotate -- also adjust or disable
rotation in the corresponding configuration file (e.g.
/etc/logrotate.d/fail2ban on Debian systems).
- socket
- socket filename. Default: /var/run/fail2ban/fail2ban.sock
This is used for communication with the fail2ban server daemon. Do not
remove this file when Fail2ban is running. It will not be possible to
communicate with the server afterwards.
- pidfile
- PID filename. Default: /var/run/fail2ban/fail2ban.pid
This is used to store the process ID of the fail2ban server.
- dbfile
- Database filename. Default: /var/lib/fail2ban/fail2ban.sqlite3
This defines where the persistent data for fail2ban is stored. This
persistent data allows bans to be reinstated and continue reading log
files from the last read position when fail2ban is restarted. A value of
None disables this feature.
- dbmaxmatches
- Max number of matches stored in database per ticket. Default: 10
This option sets the max number of matched log-lines could be stored per
ticket in the database. This also affects values resolvable via tags
<ipmatches> and <ipjailmatches> in actions.
- dbpurgeage
- Database purge age in seconds. Default: 86400 (24hours)
This sets the age at which bans should be purged from the database.
The config parameters of section [Thread] are:
- stacksize
- Stack size of each thread in fail2ban. Default: 0 (platform or configured
default)
This specifies the stack size (in KiB) to be used for subsequently created
threads, and must be 0 or a positive integer value of at least 32.
The following options are applicable to any jail. They appear in a
section specifying the jail name or in the [DEFAULT] section which
defines default values to be used if not specified in the individual
section.
- filter
- name of the filter -- filename of the filter in /etc/fail2ban/filter.d/
without the .conf/.local extension.
Only one filter can be specified.
- logpath
- filename(s) of the log files to be monitored, separated by new lines.
Globs -- paths containing * and ? or [0-9] -- can be used however only the
files that exist at start up matching this glob pattern will be
considered.
Optional space separated option 'tail' can be added to the end
of the path to cause the log file to be read from the end, else default
'head' option reads file from the beginning
Ensure syslog or the program that generates the log file isn't
configured to compress repeated log messages to "*last message
repeated 5 time*s" otherwise it will fail to detect. This is
called RepeatedMsgReduction in rsyslog and should be
Off.
- logencoding
- encoding of log files used for decoding. Default value of "auto"
uses current system locale.
- logtimezone
- Force the time zone for log lines that don't have one.
If this option is not specified, log lines from which no
explicit time zone has been found are interpreted by fail2ban in its own
system time zone, and that may turn to be inappropriate. While the best
practice is to configure the monitored applications to include explicit
offsets, this option is meant to handle cases where that is not
possible.
The supported time zones in this option are those with fixed
offset: Z, UTC[+-]hhmm (you can also use GMT as an alias to UTC).
This option has no effect on log lines on which an explicit
time zone has been found. Examples:
logtimezone = UTC
logtimezone = UTC+0200
logtimezone = GMT-0100
- banaction
- banning action (default iptables-multiport) typically specified in the
[DEFAULT] section for all jails.
This parameter will be used by the standard substitution of action
and can be redefined central in the [DEFAULT] section inside
jail.local (to apply it to all jails at once) or separately in each
jail, where this substitution will be used.
- banaction_allports
- the same as banaction but for some "allports" jails like
"pam-generic" or "recidive" (default
iptables-allports).
- action
- action(s) from /etc/fail2ban/action.d/ without the
.conf/.local extension.
Arguments can be passed to actions to override the default values from the
[Init] section in the action file. Arguments are specified by:
[name=value,name2=value,name3="values,values"]
Values can also be quoted (required when value includes a ","). More
that one action can be specified (in separate lines).
- ignoreself
- boolean value (default true) indicates the banning of own IP addresses
should be prevented
- ignoreip
- list of IPs not to ban. They can include a DNS resp. CIDR mask too. The
option affects additionally to ignoreself (if true) and don't need
to contain own DNS resp. IPs of the running host.
- ignorecommand
- command that is executed to determine if the current candidate IP for
banning (or failure-ID for raw IDs) should not be banned. The option
affects additionally to ignoreself and ignoreip and will be
first executed if both don't hit.
IP will not be banned if command returns successfully (exit code 0). Like
ACTION FILES, tags like <ip> are can be included in the
ignorecommand value and will be substituted before execution.
- ignorecache
- provide cache parameters (default disabled) for ignore failure check
(caching of the result from `ignoreip`, `ignoreself` and `ignorecommand`),
syntax:
ignorecache = key="<F-USER>@<ip-host>", max-count=100, max-time=5m
ignorecommand = if [ "<F-USER>" = "technical" ] && [ "<ip-host>" = "my-host.example.com" ]; then exit 0; fi;
exit 1
This will cache the result of
ignorecommand (does not call it repeatedly)
for 5 minutes (cache time) for maximal 100 entries (cache size), using values
substituted like "user@host" as cache-keys. Set option
ignorecache to empty value disables the cache.
- bantime
- effective ban duration (in seconds or time abbreviation format).
- findtime
- time interval (in seconds or time abbreviation format) before the current
time where failures will count towards a ban.
- maxretry
- number of failures that have to occur in the last findtime seconds
to ban then IP.
- backend
- backend to be used to detect changes in the logpath.
It defaults to "auto" which will try "pyinotify",
"gamin", "systemd" before "polling". Any of
these can be specified. "pyinotify" is only valid on Linux
systems with the "pyinotify" Python libraries. "gamin"
requires the "gamin" libraries.
- usedns
- use DNS to resolve HOST names that appear in the logs. By default it is
"warn" which will resolve hostnames to IPs however it will also
log a warning. If you are using DNS here you could be blocking the wrong
IPs due to the asymmetric nature of reverse DNS (that the application used
to write the domain name to log) compared to forward DNS that fail2ban
uses to resolve this back to an IP (but not necessarily the same one).
Ideally you should configure your applications to log a real IP. This can
be set to "yes" to prevent warnings in the log or "no"
to disable DNS resolution altogether (thus ignoring entries where
hostname, not an IP is logged)..
- prefregex
- regex (Python regular expression) to parse a common part
containing in every message (see prefregex in section FILTER FILES
for details).
- failregex
- regex (Python regular expression) to be added to the
filter's failregexes (see failregex in section FILTER FILES for
details). If this is useful for others using your application please share
you regular expression with the fail2ban developers by reporting an issue
(see REPORTING BUGS below).
- ignoreregex
- regex which, if the log line matches, would cause Fail2Ban not consider
that line. This line will be ignored even if it matches a failregex of the
jail or any of its filters.
- maxmatches
- max number of matched log-lines the jail would hold in memory per ticket.
By default it is the same value as maxretry of jail (or default).
This option also affects values resolvable via tag <matches>
in actions.
Available options are listed below.
- pyinotify
- requires pyinotify (a file alteration monitor) to be installed. If
pyinotify is not installed, Fail2ban will use auto.
- gamin
- requires Gamin (a file alteration monitor) to be installed. If Gamin is
not installed, Fail2ban will use auto.
- polling
- uses a polling algorithm which does not require external libraries.
- systemd
- uses systemd python library to access the systemd journal. Specifying
logpath is not valid for this backend and instead utilises
journalmatch from the jails associated filter config. Multiple
systemd-specific flags can be passed to the backend, including
journalpath and journalfiles, to explicitly set the path to
a directory or set of files. journalflags, which by default is 4
and excludes user session files, can be set to include them with
journalflags=1, see the python-systemd documentation for other
settings and further details. Examples:
backend = systemd[journalpath=/run/log/journal/machine-1]
backend = systemd[journalfiles="/path/to/system.journal, /path/to/user.journal"]
backend = systemd[journalflags=1]
Each jail can be configured with only a single filter, but may
have multiple actions. By default, the name of a action is the action
filename, and in the case of Python actions, the ".py" file
extension is stripped. Where multiple of the same action are to be used, the
actname option can be assigned to the action to avoid duplication
e.g.:
[ssh-iptables-ipset]
enabled = true
action = smtp.py[dest=chris@example.com, actname=smtp-chris]
smtp.py[dest=sally@example.com, actname=smtp-sally]
The time entries in fail2ban configuration (like findtime
or bantime) can be provided as integer in seconds or as string using
special abbreviation format (e. g. 600 is the same as
10m).
- Abbreviation
tokens:
-
years?, yea?, yy?
months?, mon?
weeks?, wee?, ww?
days?, da, dd?
hours?, hou?, hh?
minutes?, min?, mm?
seconds?, sec?, ss?
The question mark (?) means the optional character, so day as well as days can be used.
You can combine multiple tokens in format (separated with space
resp. without separator), e. g.: 1y 6mo or 1d12h30m.
Note that tokens m as well as mm means minutes, for month use
abbreviation mo or mon.
The time format can be tested using fail2ban-client:
fail2ban-client --str2sec 1d12h
Action files specify which commands are executed to ban and unban
an IP address.
Like with jail.conf files, if you desire local changes create an
[actionname].local file in the /etc/fail2ban/action.d
directory and override the required settings.
Action files have two sections, Definition and Init
.
The [Init] section enables action-specific settings. In
jail.conf/jail.local these can be overridden for a particular jail as
options of the action's specification in that jail.
The following commands can be present in the [Definition]
section.
- actionstart
- command(s) executed when the jail starts.
- actionstop
- command(s) executed when the jail stops.
- actioncheck
- command(s) ran before any other action. It aims to verify if the
environment is still ok.
- actionban
- command(s) that bans the IP address after maxretry log lines
matches within last findtime seconds.
- actionunban
- command(s) that unbans the IP address after bantime.
The [Init] section allows for action-specific settings. In
jail.conf/jail.local these can be overwritten for a particular jail
as options to the jail. The following are special tags which can be set in
the [Init] section:
- timeout
- The maximum period of time in seconds that a command can executed, before
being killed.
Commands specified in the [Definition] section are executed
through a system shell so shell redirection and process control is allowed.
The commands should return 0, otherwise error would be logged. Moreover if
actioncheck exits with non-0 status, it is taken as indication that
firewall status has changed and fail2ban needs to reinitialize itself (i.e.
issue actionstop and actionstart commands). Tags are enclosed
in <>. All the elements of [Init] are tags that are replaced in all
action commands. Tags can be added by the fail2ban-client using the
"set <JAIL> action <ACT>" command. <br>
is a tag that is always a new line (\n).
More than a single command is allowed to be specified. Each
command needs to be on a separate line and indented with whitespace(s)
without blank lines. The following example defines two commands to be
executed.
actionban = iptables -I fail2ban-<name> --source <ip> -j DROP
echo ip=<ip>, match=<match>, time=<time> >>
/var/log/fail2ban.log
The following tags are substituted in the actionban, actionunban
and actioncheck (when called before actionban/actionunban) commands.
- ip
- IPv4 IP address to be banned. e.g. 192.168.0.2
- failures
- number of times the failure occurred in the log file. e.g. 3
- ipfailures
- As per failures, but total of all failures for that ip address
across all jails from the fail2ban persistent database. Therefore the
database must be set for this tag to function.
- ipjailfailures
- As per ipfailures, but total based on the IPs failures for the
current jail.
- time
- UNIX (epoch) time of the ban. e.g. 1357508484
- matches
- concatenated string of the log file lines of the matches that generated
the ban. Many characters interpreted by shell get escaped to prevent
injection, nevertheless use with caution.
- ipmatches
- As per matches, but includes all lines for the IP which are
contained with the fail2ban persistent database. Therefore the database
must be set for this tag to function.
- ipjailmatches
- As per ipmatches, but matches are limited for the IP and for the
current jail.
Python based actions can also be used, where the file name must be
[actionname].py. The Python file must contain a variable
Action which points to Python class. This class must implement a
minimum interface as described by fail2ban.server.action.ActionBase,
which can be inherited from to ease implementation.
Filter definitions are those in
/etc/fail2ban/filter.d/*.conf and filter.d/*.local.
These are used to identify failed authentication attempts in log
files and to extract the host IP address (or hostname if usedns is
true).
Like action files, filter files are ini files. The main section is
the [Definition] section.
There are several standard filter definitions used in the
[Definition] section:
- prefregex
- is the regex (regular expression) to parse a common part
containing in every message, which is applied after datepattern
found a match, before the search for any failregex or
ignoreregex would start.
If this regex doesn't match the process is starting immediately with next
message and search for any failregex does not occur.
If prefregex contains <F-CONTENT>...</F-CONTENT>,
the part of message enclosed between this tags will be extracted and
herafter used as whole message for search with failregex or
ignoreregex.
- For example:
prefregex = ^%(__prefix_line)s (?:ERROR|FAILURE) <F-CONTENT>.+</F-CONTENT>$
failregex = ^user not found
^authentication failed
^unknown authentication method
- You can use prefregex in order to:
- - specify 1 common regex to match some common part present in every
messages (do avoid unneeded match in every failregex if you have
more as one);
- - to cut some interesting part of message only (to simplify
failregex) enclosed between tags <F-CONTENT> and
</F-CONTENT>;
- - to gather some failure identifier (e. g. some prefix matched by
<F-MLFID>...<F-MLFID/> tag) to identify several
messages belonging to same session, where a connect message containing IP
followed by failure message(s) that are not contain IP; this provides a
new multi-line parsing method as replacement for old (slow an ugly)
multi-line parsing using buffering window (maxlines > 1 and
<SKIPLINES>);
- - to ignore some wrong, too long or even unneeded messages (a.k.a.
parasite log traffic) which can be also present in journal, before
failregex search would take place.
- failregex
- is the regex (regular expression) that will match failed
attempts. The standard replacement tags can be used as part of the
regex:
- <HOST> - common regex for IP addresses and hostnames (if
usedns is enabled). Fail2Ban will work out which one of these it
actually is.
- <ADDR> - regex for IP addresses (both families).
- <IP4> - regex for IPv4 addresses.
- <IP6> - regex for IPv6 addresses (also IP enclosed in
brackets).
- <DNS> - regex to match hostnames.
- <CIDR> - helper regex to match CIDR (simple integer form of
net-mask).
- <SUBNET> - regex to match sub-net adresses (in form of
IP/CIDR, also single IP is matched, so part /CIDR is optional).
NOTE: the failregex will be applied to the remaining
part of message after prefregex processing (if specified), which in
turn takes place after datepattern processing (whereby the string of
timestamp matching the best pattern, cut out from the message).
For multiline regexs (parsing with maxlines greater that 1)
the tag <SKIPLINES> can be used to separate lines. This allows
lines between the matched lines to continue to be searched for other
failures. The tag can be used multiple times.
This is an obsolete handling and if the lines contain some common identifier,
better would be to use new handling (with tags
<F-MLFID>...<F-MLFID/>).
- ignoreregex
- is the regex to identify log entries that should be ignored by Fail2Ban,
even if they match failregex.
- maxlines
- specifies the maximum number of lines to buffer to match multi-line
regexs. For some log formats this will not required to be changed. Other
logs may require to increase this value if a particular log file is
frequently written to.
- datepattern
- specifies a custom date pattern/regex as an alternative to the default
date detectors e.g. %%Y-%%m-%%d %%H:%%M(?::%%S)?. For a list of valid
format directives, see Python library documentation for strptime
behaviour.
NOTE: due to config file string substitution, that %'s must be
escaped by an % in config files.
Also, special values of Epoch (UNIX Timestamp), TAI64N and
ISO8601 can be used as datepattern.
Normally the regexp generated for datepattern additionally gets word-start
and word-end boundaries to avoid accidental match inside of some word in a
message. There are several prefixes and words with special meaning that
could be specified with custom datepattern to control resulting
regex:
- {DEFAULT} - can be used to add default date patterns of
fail2ban.
- {DATE} - can be used as part of regex that will be replaced with
default date patterns.
- {^LN-BEG} - prefix (similar to ^) changing word-start
boundary to line-start boundary (ignoring up to 2 characters). If used as
value (not as a prefix), it will also set all default date patterns
(similar to {DEFAULT}), but anchored at begin of message line.
- {UNB} - prefix to disable automatic word boundaries in regex.
- {NONE} - value would allow to find failures totally without
date-time in log message. Filter will use now as a timestamp (or last
known timestamp from previous line with timestamp).
- journalmatch
- specifies the systemd journal match used to filter the journal entries.
See journalctl(1) and systemd.journal-fields(7) for matches
syntax and more details on special journal fields. This option is only
valid for the systemd backend.
Similar to actions, filters may have an [Init] section also
(optional since v.0.10). All parameters of both sections [Definition] and
[Init] can be overridden (redefined or extended) in jail.conf or
jail.local (or in related filter.d/filter-name.local). Every
option supplied in the jail to the filter overwrites the value specified in
[Init] section, which in turm would overwrite the value in [Definition]
section. Besides the standard settings of filter both sections can be used
to initialize filter-specific options.
Filters can also have a section called [INCLUDES]. This is used to
read other configuration files.
- before
- indicates that this file is read before the [Definition] section.
- after
- indicates that this file is read after the [Definition] section.
Fail2ban was originally written by Cyril Jaquier
<cyril.jaquier@fail2ban.org>. At the moment it is maintained and
further developed by Yaroslav O. Halchenko <debian@onerussian.com>,
Daniel Black <daniel.subs@internode.on.net> and Steven Hiscocks
<steven-fail2ban@hiscocks.me.uk> along with a number of contributors.
See THANKS file shipped with Fail2Ban for a full list. Manual page
written by Daniel Black and Yaroslav Halchenko.
Report bugs to https://github.com/fail2ban/fail2ban/issues
Copyright © 2013 the Fail2Ban Team
Copyright of modifications held by their respective authors.
Licensed under the GNU General Public License v2 (GPL) or (at your option) any
later version.