Specify one or more log files for monitoring for failures, separated by new lines. 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
A command that is executed to determine if the current ban's actionban is to be executed. This command will return true if the current ban should be ignored. A false return value will result in the ban's actionban executed.
Like ACTION FILES, tags like <ip> are can be included in the ignore command value and will be substitued before execution. Currently only <ip> is supported however more will be added later.
\fBbackend\fR specifies the backend used to get files modification. This option can be overridden in each jail as well.
Available options are listed below.
.TP
\fIpyinotify\fR
requires pyinotify (a file alteration monitor) to be installed. If pyinotify is not installed, Fail2ban will use auto.
.TP
\fIgamin\fR
requires Gamin (a file alteration monitor) to be installed. If Gamin is not installed, Fail2ban will use auto.
.TP
\fIpolling\fR
uses a polling algorithm which does not require external libraries.
.TP
\fIsystemd\fR
uses systemd python library to access the systemd journal. Specifying \fBlogpath\fR is not valid for this backend and instead utilises \fBjournalmatch\fR from the jails associated filter config.
.TP
\fIauto\fR
will try to use the following backends, in order: pyinotify, gamin, polling
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 \fBactname\fR option can be assigned to the action to avoid duplication e.g.:
The [Init] section allows for action-specific settings. In \fIjail.conf/jail.local\fR these can be overwritten for a particular jail as options to the jail.
command(s) that unbans the IP address after \fBbantime\fR.
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 \fBactioncheck\fR exits with non-0 status, it is taken as indication that firewall status has changed and fail2ban needs to reinitialize itself (i.e. issue \fBactionstop\fR and \fBactionstart\fR commands).
More than a single command is allowed to be specified. Each command needs to be on a separate line and indented with whitespaces without blank lines. The following example defines
Python based actions can also be used, where the file name must be \fI[actionname].py\fR. The python file must contain a variable \fIAction\fR which points to python class. This class must implement a minimum interface as described by \fIfail2ban.server.action.ActionBase\fR, which can be inherited from to ease implementation.
As per \fBfailures\fR, 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.
.TP
\fBipjailfailures\fR
As per \fBipfailures\fR, but total based on the IPs failures for the current jail.
The string of the log file lines of the matches that generated the ban. Many characters interpreted by shell get escaped. New lines are maintained, so actions should be careful to enclose the tag in quotes.
.TP
\fBipmatches\fR
As per \fBmatches\fR, 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.
.TP
\fBipjailmatches\fR
As per \fBipmatches\fR, but matches are limited for the IP and for the current jail.
For multiline regexs the tag \fI<SKIPLINES>\fR should 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.
is the regex to identify log entries that should be ignored by fail2ban, even if they match failregex.
Using Python "string interpolation" mechanisms, other definitions are allowed and can later be used within other definitions as %(defnname)s. For example.
Similar to actions, filters have an [Init] section which can be overridden in \fIjail.conf/jail.local\fR. The filter [Init] section is limited to the following options:
.TP
\fBmaxlines\fR
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.
specifies the systemd journal match used to filter the journal entries. See \fBjournalctl(1)\fR and \fBsystemd.journal-fields(7)\fR for matches syntax and more details on special journal fields. This option is only valid for the \fIsystemd\fR backend.
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> and a number of contributors. See \fBTHANKS\fR file shipped with Fail2Ban for a full list.
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Manual page written by Daniel Black and Yaroslav Halchenko.
