\fI*.conf\fR files are distributed by Fail2Ban. It is recommended that *.conf files should remain unchanged to ease upgrades. If needed, customizations should be provided in \fI*.local\fR files. For example, if you would like to enable the [ssh-iptables-ipset] jail specified in jail.conf, create jail.local containing
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.
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]:
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.
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.
The following options are applicable to any jail. They appear in a section specifying the jail name or in the \fI[DEFAULT]\fR section which defines default values to be used if not specified in the individual section.
filename(s) of the log files to be monitored. 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.
Ensure syslog or the program that generates the log file isn't configured to compress repeated log messages to "\fI*last message repeated 5 time*s\fR" otherwise it will fail to detect. This is called \fIRepeatedMsgReduction\fR in rsyslog and should be \fIOff\fR.
action(s) from \fI/etc/fail2ban/action.d/\fR without the \fI.conf\fR/\fI.local\fR 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]. Values can also be quoted. More that one action can be specified (in separate lines).
command that is executed to determine if the current candidate IP for banning should not be banned. 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. Currently only <ip> is supported however more will be added later.
backend to be used to detect changes in the logpath. It defaults to "auto" which will try "pyinotify", "gamin" 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.
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)..
regex (Python \fBreg\fRular \fBex\fRpression) to be added to the filter's failregexes. 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).
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.
The [Init] section enables action-specific settings. In \fIjail.conf/jail.local\fR these can be overridden for a particular jail as options of the action's specification in that jail.
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 whitespace(s) without blank lines. The following example defines
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.
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 \fBTHANKS\fR file shipped with Fail2Ban for a full list.
