mirror of https://github.com/fail2ban/fail2ban
232 lines
11 KiB
Groff
232 lines
11 KiB
Groff
.TH JAIL.CONF "10" "October 2013" "Fail2Ban" "Fail2Ban Configuration"
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.SH NAME
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jail.conf \- configuration for the fail2ban server
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.SH SYNOPSIS
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.I fail2ban.conf fail2ban.d/*.conf / fail2ban.local / fail2ban.d/*.local
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.I jail.conf / jail.d/*.conf / jail.local / jail.d/*.local
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.I action.d/*.conf action.d/*.local
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.I filter.d/*.conf filter.d/*.local
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.SH DESCRIPTION
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Fail2ban has four configuration file types. Failban configuration files that contain global configuration items, Action configuration files are the commands for banning and unbanning of IP address, Filter configuration files tell fail2ban how to detect authentication failures, and Jail configuration files combine filters with actions into jails.
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.SH "CONFIGUATION FILES"
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There are *.conf files that are distributed by fail2ban and *.local file that contain user customizations.
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It is recommended that *.conf files should remain unchanged. If needed, customizations should be provided in *.local files.
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For instance, if you would like to customize the [ssh-iptables-ipset] jail, create a jail.local to extend jail.conf
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(the configuration for the fail2ban server). The jail.local file will be the following if you only need to enable
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it as follows:
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.TP
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\fIjail.local\fR
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[ssh-iptables-ipset]
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enabled = true
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.PP
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Override only the settings you need to change and the rest of the configuration will come from the corresponding
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*.conf file.
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\fI*.d/\fR
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.RS
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In addition to .local, for any jail.conf or fail2ban.conf file there can be a corresponding
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\fI.d/\fR directory to contain additional .conf files that will be read after the
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appropriate .local file. Last parsed file will take precidence over
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identical entries, parsed alphabetically, e.g.
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.RS
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\fIjail.d/01_enable.conf\fR - to enable a specific jail
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.RE
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.RS
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\fIjail.d/02_custom_port.conf\fR - containing specific configuration entry to change the port of the jail specified in the configuration
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.RE
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.RS
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\fIfail2ban.d/01_custom_log.conf\fR - containing specific configuration entry to use a different log path.
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.RE
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.RE
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The order \fIjail\fR configuration is parsed is:
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jail.conf ,
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jail.d/*.conf (in alphabetical order),
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jail.local, followed by
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jail.d/*.local (in alphabetical order).
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Likewise for fail2ban configuration except the filenames/directories begin with "fail2ban" and not "jail".
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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 new lines between the values which also requires space at the beginning of the line before the second value..
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Comments: use '#' for comment lines and ';' (following a space) for inline comments. When using Python2.X ';' can only be used on the first line due to an Python library bug.
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.SH "FAIL2BAN CONFIGURATION FILES"
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These files have one section, [Definition].
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The items that can be set are:
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.TP
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\fBloglevel\fR
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Set the log level output. , 1 = ERROR, 2 = WARN, 3 = INFO, 4 = DEBUG. Default: 1
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.TP
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\fBlogtarget\fR
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Set the log target. This could be a file, SYSLOG, STDERR or STDOUT. Only one log target can be specified.
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If you change logtarget from the default value and you are using logrotate -- also adjust or disable rotation in the
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corresponding configuration file (e.g. /etc/logrotate.d/fail2ban on Debian systems). Values can be [ STDOUT | STDERR | SYSLOG | FILE ] Default: STDERR.
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.TP
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\fBsocket\fR
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Set the socket file. This is used to communicate with the fail2ban server daemon. Do not remove this file when Fail2ban runs. It will not be possible to communicate with the server afterwards. Default: /var/run/fail2ban/fail2ban.sock
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.TP
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\fBpidfile\fR
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Set the PID file. This is used to store the process ID of the fail2ban server.
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# Values: [ FILE ] Default: /var/run/fail2ban/fail2ban.pid
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.SH "JAIL CONFIGURATION FILES"
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The following options are applicable to all jails. They appear in a section specifing the jail name or in the \fI[DEFAULT]\fR section which is used if individual sections don't have a value specified.
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.TP
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\fBfilter\fR
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This maps to the filename of the filter in /etc/fail2ban/filter.d/ without the .conf/.local extension. Only one filter can be specified.
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.TP
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\fBlogpath\fR
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This is the log filename(s). Globs, like paths containing * and ? or [0-9], can be used however only the files that exist at startup matching this glob pattern will be read.
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.TP
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\fBaction\fR
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This maps to the action(s) from \fI/etc/fail2ban/action.d/\fR without the \fI.conf\fR/\fI.local\fR extension. Arguements can be passed to actions to override the default values from the [Init] section. Arguements are specified by [name=value,name2=value]. Values can also be quoted. More that one action can be specified.
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.TP
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\fBignoreip\fR
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A list of IPs not to ban. These can include a CIDR mask too.
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.TP
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\fBignorecommand\fR
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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.
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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.
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.TP
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\fBbantime\fR
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When a ban occurs the ban stays in effect for this long (measured in seconds) after which the actionunban command in the action(s) are called.
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.TP
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\fBfindtime\fR
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Specifies the time interval in seconds before the current time where failures will count towards a ban.
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.TP
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\fBmaxretry\fR
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This is the number of failures that can occur in the last findtime seconds before a ban of that IP will result.
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.TP
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\fBbackend\fR
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This is the backend 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.
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.TP
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\fBusedns\fR
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This tells fail2ban to use DNS to resolve HOST names that appear in the logs. By default it is "warn" which will preform the resolving 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 asymetric 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 necessarly the same one). Idealy 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.
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.TP
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\fBfailregex\fR
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Here a failregex can be added which is effectively added to the filter's failregexes. If this is useful for others using your application please tell the fail2ban developers by reporting an issue (REPORTING BUGS below).
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.TP
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\fBignoreregex\fR
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Here you can specify a Python regex that when applied to a log file line will be ignored. This will be ignored even if it matches a failregex of the jail or any of its filters.
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.SH "ACTION CONFIGURATION FILES"
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Action files specify which commands are executed to ban and unban an IP address. They are located under \fI/etc/fail2ban/action.d\fR.
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Like with jail.conf files, if you desire local changes create an \fI[actionname].local\fR file in the \fI/etc/fail2ban/action.d\fR directory
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and override the required settings.
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Action files are ini files that have two sections, \fBDefinition\fR and \fBInit\fR .
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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.
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The following commands can be present in the [Definition] section.
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.TP
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\fBactionstart\fR
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command(s) executed when the jail starts.
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.TP
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\fBactionstop\fR
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command(s) executed when the jail stops.
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.TP
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\fBactioncheck\fR
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the command ran before any other action. It aims to verify if the environment is still ok.
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.TP
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\fBactionban\fR
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command(s) that bans the IP address after \fBmaxretry\fR log lines matches within last \fBfindtime\fR seconds.
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.TP
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\fBactionunban\fR
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command(s) that unbans the IP address after \fBbantime\fR.
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Commands specified in the [Definition] section are executed through a system shell so shell redirection and process control is allowed. The commands should
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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).
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Tags are enclosed in <>. All the elements of [Init] are tags that are replaced in all action commands. Tags can be added by the
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\fBfail2ban-client\fR using the setctag command. \fB<br>\fR is a tag that is always a new line (\\n).
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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
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two commands to be executed.
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actionban = iptables -I fail2ban-<name> --source <ip> -j DROP
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echo ip=<ip>, match=<match>, time=<time> >> /var/log/fail2ban.log
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.SS "Action Tags"
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The following tags are substituted in the actionban, actionunban and actioncheck (when called before actionban/actionunban) commands.
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.TP
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\fBip\fR
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An IPv4 ip address to be banned. e.g. 192.168.0.2
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.TP
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\fBfailures\fR
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The number of times the failure occurred in the log file. e.g. 3
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.TP
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\fBtime\fR
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The unix (epoch) time of the ban. e.g. 1357508484
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.TP
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\fBmatches\fR
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The concatenated string of the log file lines of the matches that generated the ban. Many characters interpreted by shell get escaped.
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.SH FILTER FILES
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Filter definitions are those in \fI/etc/fail2ban/filter.d/*.conf\fR and \fIfilter.d/*.local\fR.
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These are used to identify failed authentication attempts in logs and to extract the host IP address (or hostname if \fBusedns\fR is \fBtrue\fR).
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Like action files, filter files are ini files. The main section is the [Definition] section.
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There are two filter definitions used in the [Definition] section:
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.TP
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\fBfailregex\fR
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is the regex (\fBreg\fRular \fBex\fRpression) that will match failed attempts. The tag <HOST> is used as part of the regex and is itself a regex
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for IPv4 addresses and hostnames. fail2ban will work out which one of these it actually is.
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.TP
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\fBignoreregex\fR
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is the regex to identify log entries that should be ignored by fail2ban, even if they match failregex.
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Using Python "string interpolation" mechanisms, other definitions are allowed and can later be used within other definitions as %(defnname)s. For example.
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baduseragents = IE|wget
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failregex = useragent=%(baduseragents)s
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.PP
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Filters can also have a section called [INCLUDES]. This is used to read other configuration files.
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.TP
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\fBbefore\fR
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indicates that this file is read before the [Definition] section.
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.TP
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\fBafter\fR
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indicates that this file is read after the [Definition] section.
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.SH AUTHOR
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Fail2ban was originally written by Cyril Jaquier <cyril.jaquier@fail2ban.org>.
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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.
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.
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Manual page written by Daniel Black and Yaroslav Halchenko.
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.SH "REPORTING BUGS"
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Report bugs to https://github.com/fail2ban/fail2ban/issues
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.SH COPYRIGHT
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Copyright \(co 2013 Daniel Black
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.br
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Copyright of modifications held by their respective authors.
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Licensed under the GNU General Public License v2 (GPL).
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.SH "SEE ALSO"
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.br
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fail2ban-server(1)
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