DOKK / manpages / debian 10 / fail2ban / fail2ban.1.en
FAIL2BAN(1) General Commands Manual FAIL2BAN(1)

fail2ban - a set of server and client programs to limit brute force authentication attempts.

Fail2Ban consists of a client, server and configuration files to limit brute force authentication attempts.

The server program fail2ban-server is responsible for monitoring log files and issuing ban/unban commands. It gets configured through a simple protocol by fail2ban-client, which can also read configuration files and issue corresponding configuration commands to the server.

For details on the configuration of fail2ban see the jail.conf(5) manual page. A jail (as specified in jail.conf) couples filters and actions definitions for any given list of files to get monitored.

For details on the command-line options of fail2ban-server see the fail2ban-server(1) manual page.

For details on the command-line options and commands for configuring the server via fail2ban-client see the fail2ban-client(1) manual page.

For testing regular expressions specified in a filter using the fail2ban-regex program may be of use and its manual page is fail2ban-regex(1).

Fail2Ban is able to reduce the rate of incorrect authentications attempts however it cannot eliminate the risk that weak authentication presents. Configure services to use only two factor or public/private authentication mechanisms if you really want to protect services.

A local user is able to inject messages into syslog and using a Fail2Ban jail that reads from syslog, they can effectively trigger a DoS attack against any IP. Know this risk and configure Fail2Ban/grant shell access accordingly.


Manual page written by Daniel Black and Yaroslav Halchenko

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Copyright © 2013
Copyright of modifications held by their respective authors. Licensed under the GNU General Public License v2 (GPL).

fail2ban-server(1) fail2ban-client(1) fail2ban-regex(1) jail.conf(5)

March 2013 Fail2Ban