FAIL2BAN(1)

💖 fail2ban — the group chat manual 💖

okay so bestie, welcome to the fail2ban page from the General Commands Manual. it's a whole set of server and client programs, and the entire point of them is to limit brute force authentication attempts. yes. the "stop guessing my password" squad. periodt. 🔥

✨ NAME ✨

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

🌸 DESCRIPTION 🌸

so here's the tea. Fail2Ban consists of a client, a server, and configuration files, and the whole little family exists to limit brute force authentication attempts. no cap.

the server program, fail2ban-server, is the one doing the actual work — it's responsible for monitoring log files and issuing ban/unban commands. 👑 it's giving main character energy, honestly. it gets configured through a simple protocol by fail2ban-client, which can also read configuration files and issue the corresponding configuration commands to the server. so client is like the server's bestie who relays the messages. 🫶

for details on the configuration of fail2ban, go read the jail.conf(5) manual page. and bestie, a jail (as specified in jail.conf) couples filters and actions definitions for any given list of files to get monitored. that's the vibe. 💅

• 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 — lowkey may be of use — its manual page is fail2ban-regex(1)

💀 LIMITATION 💀

ngl this part is important so listen up. Fail2Ban is able to reduce the rate of incorrect authentications attempts, however it cannot eliminate the risk that weak authentication presents. 😭 it's a rate limiter, not a miracle worker. if you really want to protect services, configure services to use only two factor or public/private authentication mechanisms. that's the only way to actually lock it down.

and here's the scary one: 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. fr fr, don't hand out shell access like it's candy.

🎀 FILES 🎀

• /etc/fail2ban/*

🦋 AUTHOR 🦋

Manual page written by Daniel Black and Yaroslav Halchenko. absolute icons, we stan. 🫶

🐛 REPORTING BUGS 🐛

found a bug? not me being dramatic but please report bugs to:

https://github.com/fail2ban/fail2ban/issues

👑 COPYRIGHT 👑

Copyright © 2013

Copyright of modifications held by their respective authors. Licensed under the GNU General Public License v2 (GPL). slay, legally. ⚖️✨

🌈 SEE ALSO 🌈

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

and that's the whole page bestie 🎀 this one's from Fail2Ban, dated March 2013 — yeah she's an older queen but she still runs the group chat. mwah 💋🧚💜