Fail2Ban : Intrusion Prevention System2024/09/09 |
|
Install and configure [Fail2Ban] that is the kind of Intrusion Detection System. |
|
| [1] | Install Fail2Ban. |
|
root@dlp:~ #
pkg install -y py311-fail2ban whois # enable packet filter root@dlp:~ # sysrc pf_enable="YES" root@dlp:~ # sysrc pflogd_enable="YES" root@dlp:~ # sysrc pf_rules="/etc/pf.conf"
root@dlp:~ #
vi /etc/pf.conf # create new file
set skip on lo
scrub in anchor "f2b/*" service pf start
|
| [2] | The default configuration is defined in [/usr/local/etc/fail2ban/jail.conf]. The default values may change with package updates, so if you want to change the settings, create a [jail.local] file and modify it. |
|
root@dlp:~ #
vi /usr/local/etc/fail2ban/jail.conf # line 87 : ignore your own local IP #ignoreself = true # line 92 : possible to add ignored networks #ignoreip = 127.0.0.1/8 ::1 # line 103 : number of seconds that a host is banned # - 1m ⇒ 1 minutes # - 1h ⇒ 1 houer # - 1d ⇒ 1 day # - 1mo ⇒ 1 month # - 1y ⇒ 1 year bantime = 10m # line 107 : A host is banned if it has generated "maxretry" during the last "findtime" findtime = 10m # line 110 : "maxretry" is the number of failures before a host get banned maxretry = 5 # line 178 : destination email address if enabling email notification destemail = root@localhost # line 181 : sender address if enabling email notification sender = root@<fq-hostname> # line 263 : default action # - %(action_)s ⇒ ban only # - %(action_mw)s ⇒ band and email notification (includes Whois info) # - %(action_mwl)s ⇒ band and email notification (includes Whois info and logs) action = %(action_)s
root@dlp:~ #
vi /usr/local/etc/fail2ban/jail.local
# create new
# possible to override the default values
[DEFAULT]
ignoreip = 127.0.0.1/8 ::1
banaction = pf[actiontype=<multiport>]
banaction_allports = pf[actiontype=<allports>]
bantime = 1d
findtime = 5m
maxretry = 5
destemail = root@localhost
sender = root@dlp.srv.world
service fail2ban enable fail2ban enabled in /etc/rc.conf root@dlp:~ # service fail2ban start Server ready |
| [3] | If you want to monitor services, add settings. (Default is unset) As an example, set the SSH as the service to be monitored. |
|
root@dlp:~ # fail2ban-client status Status |- Number of jail: 0 `- Jail list:
root@dlp:~ #
vi /usr/local/etc/fail2ban/jail.d/sshd.conf # create new [sshd] enabled = true # possible to override the default values by service bantime = 600 findtime = 3m maxretry = 5 action = %(action_mw)s
root@dlp:~ #
service fail2ban reload OK # show status root@dlp:~ # fail2ban-client status sshd Status for the jail: sshd |- Filter | |- Currently failed: 0 | |- Total failed: 0 | `- File list: /var/log/auth.log `- Actions |- Currently banned: 0 |- Total banned: 0 `- Banned IP list: # some hosts that exceed the threshold are banned root@dlp:~ # fail2ban-client status sshd Status for the jail: sshd |- Filter | |- Currently failed: 0 | |- Total failed: 5 | `- File list: /var/log/auth.log `- Actions |- Currently banned: 1 |- Total banned: 1 `- Banned IP list: 10.0.0.203 # actual ban action is controlled by pf root@dlp:~ # pfctl -a f2b/sshd -s rules block drop quick proto tcp from <f2b-sshd> to any port = ssh root@dlp:~ # pfctl -a f2b/sshd -t f2b-sshd -T show 10.0.0.203 # if enabled email notifications, you will receive the following email root@dlp:~ # s-nail you have mail s-nail version v14.9.24. Type `?' for help /var/mail/root: 3 messages 3 unread U 2 Fail2Ban 2024-09-09 10:45 21/529 [Fail2Ban] sshd: started on dlp.srv.world U 3 Fail2Ban 2024-09-09 10:47 40/1045 [Fail2Ban] sshd: banned 10.0.0.203 from dlp.srv.world & 3 [-- Message 3 -- 40 lines, 1045 bytes --]: Subject: [Fail2Ban] sshd: banned 10.0.0.203 from dlp.srv.world Date: Mon, 09 Sep 2024 10:47:59 +0900 From: Fail2Ban <root@dlp.srv.world> To: root@localhost Message-Id: <20240909014759.AAB9A200B3@dlp.srv.world> Hi, The IP 10.0.0.203 has just been banned by Fail2Ban after 5 attempts against sshd. Here is more information about 10.0.0.203 : ..... ..... |
| [4] | If you want to manually add or remove banned hosts, run the following. |
|
root@dlp:~ # fail2ban-client status sshd Status for the jail: sshd |- Filter | |- Currently failed: 0 | |- Total failed: 5 | `- File list: /var/log/auth.log `- Actions |- Currently banned: 1 |- Total banned: 1 `- Banned IP list: 10.0.0.203 # unban [10.0.0.203] root@dlp:~ # fail2ban-client set sshd unbanip 10.0.0.203 1 fail2ban-client status sshd Status for the jail: sshd |- Filter | |- Currently failed: 0 | |- Total failed: 5 | `- File list: /var/log/auth.log `- Actions |- Currently banned: 0 |- Total banned: 1 `- Banned IP list: # ban [10.0.0.192/28] root@dlp:~ # fail2ban-client set sshd banip 10.0.0.192/28 1 fail2ban-client status sshd Status for the jail: sshd |- Filter | |- Currently failed: 0 | |- Total failed: 5 | `- File list: /var/log/auth.log `- Actions |- Currently banned: 1 |- Total banned: 2 `- Banned IP list: 10.0.0.192/28 # to remove all banned hosts, run like follows root@dlp:~ # fail2ban-client unban --all |
| [5] | [jail.conf] has many predefined services other than SSH, so you can set them as monitoring targets by specifying the definition name. |
|
root@dlp:~ # grep '^\[' /usr/local/etc/fail2ban/jail.conf | tail -n +3 [sshd] [dropbear] [selinux-ssh] [apache-auth] [apache-badbots] [apache-noscript] [apache-overflows] [apache-nohome] [apache-botsearch] [apache-fakegooglebot] [apache-modsecurity] ..... ..... # for example, set up Apache2 Basic authentication root@dlp:~ # vi /usr/local/etc/fail2ban/jail.d/apache-auth.conf # create new [apache-auth] enabled = true bantime = 600 findtime = 3m maxretry = 5 action = %(action_mw)s # for example, set up Vsftpd root@dlp:~ # vi /usr/local/etc/fail2ban/jail.d/vsftpd.conf # create new [vsftpd] enabled = true action = %(action_mw)s # for example, set up Postfix SASL root@dlp:~ # vi /usr/local/etc/fail2ban/jail.d/postfix-sasl.conf # create new [postfix-sasl] enabled = true action = %(action_mw)s
root@dlp:~ #
root@dlp:~ # service fail2ban reload
fail2ban-client status Status |- Number of jail: 4 `- Jail list: apache-auth, postfix-sasl, sshd, vsftpd # verify settings by failing authentication manually root@dlp:~ # fail2ban-client status apache-auth Status for the jail: apache-auth |- Filter | |- Currently failed: 0 | |- Total failed: 10 | `- File list: /var/log/httpd/error_log `- Actions |- Currently banned: 1 |- Total banned: 1 `- Banned IP list: 10.0.0.5root@dlp:~ # pfctl -a f2b/apache-auth -t f2b-apache-auth -T show 10.0.0.5root@dlp:~ # fail2ban-client status vsftpd Status for the jail: vsftpd |- Filter | |- Currently failed: 0 | |- Total failed: 5 | `- File list: /var/log/vsftpd.log `- Actions |- Currently banned: 1 |- Total banned: 1 `- Banned IP list: 10.0.0.203root@dlp:~ # pfctl -a f2b/vsftpd -t f2b-vsftpd -T show 10.0.0.203 |