How to Install Fail2Ban on AlmaLinux 9
To install Fail2ban, The EPEL repository needs to be installed first.
yum install epel-release
Note: It will prompt for permission Press "y" and "Enter" to continue.
Next, install the fail2ban package.
yum install fail2ban
Note: This will prompt for several permissions, Press "y" and "Enter" to continue.
Set fail2ban to start on boot automatically,
systemctl enable fail2ban
Configuring local file settings.
Jail.conf contains a section in which Configuration settings can be done for the fail2ban, we are not going to edit this file because a package upgrade can overwrite this file.
Jail.local contains the same section where jail.conf file contains and it can override these values.
/etc/fail2ban/jail.d/ can override both jails.local and jails.conf files
First, we begin with the jail.local file.
Open the file for editing,
nano /etc/fail2ban/jail.local
Add the following content,
[DEFAULT]
# Ban hosts for one hour:
bantime = 3600
# Override /etc/fail2ban/jail.d/00-firewalld.conf:
banaction = iptables-multiport
[sshd]
enabled = true
If the server uses firewalld instead of iptables, simply comment the banaction line_
Restarting the Fail2Ban service to load new settings.
systemctl restart fail2ban
To check status
fail2ban-client status
Output:
[root@server ~]# fail2ban-client status
Status
|- Number of jail: 1
`- Jail list: sshd
[root@server ~]# fail2ban-client status sshd
Status for the jail: sshd
|- Filter
| |- Currently failed: 7
| |- Total failed: 158
| `- Journal matches: _SYSTEMD_UNIT=sshd.service + _COMM=sshd
`- Actions
|- Currently banned: 5
|- Total banned: 5
`- Banned IP list: 36.129.3.143 64.225.35.76 61.177.172.124 61.177.172.147 218.92.0.221
To view detailed information of sshd
fail2ban-client status sshd
Modify the content of the file /etc/fail2ban/jail.local
nano /etc/fail2ban/jail.local
Setting ban time
#ban time setting to 600sec
bantime = 600
Setting conditions to ban a client
findtime = 600
maxretry = 3
In this example, the client is blocked if he makes 3 unsuccessful login attempts within 10 mins.
To check the details of banned IPs and the number of login attempts,
fail2ban-client status sshd
Output:
[root@server ~]# fail2ban-client status sshd
Status for the jail: sshd
|- Filter
| |- Currently failed: 0
| |- Total failed: 163
| `- Journal matches: _SYSTEMD_UNIT=sshd.service + _COMM=sshd
`- Actions
|- Currently banned: 6
|- Total banned: 6
`- Banned IP list: 36.129.3.143 64.225.35.76 61.177.172.124 61.177.172.147 218.92.0.221 61.177.172.114
DONE!
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