Install Fail2Ban:

You can install Fail2Ban using the APT package manager. Use the following command to install Fail2Ban:

sudo apt install fail2ban

Or you can use the following command as an alternative:

sudo apt-get install fail2ban -y

Fail2Ban should start automatically upon installation. If not, you can start and enable it using:

sudo systemctl start fail2bansudo systemctl enable fail2ban

Configure Fail2Ban:

Fail2Ban configurations are primarily done through its configuration files. By default, Fail2Ban comes with filters for various services like SSH, Apache, and others. You can extend the configurations to monitor any other text file by creating or modifying the filter and action files in the /etc/fail2ban directory.

Configuration files are located in /etc/fail2ban, and you may need to create a local configuration file jail.local to override the default configurations specified in jail.conf.

Example of a basic configuration to protect SSH:

[sshd]
enabled = true 
port = ssh 
filter = sshd 
logpath = /var/log/auth.log 
maxretry = 3

Test Configuration and Restart Fail2Ban:

After making the necessary configurations, it’s essential to test the configurations and restart Fail2Ban to apply the changes:

sudo fail2ban-client test
sudo systemctl restart fail2ban 

Monitoring and Managing Fail2Ban:

You can monitor Fail2Ban using the Fail2Ban client. For example, to see the current status of Fail2Ban, use:

sudo fail2ban-client status

Additional Recommendations:

It’s recommended to use iptables or nftables for banning as the default installation uses iptables.

Additionally, tools like whois and python3-pyinotify can be installed for enhanced functionality like sending notification emails or efficient monitoring for log files changes.

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You should now have Fail2Ban installed and configured on your Ubuntu Server 23.10 to provide basic protection against brute-force attacks. For further customization, you can delve deeper into Fail2Ban’s extensive configuration options, and possibly consult additional tutorials or the Fail2Ban documentation.

References:

1​​: https://linuxhandbook.com/fail2ban-basic/
2​: https://linuxize.com/post/install-configure-fail2ban-on-ubuntu-20-04/
​3​: https://launchpad.net/ubuntu/mantic/+package/fail2ban
​4​​: https://www.interserver.net/tips/kb/how-to-install-and-use-fail2ban-for-security-on-ubuntu
5​: https://www.techrepublic.com/article/install-fail2ban-ubuntu-server