How to install and configure Ubuntu fail2ban?

@alivia 

Fail2ban is a security tool that monitors system logs for suspicious activity and can block IP addresses that exhibit such behavior. Here are the steps to install and configure Fail2ban on Ubuntu:

Step 1: Update system package list

Before installing Fail2ban, it's best to update the system package list:

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sudo apt-get update

Step 2: Install Fail2ban

Once the package list is updated, you can install Fail2ban using the following command:

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sudo apt-get install fail2ban

Step 3: Configure Fail2ban

By default, Fail2ban comes with a basic configuration file that should work out of the box. However, you may want to adjust some settings to better suit your needs.

To edit the configuration file, run the following command:

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sudo nano /etc/fail2ban/jail.conf

This will open the configuration file in the nano text editor. Here are a few configuration options you may want to consider:

• bantime - This option sets the duration of time that an IP address will be blocked if it's found to be engaging in suspicious activity. The default is 600 seconds (10 minutes), but you may want to adjust this based on your needs.
• maxretry - This option sets the number of times an IP address can fail to authenticate before it gets blocked. The default is 5, but you may want to adjust this based on your needs.
• ignoreip - This option allows you to specify IP addresses or ranges that should be ignored by Fail2ban. This can be useful if you have a known safe IP address that's triggering false positives.
• enabled - This option determines whether or not Fail2ban is enabled for a particular jail. By default, all jails are enabled, but you can set this to false if you don't want a particular jail to be active.

Once you've made your changes, save the file and exit nano.

Step 4: Restart Fail2ban

After making changes to the configuration file, you'll need to restart Fail2ban for them to take effect. You can do this using the following command:

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sudo systemctl restart fail2ban

Step 5: Check Fail2ban Status

You can check the status of Fail2ban using the following command:

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sudo fail2ban-client status

This will show you the status of all the jails that are currently active.

That's it! Fail2ban is now installed and configured on your Ubuntu system.