Protection Against Brute Force Attacks (Fail2Ban)

IP address banning (Fail2Ban) is an automated way to protect your server from brute force attacks. Fail2Ban uses regular expressions to monitor log files for patterns corresponding to authentication failures and other errors that are considered suspicious.

If an IP address makes too many login attempts within a time interval defined by the administrator, this IP address is banned for a certain period of time. Fail2Ban can also update firewall rules and send email notifications. When the ban period is over, the IP address is automatically unbanned.

Note: To use Fail2Ban, administrators who upgrade from Plesk 11.5 must obtain a new license key for Plesk 12 from Odin or their vendor.

To set up Plesk to automatically ban IP addresses and networks that generate malicious traffic:

  1. Go to Tools & Settings > IP Address Banning (Fail2Ban) (in the Security group). The Fail2Ban component has to be installed on your server.
  2. Select the Enable intrusion detection checkbox.
  3. Specify the following settings:
  • IP address ban period – the time interval in seconds for which an IP address is banned. When this period is over, the IP address is automatically unbanned.
  • Time interval for detection of subsequent attacks – the time interval in seconds during which the system counts the number of unsuccessful login attempts and other unwanted actions from an IP address.
  • Number of failures before the IP address is banned – the number of failed login attempts from the IP address.

     4. Click OK.

Now all active Fail2Ban jails will be used to monitor the log files and to ban suspicious IP addresses.


Fail2Ban in Plesk has the following limitations and peculiarities:

  • Fail2Ban must not be restarted manually as a Plesk service, since all accumulated statistics data, including currently banned IP addresses, will be lost.
  • Fail2Ban does not provide protection against attackers with an IPv6 address. Fail2ban in Plesk relies solely on IPs (without hostname lookups) unless reconfigured.
  • Fail2Ban cannot protect from distributed brute force attacks, since it identifies intruders by their IP address.
  • If you have your Plesk installed on a VPS, the VPS iptables records limit (numiptent) might affect the work of Fail2Ban. When this limit is exceeded, Fail2Ban will stop working properly and in the Fail2Ban log you will find a line such as:
    fail2ban.actions.action: ERROR iptables -I fail2ban-plesk-proftpd 1 -s -j REJECT --reject-with icmp-port-unreachable returned 100
    In this case, contact your VPS hosting provider to solve the issue.
  • If you had Fail2Ban installed on your server before upgrading to Plesk 12, the package will be replaced by Plesk’s Fail2Ban package. If your already installed package is newer than the one provided with Plesk, the upgrade might fail. Existing jails will not be overwritten and you can manage them in Plesk together with Plesk 12 jails.

If an IP address should not be blocked:

  1. Go to Tools & Settings > IP Address Banning (Fail2Ban) > Trusted IP Addresses > Add Trusted IP.
  2. In the IP address field, provide an IP address, an IP range, or a DNS host name, and click OK.

You can view and download Fail2Ban log files in Tools & Settings > IP Address Banning (Fail2Ban) > the Logs tab.

You can view the list of banned IP addresses, unban them, or move them to the list of trusted addresses in Tools & Settings > IP Address Banning (Fail2Ban) > the Banned IP Addresses tab.

You can view the list of IP addresses that will never be banned, add IP addresses to and remove from this list in Tools & Settings > IP Address Banning (Fail2Ban) > the Trusted IP Addresses tab.