This article describes how to create a custom firewall rule to allow or deny a remote IP address, range of addresses or subnet access through your ESET Personal firewall. Adding firewall rules is not recommended, unless:
Press the F5 key to open Advanced Setup.
Click Network Protection → Firewall, expand Advanced and click Edit next to Rules.
Click the Remote tab and type the IP address, range or subnet that you would like to allow or deny in the IP field. Click OK to close the window.
Select the check box next to Show built in (predefined) rules, scroll to the bottom of the list, select the new rule you added and then click the Top icon to move the rule to the top.