This is a tool that generates a Linux kernel module for custom rules with Netfilter hooking to block ports, run in hidden mode, perform rootkit functions, etc.
You can download it from the following link: https://packetstormsecurity.com/files/download/153254/HiddenWall-master.zip
Source: https://packetstormsecurity.com/files/153254/HiddenWall-Linux-Firewall.html