OWASP Coraza WAF is a golang modsecurity compatible firewall library
Manage port forwardings via UPnP
A java PCAP and DPI library
Webinterface to (un)ban IPs in Fail2Ban
Firewall Management Script
Jateway is a general purpose TCP/IP connection proxy
Sonicwall Configuration File Reader
Personal firewall for linux desktop and android phone
Patch to integrate URL Filter in IPCop 2.0.6
Easy to use firewall for linux beginners.
Lomalarga is a VPN-like service based on SSH and Linux.