A firewall for humans.
Free UTM appliance: firewall, VPN, WAF and antivirus in one ISO.
Programmable completion code (bash) for ip[6]tables (netfilter.org)
Open source voucher management / hotspot system
Programmable completion code (bash) for ipset (netfilter.org)
network control and reporting
flex-fw is a small and fast console frontend to iptables