narc 0.7

NARC is a free firewalling package for Netfilter/Iptables. It attempts to simplify the setup of a firewall (stateful packet filter) via the iptables tools. NARC is a bash shellscript that generates sensible and secure rules for Netfilter based on a simple configuration file.
Netfilter is the framework in Linux 2.4 kernels that allow for firewalling, NAT, and packet mangling. Iptables is the userspace tools that works with the Netfilter framework (technically a lie; Iptables is also a part of the Netfilter framework in the kernel). Think of Netfilter as the kernel space, and Iptables as the userspace.
Main features:
- Quick setup via a simple configuration file
- Connection tracking (and fragmentation reassembly)
- Customized logging
- Probe detection (TCP & UDP)
- Illegal TCP packet filtering
- FIN, NULL, ACK scan detection
- ICMP message filtering and rate limiting
- SYN packet length checking
- General rate limiting (to prevent DoS type attacks)
- IP/network based TCP connection rate limiting
- SYN flood protection
- Smurf attack protection
- Spoofed IP address filtering
- DMZ support
- Port forwarding support