 | Linux Free S/WAN IPsec tools
- VPN tools for Linux that works with many other IPSec products. |
 | Ethereal - The best network sniffer
and analysis tool.. |
 | Nessus - Vulnerability Assessment Tool |
 | Snort - Intrusion Detection System |
 | TCPDump - The "original"
network analysis tool. |
 | Nmap - The port scanner that is a
great tool and also the bane of many administrators. |