1. Active Network Smashing Tool hping2 is a network tool able to send custom ICMP/UDP/TCP packets and to display target replies like ping does with ICMP replies. It handles fragmentation and arbitrary packet body and size, and can be used to transfer files under supported protocols. Using hping2, you can: Test firewall rules, Perform [spoofed] port scanning, Test net performance using different protocols, Packet size, TOS (type of service), and Fragmentation, Do path MTU discovery, Transfer files (even between really Fascist firewall rules), Perform traceroute-like actions under different protocols, Fingerprint remote OSs, Audit a TCP/IP stack, etc. hping2 is a good tool for learning TCP/IP. From Debian 3.0r0 APT