hping is a command-line oriented TCP/IP packet assembler/analyzer. The
interface is inspired by the ping(8) unix command, but hping isn't just
for sending ICMP echo requests. It supports TCP, UDP, ICMP and RAW-IP
protocols, has a traceroute mode, the ability to send files in a covert
channel, and many other features. While hping was mainly used as a 
security tool in the past, it can be used in many ways by people that
don't care about security to test networks and hosts. A subset of the
stuff you can do using hping: 

- Firewall testing Advanced port scanning
- Network testing, using different protocols, TOS, fragmentation 
- Manual path MTU discovery 
- Advanced traceroute, under all the supported protocols 
- Remote OS fingerprinting 
- Remote uptime guessing 
- TCP/IP stacks auditing
