Nemesis is a command line, portable "human IP stack". It can be
useful for easy injection of packet streams from simple shell
scripts. It supports 8 protocols (ARP, DNS, ICMP, IGMP, OSPF,
RIP, TCP, UDP), and packets can be injected on either Layer 2 or
Layer 3.

WWW: http://www.packetninja.net/nemesis/
