The Nemesis Project is designed to be a command line based, portable human IP
stack for UNIX-like and Windows sytems.  The suite is broken down by protocol, 
and should allow for useful scripting of injected packets from simple shell 
scripts.

Key Features:

+ ARP/RARP, DNS, ETHERNET, ICMP, IGMP, IP, OSPF*, RIP, TCP, UDP protocol support
+ Layer 2 or Layer 3 injection (by presence/absence of -d <dev> switch)
  on UNIX-like systems.
+ Layer 2 injection on Windows systems (regardless of whether 
  -d <device number> is used.
+ Packet payload from file
+ IP and TCP options from file
+ Tested on OpenBSD, Linux, Solaris, Mac OS X and Windows 2000

Each supported protocol uses its own protocol "injector" which is accompanied
by a man page explaning its functionality.


WWW:  http://www.packetfactory.net/projects/nemesis/