Lcrzo is a network library, for network administrators 
and network hackers. Its objective is to easily create network programs.
This library provides network functionnalities for Ethernet, IP, UDP, TCP, 
ICMP, ARP and RARP protocols. It supports spoofing, sniffing, client and 
server creation. Furthermore, lcrzo contains high level functions dealing 
with data storage and handling. Using all these functions, you can quickly 
create a network test program.

WWW: http://www.laurentconstantin.com/en/lcrzo/