Hping is the most popular packet crafting tool. It is a free tool. With Hping you can assemble and send custom ICMP, UDP, TCP and IP packets. Hping is supported various platforms likeWindows, Linux, MacOs X, etc. You can download Hping, below.
Netcat is an user friendly Packet Crafting tool. The previous name fof this tool was Hobbit. With Netcat you can create any kind of network connection with its port binding. You can download Netcat, below.