Scapy

Scapy is a packet manipulation tool for computer networks, written in Python by Philippe Biondi. It can forge or decode packets, send them on the wire, capture them, and match requests and replies. It can also handle tasks like scanning, tracerouting, probing, unit tests, attacks, and network discovery.

Scapy provides a Python interface into libpcap, (WinPCap on Windows), in a similar way to that in which Wireshark provides a view and capture GUI. It can interface with a number of other programs to provide visualisation including Wireshark for decoding packets, GnuPlot for providing graphs, graphviz or VPython for visualisation, etc.

Scapy works only with python 2.x. There is a port for python 3 at https://github.com/phaethon/scapy.