Scapy is a powerful interactive packet manipulation program. It is able to forge or decode packets of a wide number of protocols, send them on the wire, capture them, match requests and replies, and much more. It can easily handle most classical tasks like scanning, tracerouting, probing, unit tests, attacks or network discovery (it can replace hping, 85% of nmap, arpspoof, arp-sk, arping, tcpdump, tshark, p0f, etc.). It also performs very well at a lot of other specific tasks that most other tools can’t handle, like sending invalid frames, injecting your own 802.11 frames, combining technics (VLAN hopping+ARP cache poisoning, VOIP decoding on WEP encrypted channel, …), etc.
Scapy runs natively on Linux, Windows, OSX and on most Unixes with libpcap (see scapy’s installation page). The same code base now runs natively on both Python 2 and Python 3.
Ostinato aims to be the equal and opposite package to Wireshark, which is to say it is a simple, easy to use (if you know networking, that is) packet generator which lets you construct packets from the physical layer all the way up into individual applications. Can also load, edit, and replay on the wire the contents of PCAP files.