Scapy is a powerful interactive packet manipulation tool, packet generator,
network scanner, network discovery, packet sniffer, etc. It can for the
moment replace hping, 85% of nmap, arpspoof, arp-sk, arping, tcpdump,
tethereal, p0f, ....

Scapy uses the python interpreter as a command board. That means that you
can use directly python language (assign variables, use loops, define
functions, etc.) If you give a file as parameter when you run scapy, your
session (variables, functions, intances, ...) will be saved when you leave
the interpretor, and restored the next time you launch scapy.