Scapy

Scapy is an interactive Python-based program and library for packet manipulation. It enables users to forge, decode, send, sniff, and dissect network packets. Scapy can craft packets from layers up to application protocols, letting researchers build custom packets and send them on the network, then inspect replies to perform tasks such as network discovery, tracerouting, probing, and basic security testing.

Core features include protocol support for Ethernet, IP, TCP, UDP, ICMP, ARP, DNS, and many higher-layer protocols; automatic dissection and display of packet fields; reading and writing pcap files; and the ability to integrate with Python code for automation. It supports live sniffing with optional BPF filters, sending packets at layer 2 or layer 3, and performing tasks like ARP scans, TCP/UDP scans, and port enumeration. It can also be used to craft packets to test network devices or to reproduce traffic for analysis.

Scapy has a command line interface and a Python API, enabling both interactive exploration and programmatic control. It runs on major operating systems including Linux, Windows, and macOS, and requires Python. On Unix-like systems it relies on libpcap; on Windows it uses WinPcap/Npcap backends.

Development and licensing: Scapy is an open-source project maintained by a community of contributors. It was originally created by Philippe Biondi in the early 2000s and has since evolved with regular releases and documentation.