pcap is an application programming interface for packet capturing. The implementation of pcap for Unix-like systems is known as libpcap; the Windows port of libpcap is called WinPcap.
libpcap and WinPcap may be used by a program to capture packets travelling over a network and, in newer versions, to transmit packets on a network at the link layer, as well as to get a list of network interfaces that can be used with libpcap or WinPcap.
libpcap and WinPcap are the packet capture and filtering engines of many open source and commercial network tools, including protocol analyzers, network monitors, network intrusion detection systems, packet sniffers, traffic generators and network testers.
The pcap API is designed for use from C and C++, so, for other languages such as scripting languages, Java, and .NET languages, a wrapper is generally used.
