Pcap

In the field of computer network administration, pcap is an application programming interface (API) for capturing network traffic. While the name is an abbreviation of "packet capture", that is not the API's proper name. Unix-like systems implement pcap in the "libpcap" library; for Windows, there is a port of libpcap named "WinPcap" that is no longer supported or developed, and a port named "Npcap" for Windows 7 and later that is still supported.
Monitoring software may use libpcap, WinPcap, or Npcap to capture network packets travelling over a computer network and, in newer versions, to transmit packets on a network at the link layer, and to get a list of network interfaces for possible use with libpcap, WinPcap, or Npcap.
The pcap API is written in C, so other languages such as Java, .NET languages, and scripting languages generally use a wrapper; no such wrappers are provided by libpcap or WinPcap itself. C++ programs may link directly to the C API or use an object-oriented wrapper.
Features.
libpcap, WinPcap, and Npcap provide the packet-capture and filtering engines of many open-source and commercial network tools, including protocol analyzers (packet sniffers), network monitors, network intrusion detection systems, traffic-generators and network-testers.
libpcap, WinPcap, and Npcap also support saving captured packets to a file, and reading files containing saved packets; applications can be written, using libpcap, WinPcap, or Npcap, to be able to capture network traffic and analyze it, or to read a saved capture and analyze it, using the same analysis code. A capture file saved in the format that libpcap, WinPcap, and Npcap use can be read by applications that understand that format, such as tcpdump, Wireshark, CA NetMaster, or Microsoft Network Monitor 3.x.
The MIME type for the file format created and read by libpcap, WinPcap, and Npcap is application/vnd.tcpdump.pcap. The typical file extension is .pcap, although .cap and .dmp are also in common use.
History.
libpcap was originally developed by the tcpdump developers in the Network Research Group at Lawrence Berkeley Laboratory. The low-level packet capture, capture file reading, and capture file writing code of tcpdump was extracted and made into a library, with which tcpdump was linked. It is now developed by the same tcpdump.org group that develops tcpdump.
pcap libraries for Windows.
While libpcap was originally developed for Unix-like operating systems, a successful port for Windows was made, called WinPcap. It has been unmaintained since 2013, and several competing forks have been released with new features and support for newer versions of Windows.
WinPcap.
WinPcap consists of:
Programmers at the Politecnico di Torino wrote the original code; as of 2008 CACE Technologies, a company set up by some of the WinPcap developers, developed and maintained the product. CACE was acquired by Riverbed Technology on October 21, 2010.
Because WinPcap uses the older NDIS 5.x APIs, it does not work on some builds of Windows 10, which have deprecated or removed those APIs in favor of the newer NDIS 6.x APIs. It also forces some limitations such as being unable to capture 802.1Q VLAN tags in Ethernet headers.
Npcap.
Npcap is the Nmap Project's packet sniffing library for Windows. It is based on the Winpcap / Libpcap libraries, but with improved speed, portability, security, and efficiency.
Npcap offers:
Win10Pcap.
Win10Pcap implementation is also based on the NDIS 6 driver model and works stably with Windows 10.
As of 2020, the project has however been inactive since 2016.