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Packet capture

(also PCAP, libpcap)

Packet capture definition

Packet capture is the process of recording IP (Internet Protocol) packets for analysis or review. Packet capture programs also generate files, typically in the .pcap format. Network administrators often resort to packet capture as a troubleshooting tool and to inspect network traffic for security vulnerabilities. In the case of a hack or other incident, packet captures give crucial forensic evidence. From the standpoint of a threat actor, packet captures can be exploited to steal credentials and other private information. Packet capturing, in contrast to active spying techniques like port scanning, leaves no traces that may be analyzed by security analysts.

Versions of PCAP

  • Libpcap. Portable open-source C/C++ library, written specifically for Linux and macOS. Facilitates packet capture and filtering for administrators.
  • WinPcap. Designed for Windows devices. Network packets can be captured and filtered using WinpCap.
  • PCAPng. Loopback packets can be sniffed and captured via injection by users.
  • Npcap. A packet sniffing library that works with other Windows devices. It is known for its fast and safe functions.

Benefits of packet capture

  • Improving network security. This is done by learning about vulnerabilities and intrusions through packet analysis. It's capable of identifying network attacks, security breaches, and unusual traffic surges.
  • Identifying data leaks. IT departments may learn where data is lost and what is causing it with the aid of packet analysis and monitoring.
  • Locating packet loss. Data packets that have been lost, stolen, or exfiltrated might be recovered by IT departments with the use of packet capture monitoring.
  • Improving network troubleshooting. Gives network teams complete transparency into all available network resources, which in turn speeds up and simplifies troubleshooting.

Drawbacks of packet capture

  • Large file sizes. You need a lot of storage space for full packet capture.
  • Too much information. Packet captures provide a thorough view of the network traffic, but they sometimes yield too much information. It's easy for important details to get lost in massive amounts of data.
  • Fixed Fields. Recent NetFlow versions provide customizable records, so network admins can pick what to capture. Since packet capture relies on IP packet structure, it can't be customized.