Network Protocol Analyzers and Wireshark

Network Protocol Analyzer Overview

• Definition: Also known as a sniffer, packet analyzer, network analyzer, or traffic analyzer.

• Function: Captures data in transit for analysis and review.

• Operation: Works at the data link layer of the OSI model, allowing it to capture all data on the network without restrictions.

Wireshark

• Wireshark: The most widely-used protocol analyzer.

  • Purpose: Converts binary traffic into a human-readable format.

  • Uses:

    • Network Troubleshooting: Identifying and solving network issues.

    • Security Analysis: Examining security-related problems.

    • QA Testing: Verifying network-related issues.

    • Protocol Debugging: Used by developers to debug protocols.

    • Learning Tool: Helps individuals understand network protocols.

  • Features:

    • Deep inspection of hundreds of protocols.

    • Live capture and offline analysis.

    • Three-pane packet browser.

    • Cross-platform compatibility (Windows, Linux, MacOS, etc.).

    • Graphical User Interface (GUI) and TTY-mode Tshark utility.

    • Powerful display filters and rich VoIP analysis.

    • Reads and writes various capture file formats.

    • Supports gzip compression/decompression on the fly.

    • Decryption support for various protocols (e.g., IPSec, SSL/TLS, WPA2).

    • Customizable coloring rules for quick analysis.

    • Export options to formats like XML, PostScript, CSV, plain text, etc.

Packet Capture (PCAP)

• PCAP Overview:

  • PCAP: A file format used to capture and record network traffic.

  • Uses:

    • Monitoring bandwidth usage.

    • Identifying rogue DHCP servers.

    • Detecting malware.

    • DNS resolution and incident response.

  • Wireshark: Utilizes PCAP files to store captured network data.

PCAP File Formats

1. Libpcap:

   • Used in Unix-based systems like Linux and MacOS.

   • Traditional format for packet capture.

2. PCAP:

   • Older format for Windows, not commonly used as a default anymore.

3. Pcapng (PCAP Next Generation):

   • Default format for Wireshark.

   • Captures and stores data, considered the next generation of packet capture formats.

4. Npcap:

   • Specific to Nmap, a port scanning tool with packet capture capabilities.