How to open and analyze PCAP files using Wireshark

Packet Capture (PCAP) files store raw data packets transmitted across a network. These files include critical information like source and destination IP addresses, protocols, and timestamps. Network professionals use PCAP files for troubleshooting and detecting security issues. By analyzing PCAP files, they can monitor network traffic, identify performance problems, and investigate anomalies.

Wireshark is a widely used network protocol analyzer for visualizing and dissecting PCAP data. It allows for detailed inspection of captured packets, providing insights into various layers of network protocols, such as TCP, UDP, and DNS. Wireshark enables network analysts to filter large datasets and focus on relevant traffic, simplifying the process of diagnosing network issues or identifying security breaches.

Wireshark offers an interface to filter traffic types or protocols within captured data. This helps users explore packet details, such as Ethernet frames, IP headers, and higher-layer protocols. Filtering is key to analyzing specific traffic patterns, troubleshooting issues, or investigating suspicious activity in a network environment.

1. Launch Wireshark.
2. Open the PCAP file.

   File > Open

   You can also drag and drop the PCAP file directly into the Wireshark window.

3. View the list of captured packets in the top pane.

   No.  Time   Source         Destination     Protocol Length Info
   1    0.000  192.168.1.10   192.168.1.20    TCP      74     SYN
   2    0.002  192.168.1.20   192.168.1.10    TCP      66     SYN, ACK

   Each packet contains details such as source, destination, and protocol.

4. Select any packet to view detailed breakdowns in the middle pane.
5. View the raw packet data in the bottom pane.

   0000  00 1a a0 b8 8f 3b 00 16 17 31 00 04 08 00 45 00  .....;...1....E.
   0010  00 3c 1c 46 40 00 40 06 a6 ec c0 a8 01 0a c0 a8  .<.F@.@........

   The raw data is displayed in both hexadecimal and ASCII formats.

6. Apply a display filter by typing in the filter bar.

   ip.addr == 192.168.1.10

   Filters help narrow down specific traffic, such as IP addresses, protocols, or ports.

7. Click any packet to inspect Ethernet frames, IP headers, and TCP/UDP data.
8. Right-click a TCP packet to follow a TCP stream.

   Right-click > Follow > TCP Stream

   GET / HTTP/1.1
   Host: example.com
   User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64)

   This feature shows the entire conversation between client and server, useful for HTTP or other TCP protocol analysis.

9. Export specific packets by navigating to.

   File > Export Specified Packets

10. Save the session for future reference.

    File > Save As

    Save the session as a .pcap or .pcapng file for later review or sharing.