Reading a packet capture file with Wireshark and tshark

Needle in Haystack

Article from Issue 143/2012
Author(s):

Wireshark doesn’t just work in real time. If you save a history of network activity in a pcap file using a tool such as tcpdump, you can filter the data with Wireshark to search for evidence.

Intrusion detection tools that use the libpcap C/ C++ library for network traffic capture (such as Snort and Tcpdump) can output packet capture information to a file for later reference. The format of this capture file is known as pcap. By capturing packet data to a file, an investigator can return later to study the history of an intrusion attempt – or to turn up other important clues about clandestine activity on the network.

Of course, the traffic history data stored in a pcap file is much too vast to study by just viewing the file manually. Security experts use specialized filtering tools to search through the file for pertinent information. One way to look for clues in a pcap file is to use the Wireshark protocol analysis tool [3] and its accompanying command-line utility tshark.

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy Linux Magazine

SINGLE ISSUES
 
SUBSCRIPTIONS
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Tshark

    The simple and practical Tshark packet analyzer gives precise information about the data streams on the network.

  • Security Lessons

    Building a network flight recorder with Wireshark.

  • Core Technologies

    Learn what's going on in your network, using Linux and its arsenal of packet capture tools.

  • Wireshark

    If you know your way around network protocols, you can get to the source of a problem quickly with Wireshark.

  • Wireshark 1.6 Released

    The Wireshark free network sniffer rolls out 1.6 release with advanced features.

comments powered by Disqus
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters

Support Our Work

Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

Learn More

News