Reading a packet capture file with Wireshark and tshark
Needle in Haystack
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
(incl. VAT)
Buy Linux Magazine
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.
News
-
Kali Linux Waxes Nostalgic with BackTrack Mode
For those who've used Kali Linux since its inception, the changes with the new release are sure to put a smile on your face.
-
Gnome 50 Smooths Out NVIDIA GPU Issues
Gamers rejoice, your favorite pastime just got better with Gnome 50 and NVIDIA GPUs.
-
System76 Retools Thelio Desktop
The new Thelio Mira has landed with improved performance, repairability, and front-facing ports alongside a high-quality tempered glass facade.
-
Some Linux Distros Skirt Age Verification Laws
After California introduced an age verification law recently, open source operating system developers have had to get creative with how they deal with it.
-
UN Creates Open Source Portal
In a quest to strengthen open source collaboration, the United Nations Office of Information and Communications Technology has created a new portal.
-
Latest Linux Kernel RC Contains Changes Galore
Linux kernel 7.0-rc3 includes more changes than have been made in a single release in recent history.
-
Nitrux 6.0 Now Ready to Rock Your World
The latest iteration of the Debian-based distribution includes all kinds of newness.
-
Linux Foundation Reports that Open Source Delivers Better ROI
In a report that may surprise no one in the Linux community, the Linux Foundation found that businesses are finding a 5X return on investment with open source software.
-
Keep Android Open
Google has announced that, soon, anyone looking to develop Android apps will have to first register centrally with Google.
-
Kernel 7.0 Now in Testing
Linus Torvalds has announced the first Release Candidate (RC) for the 7.x kernel is available for those who want to test it.