Rather than repeat the information in the extensive man page and on the wireshark.org documentation archive, I will provide practical examples to get you started using tshark and begin carving valuable information from the wire.
Use these as the basis for starting to build your extraction commands. As you can see, the syntax for capturing and reading a
pcap is very similar to
Capture Packets with Tshark
tshark -i wlan0 -w capture-output.pcap
Read a Pcap with Tshark
tshark -r capture-output.pcap
HTTP Analysis with Tshark
In the following example, we extract data from any HTTP requests that are seen. Using the
-T we specify we want to extract fields, and with the
-e options we identify which fields we want to extract.
tshark -i wlan0 -Y http.request -T fields -e http.host -e http.user_agent
searchdns.netcraft.com Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:36.0) Gecko/20100101 Firefox/36.0 searchdns.netcraft.com Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:36.0) Gecko/20100101 Firefox/36.0 ads.netcraft.com Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:36.0) Gecko/20100101 Firefox/36.0
The default separator for the fields in the output above is TAB. We could also use the parameter
-E seperator=, to change the delimiter to a comma.
Parse User Agents and Frequency with Standard Shell Commands
Using the previous command to extract
http.user_agent, this time extracting from a pcap rather than off the live interface. Note in this example, combining with standard shell commands allows us to
sort and count the occurrences of the
tshark -r example.pcap -Y http.request -T fields -e http.host -e http.user_agent | sort | uniq -c | sort -n
Using this, we can quickly parse a
pcap, even if it is very large and get a summary of all the user agents seen. This can be used to detect malware, old browsers on your network and scripts.
Using additional HTTP filters in Analysis
We could perform a similar analysis with the request URL in place of the user agent
-e http.request.full_uri. Other fields we could include in the output are
-e ip.dst and
-e http.request.method. As you can see, by combing different filters and output fields, we can create very complex data extraction commands for tshark that can be used to find interesting things within a capture.
tshark -r example.pcap -Y http.request -T fields -e http.host -e ip.dst -e http.request.full_uri
DNS Analysis with Tshark
Here is an example that extracts both the DNS query and the response address.
tshark -i wlan0 -f "src port 53" -n -T fields -e dns.qry.name -e dns.resp.addr
68 campus-map.stanford.edu 220.127.116.11 www.google.com itunes.apple.com 18.104.22.168 71 itunes.apple.com campus-map.stanford.edu admission.stanford.edu 22.214.171.124 74 financialaid.stanford.edu 126.96.36.199 admission.stanford.edu
Add time and source / destination IP addresses
-e frame.time -e ip.src -e ip.dst to your output.
tshark -i wlan0 -f "src port 53" -n -T fields -e frame.time -e ip.src -e ip.dst -e dns.qry.name -e dns.resp.addr
Apr 22, 2015 23:20:16.922103000 188.8.131.52 192.168.1.7 wprecon.com 184.108.40.206 1 Apr 22, 2015 23:20:17.314244000 220.127.116.11 192.168.1.7 wprecon.com 2 Apr 22, 2015 23:20:18.090110000 18.104.22.168 192.168.1.7 code.jquery.com
Let's get passwords.... in a HTTP post. By not specifying the fields option as above we will receive the full TCP stream of the HTTP Post. If we add the filter
tcp contains "password" and
grep for that password we will just get the actual POST data line.
tshark -i wlan0 -Y 'http.request.method == POST and tcp contains "password"' | grep password
For our Next Trick
The latest version of Tshark 2.4 includes a number of useful new features. To install the latest version on Ubuntu 16.04 or 17.04 use the following commands to add the package repository.
sudo add-apt-repository ppa:dreibh/ppa sudo apt-get update && sudo apt-get install wireshark tshark
Extract Files from PCAP using Tshark
An excellent feature of tshark is the ability to export objects (files) from
pcaps using the command line.
The export objects feature has been available in wireshark for a long time now. Having this ability available on the command line is an excellent addition to
You will need version 2.3.0 or higher for the export objects parameter to be available to
This command will extract files from an
SMB stream and extract them to the location
tshark -nr test.pcap --export-objects smb,tmpfolder
This command will do the same except from
HTTP, extracting all the files seen in the
tshark -nr test.pcap --export-objects http,tmpfolder
It is a quick and easy way to get all the images, html, js and other HTTP objects from a pcap containing HTTP traffic.
Hopefully this tutorial has given you a quick taste of the useful features that are available to you when using
tshark for extracting data from the wire or from pcaps.
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