Wireshark

The program that we're going to take a look at is called Wireshark. It's an open source packet sniffer with support for interpreting a vast range of network protocols.

Installation

For Windows and Linux, Wireshark can be downloaded from http://www.wireshark.org. On Debian, Ubuntu, RHEL, CentOS, and Fedora it's available as the wireshark package.

You'll need to have root or administrator access in order to install this. On Windows, make sure that you install or update the WinPcap library if it asks you to do so, and also allow it to start the WinPcap driver at boot time when prompted.

On Debian and Ubuntu, you will need to configure Wireshark to allow regular users to run captures. Run the following command:

$ sudo dpkg-reconfigure wireshark-common

Say Yes to Should non-superusers be able to capture packets? Note that this doesn't automatically allow all non-super users to use Wireshark, they still need to be added to the wireshark group. Do this now for your...