Wednesday, November 27, 2013

Wire Shark : Packet Capturing Tool

Wire-shark is a network analysis tool which captures network packets in real time. They are captured in human readable format. The tool is formally called as Ethereal.

Wire-shark includes filters, color indicators and many other features that lets admin to dig into the network traffic and see what’s going on

This article is a brief introduction of how wire-shark is installed and how one can use to dig the network details.

1. Install the package.
In order to install the Wire-shark package, go to http://www.wireshark.org/download.html  

Select the Correct packages for the installation. I will be explaining how to build the wire-shark in Red hat Linux 6.

Download the Source Code and unzip it a location and execute
yum install bison flex gtk2-devel libpcap-devel c-ares-devel libsmi-devel gnutls-devel libgcrypt-devel krb5-devel GeoIP-devel ortp-devel portaudio-devel*

Linux then tries to install the packages which are dependent for wire-shark

2.Once the packages are installed ,run the following commands
cd wireshark-1.8.11
./autogen.sh
 ./configure --enable-setcap-install
 make
 make install
 wireshark &

If everything goes fine, we can now see the Wire-shark console on the screen.


3. Start Using Wire-Shark

 We can see the Interfaces that are available in our system under the Interface list. Under the Start
Click on the Interface, in this case consider “eth0”.Once we click the interface it starts capturing packets on that interface.

As soon as you click the interface’s name, you’ll see the packets start to appear in real time. Wireshark captures each packet sent to or from your system. It captures all sorts of packets on tcp,udp,http and many more.


Click the stop capture button near the top left corner of the window when you want to stop capturing traffic.

Wire-shark follows colors to represent different information from the above screen. We can see packets highlighted in green, blue and black. Wire-shark uses colors to help you identify the types of traffic at a glance. By default, green is TCP traffic, dark blue is DNS traffic, light blue is UDP traffic and black identifies TCP packets with problems — for example, they could have been delivered out-of-order.

Wire-shark can also allow us to filter packet information based on criteria. We can use the filter option available on the top to select the packet information like



Wire-shark also provides options to select filter. Click on the Analyze menu and select Display Filters to create a new filter.Select the Filter you want to analyze packet information for.

















Another important feature with wire-shark is that it allows you to follow the Packet Stream.
Just right click on a packet and select “Follow TCP Stream” or “Follow UDP Stream”. We can get more information like the full conversation between Client and Server in this request.


Close the window and you’ll find a filter has been applied automatically — Wire shark is showing you the packets that make up the conversation.

We can also inspect packet information by just right clicking on the packet and selecting “view its Details”.

This article is basically an introduction for wire shark.I will be providing more details on the usage of this tool

Happy learning, more To Come J