HOWTO : Wireshark on Ubuntu Desktop 12.04 LTS

Wireshark is the world's foremost network protocol analyzer. It lets you capture and interactively browse the traffic running on a computer network. It is the de facto (and often de jure) standard across many industries and educational institutions.

Step 1 :

sudo apt-get update
sudo apt-get install wireshark

sudo dpkg-reconfigure wireshark-common

Answer "Yes" to the pop-up which allow non-root users to capture the packets. You can consider to enable it but it is danger.

Step 2 :

To run it. You can run it at any directory.

sudo -sH
wireshark

That's all! See you.