EtherApe 

EtherApe is a free and open source packet sniffer/network traffic monitoring tool, developed for Unix/Linux, EtherApe displays network activity graphically.. It supports Ethernet, FDDI, Token Ring, ISDN, PPP, SLIP and WLAN devices, plus several encapsulation formats. It can filter traffic to be shown, and can read packets from a file as well as live from the network. It supports Ethernet, FDDI, Token Ring, ISDN, PPP, SLIP and WLAN devices, plus several encapsulation formats. It can filter traffic to be shown, and can read packets from a file as well as live from the network. It is so simple to install and use EtherApe, and this tutorial covers the ground on the same process.