How to monitor network traffics on Ubuntu

(1) Wireshark: shows network packages

sudo apt-get install wireshark
sudo wireshark

(2) tcptrack: shows traffic per IP and port number

sudo apt-get install tcptrack
sudo tcptrack -i eth0

(3) nethogs: shows traffic per process

sudo apt-get install nethogs
sudo nethogs

(4) iftop: shows traffic per IP

sudo apt-get install iftop
sudo iftop