iftop: A Network Bandwidth Monitoring Tool for Linux

iftop is used to view the current bandwidth on a network interface. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. iftop must be run by a root user or a user who has sufficient privileges to monitor network bandwidths.

Installing iftop

On Debian/Ubuntu:

sk@sk:~$ sudo apt-get install iftop


iftop will not be found in official repositories. So let us add EPEL repository to install iftop:

[root@server ~]# rpm -ivh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

Now install it using the following command:

[root@server ~]# yum install iftop


iftop is very simple to use. Just type the iftop command on terminal with root privileges to display the bandwidth usage of the first network interface. Press Q to exit from the iftop command output.

[root@server ~]# iftop


To view the source and destination listening ports, just press SHIFT+S and SHIFT+D. It will display the traffic along with source and destination ports.


To view the network bandwidth of a particular interface, use the following command.

[root@server ~]# iftop -i eth0

root@server:~_002By default, iftop will display all traffic in kilo/mega/giga bits per second. To display all traffic in bytes instead of bits the parameter -B (Capital B).

[root@server ~]# iftop -i eth0 -B

root@server:~_003To display the traffic on which port is occurring, use -P and -N switches with iftop command.

[root@server ~]# iftop -i eth0 -P -N

The parameter -N displays the port number.

root@server:~_004To view the in and out packet flowing of a network, use the following command.

 [root@server ~]# iftop -F

For more information about iftop command, refer the man pages using the following command:

[root@server ~]# man iftop