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:

[email protected]:~$ sudo apt-get install iftop

On CentOS/RHEL:

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

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

Now install it using the following command:

[[email protected] ~]# yum install iftop

Usage

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.

[[email protected] ~]# iftop

root@server:~_001

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.

root@server:~_007

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

[[email protected] ~]# 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).

[[email protected] ~]# iftop -i eth0 -B

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

[[email protected] ~]# 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.

 [[email protected] ~]# iftop -F 192.168.1.0/24

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

[[email protected] ~]# man iftop