iftop – A Real Time Linux Network Bandwidth Monitoring Tool

In our earlier article, we have reviewed the usage of TOP Command and it’s parameters. In this article we have came up with another excellent program called Interface TOP (IFTOP) is a real time console-based network bandwidth monitoring tool.

It will show a quick overview of network activities on an interface. Iftop shows a real time updated list of network usage bandwidth every 2, 10 and 40 seconds on average. In this post we are going to see the installation and how to use IFTOP with examples in Linux.

Requirements:

1. libpcap : library for capturing live network data.
2. libncurses : a programming library that provides an API for building text-based interfaces in a terminal-independent way.

Install libpcap and libncurses

First start by installing libpcap and libncurses libraries using your Linux distribution package manager as shown.

$ sudo apt install libpcap0.8 libpcap0.8-dev libncurses5 libncurses5-dev  [On Debian/Ubuntu]
# yum  -y install libpcap libpcap-devel ncurses ncurses-devel             [On CentOS/RHEL]
# dnf  -y install libpcap libpcap-devel ncurses ncurses-devel             [On Fedora 22+]

Download and Install iftop

Iftop is available in the official software repositories of Debian/Ubuntu Linux, you can install it using apt command as shown.

$ sudo apt install iftop

On RHEL/CentOS, you need to enable the EPEL repository, and then install it as follows.

# yum install epel-release
# yum install  iftop

On Fedora distribution, iftop is also available from the default system repositories to install using the following command.

# dnf install iftop

Other Linux distributions, can download iftop source package using wget command and compile it from source as shown.

# wget http://www.ex-parrot.com/pdw/iftop/download/iftop-0.17.tar.gz
# tar -zxvf iftop-0.17.tar.gz
# cd iftop-0.17
# ./configure
# make
# make install

Basic usage of Iftop

Once installation done, go to your console and run the iftop command without any arguments to view bandwidth usage of default interface, as shown in the screen shot below.

$ sudo iftop

Sample output of iftop command which shows bandwidth of default interface as shown below.

Monitor Linux Network Interface

First run the following ifconfig command or ip command to find all attached network interfaces on your Linux system.

$ sudo ifconfig
OR
$ sudo ip addr show

Then use the -i flag to specify the interface you want to monitor. For example the command below used to monitor bandwidth on the wireless interface on the test computer.

$ sudo iftop -i wlp2s0

To disable hostname lookups, use the -n flag.

$ sudo iftop -n  eth0

To turn on port display, use the -P switch.

$ sudo iftop -P eth0

Iftop Options and Usage

While running iftop you can use the keys like S, D to see more information like source, destination etc. Please do run man iftop if you want to explore more options and tricks. Press ‘q‘ to quit from running windows.

In this article, we’ve showed how to install and use iftop, a network interface monitoring tool in Linux. If you want to know more about iftop please visit iftop website. Kindly share it and send your comment through our comment box below.