Useful Tools to Display Network Usage in Linux

In this article we would like to introduce you two simple and smart Linux command line tools to monitor bandwidth usage on all network interfaces in the real time: iftop and nload.

1. iftop – command line tool that displays bandwidth usage on an interface
iftop listens to network traffic on a named interface, or on the first interface it can find which looks like an external interface if none is specified, and displays a table of current bandwidth usage by pairs of hosts.

Installation (CentOS/Fedora/RHEL):

[root@fixxxer ~]# yum install iftop 

Examples of usage:

a) iftop invoked without parameters displays bandwidth usage on default network interface:

[root@fixxxer ~]# iftop 

b) iftop invoked with -i parameter displays bandwidth usage on particular interface

[root@fixxxer ~]# iftop -i br0p37p1 

c) iftop invoked with -p parameter is launched in promiscuous mode (captures also traffic not passing through the chosen network interface)

[root@fixxxer ~]# iftop -p 

d) iftop invoked with -F parameter displays only packets flowing in to or out of the given network

[root@fixxxer ~]# iftop -F 192.168.2.0/24

e) iftop invoked with -B parameter displays bandwidth rates in bytes/sec rather than bits/sec

[root@fixxxer ~]# iftop -B

2. nload – displays the current network usage
nload is another console application which monitors network traffic and bandwidth usage in real time. It visualizes the in- and outgoing traffic using two graphs.

Installation (CentOS/Fedora/RHEL):

[root@fixxxer ~]# yum install nload 

Examples of usage:

a) nload invoked without parameters displays bandwidth on the default interface in two graphs for incoming and outgoing traffic

[root@fixxxer ~]# nload 

You can navigate between interfaces using TAB key or arrow keys, press q key to quit.

b) nload invoked with -m parameter displays multiple interfaces bandwidth without graphs

[root@fixxxer ~]# nload -m

c) nload invoked with -t parameter determines the refresh interval of the display in milliseconds

[root@fixxxer ~]# nload -t 700