How to test network speed using two Linux machines?
Introduction
This guide will show you how you can perform a network speed test using two Linux machines. It will show you the actual network bandwidth between two points in your network. We will connect a Linux machine at each point in you network and generate traffic between them. We can use simple laptops, desktops or even virtual machines for this purpose.
I will use Ubuntu 18.04, but you can use any Linux distro you like(installation command will differ for non-Debian based Linux distro). The tool used for the bandwidth test is called iperf. This is a very simple program that needs to be installed on both machines.
Installation
Go to each of your two servers and run the following command to install iperf: sudo apt install iperf
Example:
orkhans@matrix:~$ sudo apt install iperf [sudo] password for administrator: Reading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: iperf 0 upgraded, 1 newly installed, 0 to remove and 217 not upgraded. Need to get 60,4 kB of archives. After this operation, 176 kB of additional disk space will be used. Get:1 http://az.archive.ubuntu.com/ubuntu bionic-updates/universe amd64 iperf amd64 2.0.10+dfsg1-1ubuntu0.18.04.1 [60,4 kB] Fetched 60,4 kB in 0s (130 kB/s) Selecting previously unselected package iperf. (Reading database ... 227469 files and directories currently installed.) Preparing to unpack .../iperf_2.0.10+dfsg1-1ubuntu0.18.04.1_amd64.deb ... Unpacking iperf (2.0.10+dfsg1-1ubuntu0.18.04.1) ... Setting up iperf (2.0.10+dfsg1-1ubuntu0.18.04.1) ... Processing triggers for man-db (2.8.3-2) ...
Basic speed test
To make a speed test we need to do two things:
- Run iperf on any machine in a server mode
- Run iperf on another machine in a client mode and connect to the server
Step 1.
Go to the first Linux box and run the following command:
orkhans@Linux1:~$ iperf -s ------------------------------------------------------------ Server listening on TCP port 5001 TCP window size: 85.3 KByte (default) ------------------------------------------------------------
You can see that our Linux machine is running iperf in a server mode (-s option) which is listening at port TCP 5001.
Step 2.
Go to the second Linux machine and run the following command iperf -c SERVER_IP, where SERVER_IP is the IP address of the first Linux box, running iperf in a server mode:
orkhans@Linux2:~$ iperf -c 192.168.37.79 ------------------------------------------------------------ Client connecting to 192.168.37.79, TCP port 5001 TCP window size: 85.0 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.37.76 port 55268 connected with 192.168.37.79 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 9.09 GBytes 7.81 Gbits/sec
This command instructs iperf to connect (-c option) to the first machine, running iperf server( in my case it is 192.168.37.79).
The output says that we connect to server’s port TCP 5001 and then it performs a speed test during 10 seconds and shows us the result. In my case the bandwidth between two machines was 7.81 Gbits/sec.
iperf options
We have used iperf with default settings, which are working pretty well, but you can also use different options some of which are:
-t – time in seconds to transmit for (default is 10 seconds). Specified on a client
-p – server port to listen on/connect to.
-w – TCP window size
You can find the full list of options on a man page for iperf.
Conclusion
As you can see, iperf tool is a flexible and still easy to use.
Thank you for reading.
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