Essential Linux Tools for Monitoring Network Traffic and Testing Performance

When testing network status, quality, or transmission limits in production, Linux provides several tools each focusing on different aspects.

1. nethogs (process level)

NetHogs is a simple open‑source terminal utility that groups bandwidth usage by process rather than by protocol or subnet. It helps locate the PID of a hanging program or see which processes consume bandwidth. It relies on /proc, so it works only on Linux.

Run it with: sudo nethogs You can specify an interface, e.g., sudo nethogs eth0, and adjust refresh rate (-d), version (-V), trace mode (-t), etc., as described in its man page.

2. nload (interface level)

nload is an open‑source console application that visualizes incoming and outgoing traffic in real time, showing total transferred data, minimum/maximum usage, and other statistics. It is simple and handy for quick checks.

3. cbm (interface level)

CBM is a very lightweight tool that displays colored network traffic for all active interfaces.

Running it is as easy as: cbm The output appears at the bottom of the terminal for easy monitoring.

4. iftop (host level)

iftop is a free open‑source command‑line monitor that lists network connections sorted by bandwidth usage, showing the top consumers by default.

5. iPerf (performance testing)

iPerf measures and tunes network performance, generating standardized metrics. It has client and server modes and can create traffic streams to measure bandwidth, loss, and other parameters. Two versions exist: the original iPerf 2 and the newer, non‑backward‑compatible iperf3.

Note: For all examples, if you use iPerf3, replace “iperf” with “iperf3”.

To run iPerf you need at least two machines. On the server start: iperf -s This opens listening port 5001. On the client connect with: iperf -c server_address Replace server_address with the target’s IP or hostname (e.g., ping.online.net). iperf3 provides a list of public test servers. Consult the manual pages for more options.