Essential Linux Tools for Real‑Time Network Monitoring and Performance Testing

1. nethogs (process‑level)

NetHogs is a simple open‑source terminal utility that groups bandwidth usage by process rather than by protocol or subnet, making it useful for identifying which PID is consuming network resources. It relies on /proc and works on most Linux systems. sudo nethogs You can specify an interface (e.g., sudo nethogs eth0) and adjust parameters such as refresh rate ( -d), version ( -V), or trace mode ( -t). See the manual page for additional options.

2. nload (interface‑level)

nload is an open‑source console application that visualizes incoming and outgoing traffic in real time using graphs. It also displays total transferred data, minimum/maximum usage, and other statistics, providing a quick overview of interface bandwidth.

3. cbm (interface‑level)

CBM is a lightweight tool that displays colored network traffic for all connected devices in a compact format. It is straightforward to install and run. cbm The command outputs traffic statistics at the bottom of the terminal for easy monitoring.

4. iftop (host‑level)

iftop is a free open‑source command‑line system monitor that continuously lists network connections between hosts, sorting them by bandwidth usage by default and showing the top bandwidth consumers.

5. iPerf (performance testing)

iPerf is a widely used tool for measuring and tuning network performance. It can act as a client or server and generate standardized bandwidth, loss, and other metrics in one‑direction or bidirectional mode. Two implementations exist: the original iPerf 2 and the non‑backward‑compatible iPerf 3. iperf -s This starts a server listening on port 5001. iperf -c server_address Replace server_address with the target host’s IP or hostname (e.g., ping.online.net). iPerf 3 provides a public list of test servers. For full option details, consult the manual pages ( man iperf or man iperf3).

Note: When using iPerf 3, replace all occurrences of iperf with iperf3 in the examples.