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

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 the PID of a hanging program or seeing which applications consume bandwidth. It relies on /proc and works on most Linux systems. sudo nethogs You can specify a network device (e.g., sudo nethogs eth0) and adjust options such as refresh rate ( -d), version ( -V), or trace mode ( -t) via the manual page.

nload (interface‑level)

nload is an open‑source console application that visualizes incoming and outgoing traffic in real‑time charts, also reporting total transferred data, minimum and maximum usage, and other statistics. It provides a quick, easy‑to‑read view of interface bandwidth.

cbm (interface‑level)

CBM is a lightweight tool that displays colored network traffic for all connected devices in a concise format. cbm The command prints the traffic summary at the bottom of the terminal for easy monitoring.

iftop (host‑level)

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

iPerf (performance testing)

iPerf is a network performance measurement tool that can act as both client and server, generating standardized bandwidth, loss, and other metrics. Two implementations exist: the original iPerf2 and the non‑backward‑compatible iperf3. 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). iperf3 provides a public list of test servers. For detailed options, consult the manual pages ( man iperf or man iperf3).

Note: When using iPerf3, replace all instances of iperf with iperf3 in the examples.