iPerf3

iPerf3 at a glance

iperf3 is a widely used open-source tool for measuring network throughput between two hosts — a staple for diagnosing bandwidth and network performance. It ships releases in an unhurried cadence plus occasional fixes; it's a diagnostic tool run on demand.

For admins iperf3 is simple and low-risk, but note one thing: running it in server mode opens a listening port that anyone reaching it can use to generate traffic, so don't leave an iperf3 server running exposed on the internet — start it only when testing, bind it appropriately, and stop it after. Keep it reasonably current for fixes (there have been occasional advisories in the server code). It comes from the distribution on Linux and official builds elsewhere. The results depend on test conditions — interpret them with care. Its value is purely diagnostic. Patchletter surfaces new iperf3 releases so fixes land.