Linux: Identify a Physical Network Port with ethtool

On servers with multiple ports, first determine the Linux interface name that you want to identify. The source uses ethX names; other installations may use names such as enpXsY.

1. Inspect the interface

ethtool ethX

Replace ethX with the actual interface. The source screenshot is for eth5, despite an eth4 typo in the surrounding source text.

English annotation illustration; the original output is unchanged. It reports a copper twisted-pair port (TP / Twisted Pair), speed 100Mb/s, Duplex: Full and Link detected: yes. Supported ports describes supported media, not by itself whether a cable is connected. Inspect the link-detected field for the current link state; fiber-capable interfaces may report FIBRE.

2. Blink the identification LED

ethtool -p ethX

On an adapter and driver that support identification, the corresponding port LED blinks. Press Ctrl+C to stop. For example, use eth0 in place of ethX only if eth0 is the interface being located. Do not confuse this identification option with ethtool -t, which performs diagnostic tests and can interrupt traffic.