Determine Linux ethernet interface speed and duplex

Posted September 3, 2003 by Quinn McHenry in Linux networking

Last Updated on

Determine the auto-negotiated Ethernet connection speed and duplex using the mii-tool command.

Running the following command as superuser with no options will generate basic information about all of the Ethernet interfaces on the computer:


The resulting output will look something like:

eth0: negotiated 100baseTx-FD, link ok

This output shows one interface (eth0) which was auto-negotiated to 100 Mbps (100baseTx) and full duplex (FD).

Adding the -v option to the command generates verbose output and will tell you more about the interface including the manufacturer and model (if available) and the interface’s capabilities.


About Quinn McHenry

Quinn was one of the original co-founders of Tech-Recipes. He is currently crafting iOS applications as a senior developer at Small Planet Digital in Brooklyn, New York.
View more articles by Quinn McHenry

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