ethtool : powerful simple tool to display or modify NIC parameters

I recently discovered ethtool which is a simple but effective command line tool for finding out information about your network card or to change the network settings.

Note - ethtool can only be used against physical adapters

Installation & Adapter Information

•  Install on Linux Mint, Ubuntu or Raspberry Pi:

$ sudo apt-get -y install ethtool

• Find out your adapters with ifconfig (typically starting eth0)

$ ifconfig

Adapter Information

• Running ethtool with no options prints out adapter information e.g.

 $ sudo ethtool eth0 

• Example output

• The above network card supports
• MMI (Media Independent Interface)
• Maximum of 100base T/Full 
• Auto negotiation support
• Wake on 'MagicPacket'

•  Actual device settings
• Speed 100Mb/s
• Full Duplex
• Running MII
• Physical address : 1
• Auto Negotiation : enabled
• Wake On Lan : disabled
• Link is detected

•  This information is really useful when troubleshooting a network card

Modify Settings

•  '-s' can be used to modify settings on a NIC e.g. to set to 1000baseT/Full (if your switch supports it) :

 $ sudo ethtool -s eth0 speed 1000 duplex full autoneg on

 Find a Network Card

• Occasionally on a server will many multiple cards it can be difficult to know which network card related to the system assigned ethX
• ethtool has a cool 'blinking' feature that allows you to define the number of binks on a specified network card :

 $ sudo ethtool -p eth0 10

• The above command will blink eth0 for 10 seconds

Driver Information

•  The '-i' option queries the network card for driver information on the card

 $ sudo ethtool -i eth0

• This provides a really easy and quick way to obtain the driver information

Statistics

•  It can be really useful to obtain network card statistics
• The '-S' option can be used to obtain the information

 $ sudo ethtool -S eth0