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Original author(s)David S. Miller
Developer(s)Ben Hutchings
Initial release1998; 22 years ago (1998)
Repository Edit this at Wikidata
Written inC
Operating systemLinux

ethtool is a utility for Linux kernel-based operating system for displaying and modifying some parameters of network interface controllers (NICs) and their device drivers. ethtool is developed parallel to the Linux kernel.


The command is useful for:


To display the current parameters of the first network port (eth0):

$ ethtool eth0
Settings for eth0:
       Supported ports: [ TP MII ]
       Supported link modes:   10baseT/Half 10baseT/Full
                               100baseT/Half 100baseT/Full
       Supports auto-negotiation: Yes
       Advertised link modes:  10baseT/Half 10baseT/Full
                               100baseT/Half 100baseT/Full
       Advertised auto-negotiation: No
       Speed: 100Mb/s
       Duplex: Full
       Port: MII
       PHYAD: 1
       Transceiver: internal
       Auto-negotiation: off
       Supports Wake-on: g
       Wake-on: g
       Current message level: 0x00000007 (7)
       Link detected: yes

To force its speed and duplex, in 1000BASE-T:

$ ethtool -s eth0 speed 1000 duplex full autoneg off


mii-tool is an older program performing a similar function to ethtool. Since 2003,[1] it's considered obsolete and replaced by ethtool.


To display the current parameters:

$ mii-tool
eth0: no autonegotiation, 100baseTx-HD, link ok

To force the network speed to 1 Gbit/s, and the duplex in full on the port 1 (eth0):

$ mii-tool -F 1000baseTx-FD eth0
$ mii-tool
eth0: 1 000 Mbit, full duplex, link ok

See also[edit]


External links[edit]