Thursday, September 12, 2013

How to detect the physical connected state of a network cable/connector?

Category: — SkyHi @ Thursday, September 12, 2013
You can use ethtool:
$ sudo ethtool eth0
Settings for eth0:
    Supported ports: [ TP ]
    Supported link modes:   10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Supports auto-negotiation: Yes
    Advertised link modes:  10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Advertised auto-negotiation: Yes
    Speed: 1000Mb/s
    Duplex: Full
    Port: Twisted Pair
    PHYAD: 0
    Transceiver: internal
    Auto-negotiation: on
    Supports Wake-on: umbg
    Wake-on: g
    Current message level: 0x00000007 (7)
    Link detected: yes
To only get the Link status you can use grep:
$ sudo ethtool eth0 | grep Link
    Link detected: yes

REFERENCES
http://serverfault.com/questions/15776/how-to-check-the-physical-status-of-an-ethernet-port-in-linux