$sudo cat /sys/class/net/eth0/speed 100 $sudo cat /sys/class/net/eth0/ca carrier carrier_changes $sudo cat /sys/class/net/eth0/carrier 1 $sudo cat /sys/class/net/eth0/carrier_changes 2 $sudo cat /sys/class/net/eth0/operstate up $sudo ethtool eth0 Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Advertised pause frame use: Symmetric Receive-only Advertised auto-negotiation: Yes Link partner advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Link partner advertised pause frame use: Symmetric Receive-only Link partner advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: MII PHYAD: 0 Transceiver: internal Auto-negotiation: on Supports Wake-on: pumbg Wake-on: g Current message level: 0x00000033 (51) drv probe ifdown ifup Link detected: yes $ http://www.ostechnix.com/how-to-find-out-the-connected- state-of-a-network-cable-in-linux/