Ethtool

ethtool is a program to find your NIC's type and abilities. When everything is right, it looks about like this: $ ethtool eth0 Settings for eth0: Supported ports: [ TP ] 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: Yes Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on        Supports Wake-on: umbg Wake-on: g        Current message level: 0x00000001 (1) Link detected: yes Link detected: yes means
 * your NIC is up (ifconfig eth0 up)
 * a cable is plugged in and you have a working connection to your network switch (or to another node).

= Problems = The line Link detected: no can just mean you have not done an ifup on your network DevIce.