Check if the interface hook or not

$ yum install ethtool

$ ifconfig to see how may interfaces available

$ ethtool [Interface Name]

[root@sr2s7 home]# ethtool em1

Settings for em1:

        Supported ports: [ TP ]

        Supported link modes:   10baseT/Half 10baseT/Full 

                                100baseT/Half 100baseT/Full 

                                1000baseT/Full 

        Supported pause frame use: No

        Supports auto-negotiation: Yes

        Advertised link modes:  10baseT/Half 10baseT/Full 

                                100baseT/Half 100baseT/Full 

                                1000baseT/Full 

        Advertised pause frame use: No

        Advertised auto-negotiation: Yes

        Speed: 1000Mb/s

        Duplex: Full

        Port: Twisted Pair

        PHYAD: 1

        Transceiver: internal

        Auto-negotiation: on

        MDI-X: Unknown

        Supports Wake-on: g

        Wake-on: d

        Link detected: yes Means the link is hooked.

ethtool

// man page of ethtool
$ ethtool -h

// Check statistic registers of network card
$ ethtool -S eth0

// See most of the registers of network card in interface eth0
$ ethtool -d eth0

// See the driver information
$ ethtool -i eth0

NIC: Intel e1000

more info:
http://www.globax.info/mediawiki/index.php/Intel_Gigabit_Performance