Use Mii-tool and Ethtool under Linux to see if the network cable is properly connected to the network card

Enter Mii-tool to see if the network cable is connected to the network card
#mii-tool

1. eth0:negotiated 100basetx-fd, link ok

Sometimes the driver may not support an error with the following errors
#mii-tool

1. Siocgmiiphy on ' eth0 ' failed:operation not supported
2. No MII interfaces found

You can use Ethtool to view
#ethtool eth0

2. Settings for eth0:
4. Supported ports: [TP]
6. Supported Link Modes:10baset/half 10baset/full
8. 100baset/half 100baset/full
10. 1000baset/full
12. Supports Auto-negotiation:yes
14. Advertised Link Modes:10baset/half 10baset/full
16. 100baset/half 100baset/full
18. 1000baset/full
20. Advertised Auto-negotiation:yes
22. speed:100mb/s
24. Duplex:full
26. Port:twisted Pair
28. phyad:0
30. Transceiver:internal
32. Auto-negotiation:on
34. Supports WAKE-ON:PUMBG
36. Wake-on:g
38. Current message level:0x00000033 (51)
40. Link Detected:yes

Link Detected:yes to normal no for failure

Transferred from: http://blog.sina.com.cn/s/blog_406127500101iffg.html

Use Mii-tool and Ethtool under Linux to see if the network cable is properly connected to the network card