检查维护系统的时候，经常会要查看服务器的网络端口是多大的，所以需要用到Linux的一个命令。
如何查看CentOS的网络带宽出口多大？可以用下面的命令来查看。
# ethtool eth0
前面是命令，后面跟的是设备名，如果对外连接的网络设备是eth1，那就需要改成：ethtool eth0
[root@localhost ~]# ethtool eth0
Settings for eth0:
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: 0
Transceiver: internal
Auto-negotiation: on
MDI-X: Unknown
Supports Wake-on: d
Wake-on: d
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes