步骤1、配置/etc/sysconfig/network-scripts/ifcfg-eth0 里的文件。it动力的CentOS下的ifcfg-eth0的配置详情：

[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE="eth0"
HWADDR="00:0C:29:FD:FF:2A"
NM_CONTROLLED="yes"
ONBOOT="yes"
IPADDR=192.168.1.31
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
BOOTPROTO=static

前面三行是系统睚带的，后面就是手动添加的。  这样设置扣，记得重启网卡：

[root@localhost ~]# /etc/init.d/network stop
[root@localhost ~]# /etc/init.d/network start

行了，现在就可以PING得通网关了，如果还得上网，不必须设置DNS。设置DNS就详见步骤2

步骤2、修改dns  [root@localhost ~]# vi /etc/resolv.conf  在里面添加二个dns：  nameserver 202.96.134.133  nameserver 8.8.8.8

ok，大攻告成，即可上网了！！！！

以下是参考，如果按上面步骤不行，可以详细看以下内容：  网络接口配置文件

[root@localhost ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
# Intel Corporation 82545EM Gigabit Ethernet Controller (Copper)
TYPE=Ethernet       #网卡类型
DEVICE=eth0         #网卡接口名称
ONBOOT=yes          #系统启动时是否自动加载
BOOTPROTO=static    #启用地址协议 --static:静态协议 --bootp协议 --dhcp协议
IPADDR=192.168.1.11      #网卡IP地址
NETMASK=255.255.255.0    #网卡网络地址
GATEWAY=192.168.1.1      #网卡网关地址
DNS1=10.203.104.41       #网卡DNS地址
HWADDR=00:0C:29:13:5D:74 #网卡设备MAC地址
BROADCAST=192.168.1.255  #网卡广播地址
重新导入ifcfg-eth0网络配置文件
[root@localhost ~]# /etc/init.d/network reload
Shutting down interface eth0:                             [ OK ]
Shutting down loopback interface:                         [ OK ]
Bringing up loopback interface:                           [ OK ]
Bringing up interface eth0:                               [ OK ]

网卡接口关闭与激活  [root@localhost ~]# ifdown eth0 #关闭网络  [root@localhost ~]# ifup eth0 #启动网络

网络服务启动与关闭  方法一:  [root@localhost ~]# service network stop #关闭网络服务  [root@localhost ~]# service network start #启动网络服务  [root@localhost ~]# service network restart #重启网络服务  方法二：  [root@localhost ~]# /etc/init.d/network stop  [root@localhost ~]# /etc/init.d/network start  [root@localhost ~]# /etc/init.d/network restart  网卡状态查询  [root@localhost ~]# service network status  Configured devices:  lo eth0  Currently active devices:  lo eth0

临时配置网卡信息，无需重启。  [root@localhost ~]# ifconfig eth0 10.1.1.10 netmask 255.0.0.0  查看网卡接口信息，默认列出所有接口

[root@localhost ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:13:5D:74
          inet addr:192.168.1.11  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe13:5d74/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:413 errors:0 dropped:0 overruns:0 frame:0
          TX packets:572 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:47701 (46.5 KiB)  TX bytes:64842 (63.3 KiB)
          Base address:0x2000 Memory:d8920000-d8940000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:407 errors:0 dropped:0 overruns:0 frame:0
          TX packets:407 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:70759 (69.1 KiB)  TX bytes:70759 (69.1 KiB)

查看当前路由及网关信息  [root@localhost ~]# netstat -r  Kernel IP routing table  Destination Gateway Genmask Flags MSS Window irtt Iface  192.168.1.0 * 255.255.255.0 U 0 0 0 eth0  169.254.0.0 * 255.255.0.0 U 0 0 0 eth0  default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0DNS：主机名：CentOS主DNS：202.106.46.151第二DNS:202.106.0.20第三DNS:8.8.8.8网络配置：eth0静态ip：192.168.1.106子网掩码 255.255.255.0默认网关 IP 192.168.1.1DEVICE=eth0IPADDR=192.168.1.106NETMASK=255.255.255.0BROADCAST=192.168.1.255ONBOOT=yesBOOTPROTO=noneGATEWAY=192.168.1.1TYPE=Ethernet”/etc/sysconfig/network-scripts/ifcfg-eth0” 11L, 187C