查看IP

[root@localhost ~]# ifconfig
em1 Link encap:Ethernet HWaddr F0:1F:AF:D6:17:DD
inet addr:115.238.54.116  Bcast:115.238.54.127 Mask:255.255.255.224
inet6 addr: fe80::f21f:afff:fed6:17dd/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:83248115 errors:0 dropped:0 overruns:0 frame:0
TX packets:50674679 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:10627919322 (9.8 GiB) TX bytes:13311903923 (12.3 GiB)
Interrupt:16
em1:0 Link encap:Ethernet HWaddr F0:1F:AF:D6:17:DD
inet addr:121.52.229.126  Bcast:121.52.229.127 Mask:255.255.255.224
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:16
em1:1 Link encap:Ethernet HWaddr F0:1F:AF:D6:17:DD
inet addr:120.199.8.215  Bcast:120.199.8.223 Mask:255.255.255.240
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:16
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:2228411 errors:0 dropped:0 overruns:0 frame:0
TX packets:2228411 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:667383706 (636.4 MiB) TX bytes:667383706 (636.4 MiB)
（em1表示网卡对应的三个IP；lo表示本地环回IP）

查看Gateway

[root@localhost ~]# netstat -rn 或 route -n
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
120.199.8.208 0.0.0.0 255.255.255.240 U 0 0 0 em1
115.238.54.96 0.0.0.0 255.255.255.224 U 0 0 0 em1
121.52.229.96 0.0.0.0 255.255.255.224 U 0 0 0 em1
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 em1
0.0.0.0 115.238.54.97 0.0.0.0 UG 0 0 0 em1
（以0.0.0.0开始的行的Gateway是默认网关）

查看DNS

[root@localhost ~]# cat /etc/resolv.conf
nameserver 202.101.172.47
nameserver 221.12.1.227

修改配置

在/etc/sysconfig/network-scripts目录下，用vi命令编辑ifcfg-em2：
DEVICE=em2 设备名称
HWADDR=C8:1F:66:B8:EB:9F 物理地址
ONBOOT=yes 是否启动
BOOTPROTO=static 静态IP 可以选择 dhcp
BROADCAST=192.168.0.255 广播
NETWORY=192.168.0.0 网段
IPADDR=192.168.0.123 IP地址
NETMASK=255.255.255.0 子网
GATEWAY=192.168.0.1 网关！
DNS=192.168.0.1
保存后，还需要用如下命令重启一下网络服务：
# service network restart