#ifconfig命令：用来查看和配置网络设备
显示当前激活状态的网络接口的信息：
[root@VM_168_102_centos ~]# ifconfig eth0 Link encap:Ethernet HWaddr 00:16:3E:E2:7B:D2 inet addr:10.221.168.102 Bcast:10.221.171.255 Mask:255.255.252.0 inet6 addr: fe80::216:3eff:fee2:7bd2/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3689339 errors:0 dropped:0 overruns:0 frame:0 TX packets:1724548 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:370517889 (353.3 MiB) TX bytes:211155888 (201.3 MiB) Interrupt:163 简单说明：
eth0：网络接口
link encap：网络类型
HWaddr：网卡物理地址（MAC地址）
Inet addr：IP地址
Bcast：广播地址
Mask：子网掩码
UP：代表网卡开启状态；RUNNING：代表网卡的网线被接上；BROADCAST：支持点对点通讯协议；multicast：支持组播
MTU：网卡的最大传输单元
RX packets：接收的数据包个数
TX packets：传输的数据包个数
RX byte：接受的具体数目
TX byte：传输的具体数目
Interrupt：终端信息
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:14 errors:0 dropped:0 overruns:0 frame:0 TX packets:14 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1568 (1.5 KiB) TX bytes:1568 (1.5 KiB)lo：本地循环接口
显示指定的网络接口：
[root@VM_168_102_centos ~]# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:16:3E:E2:7B:D2 inet addr:10.221.168.102 Bcast:10.221.171.255 Mask:255.255.252.0 inet6 addr: fe80::216:3eff:fee2:7bd2/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3694095 errors:0 dropped:0 overruns:0 frame:0 TX packets:1725551 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:370998440 (353.8 MiB) TX bytes:211382468 (201.5 MiB) Interrupt:163
配置IP地址（立即生效，但并不永久）：
ifconfig eth0 192.168.122.22
给eth0网卡配置IP地：192.168.120.56
ifconfig eth0 192.168.122.22 netmask 255.255.255.0（或者192.168.122.22/24）
给eth0网卡配置IP地址：192.168.120.56 ，并加上子掩码：255.255.255.0
启动/关闭指定网络接口：
ifconfig eth0 on
ifconfig eth0 down
设置最大传输单元：
[root@localhost ~]# ifconfig eth0 mtu 1480 [root@localhost ~]# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:0C:29:44:B7:60 inet addr:192.168.108.128 Bcast:192.168.108.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fe44:b760/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1480 Metric:1 RX packets:373 errors:0 dropped:0 overruns:0 frame:0 TX packets:275 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:37682 (36.7 KiB) TX bytes:35735 (34.8 KiB) [root@localhost ~]# ifconfig eth0 mtu 1500 [root@localhost ~]# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:0C:29:44:B7:60 inet addr:192.168.108.128 Bcast:192.168.108.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fe44:b760/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:399 errors:0 dropped:0 overruns:0 frame:0 TX packets:293 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:39932 (38.9 KiB) TX bytes:38155 (37.2 KiB)
#route命令：用于显示和操作IP路由表
显示当前路由信息：
[root@localhost ~]# route
Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.108.0 * 255.255.255.0 U 0 0 0 eth0 192.168.122.0 * 255.255.255.0 U 0 0 0 virbr0
简单说明：
Destination：目标主机或目标网络
Gateway：网关地址（*表示目标是本主机所属的网络，不需要路由）
Genmask：网络掩码
Flags标志说明：U：UP表示此路由当前为启动状态；H：表示目标是主机；G：表示路由指向网关
Metric：路由距离，到达指定网络所需的中转数（linux 内核中没有使用）
Ref：路由项引用次数（linux 内核中没有使用）
Use：该路由被使用的次数，可以粗略估计通向指定网络地址的网络流量
Iface：输出接口
route -n: 使用数字格式显示，不反解地址到主机名
添加到主机的路由：
[root@localhost ~]# route add -host 192.168.107.1 gw 192.168.108.25 [root@localhost ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.107.1 192.168.108.25 255.255.255.255 UGH 0 0 0 eth0 192.168.108.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
添加到网络的路由：
route add -net 10.20.30.48 netmask 255.255.255.0 gw 10.20.30.41
route add -net 10.20.30.48/24 gw 10.20.30.41
添加到默认的路由
[root@localhost ~]# route add default gw 192.168.1.55 192.168.107.1 192.168.108.25 255.255.255.255 UGH 0 0 0 eth0 192.168.108.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 0.0.0.0 192.168.108.55 0.0.0.0 UG 0 0 0 eth0
route del：删除路由
删除到主机的路由
[root@localhost ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.107.1 192.168.108.25 255.255.255.255 UGH 0 0 0 eth0 192.168.108.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 0.0.0.0 192.168.108.55 0.0.0.0 UG 0 0 0 eth0 [root@localhost ~]# route del -host 192.168.107.1 [root@localhost ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.108.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 0.0.0.0 192.168.108.55 0.0.0.0 UG 0 0 0 eth0
删除到网络的路由
route del –net 192.168.1.1
删除到默认的路由
[root@localhost ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.108.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 0.0.0.0 192.168.108.55 0.0.0.0 UG 0 0 0 eth0 [root@localhost ~]# route del default [root@localhost ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.108.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0
#配置DNS
[root@localhost ~]# vim /etc/resolv.conf
# Generated by NetworkManager
domain localdomain
search localdomain
nameserver 192.168.108.1
原文地址：http://putongren.blog.51cto.com/9086263/1547623
