10.2-3 ifup&ifdown：激活与禁用网络接口

ifup：激活网络接口

    ifup 和 ifdown 命令用于激活指定的网络接口。ifup命令其实是一个Shel脚本，有Shel基础的读者可以使用which命令来找到这个脚本并读一读。命令可读取配置文件/etc/sysconfig/network和/etc/sysconfig/network-scripts/ifcfg-<configuration>对网络接口进行相应的操作。   

ifdown：禁用网络接口

[root@cs6 ~]# ifdown eth1
[root@cs6 ~]# ifconfig
eth0 Link encap:Ethernet HWaddr 00:AA:BB:CC:DD:EE
          inet addr:10.0.0.100 Bcast:10.0.0.255 Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe8c:6a04/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
          RX packets:16249 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7819 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:20914267 (19.9 MiB) TX bytes:634620 (619.7 KiB)

eth0:0 Link encap:Ethernet HWaddr 00:AA:BB:CC:DD:EE
          inet addr:10.0.0.101 Bcast:10.0.0.255 Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

eth0:1 Link encap:Ethernet HWaddr 00:AA:BB:CC:DD:EE
          inet addr:10.0.0.8 Bcast:10.0.0.255 Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

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:65536 Metric:1
          RX packets:6 errors:0 dropped:0 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:504 (504.0 b) TX bytes:504 (504.0 b)