打开/etc/network/interfaces，输入auto eth0
1、dhcp
输入：
iface eth0 inet dhcp
2、static
输入：
iface eth0 inet static
address 192.168.0.42
network 192.168.0.0
netmask 255.255.255.0
broadcast 192.168.0.255
gateway 192.168.0.1
3、adsl
输入：
iface eth0
开机后用pon或pppoe-start连接网络，用poff或pppoe-stop断开网络
