先用ifconfig来查看所有活动网络接口
eth0 Link encap:Ethernet HWaddr b8:27:eb:1b:63:a8
inet addr:192.168.1.6 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::6502:67ff:89b:b2fd/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:43239 errors:0 dropped:24 overruns:0 frame:0
TX packets:30644 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:25068614 (23.9 MiB) TX bytes:5993030 (5.