UBuntu 14.04 LTE设置IP地址和一些服务器版本的Linux还不太一样。以Centos 7.0为例，网卡IP地址的配置文件应该是/etc/sysconfig/network-scripts/ifcfg-eth0
首先UBuntu 14.04 LTE下面IP地址的配置文件是/etc/network/interfaces。
jerry@ubuntu:/etc/network$ cat /etc/network/interfaces # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 192.168.2.100 gateway 192.168.2.2 netmask 255.255.255.0 network 192.168.2.0 broadcast 192.168.2.255 dns-nameservers 8.8.8.8 jerry@ubuntu:/etc/network$
把地址配好后用ifdown eth0后跟上ifup eth0重启网卡让前面的配置生效
jerry@ubuntu:/etc/network$ sudo ifdown eth0 jerry@ubuntu:/etc/network$ sudo ifup eth0 jerry@ubuntu:/etc/network$ ifconfig eth0 Link encap:Ethernet HWaddr 00:0c:29:e7:e6:57 inet addr:192.168.2.100 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fee7:e657/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:275 errors:0 dropped:0 overruns:0 frame:0 TX packets:374 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:31264 (31.2 KB) TX bytes:46453 (46.4 KB) 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:47566 errors:0 dropped:0 overruns:0 frame:0 TX packets:47566 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:8344572 (8.3 MB) TX bytes:8344572 (8.3 MB) jerry@ubuntu:/etc/network$ ping www.baidu.com PING www.a.shifen.com (61.135.169.121) 56(84) bytes of data. 64 bytes from 61.135.169.121: icmp_seq=1 ttl=128 time=102 ms 64 bytes from 61.135.169.121: icmp_seq=2 ttl=128 time=54.9 ms ^C --- www.a.shifen.com ping statistics --- 3 packets transmitted, 2 received, 33% packet loss, time 6396ms rtt min/avg/max/mdev = 54.940/78.678/102.417/23.740 ms
有时你在一台刚刚安装好的Ubuntu机器上运行ifdown eth0命令可能会出现ifdown: interface eth0 not configured这样的错误提示，原因是ifdown和ifup是依据/run/network/ifstate里的内容来知道有哪些网络接口。cat一下有没有eth0，没有就添加eth0=eth0到文件的尾端。然后再运行下命令就解决了。
jerry@ubuntu:/etc/network$ sudo ifdown eth0 ifdown: interface eth0 not configured jerry@ubuntu:/etc/network$ ifconfig eth0 Link encap:Ethernet HWaddr 00:0c:29:96:f1:cb inet addr:192.168.2.129 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fe96:f1cb/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5892 errors:0 dropped:0 overruns:0 frame:0 TX packets:2767 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7515173 (7.5 MB) TX bytes:232642 (232.6 KB) 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:191 errors:0 dropped:0 overruns:0 frame:0 TX packets:191 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:16954 (16.9 KB) TX bytes:16954 (16.9 KB) jerry@ubuntu:/etc/network$ ping 192.168.2.2 PING 192.168.2.2 (192.168.2.2) 56(84) bytes of data. 64 bytes from 192.168.2.2: icmp_seq=1 ttl=128 time=0.328 ms 64 bytes from 192.168.2.2: icmp_seq=2 ttl=128 time=0.153 ms 64 bytes from 192.168.2.2: icmp_seq=3 ttl=128 time=0.285 ms ^C --- 192.168.2.2 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 1998ms rtt min/avg/max/mdev = 0.153/0.255/0.328/0.075 ms jerry@ubuntu:/etc/network$ cd /run/network/ jerry@ubuntu:/run/network$ ls ifstate ifup.eth0 ifup.lo static-network-up-emitted jerry@ubuntu:/run/network$ cat if ifstate ifup.eth0 ifup.lo jerry@ubuntu:/run/network$ cat ifstate lo=lo jerry@ubuntu:/run/network$ vim ifstate jerry@ubuntu:/run/network$ sudo vim ifstate jerry@ubuntu:/run/network$ sudo ifdown eth0 RTNETLINK answers: No such process jerry@ubuntu:/run/network$ sudo ifup eth0 jerry@ubuntu:/run/network$ ifconfig eth0 Link encap:Ethernet HWaddr 00:0c:29:96:f1:cb inet addr:192.168.2.129 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fe96:f1cb/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5912 errors:0 dropped:0 overruns:0 frame:0 TX packets:2823 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7517625 (7.5 MB) TX bytes:240569 (240.5 KB) 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:279 errors:0 dropped:0 overruns:0 frame:0 TX packets:279 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:24074 (24.0 KB) TX bytes:24074 (24.0 KB) jerry@ubuntu:/run/network$ ifconfig eth0 Link encap:Ethernet HWaddr 00:0c:29:96:f1:cb inet addr:192.168.2.129 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fe96:f1cb/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5914 errors:0 dropped:0 overruns:0 frame:0 TX packets:2832 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7517805 (7.5 MB) TX bytes:242116 (242.1 KB) 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:279 errors:0 dropped:0 overruns:0 frame:0 TX packets:279 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:24074 (24.0 KB) TX bytes:24074 (24.0 KB) jerry@ubuntu:/run/network$ sudo ifdown eth0 jerry@ubuntu:/run/network$ sudo ifup eth0 jerry@ubuntu:/run/network$ ifconfig eth0 Link encap:Ethernet HWaddr 00:0c:29:96:f1:cb inet addr:192.168.2.110 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fe96:f1cb/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5936 errors:0 dropped:0 overruns:0 frame:0 TX packets:2895 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7520193 (7.5 MB) TX bytes:250378 (250.3 KB) 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:285 errors:0 dropped:0 overruns:0 frame:0 TX packets:285 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:24592 (24.5 KB) TX bytes:24592 (24.5 KB) jerry@ubuntu:/run/network$
下面是Ubuntu的官方文档专门讲网络设置的