Ubuntu / CentOS 设置静态IP
Linux 系统环境
Ubuntu 14.04.2 LTS x86_64 GNU/Linux
CentOS Linux release 7.5.1804 (Core)
Ubuntu 与 CentOS 同属于Linux 系统，但是二者配置网卡的方式不同，配置文件也不尽相同。
一、Ubuntu 系统
0. Ubuntu 查看本机网卡和DNS
# ifconfig
eth1 Link encap:Ethernet HWaddr f8:a9:63:55:83:8b
inet addr:10.10.111.15 Bcast:10.10.111.255 Mask:255.255.255.0
inet6 addr: fe80::faa9:63ff:fe55:838b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:25851 errors:0 dropped:152 overruns:0 frame:0
TX packets:25318 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:9086092 (9.0 MB) TX bytes:4059896 (4.0 MB)
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:155 errors:0 dropped:0 overruns:0 frame:0
TX packets:155 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:13617 (13.6 KB) TX bytes:13617 (13.6 KB)
# nm-tool
NetworkManager Tool
State: connected (global)
- Device: eth1 [Wired connection 1] -------------------------------------------
Type: Wired
Driver: r8169
State: connected
Default: yes
HW Address: F8:A9:63:55:83:8B
Capabilities:
Carrier Detect: yes
Speed: 100 Mb/s
Wired Properties
Carrier: on
IPv4 Settings:
Address: 10.10.111.15
Prefix: 24 (255.255.255.0)
Gateway: 10.10.111.1
DNS: 10.10.0.21
DNS: 10.10.0.20
DNS: 127.0.0.1
- Device: wlan1 ----------------------------------------------------------------
Type: 802.11 WiFi
Driver: iwlwifi
State: unavailable
Default: no
HW Address: 00:C2:C6:86:1E:92
Capabilities:
Wireless Properties
WEP Encryption: yes
WPA Encryption: yes
WPA2 Encryption: yes
Wireless Access Points
1. 找到网络文件并修改
sudo vim /etc/network/interfaces
修改如下部分：
# interfaces(5) file used by ifup(8) and ifdown(8)
#auto lo
#iface lo inet loopback
auto eth1
iface eth1 inet static
address 10.10.111.177
gateway 10.10.110.1
netmask 255.255.255.0
network 10.10.111.0
broadcast 10.10.111.255
2. 修改dns解析
因为以前是dhcp解析，所以会自动分配dns服务器地址
查看自动分配dns服务器地址
# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 10.10.0.20
nameserver 10.10.0.21
nameserver 127.0.0.1
而一旦设置为静态ip后就没有自动获取到的dns服务器了，要自己设置一个
sudo vim /etc/resolv.conf
写上一个公网的DNS
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
#nameserver 127.0.0.1
nameserver 10.10.0.20
nameserver 10.10.0.21
nameserver 8.8.8.8
注意：8.8.8.8 是谷歌的DNS服务器，但是解析速度慢，还是找到一个国内的dns来用，参见米扑博客：公共 DNS 服务器 IP 地址
重启电脑，使设置生效（重启电脑后，网络图标可能显示为不可用，实际是可联网）
3. 重启网卡（推荐重启电脑，重启网卡有时不管用）
sudo /etc/init.d/networking restart
# sudo /etc/init.d/networking restart
stop: Job failed while stopping
start: Job is already running: networking
这里有点有问题，网卡配置没能生效，查看日志：
tail -f /var/log/upstart/networking.log //查看错误日志
Stopping or restarting the networking job is not supported.
Use ifdown & ifup to reconfigure desired interface.
从以上日志内容看，传统的service重启和停止网络已经不再支持，需要使用ifdown & ifup来操作。
ifdown eth1 // ifdown: interface eth1 not configured
ifup eth1 // RTNETLINK answers: File exists Failed to bring up eth1.
但是这样操作了，网卡仍然不起作用，最后查看，用如下命令：
sudo ifconfig eth1 down
sudo ifconfig eth1 up
即使这样，重启ubuntu后，发现又不能上网了，问题出在 /etc/resolv.conf
重启后，此文件配置的dns又被自动修改为默认值，所以需要永久性修改DNS。
修改如下文件并添加：
sudo vim /etc/resolvconf/resolv.conf.d/base
nameserver 10.10.0.20
nameserver 10.10.0.21
nameserver 8.8.8.8
保存后，重启电脑（注意：测试发现重启网络不生效）
查看本机网络IP地址
$ ifconfig
eth1 Link encap:Ethernet HWaddr f8:a9:63:57:2a:b9
inet addr:10.10.111.177 Bcast:10.10.111.255 Mask:255.255.255.0
inet6 addr: fe80::faa9:63ff:fe57:2ab9/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:971 errors:0 dropped:451 overruns:0 frame:0
TX packets:141 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:83270 (83.2 KB) TX bytes:16417 (16.4 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:137 errors:0 dropped:0 overruns:0 frame:0
TX packets:137 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:12727 (12.7 KB) TX bytes:12727 (12.7 KB)
请访问米扑代理的检测页面：
https://proxy.mimvp.com/check.php
补充知识：Ubuntu下修改为永久DNS的方法
上面介绍了安装好Ubuntu之后，设置了静态IP地址，但是有时再重启后就无法解析域名，因此想重新设置一下DNS
打开/etc/resolv.conf
cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
内容是一段警告：说这个文件是resolvconf程序动态创建的，不要直接手动编辑，修改将被覆盖。
果不其然，修改后重启就失效了，搜索了Ubuntu下设置DNS的相关资料，总结出两个办法：
方法1
通过/etc/network/interfaces
vim /etc/network/interfaces
在它的最后增加一句：
dns-nameservers 8.8.8.8
8.8.8.8是Google提供的DNS服务，你也可以改成电信运营商的DNS，参见米扑博客：公共 DNS 服务器 IP 地址
sudo reboot
重启服务器后，DNS就生效了，这时候再看 /etc/resolv.conf，最下面就多了一行：
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 8.8.8.8
方法2
修改配置文件
vim /etc/resolvconf/resolv.conf.d/base（这个文件默认是空的）
在里面插入：
nameserver 8.8.8.8
nameserver 8.8.4.4
如果有多个DNS就一行一个
修改好保存，然后执行
resolvconf -u
再看/etc/resolv.conf，最下面就多了2行：
cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 8.8.8.8 nameserver 8.8.4.4
可以看到我们的设置已经加上了，然后再ping一个域名，当时就可以解析了，无需重启。
二、CentOS 系统
CentOS下修改DNS很容易，直接修改/etc/resolv.conf，内容是：
vim /etc/resolv.conf
# vim /etc/resolv.conf # Generated by NetworkManager nameserver 114.114.114.114 nameserver 8.8.8.8
保存就生效了，重启也没问题。
CentOS重启后resolv.conf被重置的解决方案
修改 /etc/resolv.conf 文件后，重启服务器后，有时 DNS 会被重置还原，如何解决呢？
1）修改 /etc/sysconfig/network-scripts/ifcfg-eth0 文件
# vim /etc/sysconfig/network-scripts/ifcfg-eth0 UUID= DEVICE=eth0 BOOTPROTO=none ONBOOT=yes TYPE=Ethernet DEFROUTE=yes IPV6INIT=yes IPV4_FAILURE_FATAL=no PEERDNS=yes NAME=eth0 IPADDR=192.168.137.26 NETMASK=255.255.255.0 GATEWAY=192.168.137.1 DNS1=114.114.114.114 DNS2=8.8.8.8
2）重启网卡
命令重启已经被淘汰，不要使用命令：service network restart （已舍弃）
命令推荐使用
# ifdown ppp0
# ifup ppp0
3）查看 /etc/resolv.conf 文件自动生成的DNS
# cat /etc/resolv.conf # Generated by NetworkManager nameserver 114.114.114.114 nameserver 8.8.8.8
还有一种简单方法，在网卡 ifcfg-eth0 文件里，修改参数 PEERDNS=no，然后在 /etc/resolv.conf 文件里直接配置 DNS，这样重启服务器后，修改后的 /etc/resolv.conf DNS 也是永久的，不会被重置。
查看 /etc/sysconfig/network 文件
# vim /etc/sysconfig/network # Created by anaconda
修改静态DNS，需要在 ifcfg-eth0 文件（ifcfg-eth1文件一般为空）里添加两行，例如：
DNS1=114.114.114.114
DNS2=8.8.8.8
查看 /etc/sysconfig/network-scripts/ifcfg-eth0 文件
# vim /etc/sysconfig/network-scripts/ifcfg-eth0 UUID= DEVICE=eth0 BOOTPROTO=none ONBOOT=yes TYPE=Ethernet DEFROUTE=yes IPV6INIT=yes IPV4_FAILURE_FATAL=no PEERDNS=yes NAME=eth0 IPADDR=192.168.137.26 NETMASK=255.255.255.0 GATEWAY=192.168.137.1 DNS1=114.114.114.114 DNS2=8.8.8.8
查看 /etc/sysconfig/network-scripts/ifcfg-eth1 文件
# vim /etc/sysconfig/network-scripts/ifcfg-eth1
查看 ifconfig 命令
# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.137.26 netmask 255.255.255.0 broadcast 192.168.137.255
inet6 fe80::215:5dff:fe09:64b3 prefixlen 64 scopeid 0x20<link>
ether 00:15:5d:09:64:b3 txqueuelen 1000 (Ethernet)
RX packets 79214 bytes 8765241 (8.3 MiB)
RX errors 0 dropped 835 overruns 0 frame 0
TX packets 613 bytes 77201 (75.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 fe80::215:5dff:fe09:64b5 prefixlen 64 scopeid 0x20<link>
ether 00:15:5d:09:64:b5 txqueuelen 1000 (Ethernet)
RX packets 108802 bytes 11866450 (11.3 MiB)
RX errors 0 dropped 12 overruns 0 frame 0
TX packets 313 bytes 10790 (10.5 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 720 bytes 65674 (64.1 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 720 bytes 65674 (64.1 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ppp0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST> mtu 1492
inet 221.202.153.166 netmask 255.255.255.255 destination 221.202.153.1
ppp txqueuelen 3 (Point-to-Point Protocol)
RX packets 27 bytes 1283 (1.2 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4 bytes 37 (37.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
补充：
当然，默认情况下 /etc/resolv.conf 都是由系统自动生成的，例如
1、CentOS 服务器拨号（pppoe）
# cat /etc/resolv.conf # Generated by NetworkManager nameserver 114.114.114.114 nameserver 8.8.8.8 nameserver 192.168.2.1
2、CentOS 服务器（阿里云）
# cat /etc/resolv.conf options timeout:2 attempts:3 rotate single-request-reopen ; generated by /usr/sbin/dhclient-script nameserver 100.100.2.138 nameserver 100.100.2.136
3、Ubuntu 服务器
# cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 8.8.8.8 nameserver 127.0.1.1
4、MacOS 服务器
$ cat /etc/resolv.conf # # macOS Notice # # This file is not consulted for DNS hostname resolution, address # resolution, or the DNS query routing mechanism used by most # processes on this system. # # To view the DNS configuration used by this system, use: # scutil --dns # # SEE ALSO # dns-sd(1), scutil(8) # # This file is automatically generated. # nameserver 192.168.31.1
参考推荐：
Linux/Windows 设置本地DNS域名解析Hosts
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