CentOS 7 中静态 IP 以及 DNS 的配置

设置静态 IP

编辑配置文件

root@localhost:~# vim /etc/sysconfig/network-scripts/ifcfg-enp0s3

修改以下配置项

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BOOTPROTO="static" #dhcp改为static 
ONBOOT="yes" #开机启用本配置
IPADDR=192.168.5.192 #静态IP
GATEWAY=192.168.4.1 #默认网关
NETMASK=255.255.252.0 #子网掩码

修改后的配置

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root@localhost:~# cat /etc/sysconfig/network-scripts/ifcfg-enp0s3
TYPE="Ethernet"
BOOTPROTO="static"
DEFROUTE="yes"
PEERDNS="yes"
PEERROUTES="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="enp0s3"
UUID="9281a4f6-b04e-4007-8af0-b05a69e6a5aa"
DEVICE="enp0s3"
ONBOOT="yes"
IPADDR=192.168.5.192
GATEWAY=192.168.4.1
NETMASK=255.255.252.0

重启网络服务

root@localhost:~# systemctl restart network.service

查看修改后的网络信息

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root@localhost:~# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp0s3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:79:22:ab brd ff:ff:ff:ff:ff:ff
    inet 192.168.5.192/22 brd 192.168.7.255 scope global enp0s3
       valid_lft forever preferred_lft forever
    inet6 fe80::3723:8466:a91:fc59/64 scope link
       valid_lft forever preferred_lft forever

配置 DNS

Red Hat Enterprise Linux 7 与 CentOS 7 中默认的网络服务由 NetworkManager 提供，这是动态控制及配置网络的守护进程，它用于保持当前网络设备及连接处于工作状态，同时也支持传统的 ifcfg 类型的配置文件。

因此在 CentOS 7 中，手工设置 /etc/resolv.conf 里的 DNS，过了一会，发现被系统重新覆盖或者清除了。

NetworkManager 可以用于以下类型的连接：Ethernet，VLANS，Bridges，Bonds，Teams，Wi-Fi，mobile boradband（如移动3G）以及 IP-over-InfiniBand。针对与这些网络类型，NetworkManager 可以配置他们的网络别名，IP 地址，静态路由，DNS，VPN连接以及很多其它的特殊参数。

可以用命令行工具 nmcli 来控制 NetworkManager。

验证网络管理器服务的状态

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root@localhost:~# systemctl status NetworkManager.service
● NetworkManager.service - Network Manager
   Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2017-03-19 13:22:05 CST; 8min ago
     Docs: man:NetworkManager(8)
 Main PID: 626 (NetworkManager)
   CGroup: /system.slice/NetworkManager.service
           └─626 /usr/sbin/NetworkManager --no-daemon

显示设备状态

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root@localhost:~# nmcli device status
DEVICE  TYPE      STATE      CONNECTION
enp0s3  ethernet  connected  enp0s3
lo      loopback  unmanaged  --

显示当前连接(包括不活动的)

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root@localhost:~# nmcli connection show
NAME    UUID                                  TYPE            DEVICE
enp0s3  9281a4f6-b04e-4007-8af0-b05a69e6a5aa  802-3-ethernet  enp0s3

添加 DNS 设置到指定连接中

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root@localhost:~# nmcli connection modify "enp0s3" ipv4.dns 8.8.8.8
root@localhost:~# nmcli connection modify "enp0s3" +ipv4.dns 223.5.5.5
root@localhost:~# nmcli connection modify "enp0s3" +ipv4.dns 223.6.6.6

将配置生效

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root@localhost:~# nmcli connection up enp0s3
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/3)

查看网络接口属性

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root@localhost:~# nmcli dev show enp0s3
GENERAL.DEVICE:                         enp0s3
GENERAL.TYPE:                           ethernet
GENERAL.HWADDR:                         08:00:27:79:22:AB
GENERAL.MTU:                            1500
GENERAL.STATE:                          100 (connected)
GENERAL.CONNECTION:                     enp0s3
GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnection/3
WIRED-PROPERTIES.CARRIER:               on
IP4.ADDRESS[1]:                         192.168.5.192/22
IP4.GATEWAY:                            192.168.4.1
IP4.DNS[1]:                             8.8.8.8
IP4.DNS[2]:                             223.5.5.5
IP4.DNS[3]:                             223.6.6.6
IP6.ADDRESS[1]:                         fe80::3723:8466:a91:fc59/64
IP6.GATEWAY: