目前，各种OS操作系统版本疯狂升级，并且随之而变的操作系统设置也有很大的改变。对于CENTOS目前最新版本已经
是8.x，但是，centos 7.6相对与以前的老版本，操作系统相关的部分配置已经有比较大的变化，举例：静态IP与配置参数
NM_CONTROLLED，当网络配置文件中没有改参数时，即便其IP配置使用静态IP，也不起作用。
--ifcfg-ens34的配置
[root@centos76mysqlpri network-scripts]# cat ifcfg-ens34
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static #此处已经声明使用静态IP
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens34
UUID=af87d788-f524-4095-81c9-367eba488f9a
DEVICE=ens34
ONBOOT=yes
IPADDR=192.168.192.201
PREFIX=24
GATEWAY=192.168.192.1
IPV6_PRIVACY=no
[root@centos76mysqlpri network-scripts]#
--ifcfg-ens34启动后的IP地址缺不是期望中的
[root@centos76mysqlpri network-scripts]# ifup ens34
[root@centos76mysqlpri network-scripts]# ifconfig -a
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.248.129 netmask 255.255.255.0 broadcast 192.168.248.255
inet6 fe80::7391:3e5e:cead:f642 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:26:76:0c txqueuelen 1000 (Ethernet)
RX packets 13523 bytes 17404331 (16.5 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 5554 bytes 343077 (335.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ens34: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.192.128 netmask 255.255.255.0 broadcast 192.168.192.255
inet6 fe80::2162:583:8ee:d0be prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:26:76:16 txqueuelen 1000 (Ethernet)
RX packets 63 bytes 7008 (6.8 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 138 bytes 20565 (20.0 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 1000 (Local Loopback)
RX packets 224 bytes 18384 (17.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 224 bytes 18384 (17.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:2f:86:09 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0-nic: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 52:54:00:2f:86:09 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@centos76mysqlpri network-scripts]#
到此，感觉有点莫名其妙！经查询是：centos7.6使用NM_CONTROLLED参数控制是否通过网络管理器进行管理。
--修改ifcfg-ens34的配置
[root@centos76mysqlpri network-scripts]# cat ifcfg-ens34
TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=static
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
IPV6_ADDR_GEN_MODE=stable-privacy
NAME=ens34
UUID=af87d788-f524-4095-81c9-367eba488f9a
DEVICE=ens34
ONBOOT=yes
NM_CONTROLLED=no
IPADDR=192.168.192.201
PREFIX=24
GATEWAY=192.168.192.1
IPV6_PRIVACY=no
[root@centos76mysqlpri network-scripts]#
--ifcfg-ens34网卡重启后
[root@centos76mysqlpri network-scripts]# ifup ens34
[root@centos76mysqlpri network-scripts]# ifconfig -a
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.248.129 netmask 255.255.255.0 broadcast 192.168.248.255
inet6 fe80::7391:3e5e:cead:f642 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:26:76:0c txqueuelen 1000 (Ethernet)
RX packets 13523 bytes 17404331 (16.5 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 5554 bytes 343077 (335.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
ens34: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.192.201 netmask 255.255.255.0 broadcast 192.168.192.255
inet6 fe80::20c:29ff:fe26:7616 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:26:76:16 txqueuelen 1000 (Ethernet)
RX packets 81 bytes 8664 (8.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 167 bytes 24573 (23.9 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 1000 (Local Loopback)
RX packets 224 bytes 18384 (17.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 224 bytes 18384 (17.9 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 52:54:00:2f:86:09 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
virbr0-nic: flags=4098<BROADCAST,MULTICAST> mtu 1500
ether 52:54:00:2f:86:09 txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@centos76mysqlpri network-scripts]#