CentOS配置多个IP

1. 进入网卡配置目录

   cd /etc/sysconfig/network-scripts
   
   [root@www network-scripts]# ls
   ifcfg-em1  ifcfg-lo ..

2. 运行ifconfig查看当前使用的网卡配置

   [root@www network-scripts]# ifconfig 
   em1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.90  netmask 255.255.255.248  broadcast 192.187.112.95
        inet6 fe80::226:6cff:fef0:1158  prefixlen 64  scopeid 0x20<link>
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        RX packets 541372  bytes 746304201 (711.7 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 99758  bytes 28932462 (27.5 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device memory 0xfbde0000-fbdfffff  
   
   em2: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 00:26:6c:f0:11:59  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
        device memory 0xfbd20000-fbd3ffff  
   
   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 128  bytes 11776 (11.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 128  bytes 11776 (11.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
   

   如上， 根据IP可以确认外网配置是em1

3. 复制一个配置文件

   cp ifcfg-em1 ifcfg-em1:1

4. 修改几项配置

   # Generated by dracut initrd
   NAME="em1"
   DEVICE="em1:1"   # 后面加:1
   ONBOOT="yes"
   NETBOOT="yes"
   UUID="75e73492-9586-45fc-951f-3d99ab134668"
   IPV6INIT="yes"
   BOOTPROTO="none"
   TYPE="Ethernet"
   PROXY_METHOD="none"
   BROWSER_ONLY="no"
   IPADDR="192.187.112.91"  # 改成其他IP
   PREFIX="29"
   GATEWAY="192.187.112.89"
   DNS1="127.0.0.1"
   DEFROUTE="yes"
   IPV4_FAILURE_FATAL="no"
   IPV6_AUTOCONF="yes"
   IPV6_DEFROUTE="yes"
   IPV6_FAILURE_FATAL="no"

   如果需要配置更多IP， 可以继续复制ifcfg-em1文件为ifcfg-em1:2, 相应的修改复制后的文件, 示例：

   DEVICE="em1:2"   # 后面加:2
   IPADDR="192.187.112.92"  # 改成其他IP

5. 重启网卡使配置生效

   systemctl restart network
   
   ### CentOS8使用如下命令：
   nmcli c reload  # 重新加载配置文件
   nmcli c up em1  # 重新激活网卡em1

6. 查看是否生效

   [root@www network-scripts]# ifconfig 
   em1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.90  netmask 255.255.255.248  broadcast 192.187.112.95
        inet6 fe80::226:6cff:fef0:1158  prefixlen 64  scopeid 0x20<link>
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        RX packets 542683  bytes 746406082 (711.8 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 100544  bytes 29029241 (27.6 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device memory 0xfbde0000-fbdfffff  
   
   em1:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.91  netmask 255.255.255.248  broadcast 192.187.112.95
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        device memory 0xfbde0000-fbdfffff  
   
   em2: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 00:26:6c:f0:11:59  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
        device memory 0xfbd20000-fbd3ffff  
   
   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 128  bytes 11776 (11.5 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 128  bytes 11776 (11.5 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

   em1:1就是新增的虚拟网卡

加5个IP的最终效果:

[root@www network-scripts]# ifconfig 
em1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.90  netmask 255.255.255.248  broadcast 192.187.112.95
        inet6 fe80::226:6cff:fef0:1158  prefixlen 64  scopeid 0x20<link>
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        RX packets 543663  bytes 746488748 (711.9 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 101167  bytes 29138923 (27.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device memory 0xfbde0000-fbdfffff  

em1:1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.91  netmask 255.255.255.248  broadcast 192.187.112.95
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        device memory 0xfbde0000-fbdfffff  

em1:2: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.92  netmask 255.255.255.248  broadcast 192.187.112.95
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        device memory 0xfbde0000-fbdfffff  

em1:3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.93  netmask 255.255.255.248  broadcast 192.187.112.95
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        device memory 0xfbde0000-fbdfffff  

em1:4: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.94  netmask 255.255.255.248  broadcast 192.187.112.95
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        device memory 0xfbde0000-fbdfffff  

em1:5: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.187.112.95  netmask 255.255.255.248  broadcast 192.187.112.95
        ether 00:26:6c:f0:11:58  txqueuelen 1000  (Ethernet)
        device memory 0xfbde0000-fbdfffff  

em2: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 00:26:6c:f0:11:59  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
        device memory 0xfbd20000-fbd3ffff  

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 136  bytes 12464 (12.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 136  bytes 12464 (12.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0