CentOS7 internal and external network dual IP configuration practice

1. Configure intranet IP: ifcfg-eno1

 

TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="eno1"
UUID="e4f6837c-e6a0-44ed-a8bf-0145d87a3493"
DEVICE="eno1"
ONBOOT="yes"
IPADDR="128.0.3.251"
PREFIX="21"
GATEWAY="128.0.3.1"
DNS1="内网DNS"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
IPV6_PRIVACY="no"

 

 

2. Configure the external network IP: ifcfg-eno2

 

TYPE="Ethernet"
BOOTPROTO="none"
DEFROUTE="yes"
NAME="eno2"
UUID="2eaf6606-516b-44d7-bb94-23f0f66dae0a"
DEVICE="eno2"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
ONBOOT="yes"
IPADDR="121.126.29.242"
GATEWAY="121.126.29.241"
DNS1="外网DNS"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
IPV6_PRIVACY="no"
NETMASK="255.255.255.252"
HWADDR="fc:15:b4:10:ca:55"
NM_CONTROLLED=yes

 

 

3. Configure routing: this step is the key 

route add -net 128.0.0.0 netmask 255.255.248.0 gw 128.0.3.1 eno1
route add -net 121.126.29.240 netmask 255.255.255.252 ge 121.126.29.241 eno2
route add default gw 121.126.29.241 eno2

 The last sentence of the default gateway is the point

 

4. The configuration takes effect permanently: /etc/rc.local

 

route add -net 128.0.0.0 netmask 255.255.248.0 gw 128.0.3.1 eno1
route add -net 121.126.29.240 netmask 255.255.255.252 ge 121.126.29.241 eno2
route add default gw 121.126.29.241 eno2

  

5. Debugging process:

 》 1. Unplug the external network cable and test whether the internal network is connected

 》 2. Unplug the internal network cable and test whether the external network is connected

 》3, plug in the internal and external network cables at the same time, network connectivity

 > 4, view the routing table:

netstat -rn

  > 5, delete the routing table:

route del -net default netmask 0.0.0.0 gw 128.0.3.1 eno1