How CentOS6 implements router function

Configuration

Configure all IP addresses first as shown in the figure

Configure routing for different machines

Aubin-CentOS1

    route add default gw 10.0.1.1

CentOS-R1

    route add -net 10.0.3.0/24 gw 10.0.2.2
    route add -net 10.0.4.0/24 gw 10.0.2.2
    echo 1 > /proc/sys/net/ipv4/ip_forward                #启用转发功能(可以理解为启用路由功能)
    iptables -F                                           #关闭防火墙

CentOS-R2

    route add -net 10.0.1.0/24 gw 10.0.2.1
    route add -net 10.0.4.0/21 gw 10.0.3.1
    echo 1 > /proc/sys/net/ipv4/ip_forward
    iptables -F

CentOS-R3

    route add -net 10.0.2.0/24 gw 10.0.3.2
    route add -net 10.0.1.0/24 gw 10.0.3.2
    echo 1 > /proc/sys/net/ipv4/ip_forward
    iptables -F

Aubin-CentOS1

    route add default gw 10.0.4.1

The above is the complete configuration, and then use the CentOS1 zone to test and ping the CentOS2 IP address 10.0.4.100. If the ping is successful, all configurations are fine. If there is no pass, please check the following points at the exhibition

0. Although the configuration is simple, it is cumbersome enough. If you encounter problems, please be patient and check the following items.

1. Use route -n to check whether the route is effective.

2.cat /proc/sys/net/ipv4/ip_forward Check whether the output is 1. If it is 0, it means that the forwarding function is not enabled.

Check whether echo 1 > /proc/sys/net/ipv4/ip_forward is executed successfully.

3. Check whether the IP and mask are configured correctly, because it is easy to get confused with multiple IP addresses, so check carefully.

4. Check whether the firewall is turned off and execute iptables -F.

5. If you are doing experiments in a virtual machine environment, check whether the MAC address conflicts

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