Use iptables and iproute2 to balance network load

Iptables and iproute2 are used to achieve network load balancing. Assume that there are two external interfaces in the Network: eth0 172.16.1.1/24, eth1 10.0.0.1/24, and the interface connecting to the internal network is eth2 192.168.1.1. Now we have designed such a policy to export all the web service data from the internal network to 172.16.1.1. Other data goes to the exit 10.0.0.1. # Set ifconfig eth0 172.16.1.1 netmask 255.255.255.0ifconfig eth1 10.0.0.1 netmask 255.255.255.0ifconfig eth2 192.168.1.1 netmask 255.255.255.0echo 1>; /proc/sys/net/ipv4/ip_forward www.2cto.com # mark the web service class package 100 # This step is critical. iproute2 toolkit is used to implement policy routing, however, the iproute2 toolkit cannot match based on the port. Therefore, use iptables to work with iptables-t mangle-a prerouting-p tcp -- dport 80-j MARK -- set-mark 100 # add multiple route tables. Assume that the gateway at 172.16.1.1 is 172.16.1.254ip route. add 0/0 via 172.16.1.254 table 100 www.2cto.com # Set the routing policy. For data packets with 100 mark bits, query route table no. 100 ip address rule add fwmark 100 table 100 # If NAT is not required, directly route iptables-t NAT-a postrouting-o eth2-j MASQUERADE