How do I set Ubuntu server to two static IP addresses and proper routing with two interfaces

Question

I'm trying to set up the routing table on Ubuntu 12.04. The network environment is as follows:

server -----eth0 192.168.0.1 (DMZ)---LAN----10.13.x.x 

Because the communication between 192.168.0.1 and LAN is too heavy, the firewall will crash. Therefore, I try to temporarily and a interface to server so that we can bypass the firewall. The configuration is as follows.

 ---eth0 192.168.0.1(DMZ) | server-----eth1 10.13.0.1 (LAN) 

When the eth1 is up, a host(10.13.x.x) in the lan can ping eth1 but can not ping eht0. The routing tables is as follows

Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 192.168.0.254 0.0.0.0 UG 0 0 0 eth0 10.13.0.0 0.0.0.0 255.255.255.0 U 1 0 0 eth1 192.168.0.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0 

How do i set the routing table so that a host in the lan can connection with eth0 and eth1 simultaneously (The host with ip address 10.13.x.x can ping eth1 and eth2)?

Answer 1

You need to enable ip_forwarding in the server.

You can do this by editing /etc/sysctl.conf and changing:

net.ipv4.ip_forward = 1