Good morning one and all. In our network we have a single Linux machine that has aliased IP addresses. Each of these IP addresses sit on a network controlled by a remote router to an ISP.
We want to use our Linux box as the gateway for our internal network (10.0.0.x) and for the Linux box to then forward the outgoing traffic to one of our routers on another network.
All things i have read is about masquerading between two physical interface cards; however we have only one network card, listening to multiple IP addresses.
On the Linux box itself; it can ping and access the internet fine using one of the routers as the upstream gateway.
So our configuration is as follows:
: Linux Box eth0:0 = 10.0.0.5 eth0:1 = 192.168.137.5 GW: 192.168.137.1 : Router#1 IP: 192.168.137.1 Connection to internet via ISP : Network Machines IP: 10.0.0.x GW: 10.0.0.5
So the question is, what is my setup for iptables/nat on the Linux box to allow it to accept packets on the 10.0.0.x subnet and route them out to the specific IP address configured for the gateway. When i try to use eth0:1 as my -d then iptables complains of invalid characters and from what I read on the internet, this was disabled in iptables (http://lkml.indiana.edu/hypermail/linux/net/9705.1/0016.html).
Can someone assist please? I am sure I am missing something real obvious here; all my historical knowledge has been two separate ethX network interfaces.
Update; here is the "hackity" iptables script
WIFIBACKUP=192.168.137.1 iptables -F INPUT iptables -F FORWARD iptables -F OUTPUT iptables -F -t nat echo 1 > /proc/sys/net/ipv4/ip_forward iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT iptables -t nat -A PREROUTING -s 10.0.0.0/32 -j REDIRECT --to $WIFIBACKUP iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT