Ok I am having a bit of trouble setting up the routing on my system.

I have 3 nics, eth0 (10.1.0.1/24) internal network, eth1 (172.19.14.0/26) external network attached to router (172.19.14.129) and then I have eth3 (10.0.0.1/8) and ADSL router with IP address 10.0.0.2.

I need all data to go to the 10.0.0.0/8 network (Internet) and then all 196.37.193.0/24 data to go via the 172.19.14.129 router.

I also need to get squid to do transparent proxy.

How do you suggest I do all of this ?
Must I have ip_forwarding enabled and masquerading on ?

Thanks.

First thing is you are going to need to make sure that your system has the proper routes. You can do a "route -n" to check this.

Then you'll most likely want to create an IPTables firewall to set up NAT (Network Address Translation).

There are a few resources for creating IPTables firewalls. Once good place to start is easyfwgen. You can create a 2 interface firewall there, and then modify the firewall to add the 3rd interface.

If you need more help let me know.