I have clients that will be connecting to a server (ServerA) through a switch. ServerA connects to the switch through eth0 and i use another ethernet card - eth1 to connect to the Internet through an ADSL router. The clients can access the internet with no problem, i have set up IP forwarding and IP masquerading on ServerA.
The problem is that i have another server (ServerB) with an external IP address which is where i want all the traffic from the clients to pass through before going out to the Internet. So i want any clients internet access to go out through the ADSL router into the internet and then through ServerB before going to the actual Internet site. ServerB is where the billing and statistics of the clients will be recorded, so I need to pass the clients requests through ServerB. I cannot modify the ADSL router configuration and I dont want to use VPN. Is there some way to achieve this by modifying ServerA or ServerB?

I am using Linux Red Hat 9 on both servers with Apache version 2 and also running a DHCP server and a DNS server.