Tinyproxy: listening and binding on different NICs (eth0, eth1). Routing issues

On a Linux server I have 2 NICs: eth0 and eth1. The server has the IPs: 192.168.2.200/24 on eth0 192.168.3.200/24 on eth1 Both the networks have the default subnet mask (255.255.255.0) and the default gateway is 192.168.x.254. On the server is running tinyproxy with the following configuration. Listen 192.168.2.200 Bind 192.168.3.200 The idea is to expose publicly on Internet a proxy where the traffic coming from eth0 should reach the required resources on Internet via the other interface eth1. It works in LAN only if I put 192.168.3.0 as default route with a lower metric. But then I can't forward ports anymore from the router on eth0, so I can only use the proxy inside my LAN but it's not accessible from outside. Instead if I put 192.168.2.0 as default route with a lower metric I can access the proxy from the Internet but it's not able to retrieve the resources via the eth1 interface. Maybe I need help with routing. What am I doing wrong? Thanks in avance.