This behavior is a simple IP routing issue.
When you configure the network cards on a proxy server, you only configure one default gateway. You should set the default gateway on the external (Internet) network card of the proxy server. The default gateway points to the router that is used to communicate with the Internet.
You should not assign a default gateway to the internal (Intranet) network card. If you assign a default gateway to the internal interface, the proxy server can send all IP traffic out the external Network Interface Card (NIC) that the default gateway does not have a specific route for in the route table.
For example, when a client on Network A sends an IP packet to the proxy server on Network B, the proxy server does not know how to send packets back to Network B.
To provide the correct routing information for the proxy server to route packets from itself to the remote subnet, you need to insert a persistent static route into the route table of the proxy server that points back to the remote subnet.
To add a persistent route, type
route add -p (destination network) MASK (subnet mask) (gateway IP)
For example, if the proxy server is on the 192.168.6.0 network, and the clients are on the 192.168.7.0 network where the IP of the router to the remote network is 192.168.6.1, you would add a route by typing
route add -p 192.168.7.0 MASK 255.255.255.0 192.168.6.1
It is a good idea to type route print at the command prompt after adding the persistent route to verify that you entered the route in correctly.
For more information on the route command, type route /? at the command prompt.
ID d'article : 209404 - Dernière mise à jour : 6 déc. 2000 - Révision : 1