Publishing Internal Servers for Telnet in Back to Back ISA Firewall

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Diagram

Internal Server ===> Back End Firewall <=========> Front End Firewall ========> Internet

If you want to publish Internal server for telnet, follow the below steps to do so:

1. Make sure that you have the Default Gateway on Back End Firewall as the Perimeter NIC address of the Front End Firewall 
2. Create a Non-Publish rule on Back End Firewall with the IP address of the internal server and protocol as TELNET SERVER
3. Create a Non-Publish rule on Front End Firewall with the IP address of the External NIC Address of Back End Firewall with protocol as TELNET SERVER
4. Goto the Client Machine outside your network and telnet the External IP of the Front End Firewall

Note: Make sure that when you are creating the Non-Web Publishing rules to publish TELNET goto its properties and Uncheck the RPC Filter from the bottom mentioned list of filters. If not done then the connection will be handed over to the localhost rather than to be proxied.