Front-End Server behind a Firewall

The following figure illustrates a front-end and back-end topology where the front-end server is behind the firewall.

A simple Exchange firewall topology

Scenario

To achieve security and still provide access to Outlook Web Access, POP, or IMAP from the Internet, a corporation wants to put the Exchange system behind the corporate firewall.

Setup Instructions

For detailed setup instructions, see How to Set Up a Front-End and Back-End Topology with a Front-End Server Behind a Firewall.

Discussion

Because the whole configuration is inside the firewall, Exchange does not require any special configuration. After a request comes through the firewall to the front-end server, the front-end server returns a response without any configuration changes.

IP address filtering is highly recommended to limit requests through the firewall to only those going to the front-end server (or servers) that are running Exchange and block requests through the firewall to other servers in the organization.