Firewall Scenarios and Configuration

Properly configured firewalls and reverse proxy servers provide a high level of first-line defense in your Office Communications Server infrastructure. The goal is to design a defense-in-depth strategy, of which the firewalls play an initial role. Regardless of how external communication is reaching your internal deployment, the traffic needs to be confined in such a way that only expected data flows of a predictable type are being allowed into your domain and enterprise. This is the express purpose of the firewalls and reverse proxies.

A number of firewall configurations can be implemented. Two of these implementations will be discussed and detailed in the following sections:

• Back-to-back firewall

• Three-legged firewall