Microsoft® Lync® Server 2013 Unleashed Second Edition

Firewall Requirements Overview

Wikipedia defines a firewall as a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications. It is a device or set of devices configured to permit or deny computer applications based on a set of rules and other criteria.

There are several types of firewall techniques, including these:

• Packet Filtering—Packet filtering inspects packets as they are passed through the network and rejects or accepts these packets based on defined rules. Typically, these rules will specify a source and destination address, a port, and either an allow or deny statement to define the behavior of the packet-filtering rule. Packet-filtering firewalls are generally fast ...