Configuring SonicWALL Firewalls
Delivering an in-depth look at the SonicWALL firewall product line, this book covers all aspects including the SOHO devices and the Enterprise SonicWALL firewalls.
TABLE OF CONTENTS Configuring SonicWALL Firewalls
Understanding Networking
To understand networking is to understand the language of firewalls. A firewall is used to segment resources and limit access between networks. Before we can really focus on what a firewall does for us, we need to understand how networking works. Today in most environments and on the Internet, the protocol suite TCP/IP (Transmission Control Protocol/Internet Protocol) is used to transport data from here to there. We will begin this chapter by looking at networking as a whole with a focus on the Open System Interconnection (OSI) model.
The OSI Model
The OSI model was originally developed as a framework to build networking protocols on. During the time when then Internet was being developed, a protocol suite named TCP/IP was developed. TCP/IP was found to meet the requirements of the Internet s precursor, ARPANET. At this point, TCP/IP was already integrated into UNIX and was quickly adopted by the academic community as well. With the advent of the Internet and its widespread usage, TCP/IP has become the de facto standard protocol suite of internetworking today.
The OSI model consists of seven distinct layers. These layers each contain the fundamental ideas of networking. In Figure 1.1 we can see the way that the seven layers stack on top of each other. The idea is that each upper layer is encapsulated inside of each lower layer. So ultimately, any data communications are transformed into the electrical impulses that pass over the cables or through the air that surrounds us. Understanding the...
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