Appendix C - Introduction To Networking - SonicWALL Internet Security Appliances Administrator's Manual

Appendix C - Introduction to Networking

This appendix provides a non-technical overview of the network protocols supported by the
SonicWALL and includes a discussion of Internet Protocol (IP) addressing.
It can be helpful to review a book on TCP/IP for an overview of protocols such as TCP (Transmission
Control Protocol), UDP (User Datagram Protocol), and ICMP (Internet Control Message Protocol). The
following book is recommended for beginner and intermediate network administrators:
Teach Yourself TCP/IP in 14 Days Second Edition
Timothy Parker, Ph.D
SAMS Publishing
ISBN # 0-672-30885-1
Network Hardware Components
• Computers - IBM- compatible, MAC, notebooks, and PDAs
• Resources - printers, fax machines, tape backup units, and file storage devices
• Cables - crossover, ethernet
• Connectors - bridges, routers
• Network Interface Card (NIC) - a card installed inside a computer that physically connects a
computer to a network and controls the flow of data from the network to the computer. The NIC
has a port where the network cable is connected.
Network Types
• LAN stands for Local Area Network. Local area refers to a network in one location, Local Area
Networks connect computers and devices close to each other such as on one floor of a building,
one building, or a campus. LANs can connect as few as two computers or as many as 100
computers.
• WAN (Wide Area Network) connects LANs together. The networks that make up a WAN can be
located throughout a country or even around the world. If a single company owns a WAN, it is
often referred to as an enterprise network. The Internet is currently the largest WAN.
Firewalls
A firewall is a software or hardware system that prevents unauthorized outside access, theft,
deletion, or modification of information stored on a local network. Typically, unauthorized access
would be via an organization's Internet connection.
Gateways
A gateway can be a computer that acts as a connector between a private internal network and
another network such as the Internet. A gateway used as a firewall can transmit information from
an internal network to the Internet. Also, gateways can examine incoming information and
determine if the information is allowed access to the network.
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