About Ip Addresses; Private Addresses And Gateways - Watchguard Firebox X15 User Manual

The TCP and IP protocols are used to send and receive these packets. TCP disassembles the data and
assembles it again. IP adds information to the packets, such as the sender, the recipient, and any special
instructions.

About IP addresses

To send ordinary mail to a person, you must know his or her street address. For one computer on the Internet
to send data to a different computer, it must know the address of that computer. a computer address is known
as an Internet Protocol (IP) address. All devices on the Internet have unique IP addresses, which enable other
devices on the Internet to find and interact with them.
An IP address consists of four octets (8-bit binary sequences) expressed in decimal format and separated by
periods. Each number between the periods must be within the range of 0 and 255. Some examples of
IP addresses are:
206.253.208.100 = WatchGuard.com
4.2.2.2 = core DNS server
10.0.4.1 = private IP

Private addresses and gateways

Many companies create private networks that have their own address space. The addresses 10.x.x.x and
192.168.x.x are set aside for private IP addresses. Computers on the Internet cannot use these addresses. If
your computer is on a private network, you connect to the Internet through a gateway device that has a public
IP address.
Usually, the default gateway is the router that is between your network and the Internet. After you install the
Firebox on your network, it becomes the default gateway for all computers connected to its trusted or
optional interfaces.
User Guide
Introduction to Network Security
3