Fundamentals; The Address Book; Overview; Ip Addresses - D-Link NetDefend DFL-210 User Manual

Chapter 3. Fundamentals
This chapter describes the fundamental logical objects upon which NetDefendOS is built. These
objects include such items as addresses, services and schedules. In addition, the chapter explains
how the various supported interfaces work, it outlines how security policies are constructed and how
basic system settings are configured.
• The Address Book, page 70
• Services, page 75
• Interfaces, page 80
• ARP, page 94
• The IP Rule Set, page 101
• Schedules, page 107
• Certificates, page 109
• Date and Time, page 113
• DNS, page 119

3.1. The Address Book

3.1.1. Overview

The Address Book contains named objects representing various types of addresses, including IP
addresses, networks and Ethernet MAC addresses.
Using Address Book objects has three distinct benefits; it increases readability, reduces the danger
of entering incorrect network addresses, and makes it easier to change addresses. By using objects
instead of numerical addresses, you only need to make changes in a single location, rather than in
each configuration section where the address appears.

3.1.2. IP Addresses

IP Address objects are used to define symbolic names for various types of IP addresses. Depending
on how the address is specified, an IP Address object can represent either a host (a single IP
address), a network or a range of IP addresses.
In addition, IP Address objects can be used for specifying the credentials used in user
authentication. For more information on this topic, see Chapter 8, User Authentication.
The following list presents the various types of addresses an IP Address object can hold, along with
what format that is used to represent that specific type:
Host
IP Network
A single host is represented simply by its IP address.
For example: 192.168.0.14.
An IP Network is represented using Classless Inter Domain Routing (CIDR) form.
CIDR uses a forward slash and a digit (0-32) to denote the size of the network as a
postfix. This is also known as the netmask.
/24 corresponds to a class C net with 256 addresses (netmask 255.255.255.0), /27
corresponds to a 32 address net (netmask 255.255.255.224) and so on.
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