ZyWALL 50 Internet Security Gateway

6.2.1

SUA (Single User Account) Versus NAT ..........................................................................

6-6

6.2.2

Applying NAT ....................................................................................................................

6-6

6.3

NAT Setup ..................................................................................................................................

6-8

6.3.1

Address Mapping Sets ........................................................................................................

6-8

6.4

NAT Server Sets – Port Forwarding.........................................................................................

6-13

6.4.1

Configuring a Server behind NAT....................................................................................

6-14

6.5

General NAT Examples............................................................................................................

6-16

6.5.1

Internet Access Only.........................................................................................................

6-16

6.5.2

Example 2: Internet Access with an Inside Server............................................................

6-17

6.5.3

Example 3: Multiple Public IP Addresses With Inside Servers........................................

6-18

6.5.4

Example 4: NAT Unfriendly Application Programs.........................................................

6-22

FIREWALL AND CONTENT FILTERS.....................................................................................................

III

Chapter 7 Firewalls..................................................................................................................................

7-1

7.1

What Is a Firewall? .....................................................................................................................

7-1

7.2

Types of Firewalls ......................................................................................................................

7-1

7.2.1

Packet Filtering Firewalls ...................................................................................................

7-1

7.2.2

Application-level Firewalls.................................................................................................

7-1

7.2.3

Stateful Inspection Firewalls...............................................................................................

7-2

7.3

Introduction to ZyXEL’s Firewall ..............................................................................................

7-2

7.4

Denial of Service ........................................................................................................................

7-3

7.4.1

Basics..................................................................................................................................

7-3

7.4.2

Types of DoS Attacks .........................................................................................................

7-4

7.5

Stateful Inspection ......................................................................................................................

7-7

7.5.1

Stateful Inspection Process .................................................................................................

7-8

7.5.2

Stateful Inspection and the ZyWALL.................................................................................

7-9

7.5.3

TCP Security.....................................................................................................................

7-10

7.5.4

UDP/ICMP Security .........................................................................................................

7-10

7.5.5

Upper Layer Protocols ......................................................................................................

7-11

 

 

 

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