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Prestige 660H/HW Series User’s Guide
11
9.4 SIP ALG ...........................................................................................................119
9.5 Selecting the NAT Mode ..................................................................................120
9.6 Configuring SUA Server ...................................................................................120
9.7 Configuring Address Mapping ..........................................................................122
9.8 Editing an Address Mapping Rule ....................................................................123
Chapter 10
Dynamic DNS Setup............................................................................................. 126
10.1 Dynamic DNS .................................................................................................126
10.1.1 DYNDNS Wildcard ................................................................................126
10.2 Configuring Dynamic DNS .............................................................................126
Chapter 11
Time and Date....................................................................................................... 128
11.1 Configuring Time and Date .............................................................................128
Chapter 12
Firewalls................................................................................................................ 130
12.1 Firewall Overview ...........................................................................................130
12.2 Types of Firewalls ..........................................................................................130
12.2.1 Packet Filtering Firewalls ......................................................................130
12.2.2 Application-level Firewalls ....................................................................130
12.2.3 Stateful Inspection Firewalls ................................................................131
12.3 Introduction to ZyXEL’s Firewall .....................................................................131
12.3.1 Denial of Service Attacks ......................................................................132
12.4 Denial of Service ............................................................................................132
12.4.1 Basics ...................................................................................................132
12.4.2 Types of DoS Attacks ...........................................................................133
12.4.2.1 ICMP Vulnerability ......................................................................135
12.4.2.2 Illegal Commands (NetBIOS and SMTP) ....................................135
12.4.2.3 Traceroute ...................................................................................136
12.5 Stateful Inspection ..........................................................................................136
12.5.1 Stateful Inspection Process ..................................................................137
12.5.2 Stateful Inspection and the Prestige .....................................................138
12.5.3 TCP Security .........................................................................................138
12.5.4 UDP/ICMP Security ..............................................................................139
12.5.5 Upper Layer Protocols ..........................................................................139
12.6 Guidelines for Enhancing Security with Your Firewall ....................................139
12.6.1 Security In General ...............................................................................140
12.7 Packet Filtering Vs Firewall ............................................................................141
12.7.1 Packet Filtering: ....................................................................................141
12.7.1.1 When To Use Filtering .................................................................141
12.7.2 Firewall .................................................................................................141