802.11g Wireless 4-port Router User's Guide
Table Of Contents
- User’s Guide
- Copyright
- Federal Communications Commission (FCC) Interference Statement
- ZyXEL Limited Warranty
- Customer Support
- Table of Contents
- List of Figures
- List of Tables
- Preface
- Getting to Know Your ZyAIR
- 1.1 Introducing the ZyAIR
- 1.2 ZyAIR Features
- 1.2.1 Physical Features
- 1.2.2 Firmware Features
- 1.2.2.1 Internal RADIUS Server
- 1.2.2.2 Wi-Fi Protected Access
- 1.2.2.3 802.11b Wireless LAN Standard
- 1.2.2.4 802.11g Wireless LAN Standard
- 1.2.2.5 STP (Spanning Tree Protocol) / RSTP (Rapid STP)
- 1.2.2.6 Certificates
- 1.2.2.7 Limit the number of Client Connections
- 1.2.2.8 SSL Passthrough
- 1.2.2.9 Firewall
- 1.2.2.10 Brute-Force Password Guessing Protection
- 1.2.2.11 Wireless LAN MAC Address Filtering
- 1.2.2.12 WEP Encryption
- 1.2.2.13 IEEE 802.1X Network Security
- 1.2.2.14 Universal Plug and Play (UPnP)
- 1.2.2.15 Dynamic DNS Support
- 1.2.2.16 PPPoE Support (RFC2516)
- 1.2.2.17 PPTP Encapsulation
- 1.2.2.18 Network Address Translation (NAT)
- 1.2.2.19 Traffic Redirect
- 1.2.2.20 NAT for Single-IP-address Internet Access
- 1.2.2.21 DHCP (Dynamic Host Configuration Protocol)
- 1.2.2.22 Multicast
- 1.2.2.23 IP Alias
- 1.2.2.24 IP Policy Routing
- 1.2.2.25 SNMP
- 1.2.2.26 Full Network Management
- 1.2.2.27 Logging and Tracing
- 1.2.2.28 Diagnostics Capabilities
- 1.2.2.29 Embedded FTP and TFTP Servers
- 1.2.2.30 Wireless Association List
- 1.2.2.31 Wireless LAN Channel Usage
- 1.3 Applications for the ZyAIR
- Introducing the Web Configurator
- Wizard Setup
- System Screens
- LAN Screens
- Wireless Configuration and Roaming
- Wireless Security
- 7.1 Wireless Security Overview
- 7.2 Security Parameters Summary
- 7.3 WEP Overview
- 7.4 Configuring WEP Encryption
- 7.5 Introduction to WPA
- 7.6 Configuring WPA-PSK Authentication
- 7.7 Wireless Client WPA Supplicants
- 7.8 Configuring WPA Authentication
- 7.9 Introduction to RADIUS
- 7.10 Configuring RADIUS
- 7.11 802.1x Overview
- 7.12 Dynamic WEP Key Exchange
- 7.13 Configuring 802.1x and Dynamic WEP Key Exchange
- 7.14 Configuring 802.1x and Static WEP Key Exchange
- 7.15 Configuring 802.1x
- 7.16 MAC Filter
- Internal RADIUS Server
- WAN
- Single User Account (SUA) / Network Address Translation (NAT)
- Static Route Screens
- Remote Management Screens
- UPnP
- Firewalls
- Firewall Screens
- Content Filtering
- Certificates
- 17.1 Certificates Overview
- 17.2 Self-signed Certificates
- 17.3 Configuration Summary
- 17.4 My Certificates
- 17.5 Certificate File Formats
- 17.6 Importing a Certificate
- 17.7 Creating a Certificate
- 17.8 My Certificate Details
- 17.9 Trusted CAs
- 17.10 Importing a Trusted CA’s Certificate
- 17.11 Trusted CA Certificate Details
- Log Screens
- Maintenance
- Introducing the SMT
- General Setup
- Menu 2 WAN Setup
- LAN Setup
- Internet Access
- Remote Node Configuration
- Static Route Setup
- Dial-in User Setup
- Network Address Translation (NAT)
- Filter Configuration
- Enabling the Firewall
- SNMP Configuration
- System Security
- System Information and Diagnosis
- Firmware and Configuration File Maintenance
- System Maintenance and Information
- Remote Management
- Call Scheduling
- Appendix A
- Appendix B
- Appendix C
- Appendix D
- Appendix E
- Appendix F
- Appendix G
- Appendix H
- Appendix I
- Appendix J
- Appendix K
- Appendix L
- Index
Note: NAT never changes the IP address (either local or global)
of an outside host.
ZyAIR G-2000 Plus User’s Guide
137 Chapter 10 Single User Account (SUA) / Network Address Translation (NAT)
10.1.2 What NAT Does
In the simplest form, NAT changes the source IP address in a packet received from a
subscriber (the inside local address) to another (the inside global address) before forwarding
the packet to the WAN side. When the response comes back, NAT translates the destination
address (the inside global address) back to the inside local address before forwarding it to the
original inside host. Note that the IP address (either local or global) of an outside host is never
changed.
The global IP addresses for the inside hosts can be either static or dynamically assigned by the
ISP. In addition, you can designate servers (for example a web server and a telnet server) on
your local network and make them accessible to the outside world. If you do not define any
servers (for Many-to-One and Many-to-Many Overload mapping), NAT offers the additional
benefit of firewall protection. With no servers defined, your ZyAIR filters out all incoming
inquiries, thus preventing intruders from probing your network. For more information on IP
address translation, refer to RFC 1631, The IP Network Address Translator (NAT).
10.1.3 How NAT Works
Each packet has two addresses – a source address and a destination address. For outgoing
packets, the ILA (Inside Local Address) is the source address on the LAN, and the IGA (Inside
Global Address) is the source address on the WAN. For incoming packets, the ILA is the
destination address on the LAN, and the IGA is the destination address on the WAN. NAT
maps private (local) IP addresses to globally unique ones required for communication with
hosts on other networks. It replaces the original IP source address (and TCP or UDP source
port numbers for Many-to-One and Many-to-Many Overload NAT mapping) in each packet
and then forwards it to the Internet. The ZyAIR keeps track of the original addresses and port
numbers so incoming reply packets can have their original values restored. The following
figure illustrates this.