ZyXEL NBG6615 User Guide - Page 87

General NAT Screen, How NAT Works

Page 87 highlights

Chapter 10 Network Address Translation 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). 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 in each packet and then forwards it to the Internet. The NBG6615 keeps track of the original addresses and port numbers so incoming reply packets can have their original values restored. The following figure illustrates this. Figure 56 How NAT Works 10.3 General NAT Screen Use this screen to enable NAT and set a default server. Click Network > NAT to open the General screen. Figure 57 Network > NAT > General NBG6615's User's Guide 87

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Chapter 10 Network Address Translation
NBG6615’s User’s Guide
87
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)
.
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 in each packet and then forwards it to the Internet. The NBG6615 keeps track of the original
addresses and port numbers so incoming reply packets can have their original values restored. The
following figure illustrates this.
Figure 56
How NAT Works
10.3
General NAT Screen
Use this screen to enable NAT and set a default server. Click
Network > NAT
to open the
General
screen.
Figure 57
Network > NAT > General