Nat Config - Compex SGX3226 User Manual

Chapter 5 Using Menu Tools
5.1.6

NAT Config

Network Address Translation allows an IP-based network to manage its public
(Internet) addresses separately from its private (intranet) addresses. With NAT, each
private IP address can be translated to a different public address, or multiple private
addresses can be aliases to a single public one. To accomplish this, NAT software
snoops both incoming and outgoing packets on the network. It modifies the source or
destination address in the IP header to reflect the mapping between internal and
external addressing for that network.
NAT functionality appears on Compex SGX3226 with low-level access to packets at
the network boundary. Several variations on NAT have also been implemented to
provide additional support for application-level protocols.
Defining Port-Forwarding Virtual Server
Port Forwarding redirects any incoming Internet request on the Public IP, based on its
TCP/UDP Port number to another computer in the Private IP.
Hence, when a user from WAN sends a request to your network, Compex SGX3226
(based on the Port–Forwarding configurations) will forward these requests to the
assigned PC.
When to use Port–Forwarding Virtual Server
When your ISP assign you with only one fixed Public IP address, and you want to
define the various servers (such as, FTP, HTTP, Netmeeting, Mail server etc) to
specific Private IP address in your LAN; hence, you can choose to host the servers by
using the port-Forwarding Virtual server.
Example, suppose that you have a FTP Server with an IP address of 192.168.168.41.
And your broadband ISP has assigned a Public IP address of 203.120.12.100 to the
gateway. To support a Web Server in your Private Network, you need to define an
NAT Static Port-based Entry to forward TCP port 21 (used by FTP) to
192.168.168.41. Every http://203.120.12.100 requests will then be forwarded to the
FTP Server.
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