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RX3141 User’s Manual Chapter 11. System Management
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10
Virtual Sever and Special Application
This chapter describes the configuration procedures for:
f Virtual Server
f Special Application
NAT is the technology used to support the above applications.
10.1 NAT Overview
Network Address Translation allows use of a single device, such as the RX3141, to act as an agent between
the Internet (public network) and a local (private) network. This means that a NAT IP address can represent an
entire group of computers to any entity outside a network. Network Address Translation (NAT) is a mechanism
for conserving registered IP addresses in large networks and simplifying IP addressing management tasks.
Because of the translation of IP addresses, NAT also conceals true network address from privy eyes and
provide a certain degree security to the local network.
10.1.1 NAPT (Network Address and Port Translation) or PAT (Port Address Translation)
Also called IP Masquerading, this feature maps many internal hosts to one globally valid Internet address. The
mapping contains a pool of network ports to be used for translation. Every packet is translated with the globally
valid Internet address and the port number is translated with an un-used port from the pool of network ports.
Figure 10.1 shows that all the hosts on the local network gain access to the Internet by mapping to only one
globally valid IP address and different port numbers from a free pool of network ports.
Figure 10.1 NAPT – Map Any Internal PCs to a Single Global IP Address