User's Manual

UTT Technologies Chapter 7 Advanced
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7.1.1.3 NAT Types
The Wirele ss Router provides two types of NAT: One2One and EasyIP.
● One2One (One to One): It indicates static network address translati on. It is always
referred to as Basic NAT, which provides a one to one mapping between an internal
and an external IP address . In this type of NAT, IP address needs to be changed, but
port needn’t.
One to One NAT can be used to allow the outside users to access a LAN server: In the
local network , the LAN server still use the private IP address, which is provided to the
local computers to access; and on the Internet, the Wireless Router will assign an
external IP addres s to the local server, then the outside users can using this external IP
address to access the server through the Wirel e ss Router.
● EasyIP: It indicates network address and port translation (NAPT). Since it is the most
common type of NAT, it is often simply referred to as NAT. NAPT provides many-to-one
mappings between multiple internal IP addresses and a single external IP addresses ,
that is, these multiple internal IP addresses will be translated to the same external IP
address. In this type of NAT, to avoid ambiguity in the handling of returned packets, it
must dynamically assign a TCP/UDP port to an outgoing session and change the
packets’ source port to the assigned port before forwarding them. Besides, the
Wireless Router must maintain a translation table so that return packets can be
correctly transl ate d back.
When you obtain multiple public IP addresses from your ISP, you can create more than
one NAT rule for either type of NAT. In actual network environment, the two types of NAT
rules are often used together.
7.1.1.4 Port Forwarding and DMZ Host
When NAT is enabled on the Wireless Router, the Wireless Router will block all the
requests initiated from outside users. However, in some cases, the outside users want to
access the LAN internal servers through the Wireless Router. To achieve this purpose,
you need to configure port forwarding entries or DMZ host on the Wireless Router.
1. Port Forwarding
Port forwarding feature allows you to create the mapping between <external IP address:
external port> and <internal IP address: internal port>, then all the requests from outside
users to the specified external IP address: port on the Wireless Router will be forwarded to
the mapped local server, so the outside users can access the service offered by the
server.
For example , if you want to allow the local SMTP server (IP address: 192.168.1.88) to be