Network Address Translation; Nat; Nat Interface Configuration - D-Link DRO-220i User Manual

Network Address Translation

When a computer wants to connect to the Internet, it needs a legal and unique Global IP
address to traverse the internet. With the explosion of Internet, the unique IP address
space available is insufficient. NAT solves this problem by allocating single or a small
range of legal Global IP addresses. A NAT router translates the unregistered local (or
Private) IP addresses to the registered global (or Public) Internet IP addresses.
NAT allows hosts within a private network to transparently access hosts in the external
network. The NAT sessions are unidirectional, outbound from the private network. NAT
does not advertise private network addresses to the external network, hence preventing
direct access to the enterprises' private network from the internet. So in addition to
solving the addressing problem, NAT also acts as a security agent.
The router provides ALG (Application Level Gateway) support for common applications
to enable smooth operation behind NAT. The ALG Support involves:
Allowing client applications to use dynamic ephemeral TCP/ UDP ports to
communicate with the server applications, even though firewall may allow only a
limited number of known ports. In the absence of an ALG, either the ports would
get blocked or the network administrator would need to explicitly open up a large
number of ports in the firewall — rendering the network vulnerable to attacks on
those ports.
Converting the network layer address information found inside an application
payload to addresses acceptable by the hosts on either side of the firewall/NAT.

6.1 NAT

6.1.1 NAT Interface Configuration

NAT can be enabled or disabled on a specific interface. Typically NAT must be enabled
at the WAN interface used for internet connectivity.
Select NAT → Interface Configuration to configure the NAT Interface Configuration
as explained below.
Web UI
Interface Name
Status
Press the Apply button.
Dlink DRO-220i User Guide
6 Network Address Translation
NAT Interface Configuration
The interface on which NAT can be enabled/disabled.
Select Enable to activate NAT on the corresponding interface.
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