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4.74 Confi gure
>
Static NAT Mappings
The unit supports Network Address Translation (NAT) and Network Address and Port Translation
(NAPT). NAT or NAPT may be enabled on a particular interface such as a PPP instance. When
operating with NAT enabled, this interface has a single externally visible IP address. When sending IP
packets, the local IP addresses (for example, on a local area network) are replaced by the single IP
address of the interface. The unit keeps track of the local IP addresses and port numbers so that if a
matching reply packet is received it is directed to the correct local IP address. With only one externally
visible IP address, NAT effectively prevents external computers from addressing speci
fi
c local hosts,
thus providing a basic level of “
fi
rewall” security.
Static NAT mappings allow received packets destined for particular ports to be directed to speci
fi
c
local IP addresses. For example, if you wanted to run a server on a local area network and make it
externally accessible you would need to set up a static NAT mapping using the local IP address of the
server and the port number used to access the required service.
Note:
Static NAT mapping is often referred to as port redirection.
Using the Web Page(s)
The
Confi gure
>
Static NAT Mappings
page displays a table that allows you to set the following
values for each mapping:
Min Port #
This parameter is used to specify the lowest port number to be redirected.
Max Port #
This parameter is used to specify the highest port number to be redirected.
Map to IP address
Enter an IP address to which packets containing the speci
fi
ed destination port number are to be
redirected.
Map to port
Enter an IP port number to which packets containing the speci
fi
ed destination port number are to be
redirected. When set to “0” no port remapping occurs, and the original port number is used. The NAT
mode parameter of the appropriate interface must be set to “NAPT” rather than “NAT” or “OFF” for this
parameter to function.
