Netopia R2121, User Reference Manual

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Understanding Netopia NAT Behavior D-7
Toggling Address Translation Enabled to Yes enables the Netopia R2121 to send out an all-zeros IPCP address
that requests an IP to be assigned to the Netopia R2121’s WAN inter face. Note that the remote IP address is
127.0.0.2, which should also be the Default Gateway under IP Setup in System Configuration. This is done for
profile matching purposes and because the IP address of the router the Netopia R2121 is dialing is not always
known.
As mentioned earlier in this appendix, NAT works well for IP sessions originated on the Netopia R2121’s LAN
inter face destined for the Internet without any additional configuration. For incoming IP connections from the
Internet to a host on the Netopia R2121’s LAN inter face, Expor ted Ser vices need to be used.
Expor ted Ser vices are configured under IP Setup in System Configuration. This is where a par ticular type of TCP
or UDP ser vice originating from the Internet is redirected to a host on the Netopia R2121’s LAN inter face. An
example of this screen is as follows:
IP Profile Parameters
Remote IP Address: 127.0.0.2
Remote IP Mask: 255.255.255.0
Address Translation Enabled: Yes
Filter Set...
Remove Filter Set
Receive RIP: No
Enter the remote IP network's IP address (form xxx.xxx.xxx.xxx decimal).
Configure IP requirements for a remote network connection here.