Re: network problem: configuration/DNS? cannot access internal machine using our external IP

[Gary Turner <kk5st@sbcglobal.net>]

Jerome Lacoste (Frisurf) wrote:

>Summary: If I try to connect to an internal server given its dyndns.org
>hostname, it works from the outside world, but fails if I try from
>within our intranet.
>
>I have this network configuration
>
>   E
>   |
>Internet
>   |
>   | (EXT-IP)
>** R ** (Firewall)
>   | (192.168.1.1)
>___|___
>| | | | 
>M S M M
>
>
>E: external machine
>R: router firewall for our intranet
>S: internal server running Linux (in fact it runs Mandrake 9.0)
>M: internal machines
>
Your gateway/router is working as designed.  The internal (LAN) and
external (WAN/Internet) are kept separated.  This means that no WAN IP
can try to connect directly with an internal address.  Nor is it allowed
to use a LAN IP from outside.  When you try to connect to your public
address from within the LAN, the name resolves to your own address.  So
the router sees it as an internal address trying to get in, and that's
not allowed.

--
gt                  kk5st@sbcglobal.net
 If someone tells you---
 "I have a sense of humor, but that's not funny." 
                                  ---they don't.