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Unable to access internal network from external address


Unable to access internal network from external address

I have a server set up that I regularly need to access from outside of my home network. Port forwarding is set up correctly on the router (Motorola NVG510) and it is fully accessible outside of my home network. I use dyndns to keep my IP up-to-date and it is working. However internally (say from my desktop or my laptop connected to my home network) I cannot access it by the full URL ( and I am forced to use the internal IP. This is inconvenient to have to change every time I need to access the server when going from inside my home to anywhere outside and visa versa. Is there a setting or a way past this so the address will resolve correctly within my own network?

Message 1 of 5
Accepted by Employee (Employee)
Accepted by ATTDelia
‎09-30-2015 1:39 AM

Re: Unable to access internal network from external address
What you want is the have a record in your own DNS Server for these sites' "Domain Names" that resolve to the internal Private IP instead of the Public IP and then make sure that your own DNS is the first DNS Server requested from by these machines. This allows these web servers to communicate directly to each other without involving the Firewall at all (it also allows your internal users to work the same way). The only time that the firewall should be involved is when an outside host makes a request to those machine from the Internet. Any internal machine should *never* have to go to the firewall to get to something that is already positioned physically on the same side of the firewall that the requesting machine is already on.

Possible Fix:
First find out what the IP address is of the external web server if
you do not already know it (You can get it by pinging the

Go to Start > Control Panel > Administrative Tools >
DNS and locate Right-click and choose “New
Host (A or AAAA)”. Type “www” into the name field, and the IP
address of your external web server into the IP Address field.
Click the “Add Host” button to save it.
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Message 2 of 5

Re: Unable to access internal network from external address

Thanks! I hadn't thought of this. I will try it when I get the chance but your right, this seems like it would be the best choice. I think because the server is already registered in DNS however I should use a CNAME record (pointer) instead, but the idea is the same.

Message 3 of 5

Re: Unable to access internal network from external address

yes remain privite 

Message 4 of 5

Re: Unable to access internal network from external address

This is unacceptable for portable devices, however, that automatically switch between an intranet and internet context as you move it around.  At least, I've yet to find network settings that let you use a different 'host' file depending on what network it is connected to.  

What WOULD be nice is:

1. During DHCP, the AT&T router returned ITSELF as the primary DNS server.
2. The AT&T router then reported the Internal IP Address instead of the external one when requests for those DNS entries are made.


The AT&T router was smart enough to detect that a packet coming from inside the network is bound for somewhere else inside the network, even though the destination address is remote, and routed it properly.  The router has all the necessary information to make this determination.

Message 5 of 5
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