Port forwarding used from intern

[trockstr]

Hi,

i have an problem with my new Cisco 876 Router. I configured port forwarding to access internal network devices from the internet (dyndns adress). This works good from external but  with my old Fritzbox I was able to connect to this internal devices from the same internal network with the dyndns adress.

So here is a short review for this:

DYNDNS Adress port tcp 80 - > 192.168.0.80 tcp port 80

from extern it works but with source adress example 192.168.0.20 to destination DYNDNS adress tcp 80 (maps to 192.168.0.80 tcp 80 ) it doesn't work.

Is ther any trick in the config of cisco to let this scenario work?

Thanks for help

[eduardopozo56]

I think you cant, because after the router nats the Inside Address to the Public One, you will be trying to access ¿yourself?

Now the question is.. Why would you try to access that device with the External IP if you are on the same LAN?.. you would just sending traffic to your router, getting a lot of hops... with no reason

[cadet alain]

Hi,

this is called hairpinning and is not supported on enterprise router models but you can use dns doctoring which is the default on these routers by accessing the ressource from inside by fqdn instead of IP address.

Regards.

alain

[trockstr]

Hi,

reason why I want to configure this solution is:

I have some laptops that should get access from outside and inside the network. So I don't want to add double bookmarks for the same website. For not IT specialists, that use this websites too, this is a little confusing to use two bookmarks for the same website.

So how I can solve this with dns? What configuration is needed on the cisco router or on the dns server?

Thanks for your help.

[cadet alain]

Hi,

the dns doctoring trick will work only if you're using an external DNS server for this address.

It is a default feature so you've got nothing to do on the router.

regards.

Alain