IP addressing solution - question

[h2009]

Hi there,
Not really too sure if this is the right location for the question, but the internet section wouldn't really yield the type of response I'm looking for.

Basically I have a Radius server, which requires each remote site to authorise against every 10 seconds. The software which I use on the radius server only allows IP addresses to be input and can't be changed to use DNS addresses.

The remote sites all have dynamic IP addresses which change, causing me to have update the radius server. The remote sites are all running DYNDNS names so I always know that I can connect in remotely no matter what.

The only solution to my problem I can think of is to somehow do the following;

Remote site > DYNDNS > Static IP DNS lookup > Radius Server.
: 10.4.50.1 > site1.domain.com > 182.55.33.33 > Radius Server auth check on 182.55.33.33.

If the IP address changes:
: 88.3.53.4 > site1.domain.com > 182.55.33.33 > Radius Server auth check on 182.55.33.33.

Does anyone know of a solution which would allow a static IP address to always route to a DYNDNS address? This would need to allow 2 way traffic.

 

[Saundie]

Correct me if I'm wrong, but essentially you want a lookup of an IP to resolve to a specific DNS host name? Could you create a reverse lookup zone for the subnet that the static IP is on, and then create a pointer record for that IP to your dynamic DNS address? For example, create a reverse lookup zone for 10.4.50.0 and then create a pointer record for 10.4.50.1 to go to site1.domain.com. I just did this on my DNS server and I think it gives the result you're after;

C:\Users\saundie>ping -a 10.4.50.1

Pinging site1.domain.com [10.4.50.1] with 32 bytes of data:

Although if they're going to be coming from various subnets then it's going to get very messy; unless you enable dynamic updates on the DNS server then the pointer records will get stale and then you'll be no better off... sounds like an utter pig of a problem to have to deal with. Hopefully somebody else will have experienced something similar and offer you a proper solution!

Edit: reading your post again, the IP of the remote site doesn't change (as in the static IP you assign it, not it's real address on the internet), right? In that case, there's no problem with dynamic updates after all, and so I think what I suggested should work. To be honest, it's a bit of a struggle for me to get my head around it