Smart Hub 2 for dynamic DNS

[grepkin]

I want to set up dynamic DNS for a home server on my BT internet connection.  The Smart Hub 2 offers me five well-known dynamic DNS services, two of which offer a basic free package.

I'd rather run my own dynamic DNS, so that I can use a domain I own that runs on an external server.  That way it can be (e.g.) homeserver.mydomain.com and not (e.g.) freds-server.noip.com.

This would require the router to send a message, any message, to an address I specify, whenever it reconnects to a new external IP address.  Can it be made to do this? 

Or is there some other way to know  when the IP address changes?  I can poll every five minutes of course.  But what happens if I establish a connection from the server and keep it alive?  Would this make the router use the same IP address?  I imagine the network lease would expire at some point.  Would that break the connection?

[Crimliar]

You can run DDNS software on a server within your network.  That software then sends a specially prepared query to the DDNS service that you've "delegated" your domains to.

For basic DDNS the company you registered your domain name with will probably provide that service (check first), for IPv6 and the ability to specifiy specific hosts using just the one query it gets more complicated!

*I've been doing this for years!

[grepkin]

Thanks Crimliar,

but I'm confused.  So I run DDNS software on my home server.  And I use a DDNS service, by which I assume you mean one of DynDNS, NoIP etc, which my software connects to.

In that case, the SmartHub must surely still be configured to send a message to the DDNS service when the external IP address changes.  If not, the DDNS service will not get told of that event - unless it polls or leaves a TCP connection established.

And using a DDNS service means I must use a subdomain of one of the domains they provide, surely.  One reason I'm asking is that I want to use a subdomain of a domain that I own.  Do you do that?  And if so, how? 

[licquorice]

One thing is certain, the hub will not provide the functionality you require, it only provides DDNS capability for the pre-configured options.

[grepkin]

Yes I thought as much.  I'd go for one of the pre-configured DDNS providers if I could use my own domain with it.  But even if that's technically possible I doubt it would be available on a free plan.

[licquorice]

I don't see why not, surely you can use any domain.

https://www.noip.com/support/knowledgebase/can-i-use-my-own-domain-name-with-no-ip

$2.92/m

[Crimliar]

IPv4 DDNS is pretty simple.  Your client sends a request to the DDNS server that contains the information to identify you.  It doesn't even send the IP address, as that's your WAN IP that's already encoded by the protocols.  So it doesn't matter if it's the router, or a device within your network the WAN IP the DDNS server sees is the same!

I't a bit more complex with IPv6, but with that complexity comes the ability to diectly route to host.domain!

HIstorically, I've used the free DDNS services from Hurricane Electric and DynV6, *with my own paid for domain names!

[grepkin]

Thanks all.

With your help and more searching, I've worked out what is possible.

I can't make a Smart Hub 2 send a notification anywhere on change of external IP, except to the five pre-configured DDNSs.

With my home server communicating to another server, it's possible and practical to get a notification (at either end) of an IP change.

But my ideas about how to point a subdomain to the dynamic address won't work.  The only way to do that is to change a record at the DNS(s) for the domain.  I could do that by running my own DNS, but don't want to for the moment.

So I will just use a DDNS free package.   I won't get my own subdomain pointed for free, and in any case that looks like it would be done by having the DDNS act as the DNS for the whole domain.

Which means I'll have a domain like fredshomeserver.toddleoverto.com.  But frankly, it's not really necessary for me to do what I originally asked.  I mainly liked the idea of being able to "because I can".

[Crimliar]

That specific usage would work with IPv6 and your paid for domain delegated to DynV6.  You could then point directly to fredshomeserver.toddleoverto.com  (host.domain).  If there was anything else it was worthwhile pointing to you can mask off the end of the IP address and  using the MAC address of the other device have it's host.domain updated from the info provided from the main one.  *won't work if you randomize MAC addresses, slightly increases the area of attack for your devices as you'll need to poke holes in the router firewall (third party router would probably offer better security).

It can work with IPv4 but not with the BT router, as there's a lot more faffing about and configuration needed in the router!

*DynV6 is a free service and is provided with zero support.  It is reliable, but there is absolutely no hand holding to get it working!

[grepkin]

Thanks @Crimliar .  I'll need to do some more work, and understand IPv6.  Will probably not be for a while, I don't have the hardware yet.