Independent PTR Records

[HB9HIL]

Hello
I'm managing some public IPs in an ISP environment. We added all IP addresses in the various prefixes and used DNSsync of Netbox DNS to create the corresponding PTR records (by using the DNS Name Field in the IP Address). We imported the IP addresses by a script-generated CSV for generic PTR records.

Now there are customers who want to customize their PTR records for their own purposes. In 99% of the cases they want PTR records for domains, we are not authoritative for. This means I have to create the zone in Netbox DNS first in order to use the DNS Name field in the IP address.

Yeah sure I could (and we currently do) create the records manually. But then you don't see the records in the detail view of the IP address.

I searched throuh the documentation to find any option which could help me here, but wasn't lucky.

In fact I'm looking for one of the two options:

1. Currently the PTR records depends on the A record. If the zone in the A record does not exist, there won't be any PTR record, even if the Reverse Zone exists. This should be independent. The PTR record can exists even there is no A record. Or am I wrong here?

2. If I create an manual A or PTR record for an IP address which exists (without using the DNS Name field), It would be super handy if I can see those records in the IP address detail view which is currently not the case. It should be easily possible to check for records with the current IP address or records in a reverse zone (which exists).

Cheers from switzerland and thanks for this great plugin :)

PS: We are currently managing over 45 thousand records with this plugin.

[peteeckel]

@HB9HIL I seem to remember having had that discussion before ...

You have a valid point, and I actually have an item on my to-do list that covers exactly that use case. Unfortunately the mechanism required to make that work is completely separate from the way DNSsync works at the moment, so it's not a trivial addition, and there are some other things that are further up the list (e.g. a completely different, but related plugin ... there's some pretty good stuff in the queue).

In other words: It will eventually be implemented, but some patience is required ... until then, there is still the option of hacking something together with a custom script. This is actually much simpler than the general implementation in the plugin as I can't make assumptions about specific use cases and try to implement a general solution that works for everyone. An application-specific custom script (potentially triggered by create/updarte/delete object event hooks for IPAddress objects) wouldn't be too difficult to implement.

For example code, you can look at examples/custom_scripts/DNS_IPAM_Updater.py. That should be pretty easy to adapt to your use case.

A potential algorithm could look like this:

Create:

• If no dns_name is set or no forward zone can be found for the value of dns_name, look for the reverse zone and, if found, insert a PTR record

Update:

• If the IPAddress does not have an associated PTR record (that's the only tricky part, could be solved with a custom field), proceed as for "Create"
• If there is an associated PTR record and it does not match the current IP address, delete it and proceed as for "Create"

Delete:

• If the IPAddress has an associated PTR record, delete it

The general solution is more complex. It has to take into account that zones may change (e.g. the name of a PTR zone may be changed, which requires all PTR records to be re-evaluated, a new forward zone may be created that causes A records to be created for the IP addresses and the "standalone" PTR records to be deleted etc. - something you can take care for by just documenting "don't do that" :-)

And that's exactly the reason why the general solution takes a bit longer to implement ... all the cases need corresponding tests too, documentation etc., so it's rather a work of some days, maybe weeks, than one of some hours.

[HB9HIL]

haha sorry I just added the comment below right in the same second you answered :-D

I fully understand your arguments. My intention was to ask you as maintainer to see how would you work around that. I'll definitly try to solve this with scripts.

thanks!

[HB9HIL]

Just found this discussion which goes kinda in the same direction:

#493

[peteeckel]

OK, so it wasn't you :-)

Anyway, PRs are still welcome ...

[HB9HIL]

I know and thought about to create a PR :-D haha

well I'm in PHP, JS

Python is still some Alien for me but probably one day I will wrap my head around it :-D

[peteeckel]

It's not only Python ... Django adds some peculiarities of its own, and then there's NetBox to add some more (they really did some amazing stuff that causes plugin code to break in totally unexpected places, see e.g. https://github.com/peteeckel/netbox-plugin-dns/blob/main/netbox_dns/signals/ipam_dnssync.py line 160ff.), and if that isn't enough there's the NetBox Branching plugin which currently breaks every other plugin that does more complex stuff involving the Django ORM ... don't get me started.

But it is possible. And the NetBox ecosystem is awesome.

[HB9HIL]

Thank you for motivating me and giving me courage hahahaha

[peteeckel]

Can't be too bad ... I've been doing it for years now, and it's still fun.