UCS DHCP Client hostname


I am using UCS as my LDAP, DNS, and DHCP server. I would like to resolve my clients’ IP addresses but just looking up their hostnames. Looking at the documentation, it seems like the option that I am looking for is the DHCP Dynamic DNS option. I tried to set this up, but I still could not resolve the hostnames of my clients.

My settings is below:

I think you forgot to add your settings.

For your use-case you need to tell the DHCP server to push the search domain option. Wikipedia says, that Windows DHCP clients ignore this option.

How do I do that in Univention?

Funnily, UCS does not seem to support this option via GUI. I guess Univention had a focus on Windows clients which can’t digest this option anyway. You’d have to explore Group Policies to make it work with those.

Assuming you already configured the UCS DHCP server component and it works by at least providing IP leases you can take a look at the templates used for building the config for ISC DHCP. SSH into your server, then cat /etc/dhcp/dhcpd.conf and look at the template referenced there. Then edit this template. Disclaimer: Updates might overwrite your changes so keep a backup so you can restore your changes.

I can’t help you more specifically because I don’t use the DHCP server of UCS.

I don’t have any Windows system in my network. It seems like doing this in CLI I have to mess with the /etc/bind as well.
I found this ISC wiki from Debian https://wiki.debian.org/DDNS
Would this work with Univention?

You could adapt what’s documented there if –IF– you need DynDNS. I’d suggest to assign fixed IP addresses in the DNS application of UCS instead.

Generally, I’d advise against editing the config files directly. They are generated from templates in /etc/univention/templates/files. For almost all services UCS provides there are template files it generates the configs from. Each config file that’s generated in such a way has a header referencing the templates it was built upon.

It’s still not ideal to edit templates (see above) but better than editing the config files themselves. I’m not sure what Univention’s stance on editing template files is.

To return to your issue: You have two tasks at hand. You want your DNS server to know about the IP addresses of your clients. As I don’t use the DHCP server in UCS I don’t know if it tells bind9 about the dynamic clients. If your clients are members of the domain you could just assign fixed IP addresses. Well, you could assign fixed IP addresses even if they are not members of your domain.

If you don’t want to assign fixed IP address ISC-DHCP has to update the zone info of bind9. I did this once manually and I really hope that Univention thought of linking those two services as it’s no trivial task as you can see by reading the instructions you linked. Either way, this is how your DNS will know about the clients.

For your clients to reolve hostnames by implicitly adding your domain name you need to tell them the search-domain.