Ubuntu update to isc-dhcp-server seems to have broken config file processing

[Simon Hobson]

bls s <bls3427 at outlook.com> wrote:

> I'm using isc-dhcp-server 4.4.1-2 on RasPiOS Buster, and it's working fine with the following subnet declaration:
>  
> subnet 192.168.92.0 netmask 255.255.255.0 {
>     option domain-search "foo.com", "dyn.foo.com";
>     option broadcast-address 192.168.92.255;
>     allow duplicates;
>     ddns-updates off;
>     pool {
>         ddns-updates on;
>         allow unknown-clients;
>         option domain-name "dyn.foo.com";
>         ddns-rev-domainname "dhcp";
>         default-lease-time 86400;
>         max-lease-time 86400;
>         range 192.168.92.101 192.168.92.127;
>     }
> }

That looks fine

> This same subnet config worked on Ubuntu 21.04 a couple of weeks ago, with isc-dhcp-server V4.4.1-2.2-ubuntu6 on it. Today I updated on Ubuntu, got isc-dhcp-server V4.4.1-2.2ubuntu6.1 and now isc-dhcp-server complains about "Can't clone pool group".
>  
> I found that I can put the pool declaration outside of the subnet declaration on Ubuntu, and it works correctly. Unfortunately, doing this on RasPiOS fails!

Having a pool outside of a subnet isn't a valid config. It may appear to work, as do some other config errors, but may cause some really "interesting" issues.

> Am I totally using subnet and pool incorrectly, or is this an incompatible change in isc-dhcp-server? And, is it an intended change coming to mainline isc-dhcp-server or did Ubuntu bork it?

I'd be thinking that there's something changed in the Ubuntu version. Can you roll-back to the earlier version and try it again ?

Simon