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

Discussion:

bls s

2021-06-03 23:46:19 UTC

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;
}
}

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!

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?

This is important (to me, anyhow), since I have a tool that automatically builds dhcpd.conf from a database, and now it's broken with no easy way to fix other than putting in "do it this way/that way" switches.

Thanks for your help!

Simon Hobson

2021-06-04 12:03:26 UTC

Permalink

Post by bls s
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

Post by bls s
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.

Post by bls s
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?

bls s

2021-06-04 14:01:52 UTC

Permalink

Thanks, Simon for confirming my understanding.

Yes, have backed off to the previous version and it works, so there's a workaround.

I'm off to sort out how to file an actual bug report on Ubuntu in the hope that they revert the change (whatever it is!).

Benn

-----Original Message-----
From: dhcp-users <dhcp-users-***@lists.isc.org> On Behalf Of Simon Hobson
Sent: Friday, June 4, 2021 5:03 AM
To: Users of ISC DHCP <dhcp-***@lists.isc.org>
Subject: Re: Ubuntu update to isc-dhcp-server seems to have broken config file processing

That looks fine

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.

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

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bls s

2021-06-07 13:52:46 UTC

Permalink

Response from Ubuntu on Launchpad (https://bugs.launchpad.net/bugs/1930917):

I can confirm the update introduced a regression on Hirsute (and Impish I presume). Focal and Groovy work properly. Unfortunately, it's not related to the security patch, but it stems from the package being rebuilt with the newer toolchain in Hirsute, so removing the patch won't fix the issue.

I am currently investigating how to fix this.

** Also affects: isc-dhcp (Ubuntu Hirsute)
Importance: Undecided
Status: New

** Also affects: isc-dhcp (Ubuntu Impish)
Importance: Undecided
Status: Confirmed

** Changed in: isc-dhcp (Ubuntu Hirsute)
Status: New => Confirmed

** Changed in: isc-dhcp (Ubuntu Hirsute)
Assignee: (unassigned) => Marc Deslauriers (mdeslaur)

** Changed in: isc-dhcp (Ubuntu Impish)
Assignee: (unassigned) => Marc Deslauriers (mdeslaur)

** Changed in: isc-dhcp (Ubuntu Hirsute)
Importance: Undecided => Critical

** Changed in: isc-dhcp (Ubuntu Impish)
Importance: Undecided => Critical

-----Original Message-----
From: dhcp-users <dhcp-users-***@lists.isc.org> On Behalf Of bls s
Sent: Friday, June 4, 2021 7:02 AM
To: Users of ISC DHCP <dhcp-***@lists.isc.org>
Subject: RE: Ubuntu update to isc-dhcp-server seems to have broken config file processing

Thanks, Simon for confirming my understanding.

Yes, have backed off to the previous version and it works, so there's a workaround.

I'm off to sort out how to file an actual bug report on Ubuntu in the hope that they revert the change (whatever it is!).

Benn

-----Original Message-----
From: dhcp-users <dhcp-users-***@lists.isc.org> On Behalf Of Simon Hobson
Sent: Friday, June 4, 2021 5:03 AM
To: Users of ISC DHCP <dhcp-***@lists.isc.org>
Subject: Re: Ubuntu update to isc-dhcp-server seems to have broken config file processing

That looks fine

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.