#971275 isc-dhcp-server-ldap: fails to activate the service

Package:
isc-dhcp-server-ldap
Source:
isc-dhcp
Description:
DHCP server that uses LDAP as its backend
Submitter:
Wolfgang Schweer
Date:
2026-08-05 17:34:33 UTC
Severity:
important
#971275#5
Date:
2020-09-28 16:59:43 UTC
From:
To:
Dear Maintainer,

while working on Debian Edu Bullseye, I noticed that the DHCP service
stopped working after upgrading the system.

Reason seems to be that the init script timed out, maybe
/etc/default/isc-dhcp-server could not be sourced:

root@tjener:~# service isc-dhcp-server status
* isc-dhcp-server.service - LSB: DHCP server
     Loaded: loaded (/etc/init.d/isc-dhcp-server; generated)
     Active: activating (start) since Mon 2020-09-28 18:24:25 CEST; 2min 36s ago
       Docs: man:systemd-sysv-generator(8)
Cntrl PID: 1280 (isc-dhcp-server)
      Tasks: 8 (limit: 4671)
     Memory: 17.6M
     CGroup: /system.slice/isc-dhcp-server.service
             |-1280 /bin/sh /etc/init.d/isc-dhcp-server start
             `-1310 /usr/sbin/dhcpd -t -4 -q -cf /etc/dhcp/dhcpd.conf

Sep 28 18:24:25 tjener.intern systemd[1]: Starting LSB: DHCP server...
Sep 28 18:24:26 tjener.intern isc-dhcp-server[1280]: Launching IPv4 server only.

The installed version:

root@tjener:~# dpkg -l isc-dhcp-server-ldap
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                 Version      Architecture Description
+++-====================-============-============-=========================================
ii  isc-dhcp-server-ldap 4.4.1-2.1+b2 amd64        DHCP server that uses LDAP as its backend

I was wondering if downgrading to the Buster version would help:

root@tjener:~# apt install isc-dhcp-server-ldap/buster
Reading package lists... Done
Building dependency tree
Reading state information... Done
Selected version '4.4.1-2' (Debian:10.6/stable [amd64]) for 'isc-dhcp-server-ldap'
Selected version '4.4.1-2' (Debian:10.6/stable [amd64]) for 'isc-dhcp-server' because of 'isc-dhcp-server-ldap'
The following additional packages will be installed:
  isc-dhcp-server
Suggested packages:
  policykit-1
The following packages will be DOWNGRADED:
  isc-dhcp-server isc-dhcp-server-ldap
0 upgraded, 0 newly installed, 2 downgraded, 0 to remove and 0 not upgraded.
Need to get 994 kB of archives.
After this operation, 22.5 kB disk space will be freed.
Do you want to continue? [Y/n]
Get:1 http://ftp.debian.org/debian buster/main amd64 isc-dhcp-server-ldap amd64 4.4.1-2 [446 kB]
Get:2 http://ftp.debian.org/debian buster/main amd64 isc-dhcp-server amd64 4.4.1-2 [548 kB]
Fetched 994 kB in 0s (7729 kB/s)
Preconfiguring packages ...
dpkg: warning: downgrading isc-dhcp-server-ldap from 4.4.1-2.1+b2 to 4.4.1-2
(Reading database ... 259124 files and directories currently installed.)
Preparing to unpack .../isc-dhcp-server-ldap_4.4.1-2_amd64.deb ...
Unpacking isc-dhcp-server-ldap (4.4.1-2) over (4.4.1-2.1+b2) ...
dpkg: warning: downgrading isc-dhcp-server from 4.4.1-2.1+b2 to 4.4.1-2
Preparing to unpack .../isc-dhcp-server_4.4.1-2_amd64.deb ...
invoke-rc.d: policy-rc.d denied execution of stop.
Unpacking isc-dhcp-server (4.4.1-2) over (4.4.1-2.1+b2) ...
Setting up isc-dhcp-server (4.4.1-2) ...
invoke-rc.d: policy-rc.d denied execution of start.
Setting up isc-dhcp-server-ldap (4.4.1-2) ...
Processing triggers for systemd (246.6-1) ...
Processing triggers for man-db (2.9.3-2) ...

It did so (process 1310 stems from the Bullseye version):

root@tjener:~# service isc-dhcp-server stop
root@tjener:~# service isc-dhcp-server start
root@tjener:~# service isc-dhcp-server status
* isc-dhcp-server.service - LSB: DHCP server
     Loaded: loaded (/etc/init.d/isc-dhcp-server; generated)
     Active: active (running) since Mon 2020-09-28 18:27:57 CEST; 4s ago
       Docs: man:systemd-sysv-generator(8)
    Process: 3264 ExecStart=/etc/init.d/isc-dhcp-server start (code=exited, status=0/SUCCESS)
      Tasks: 8 (limit: 4671)
     Memory: 27.4M
     CGroup: /system.slice/isc-dhcp-server.service
             |-1310 /usr/sbin/dhcpd -t -4 -q -cf /etc/dhcp/dhcpd.conf
             `-3277 /usr/sbin/dhcpd -4 -q -cf /etc/dhcp/dhcpd.conf eth0 eth1

Sep 28 18:27:55 tjener.intern systemd[1]: Starting LSB: DHCP server...
Sep 28 18:27:55 tjener.intern isc-dhcp-server[3264]: Launching IPv4 server only.
Sep 28 18:27:55 tjener.intern dhcpd[3277]: Wrote 3 leases to leases file.
Sep 28 18:27:55 tjener.intern dhcpd[3277]: Server starting service.
Sep 28 18:27:57 tjener.intern isc-dhcp-server[3264]: Starting ISC DHCPv4 server: dhcpd.
Sep 28 18:27:57 tjener.intern systemd[1]: Started LSB: DHCP server.
root@tjener:~#


Wolfgang
#971275#14
Date:
2021-06-04 12:08:51 UTC
From:
To:
[ Wolfgang Schweer, 2020-09-28 ]

[..]

This isn't the case; it seems that testing the configurations is the
cause.

I've found two ways to work around this issue:

(1) Commenting the related code in /etc/init.d/isc-dhcp-server

test_config()
{
	VERSION="$1"
	CONF="$2"

	#if ! /usr/sbin/dhcpd -t $VERSION -q -cf "$CONF" > /dev/null 2>&1; then
	#	echo "dhcpd self-test failed. Please fix $CONF."
	#	echo "The error was: "
	#	/usr/sbin/dhcpd -t $VERSION -cf "$CONF"
	#	exit 1
	#fi
}

and adjusting related lines in /etc/default/isc-dhcp-server (for a
Debian Edu combined server with two network interfaces as an example):

# On what interfaces should the DHCP server (dhcpd) serve DHCP requests?
#	Separate multiple interfaces with spaces, e.g. "eth0 eth1".
INTERFACESv4="eth0 eth1"
#INTERFACESv6=""

----------------------

(2) Use a systemd unit file /etc/systemd/system/isc-dhcp-server.service

[Unit]
Description=DHCP server
After=network.target network-online.target
Requires=slapd.service

[Service]
Type=forking
RestartSec=2s
Restart=on-failure
ExecStartPre=-/usr/bin/touch /var/lib/dhcp/dhcpd.leases
ExecStart=/usr/sbin/dhcpd -4 -q -cf /etc/dhcp/dhcpd.conf

[Install]
WantedBy=multi-user.target



---------------------

Please note that I'm no expert, I guess the unit file could be improved.

Wolfgang
#971275#19
Date:
2025-05-13 13:53:36 UTC
From:
To:
Tried your work around (1) and failed, activating both, INTERFACESv4=""
and INTERFACESv6="" for eth0. Worked, when only activating
INTERFACESv4="" for eth0. Wondered if changes in
/etc/init.d/isc-dhcp-server are necessary: For me, they're not! Only
activating INTERFACESv4="" for eth0 in /etc/default/isc-dhcp-server does
the trick. BUT: I  changed to systemv-init during installation of debianedu!
#971275#24
Date:
2026-08-05 17:31:09 UTC
From:
To:
Dear submitter,

as the package isc-dhcp has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1143544

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)