ddclient installations breaks dhclient hooks

[Marco Bicca]

It seems that this is a variation of this same bug:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=807707

Deployed a new Ubuntu 16.04 LTS image on Microsoft Azure:
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"
NAME="Ubuntu"
VERSION="16.04.1 LTS (Xenial Xerus)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 16.04.1 LTS"
VERSION_ID="16.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
VERSION_CODENAME=xenial
UBUNTU_CODENAME=xenial

Kernel:
4.4.0-62-generic

Installed ddclient:
3.8.2-2ubuntu2

After ddclient is installed and running, you can see its exit-hook script under /etc/dhcp/dhclient-exit-hooks.d

#!/bin/sh
# /etc/dhcp/dhclient-exit-hooks.d/ddclient - exit hook for dhclient

[ -x /usr/sbin/ddclient ] || exit 0
[ -f /etc/default/ddclient ] || exit 0
. /etc/default/ddclient
[ $run_dhclient = "true" ] || exit 0

case $reason in
    BOUND | RENEW | REBIND)
        /usr/bin/logger -t dhclient $reason, updating IP address with ddclient
        /usr/sbin/ddclient -daemon=0 -syslog > /dev/null 2>&1
        ;;
    *)
        ;;
esac

If you reboot , the VM won't come back again with issues getting route/gateway info from DHCP server.

It seems like, changing the script to the one below, fixes the issue:

#!/bin/sh
# /etc/dhcp/dhclient-exit-hooks.d/ddclient - exit hook for dhclient

[ -x /usr/sbin/ddclient ] || return
[ -f /etc/default/ddclient ] || return
. /etc/default/ddclient
[ $run_dhclient = "true" ] || return

case $reason in
    BOUND | RENEW | REBIND)
        /usr/bin/logger -t dhclient $reason, updating IP address with ddclient
        /usr/sbin/ddclient -daemon=0 -syslog > /dev/null 2>&1
        ;;
    *)
        ;;
esac

Somehow the reported version on Debian to have a fix is 3.8.2-2 (which is the same) but maybe the patch didn't get through?

Thank you!

[Jon Schewe (jpschewe)]

I've seen the same problem on my system. Calling exit from a dhclient hook causes dhclient to stop processing the other hooks in the directory.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.