Poor man's ddns in AD environment for Linux

bgstack15 — Sun, 12 Jul 2020 12:20:40 GMT

Somewhere, something is busted and my sssd is not keeping the dynamic dns entries for my statically assigned IP addresses in Microsoft DNS. So I threw together a cronjob for this script

#!/bin/sh
# Poor man's ddns
# Because AD keeps losing the dns record for my dhcp ip address
# reference: /posts/2018/04/15/wrapper-script-for-ansible-to-use-nsupdate-with-gsstsig/

IPADDR=$( ip -o a s | awk '$1 !~ /lo/ && $2 !~ /lo/' | grep -oE '([0-9]{1,3}\.){3}[0-9]{1,3}\/[0-9]+' | awk -F'/' '{print $1}' )
RR=$( echo ${IPADDR} | tr '.' '\n' | tac | tr '\n' '.' )in-addr.arpa

$( which kinit-host )

nsupdate <<EOF
update add ${HOSTNAME}. 86400 A ${IPADDR}
send
gsstsig
update add ${RR} 300 IN PTR ${HOSTNAME}.
send
EOF

Obviously this depends on kinit- host (from bgscripts package)

Wrapper script for ansible to use nsupdate with gsstsig

bgstack15 — Sun, 15 Apr 2018 12:59:38 GMT

The ansible module nsupdate is a great module. However, if you have dns zones that only accept kerberos- authenticated secure dynamic updates (gsstsig), you're out of luck for the time being. I wrote a shell script as a wrapper around nsupdate -g, and it adds a delimiting character so you can pass in multiple statements if you wish. Check out the code below, or at https://gist.github.com/bgstack15/2d484428c1ba60c0172459d49b7033b0 https://gist.github.com/bgstack15/2d484428c1ba60c0172459d49b7033b0

Knowledge Base (Posts about nsupdate)

Poor man's ddns in AD environment for Linux

Wrapper script for ansible to use nsupdate with gsstsig