script for use with `nsupdate` to update linux client DNS on a DNS server... in this instance, I am targeting a Windows Server DNS server 2003/2008/2012+. I have manually created the PTR and A records once, and granted the Everyone ACE the "Write" permission in the DACL of the PTR and A records.

nsclient_update.sh

#!/bin/sh
#original from http://community.spiceworks.com/topic/262635-linux-does-not-register-on-the-windows-ad-dns
# reply of Phil6196 Oct 1, 2012 at 12:41 AM (EDT)
ADDR=`/sbin/ifconfig eth0 | grep 'inet addr' | awk '{print $2}' | sed -e s/.*://`
HOST=`hostname`
echo "update delete $HOST A" > /var/nsupdate.txt
echo "update add $HOST 86400 A $ADDR" >> /var/nsupdate.txt
echo "update delete $HOST PTR" > /var/nsupdate.txt
echo "update add $HOST 86400 PTR $ADDR" >> /var/nsupdate.txt
nsupdate /var/nsupdate.txt

Thought I would provide an update for my own sanity:

# ip=1.2.3.4
# arpa=$(ruby -ripaddr -e 'puts "#{IPAddr.new(ARGV[0]).reverse}."' $ip)
# echo $arpa
4.3.2.1.in-addr.arpa.
# fqdn=bar.urdomain1.com.
# echo "server 10.207.39.2
update add $fqdn 3600 IN A $ip
send
update add $arpa 3600 IN PTR $fqdn
send
quit
" | nsupdate -k /etc/bind/rndc.key

I'm loving this Unix-y version without needing a temporary file that can check your domain (if machine is domain joined) and update the domain's DNS server ad hoc say if your sssd.conf had been missing ad_hostname when you don't use the FQDN as the hostname.

ipaddress=$(hostname -i)
arpa=$(printf 'arpa.in-addr.%s.' "$ipaddress" | tac -s.)
fqdn=$(hostname -f).
mydnsserver=$(nslookup -type=soa $(hostname -d) | grep origin | awk -F'= ' '{print $2}')
echo "server $mydnsserver
update add $fqdn 3600 IN A $ipaddress
send
update add $arpa 3600 IN PTR $fqdn
send
quit
" | nsupdate

Add -d and -D after nsupdate to get a really verbose listing of what it is doing as it updates.

Hey I don't know if this is related but I need nsupdate to be one line for a specific use case is this possible?

Hey I don't know if this is related but I need nsupdate to be one line for a specific use case is this possible?

It depends on what you define as 'one line'. The nsupdate commands (update add ...) have to be on separate lines, i.e. they are newline delimited. You could use the printf command to have it as a single line and use '\n' newline character where needed, but it gets ugly:

ipaddress=$(hostname -i); arpa=$(printf 'arpa.in-addr.%s.' "$ipaddress" | tac -s.); fqdn=$(hostname -f).; mydnsserver=$(nslookup -type=soa $(hostname -d) | grep origin | awk -F'= ' '{print $2}'); printf "server $mydnsserver\nupdate add $fqdn 3600 IN A $ipaddress\nsend\nupdate add $arpa 3600 IN PTR $fqdn\nsend\nquit\n" | nsupdate

I haven't tested this btw, but the general structure should work. Remove the | nsupdate to check the syntax.