Untangle DDNS setup using your own DNS server

Get on your webserver
SSH into your webserver and su into root.

grep directory /etc/named.conf

cd into the directory displayed.

Create a dnssec key

<pre escaped="true">dnssec-keygen -a hmac-md5 -b 512 -n HOST -r /dev/urandom subdomain.domain.com.

Make sure that you put the period at the end of your domain. The subdomain should be the name of your untangle box or whatever machine you’re trying to setup for ddns.

cat Ksubdomain.domain.com.+005+RANDOM#.key

replace RANDOM with whaterver the .key file has.
You should see something like this

subdomain.domain.com. IN KEY 512 3 157 UR4Bu3vzaTYUtmzQA4hJl6GzRwRhY9CoWS2V1ukF6nUfSt0vxKCsEoq6 WAuDCySzmPINAtSD/OjWJfgB5eAVsA==

We want the very long string. Make note of this for the next step. If it has a space in the string, you still want every bit after it. It threw me off when i had a space in it and i wasn’t sure what i needed until i tried the different combinations and fount that it was the whole string.

Edit the named.conf
We need to add a couple of things.

key "subdomain.domain.com." {
algorithm hmac-md5;
secret "UR4Bu3vzaTYUtmzQA4hJl6GzRwRhY9CoWS2V1ukF6nUfSt0vxKCsEoq6 WAuDCySzmPINAtSD/OjWJfgB5eAVsA==";
};

Now, under your zone (domain.com.) add the following

allow-update { key "subdomain.domain.com."; };

All done, now

/etc/init.d/bind9 reload

Now, SSH into your Untangle server
Copy the key’s from your webserver

scp -P 22 root@webserver.com:/var/named/Ksubdomain.domain.com.* .

/var/named = directory that we found out from your named.conf on your webserver

Create a file named ddupate

#!/bin/bash
# Script to update DNS zones on a remote server
# Copyright © 2005-2007 - Julien Valroff
# Parts of the script Copyright © 2001-2002 - Dag Wieers 
 
KEY="/root/Kkeyname.+157+29630.private"
SERVER="ns.domain.com"
LOGFILE="/var/log/syslog"
PPP_IFACE="ppp0"
DOMAIN="domain.com."
HOST="subdomain.domain.com."
EMAIL="you@domain.com"
 
if [ "$PPP_LOCAL" != '' ]; then
   if [ "$PPP_IFACE" != "$PPP_IFACE" ]; then
      echo "$(LANG=C date +'%b %e %X') $(hostname) ddupdate[$$]: ABORTED: Not updating dynamic IP \
        address $PPP_LOCAL (already done for $(ip addr show $PPP_IFACE | awk '/inet/ { print $2 }'))" >>$LOGFILE 2>&1
      exit 0
   fi
   IPADDR=$PPP_LOCAL
   sleep 3
else
   IPADDR=$(ip addr show $PPP_IFACE | awk '/inet/ { print $2 }')
fi
 
(
cat <>$LOGFILE 2>&1
 
exit $RC

You will want to change the variables at the top to fit your needs.

Make this file executable

chmod +x ddupate

Place this file in

/etc/ppp/ip-up.d

Now execute it

/etc/ppp/ip-up.d/ddupdate

Check your syslogs for both servers. if you don’t have any errors that look like

; TSIG error with server: tsig indicates error
update failed: NOTAUTH(BADSIG)

You have successfully setup a ddns server Check your webservers DNS and make sure that the entry has been entered.

Everytime your IP changes (release and renew), this script should get ran. You could also run this in a cronjob.

Trouble shooting
In the ddupdate file you made you will see the commands executed in order to make the update possible. Preform these manually but add the -d option in nsupdate. This will add some extra information on what might be going on. In most cases it will either be a typo of the secret, both keys don live on the HOST machine or a permissions issue. I “chmod 664″ the dnssec key files on both servers.

resources and thanks go to:
http://www.kirya.net/articles/running-a-secure-ddns-service-with-bind/
http://www.semicomplete.com/articles/dynamic-dns-with-dhcp/