I spawned a VM and install Ubuntu on it. During the installation, I selected DNS server as part of the feature to be installed.
Here are the steps I took to set it up:
Step #1 - Edit /etc/bind/named.conf.local
key "domain.com.au." {
algorithm hmac-md5;
secret "w81WcwhateverhereGnCQ==";
};
zone "domain.com.au" {
type master;
allow-update { key "domain.com.au."; };
journal "/var/cache/bind/db.domain.com.au.jnl";
file "/etc/bind/master/db.domain.com.au";
};
The key section is used for the automatic update using nsupdate tool which is part of BIND installation package. the secret value is generated by using the following:
dnssec-keygen -a HMAC-MD5 -b 128 -n HOST domain.com.au
This tool generates 2 files = .key and .private
open the .key file and copy the key, e.g. w81WcwhateverhereGnCQ==, and put it in the key section above.
Note: That is NOT my KEY -
Then you need to save the .private file and keep is safe to be used later with nsupdate
The zone section is where my DNS zone is configured
Step #2 - Create Zone File
Create a master folder within /etc/bind
Copy /etc/bind/db.local to /etc/bind/master/db.domain.com.au
Change permission on the folder
chown -R bind:bind /etc/bind/master
chmod 775 -R /etc/bind/master
Step #3 - Edit /etc/bind/master/db.domain.com.au
Edit the file and adjust the content to suit your need
Restart the BIND process:
sudo /etc/init.d/bind9 restart
Have a look the syslog file to make sure everything is OK
tail -f /var/log/syslog
Step #4 - Create Dynamic DNS Script File
Create ddns.sh file with the following content:
#!/bin/bash
# This script fetches the current external IP Address, writes out an nsupdate file
# Then performs an nsupdate to our remote server of choice
# This script should be placed on a 10 minute crontab
WGET=$(which wget)
ECHO=$(which echo)
NSUPDATE=$(which nsupdate)
IP_FILE="/home/ddns/ip"
IP=$($WGET -q -O - checkip.dyndns.org|sed -e 's/.*Current IP Address: //' -e 's/<.*$//')
IS_UPDATE="no"
if [ -f $IP_FILE ]
then
#Get file content
IP_OLD=$(<$IP_FILE)
$ECHO "File IP exists with the content: $IP_OLD"
$ECHO "Old IP: $IP_OLD"
if [ "$IP_OLD" == "$IP" ]
then
$ECHO "IP is not changing: $IP"
else
$ECHO "IP changes. OLD IP: $IP_OLD, NEW IP: $IP"
$ECHO "$IP" > $IP_FILE
IS_UPDATE="yes"
fi
else
$ECHO "File IP does not exist, creating one..."
IS_UPDATE="yes"
$ECHO "$IP" > $IP_FILE
fi
$ECHO "server bind.domain.com.au" > /tmp/nsupdate
$ECHO "debug yes" >> /tmp/nsupdate
$ECHO "zone domain.com.au." >> /tmp/nsupdate
$ECHO "update delete domain.com.au A" >> /tmp/nsupdate
$ECHO "update add domain.com.au 600 A $IP" >> /tmp/nsupdate
$ECHO "update delete www.domain.com.au A" >> /tmp/nsupdate
$ECHO "update add www.domain.com.au 600 A $IP" >> /tmp/nsupdate
$ECHO "send" >> /tmp/nsupdate
$ECHO "Is Update: $IS_UPDATE"
if [ "$IS_UPDATE" == "yes" ]
then
$NSUPDATE -k /home/ddns/Kdomain.com.au.+157+05161.private -v /tmp/nsupdate 2>&1
$ECHO "Updating..."
fi
The script does the following:
- Get the Public IP address from checkip.dyndns.org
- Check whether or not the IP has changed from the previous pooling. This is done by storing the IP to a file and compare it on the next query
- If the IP has changed, run nsupdate
Notice the .private key is used here.
Then you can do cronjob to run ddns.sh regularly
