Dynamic DNS service
Dynamic DNS allows you to have a DNS name while your IP address changes frequently. You will need to register for an account with one of the dynamic DNS providers. This service is often provided freely.
More information:
Popular dynamic DNS registration sites:
Installation ddclient (dyndns and others)
This client updates the DynDNS record automatically.
sudo apt-get install ssh libio-socket-ssl-perl ddclient
Follow the instructions. Additionally configure a longer update interval 'daemon=3600' and use SSL:
sudo gedit /etc/ddclient.conf
protocol=dyndns2 use=web, web=checkip.dyndns.com, web-skip='IP Address' server=members.dyndns.org login=**dyndns-login** password='**dyndns-pwd**' wilbertvolkers.dyndns.org daemon=3600 ssl=yes
View ddclient logging:
cat /var/log/syslog* | grep 'ddclient'
Test/force refresh:
sudo ddclient -force
Reconfigure and restart, you can edit the config file instead:
sudo dpkg-reconfigure ddclient sudo /etc/init.d/ddclient restart
Installation ipUpdate (dnsexit)
The interface uses an (unsecure) http protocol and it is strongly recommended to configure a different password for this service. Logon at http://www.dnsexit.com and go to My Account -> Account profile -> IP Update Password.
WAN IP update script using Linux Upstart method:
sudo /etc/init/dyndns-ip-update.conf
Contents:
author "Wilbert Volkers"
description "Update WAN IP address at DynDNS service www.dnsexit.com"
start on (local-filesystems and net-device-up IFACE!=lo)
stop on runlevel [!023456]
# write stdout to log
console log
script
echo "$(date '+%Y-%m-%d %H.%M.%S') dyndns : start ..."
# settings
host="wilbertvolkers.linkpc.net"
login="dnsexitusername"
passtoken="dnsexitpassword"
storedipfile="/opt/dyndns-ip-update.ip"
# get current IP from checkip.dyndns.com
currentIP=$( wget --quiet --output-document=- http://checkip.dyndns.com | sed -ne "s/.*[^0-9]\([0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\)[^0-9].*/\1/p" )
echo "$(date '+%Y-%m-%d %H.%M.%S') dyndns : current IP address = $currentIP"
# get previous IP from a file, only if from today
storedIP="none"
if [ -f "$storedipfile" ] ; then
# get storedipfile modify date
storedipfiledate=$( stat -c %y $storedipfile | cut -d ' ' -f1 )
# only skip update if IP is from today
if [ $storedipfiledate = $(date '+%Y-%m-%d') ] ; then
storedIP=$(cat $storedipfile)
fi
fi
echo "$(date '+%Y-%m-%d %H.%M.%S') dyndns : previous IP address = $storedIP"
# update the dyndns IP if needed
if [ $currentIP = $storedIP ] ; then
echo "$(date '+%Y-%m-%d %H.%M.%S') dyndns : update not needed, skipped"
else
update_url="http://update.dnsexit.com/RemoteUpdate.sv?login=$login&password=$passtoken&host=$host"
echo "$(date '+%Y-%m-%d %H.%M.%S') dyndns : $( wget --quiet --output-document=- $update_url | tail -1 )"
echo $currentIP > $storedipfile
fi
echo "$(date '+%Y-%m-%d %H.%M.%S') dyndns : done."
end script
Test script with:
sudo start dyndns-ip-update
Check log:
sudo cat /var/log/upstart/dyndns-ip-update.log | tail -10
Remarks
Note that when your IP address has changed, the ddcient needs to announce this to your dyndns service. Then it is still possible that the DNS you are using does not give you the new IP address, it may take some time before updates are routed through the DNS network.
