DDclient is used to update your IP-address when you use a DDNS-provider.
If you havent yet set up your Raspberry Pi my step 1-3 in my earlier article can help you:
sudo apt-get install ddclient
You will be guided through a installation. Use your dynamic DNS-information from your provider.
wget http://plugwash.raspbian.org/jessietest/private/pool/main/d/ddclient/ to check for lastest ddclient.
sudo wget http://plugwash.raspbian.org/jessietest/private/pool/main/d/ddclient/ddclient_3.8.2-4_all.deb
sudo dpkg -i ddclient_3.8.2-4_all.deb
You will be guided through a installation. Use your dynamic DNS-information from your provider. Leave blank when network interface is asked or else your local address instead of your global adress will be used. In my case dtdns wasn´t a choice so I had to edit the ddclient.conf file with the below (use your favorite editor, in my case nano):
Change the protocol line to:
Add the following after the comments in top of file:
use=web, web=checkip.dyndns.org/, web-skip='IP Address'
service ddclient restart
You can check that ddclient is working by:
ddclient -daemon=0 -noquiet -debug