This small tutorial will teach you how you can make your Belgacom B-BOX 2 update your DynDNS ip without installing any additional software.
Go to: http://192.168.1.1/index.cgi?user_name=admin&password=BGCVDSL2
If you have changed the B-BOX2 ip, replace 192.168.1.1 in the uri with the ip you have assigned.
Copy/Paste the following line into the address bar of your browser and press enter.
Change the settings
Connection to Update: WAN PPPoE
User Name: yourDynDNSusername
Password : yourDynDNSpassword
Host Name: your.dyndns-server.com