To update namecheap dynamic DNS on Ubuntu, you will you need to install ddclient. What does ddclient do? Ddclient was first developed in Perl by Paul Burry to update dynamic DNS and has been maintaining by developers via SourceForge project.
To install ddclient on Ubuntu
$ sudo apt-get install ddclient
After installed ddclient, you need to config ddclient file
$ sudo nano /etc/ddclient/ddclient.conf
############ # ddclient.conf # namecheap ############ ## update time in 300 seconds daemon=300 ## you can open this file with any text editor to see what is being sent cache=/tmp/ddclient.cache pid=/var/run/ddclient.pid ## This line will get your public IP address if you're system is not directly connected ## to the internet, such as behind a firewall/router use=web, web=http://whatismyipaddress.com/, web-skip='Your IP address is' protocol=namecheap server=dynamicdns.park-your-domain.com ## Your Domain name login=example.com password='password from namecheap' ssl=yes address with a comma then space @, forum, img, ssl, tracker, webmail, www
Make ddclient start when you boot up your ubuntu system
$ sudo update-rc.d ddclient defaults $ sudo update-rc.d ddclient enable