If you are using community builder login module on Joomla and If you want to record the IP addresses of the registered users when they are logging in to the site you can do it by making some modifications on cblogin module.. Follow these steps to do it..

In my case I am using phpmyadmin and my platform is Linux Ubuntu 10.04
And also I am using Joomla 1.5.20 and Community Builder 1.2.1
   
1. Goto your database and insert one column to the jos_users
    1->1 select jos_users table on your database...
Continue reading ...