Username mapping to hostnames

[WALI <hkhasgiwale () gmail com>]

Hi All…I need to map currently assigned DHCP IPs to the usernames logged on 
the machine (using Active Directory authentication).
At a forum, someone says that use the following php script:
http://www.koders.com/php/fid38A709B60859219F209C9DAFB861434CF966A752.aspx

An alternate paid version for doing this task is:
http://www.badblue.com/prodwip.htm ; but I want to try free php script 
first.  How and where can this be hosted?

Anything else....??

OPenNMS...or Nessus plugin? Can something available for accomplish this?