Application to change password

Hi, I'm testing openvpn with freeradius and mysql to store users. I'm using dialupadmin to manage users. All is more or less ok, but I haven't found (I have search in google in several ways) an application to allow users to change their passwords (or any other data related to them). Do you know such an application? or I have to do it myself. Thanks a lot for tour time, MIGUEL.