Changing User passwords for non Mac users

So basically this would be simple you would think, I've looked around everywhere but haven't found much of a solution. Problem: Open Directory is used for VPN authentication via a Juniper device. Not all users in my domain are on Macs but all have OD account. Passwords are set to rotate every 90 days but I need a way for non-Mac users to be able to change their passwords. Preferably like a website or utility that can be run while they are in their VPN session. Surely someone has dealt with this, are their any solutions out there? Bit about my network: SSL LDAP Kerberos Realm No Anon lookups in LDAP Any unnecessary ports are locked down.