Report of services used by user on a VPN connection

Hello there,

I have a question about a requirement made by a client, who wants to get a report of the source IP, the duration time of VPN session and the services accessed in each VPN session.  I have covered the first and second requirements but the third it's not easy to me to fulfill because I don't have any idea of where I can get that detail of information about each VPN session.

Thanks for your help.