ppp from poptop problem...

[fifty]

I need to modify SNMP Interface Statistics to show traffic from clients conected over vpn (poptop) server. It found interfaces but with no ip for that device... and I need client to be monitored by ip not by ppp because they are dynamic...
I'll try to develop something like this but I don't know tthe snmp query for ip over PPP. (Anyway is not the same as eth query... )