Multi wan, active directory and traffic log. how to?

[dannyb78]

Hi all, I have a 2.0.1 installation (single server-dedicated hardware) in a small enterprise environnement with
2 WAN interface with DSL access, configured in load balance+failover
1 LAN interface wich is connected with 8 subnets via another firewall
1 openVPN interface for external client connections

I would like to store traffic data for monitoring and statistics.

Actually I'm using squid as transparent proxy without login, and storing data by ip address.
I doesn't really need a proxy but I'm quite interesting in store data by user instead of ip. Also I dont want to force users to log in manually, so I'm wondering if there's a way to configure a captive portal or a proxy server wich auto log-in users by active directory network credentials that can log trafic for report and statistics purposes.

thanks