Monitoring User in CRM Portal

Hi All,

Our company have finished CRM portal and this week we will doing a stress test by using portal system at a time with lot of user. How to monitoring users that have been logged into portal in one day?Not only the total number of user but also all user ID.

I have try to monitoring from 'System Administration->Monitoring->Activity Reports' but it only show total number of user and the most active users (10) in last 3 hours. Any helpful answer will be rewarded. Thank You.

Regards,

Aleluya SAP.