Our small and medium client often ask about small system to log "user in Internet" activity.
We tested couple solution but none of them meet the expectations.
What we need:
- of course syslog based;
- one device (SRX) support;
- per user statistics (perfectly if based on active-directory-access options from junos);
- user in Internet activity with URL(most imported!);
- of course can be non-free 
Please give us some advice about software that can do this.