Logs with the following conditions met are considered usable for the calculation of estimated browsing time:

Traffic logs with logid of 13 or 2, when logid == 13, hostname must not be empty. The service field should be either HTTP, 80/TCP or 443/TCP.

If all above conditions are met, then devid, vdom, and user (srcip if user is empty) are combined as a key to identify a user. For time estimation, the current value of duration is calculated against history session start and end time, only un-overlapped part are used as the ebtime of the current log.