From b2evolution manual

This manual page is outdated. NEW PAGE: Who's online in b2evolution v5+.

This page refers to b2evolution 0.9.2

Due to the very nature of the WWW, the "who's online?" session tracker can only offers an approximative view of who's actually online.

There are two main reasons for this:

• One can never know when a user leaves the website. So we'll consider them online for a given amount of time after the last time they requested a page. (The default is 5 minutes. You can change this setting ($online_session_timeout or "Reload-page timeout") in the Settings tab)
• When using proxy servers or NAT routers, several users may share the same IP address. When not logged in, all those anonymous users will be seen as a single user.

Note: please also keep in mind that users who unchecked "Show Online" in their profile will always be listed as anonymous.