Reading an Access-lockfile (*.ldb) you may determine which users (with their computer-names) are connected to a given Access backend-database.
However, information obtained this way isn't really precise, as i.e. a user may have failed to log out correctly, leaving a trace in the .LDB.
Using an ADO-recordset in conjunction with a specific schema instead will allow to create a recordset that will retrieve more exact information.
This is a sample database which comes with a form (screenshot) that you may incorporate into your own application and which will show a roster of users currently connected to a given database-backend.
This is one of the older entries that can also be found on the original Access-site.
Download: NetworkUsers.zip (72.97 kb)