To view who is currently online and connected to your system you may log in as an administrator and from your Administration Panel click on Maintenance section. Over there among other options, you will be able to view the Online Users (1) option.
Clicking on Online users will present you a tabular listing of all users that currently online and connected with your system.
Appart from the users' formatted name and the branch they belong to, if any, you will be able to view other information such as when users last accessed the system and when each user was created, as well as, what device your users used to access eFrontPro and what browser.
Finally, from the Operations column (2) you have the option to disconnect any user you want.