You can automatically disconnect users after a specified time of inactivity, set per user or at the User Setting Level. The idle timeout setting applies across all connection protocols supported by the Server. If a session has been idle for more than the specified timeout, the user has to log back in.
To set a maximum idle limit for a user or User Setting Level
In the Administrator, connect to the server, then click the Server tab.
Click the User or User Setting Level you want to configure.
In the right pane, click the Quota tab.
Select the Enable time out check box, then type or select the maximum allowable seconds of inactivity allowed before the user is disconnected. (A gray check on a User account indicates the account is inheriting parameters from the User Setting or Site level.)
Many popular FTP clients have keep-alive functionality that attempts to issue do-nothing commands such as NOOP in order to simulate user activity and prevent a time-out. If Block anti-timeout schemes is enabled for the Server, such do-nothing commands are ignored and will not reset the counter for the timeout limit.