SQL Server does not provide this functionality natively. You'll have to create a job that looks for connections that have been idle for a while and KILL them.
You can find a lot of the information that you're looking for in the sysprocesses table which is in the master database. Specifically, the table contains a column called last_batch. last_batch contains the date/time that the connection last executed a batch.
The job will have to run under a login that is in either the sysadmin or processadmin fixed server roles. My suggestion is to create a login and put it in the processadmin role.
BTW, is there a particular reason that you're looking to implement something like this?
-Mike
>Hello *.*
>
>Are there some property, function, SP, parameter (anything) who disconnect an user automaticaly?
>
>If my user is inactive for "n" time I want disconect this user.
>
>I dont want to do it from VFP, I´d like to do it from SQL SERVER.
>
>Does Someone can help me?
>
>Thanks in advance.