Here is a registry key I run from a startup script to disable the option that allows users to invoke a "Log on using dial-up connection". Having had experience of working in a school I know how kids will use any excuse to distract them from logging onto a computer and starting the lesson!
Here is the logon screen before the registry key has been added:
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Here is what happens if a user selects the "Log on using dial-up connection" checkbox before logging on:
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Setting the following registry key will disable the checkbox, disabling all users from using the dial-up connection feature:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
you will need to manually create a new string value (REG_SZ) called RasDisable. Set the value's data to 1.
Here is the final result:
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And finally here is what I wrote to add the regkey to all computers using a KiXtart startup script through Group Policy:
;===============================================
;===============================================
;
; DISABLE LOGON USING DIAL-UP CONNECTION
;
;===============================================
;===============================================
IF READVALUE("HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon", "RasDisable") <>"1"
WRITEVALUE("HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon", "RasDisable", "1", "REG_SZ")
ENDIF
NOTE: I've noticed that the quote marks are not displayed properly on this page. Here is the KiXtart script in its intended form: