Do not allow COM port redirection Specifies whether to prevent the redirection of data to client COM ports from the remote computer in a Remote Desktop Services session. You can use this setting to prevent users from redirecting data to COM port peripherals or mapping local COM ports while they are logged on to a Remote Desktop Services session. By default, Remote Desktop Services allows this COM port redirection. If the status is set to Enabled, users cannot redirect server data to the local COM port. If the status is set to Disabled, Remote Desktop Services always allows COM port redirection. If the status is set to Not Configured, COM port redirection is not specified at the Group Policy level. However, an administrator can still disable COM port redirection using the Remote Desktop Session Host Configuration tool.

[enable/disable]

(1) GPO: Computer ConfigurationAdministrative TemplatesWindows ComponentsRemote Desktop ServicesRemote Desktop Session HostDevice and Resource Redirection!Do not allow COM port redirection (2) REG: HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindows NTTerminal Services!fDisableCcm