Policy
Do not allow COM port redirection
This policy setting 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 you enable this policy setting, users cannot redirect server data to the local COM port. If you disable this policy setting, Remote Desktop Services always allows COM port redirection. If you do not configure this policy setting, COM port redirection is not specified at the Group Policy level.
ad1cb9c89420 TS_CLIENT_COM Registry
Copy registry mappings
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\fDisableCcm (enabled) = 1
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\fDisableCcm (disabled) = 0Policy notes
This policy setting 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 you enable this policy setting, users cannot redirect server data to the local COM port. If you disable this policy setting, Remote Desktop Services always allows COM port redirection. If you do not configure this policy setting, COM port redirection is not specified at the Group Policy level.