Hello,
Thank you for reaching out!
Could you clarify why this would be needed? I'm not very familiar with GRC, but from what I sound online, a "stealth" port is just a port, that does not reply with a "rejected" message but rather drops the packet. It does not help with the security of the system in any way.
It seems like the status of this port is controlled by the system and cannot be overwritten by the user very easily. However if you can explain to me why this is needed, I might be able to find a better solution on how to achieve it.
Awaiting your response!
Best regards,
DaumantasG