That question contains a logical paradox. If someone's accessing your pc without your knowledge and you know about it, they are no longer accessing your pc without your knowlege
The best way to monitor (and prevent) such activity is to install a firewall and configure it to raise alerts for any connection attempt which is not allowed.
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Dmitry Korolyov [[email protected]]
MVP: Windows Server - Active Directory
how to know if someone is having access to my pc without
my knowledge?