What is NAC (network access control)?

NAC (network access control) checks devices before they are allowed onto the network, for example requiring a company certificate, an up-to-date operating system or a known hardware address before a switch port or Wi-Fi network lets them in. Unknown devices can be refused or sent to a guest network. NAC reduces the risk of someone simply plugging into a wall socket, but it does not watch what admitted devices do afterwards: a compromised company laptop passes the check. Network detection complements it by watching behaviour once devices are on the network.

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