Network Access Control (802.1X, NAC)

Network Access Control (NAC) is the security discipline that determines which devices and users are allowed to connect to the network and what level of access they receive. It enforces security policies at the point of connection — before a device can send or receive any data.

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Why NAC Matters

Without NAC, any device plugged into a network port or connecting to Wi-Fi gains immediate access:

Risk Without NAC	Consequence
Rogue devices connect freely	Attackers plug in a laptop and access the network
Unpatched devices join the network	Vulnerable systems introduce risk to the entire network
No visibility into connected devices	Cannot inventory or monitor what is on the network
BYOD devices uncontrolled	Personal devices may carry malware
Compliance failures	Cannot demonstrate device-level access controls

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How NAC Works

NAC evaluates devices and users at the time of connection and applies policies based on the results: