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Security Fundamentals & Crypto · Foundational

Port Security

Switch feature that limits which or how many MAC addresses can use a port.

Definition

Port security restricts a port to specific or a maximum number of learned MAC addresses and takes action on violation: protect (drop), restrict (drop and log), or shutdown (err-disable). Sticky learning saves dynamically learned MACs to the configuration. It mitigates MAC flooding and casual unauthorized connections but can be bypassed by MAC spoofing.

Example

switchport port-security maximum 2 with violation restrict limits a port to two devices.

Exam tip

Port security is weaker than 802.1X because MAC addresses can be spoofed.

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