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The layer 2 switch must have BPDU Guard enabled on all user-facing or untrusted access switch ports.


Overview

Finding ID Version Rule ID IA Controls Severity
V-206655 SRG-NET-000362-L2S-000022 SV-206655r383575_rule Medium
Description
If a rogue switch is introduced into the topology and transmits a Bridge Protocol Data Unit (BPDU) with a lower bridge priority than the existing root bridge, it will become the new root bridge and cause a topology change, rendering the network in a suboptimal state. The STP PortFast BPDU guard enhancement allows network designers to enforce the STP domain borders and keep the active topology predictable. The devices behind the ports that have STP PortFast enabled are not able to influence the STP topology. At the reception of BPDUs, the BPDU guard operation disables the port that has PortFast configured. The BPDU guard transitions the port into errdisable state and sends a log message.
STIG Date
Layer 2 Switch Security Requirements Guide 2021-05-17

Details

Check Text ( C-6913r298395_chk )
Review the switch configuration to verify that BPDU Guard is enabled on all user-facing or untrusted access switch ports.

If the switch has not enabled BPDU Guard, this is a finding.
Fix Text (F-6913r298396_fix)
Configure the switch to have BPDU Guard enabled on all user-facing or untrusted access switch ports.