Detections
Analytics
CISC-L2-000230 - The Cisco switch must have the default VLAN pruned from all trunk ports that do not require it.
Information
The default VLAN (i.e., VLAN 1) is a special VLAN used for control plane traffic such as Spanning-Tree Protocol (STP), Dynamic Trunking Protocol (DTP), VLAN Trunking Protocol (VTP), and Port Aggregation Protocol (PAgP). VLAN 1 is enabled on all trunks and ports by default. With larger campus networks, care needs to be taken about the diameter of the STP domain for the default VLAN. Instability in one part of the network could affect the default VLAN, thereby influencing control-plane stability and therefore STP stability for all other VLANs.NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
Prune VLAN 1 from any trunk links as necessary.SW1(config)#int g0/2
SW1(config-if)#switchport trunk allowed vlan except 1
Verify VLAN 1 is not allowed on the trunk link.
SW1#show interfaces trunk
Port Mode Encapsulation Status Native vlan
Gi0/1 on 802.1q trunking 1
Gi0/2 on 802.1q trunking 1
Port Vlans allowed on trunk
Gi0/1 1-998,1000-4094
Gi0/2 2-4094
See Also
https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XE_Switch_Y26M01_STIG.zip
Item Details
Audit Name: DISA Cisco IOS XE Switch L2S STIG v3r2
Category: SYSTEM AND COMMUNICATIONS PROTECTION
References: 800-53|SC-7, CAT|II, CCI|CCI-004891, Rule-ID|SV-220669r991906_rule, STIG-ID|CISC-L2-000230, STIG-Legacy|SV-110313, STIG-Legacy|V-101209, Vuln-ID|V-220669
Plugin: Cisco
Control ID: 5bb4011670803be86af752cbb0e1e11ce19d1f57e2dc9e43422af776f145073e