The Arista MLS layer 2 switch must have all disabled switch ports assigned to an unused VLAN.
Overview
Finding ID | Version | Rule ID | IA Controls | Severity |
V-255980 | ARST-L2-000170 | SV-255980r991774_rule | Medium |
Description |
It is possible that a disabled port that is assigned to a user or management VLAN becomes enabled by accident or by an attacker and as a result gains access to that VLAN as a member. |
STIG | Date |
Arista MLS EOS 4.X L2S Security Technical Implementation Guide | 2025-05-19 |
Details
Check Text (C-59656r882280_chk) |
Step 1: Review the switch configuration and examine all access switch ports. Verify the unused port is configured to be intentionally shut down and assigned to an inactive VLAN. switch(config)#sh run int eth8 interface Ethernet8 description PORT IS INTENTIONALLY SHUTDOWN switchport access vlan 999 shutdown switch(config)# Step 2: Verify traffic from the inactive VLAN is not allowed on any trunk links as shown in the example below: switch(config)#sh run int eth9 interface Ethernet9 switchport trunk native vlan 1000 switchport trunk allowed vlan 2-998, 1001-4094 switchport mode trunk switch(config)# If any access switch ports are not in use and not in an inactive shutdown, this is a finding. Note: Switch ports configured for 802.1x are exempt from this requirement. |
Fix Text (F-59599r882281_fix) |
Configure all Arista MLS switch ports not in use to be shut down and assigned to an unused VLAN. Step 1: Configure all unused ports to be shut down and assigned to an unused VLAN. switch(config)#interface ethernet 9 switch(config-eth9)#shutdown switch(config-eth9)# description this port is intentionally shutdown switch(config-eth9)# switchport access vlan 999 Step 2: Configure any trunk links to exclude the unused VLAN. switch(config)# interface ethernet 10 switch(config-eth10)# switchport trunk native vlan 1000 switch(config-eth9)# switchport trunk allowed vlan 2-998, 1001-4094 switch(config-eth9)# switchport mode trunk |