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 | CCI-004891 | 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-255980r991774_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