STIGQter: STIG Summary: Juniper EX Series Switches Layer 2 Switch Security Technical Implementation Guide Version: 2 Release: 5 Benchmark Date: 01 Jul 2026:

The Juniper EX switch must be configured to enable Dynamic Address Resolution Protocol (ARP) Inspection (DAI) on all user VLANs with active access interfaces.

DISA Rule

SV-253961r1212017_rule

Vulnerability Number

V-253961

Group Title

SRG-NET-000362-L2S-000027

Rule Version

JUEX-L2-000140

Severity

CAT II

CCI(s)

• CCI-002385 - Protect against or limit the effects of organization-defined types of denial of service events.

Weight

10

Fix Recommendation

Configure the switch to have DAI enabled on all user VLANs with active access interfaces.

1. Enter configuration mode.
2. Configure user-facing or untrusted VLANs with active access interfaces with DAI.
3. Commit the configuration.

user@host> configure
Entering configuration mode

user@host# set vlans <untrusted VLAN name> vlan-id <untrusted VLAN ID>

user@host# set vlans <untrusted VLAN name> forwarding-options dhcp-security arp-inspection

user@host# commit
commit complete

Check Contents

Review the switch configuration to verify that DAI is enabled on all user VLANs with active access interfaces. Configuring DAI automatically enables DHCP snooping.

Devices such as printers, servers, and VoIP phones are under enterprise control and connected to controlled access interfaces (802.1x, Static MAC Bypass, or MAC RADIUS), making them trusted sources in nonuser-facing VLANs.

Verify DAI on user-facing or untrusted VLANs with active access interfaces.

user@host> show configuration vlans
<untrusted VLAN name> {
vlan-id <VLAN ID>;
forwarding-options {
dhcp-security {
arp-inspection;
}
}
}
Note: DAI depends on DHCP snooping or static MAC address bindings.

This check is not applicable to switches configured with user-facing or untrusted VLANs merely for inclusion in trunks (e.g., core or distribution switch without access interfaces assigned to user-facing or untrusted VLANs).

If DAI is not enabled on all user VLANs with active access interfaces, this is a finding.

Vulnerability Number

V-253961

Documentable

False

Rule Version

JUEX-L2-000140

Severity Override Guidance

Review the switch configuration to verify that DAI is enabled on all user VLANs with active access interfaces. Configuring DAI automatically enables DHCP snooping.

Devices such as printers, servers, and VoIP phones are under enterprise control and connected to controlled access interfaces (802.1x, Static MAC Bypass, or MAC RADIUS), making them trusted sources in nonuser-facing VLANs.

Verify DAI on user-facing or untrusted VLANs with active access interfaces.

user@host> show configuration vlans
<untrusted VLAN name> {
vlan-id <VLAN ID>;
forwarding-options {
dhcp-security {
arp-inspection;
}
}
}
Note: DAI depends on DHCP snooping or static MAC address bindings.

This check is not applicable to switches configured with user-facing or untrusted VLANs merely for inclusion in trunks (e.g., core or distribution switch without access interfaces assigned to user-facing or untrusted VLANs).

If DAI is not enabled on all user VLANs with active access interfaces, this is a finding.

Check Content Reference

M

Target Key

5478