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The Juniper EX switch must be configured to enable DHCP snooping for all user VLANs with active access interfaces to validate DHCP messages from untrusted sources.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-253959JUEX-L2-000120SV-253959r1212011_ruleCCI-002385medium
Description
In an enterprise network, devices under administrative control are trusted sources. These devices include the switches, routers, and servers in the network. Host (i.e., access) interfaces and unknown DHCP servers are considered untrusted sources. An unknown DHCP server on the network on an untrusted interface is called a spurious DHCP server, any device (PC, Wireless Access Point) that is loaded with DHCP server enabled. The DHCP snooping feature determines whether traffic sources are trusted or untrusted. The potential exists for a spurious DHCP server to respond to DHCPDISCOVER messages before the real server has time to respond. DHCP snooping allows switches on the network to trust the interface a DHCP server is connected to and not trust the other interfaces. The DHCP snooping feature validates DHCP messages received from untrusted sources, filters out invalid messages, and rate-limits DHCP traffic from trusted and untrusted sources. The DHCP snooping feature builds and maintains a binding database, which contains information about untrusted hosts with leased IP addresses, and it uses the database to validate subsequent requests from untrusted hosts. Other security features, such as IP Source Guard and Dynamic Address Resolution Protocol (ARP) Inspection (DAI), also use information stored in the DHCP snooping binding database. Hence, it is imperative that the DHCP snooping feature is enabled on all user-facing or untrusted VLANs with active access interfaces.
STIGDate
Juniper EX Series Switches Layer 2 Switch Security Technical Implementation Guide2026-06-03

Related Frameworks

1 mapping across 4 frameworks
SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (13) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

MON-01Continuous Monitoring
1.00
MON-01.1Intrusion Detection & Prevention Systems (IDS & IPS)
1.00
MON-01.3Inbound & Outbound Communications Traffic
1.00
MON-01.4System Generated Alerts
1.00
MON-01.8Security Event Monitoring
1.00
NET-01Network Security Controls (NSC)
1.00
NET-02Layered Network Defenses
1.00
SEA-01Secure Engineering Principles
1.00
SEA-02Alignment With Enterprise Architecture
1.00
CAP-01Capacity & Performance Management
0.50

+3 more (top 10 by confidence shown)

NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (36) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

AC-10Concurrent Session Control
1.00
AC-17(9)Disconnect or Disable Access
1.00
AC-2(4)Automated Audit Actions
1.00
AC-3Access Enforcement
1.00
AC-4Information Flow Enforcement
1.00
AC-6(9)Log Use of Privileged Functions
1.00
AU-12Audit Record Generation
1.00
AU-3Content of Audit Records
1.00
AU-5Response to Audit Logging Process Failures
1.00
CM-11(2)Software Installation with Privileged Status
1.00

+26 more (top 10 by confidence shown)

CCI1 mapping
CCI-002385
1.00
NIST CSF 2.00 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (3) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

DE.CM-01
1.00
PR.IR-01
1.00
PR.IR-04
0.50

Who does this work

12 NICE work roles and 9 EC-Council certifications.

This is an inference across published mappings, not a single claim by anyone. This check maps to a control, which maps to a Cybersecurity Framework outcome, which NIST assigns to the work roles below. EC-Council separately maps its certifications to those same roles.

A certification prepares someone for a role. It is not evidence that a holder is qualified, and neither NIST nor EC-Council has stated that any certification here addresses this check.

Work-role assignments published by NIST (NICE Framework Components 2.2.0 and the CSF 2.0 OLIR crosswalk). Certification mappings published by EC-Council.

Details

Check Text (C-253959r1212011_chk)

Review the switch configuration and verify that DHCP snooping is enabled on all user-facing or untrusted VLANs with active access interfaces. DHCP snooping is enabled if dhcp-security is configured for any VLAN, and is automatically enabled whenever any other VLAN port security feature is configured (e.g., IP Source Guard or Dynamic ARP Inspection). Devices such as printers, servers, and VoIP phones are under administrative control and connected to controlled access interfaces (802.1x, Static MAC Bypass, or MAC RADIUS), making them trusted sources in nonuser-facing VLANs. Trunked interfaces are trusted sources. Verify DHCP snooping on user-facing or untrusted VLANs is configured with active access interfaces. [edit vlans] <untrusted VLAN name> { vlan-id <VLAN ID>; forwarding-options { dhcp-security; } } 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 the switch does not have DHCP snooping enabled for all user-facing or untrusted VLANs with active access interfaces to validate DHCP messages from untrusted sources, this is a finding.

Fix Text (F-57362r1212010_fix)

Configure the switch with DHCP snooping for all user-facing or untrusted VLANs with active access interfaces to validate DHCP messages from untrusted sources. 1. Enter configuration mode. 2. Configure user-facing or untrusted VLANs with active access interfaces with DHCP snooping. 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 user@host# commit commit complete