The multicast Designated Router (DR) must be configured to filter the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Report messages to allow hosts to join only multicast groups that have been approved by the organization.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-78331	SRG-NET-000364-RTR-000114	SV-93037r2_rule		Low

Description
Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone doing a file download here or there), whereas multicast can have broader impact on bandwidth consumption, resulting in extreme network congestion. Hence, it is imperative that there is multicast admission control to restrict which multicast groups hosts are allowed to join via IGMP or MLD.

Description

Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone doing a file download here or there), whereas multicast can have broader impact on bandwidth consumption, resulting in extreme network congestion. Hence, it is imperative that there is multicast admission control to restrict which multicast groups hosts are allowed to join via IGMP or MLD.

STIG	Date
Router Security Requirements Guide	2020-06-30

Details

Check Text ( C-77889r2_chk )
Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to join only those groups that have been approved. Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. This requirement is not applicable to Any Source Multicast (ASM) since the filtering is being performed by the Rendezvous Point router. If the DR is not filtering IGMP or MLD report messages, this is a finding.

Check Text ( C-77889r2_chk )

Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to join only those groups that have been approved.

Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. This requirement is not applicable to Any Source Multicast (ASM) since the filtering is being performed by the Rendezvous Point router.

If the DR is not filtering IGMP or MLD report messages, this is a finding.

Fix Text (F-85059r1_fix)
Configure the DR to filter the IGMP and MLD report messages to allow hosts to join only those multicast groups that have been approved.