Title

The Juniper multicast Designated Router (DR) must be configured to filter the IGMP and MLD Report messages to allow hosts to join a multicast group only from sources that have been approved by the organization. (Cat II impact)

Discussion

Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone downloading a file 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.

Check Content

Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to only join multicast groups from sources that have been approved. Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. [edit policy-options] policy-statement <name> { term unauth-sources { from { source-address-filter <IPv4 address>/<mask> orlonger; } then reject; } term allow-others { then accept; } } policy-statement <name IPv6> { term unauth-sources { from { source-address-filter <IPv6 address>/<prefix> orlonger; } then reject; } term allow-others { then accept; } } [edit protocols] igmp { interface <name>/<logical unit> { group-policy <policy name>; } } mld { interface <name>/<logical unit> { group-policy <policy name IPv6>; } } If the DR is not filtering IGMP or MLD report messages, this is a finding.

Fix Text

Configure the DR to filter the IGMP and MLD report messages to allow hosts to join only those multicast groups from sources that have been approved. set policy-options policy-statement <name> term unauth-sources from source-address-filter <IPv4 address>/<mask> orlonger set policy-options policy-statement <name> term unauth-sources then reject set policy-options policy-statement <name> term accept-others then accept set policy-options policy-statement <name IPv6> term unauth-sources from source-address-filter <IPv6 address>/<prefix> orlonger set policy-options policy-statement <name IPv6> term unauth-sources then reject set policy-options policy-statement <name IPv6> term accept-others then accept set protocols igmp interface <name>.<logical unit> group-policy <policy name> set protocols mld interface <name>.<logical unit> group-policy <policy name IPv6>

Additional Identifiers

Rule ID: SV-254051r844263_rule

Vulnerability ID: V-254051

Group Title: SRG-NET-000364-RTR-000115

Expert Comments

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