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V-283863

CAT II (Medium)

The Nokia 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 a multicast group only from sources that have been approved by the organization.

Rule ID

SV-283863r1203838_rule

STIG

Nokia Service Router OS 25.x Router Security Technical Implementation Guide

Version

V1R1

CCIs

CCI-002403

Discussion

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 the hosts are allowed to join via IGMP or MLD.

Check Content

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

Verify the import policy is applied on the IGMP and MLD interface using the command below:

- show router igmp interface "TO-CE" detail | match "Import-Policy"
Import-Policy      : IMPORT_IGMP_JOIN   Subnet Check       : Enabled

- show router mld interface "TO-CE" detail | match "Import-Policy"
Import-Policy          : IMPORT_IGMP_JOIN

If the DR is not filtering IGMP and 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 multicast groups from sources that have been approved, as shown in the example below: 

Create Prefix-List IPv4 Multicast Source:

- configure router policy-options
- config>router>policy-options# begin
- config>router>policy-options# prefix-list Multicast-Source-IPv4
- config>router>policy-options>prefix-list$ prefix 172.200.200.2/32 exact
- config>router>policy-options>prefix-list$ exit

Create Prefix-List IPv6 Multicast Source:

- configure router policy-options
- config>router>policy-options# begin
- config>router>policy-options# prefix-list Multicast-Source-IPv6
- config>router>policy-options>prefix-list$ prefix 2001:acad:1234:200::2/128 exact
- config>router>policy-options>prefix-list$ exit

Create a policy statement for IGMP:

- config>router>policy-options# policy-statement IMPORT_IGMP_JOIN
- config>router>policy-options>policy-statement$ entry 10
- config>router>policy-options>policy-statement>entry# from prefix-list "Multicast-Source-IPv4"
- config>router>policy-options>policy-statement>entry$ action accept
- config>router>policy-options>policy-statement>entry>action$ exit
- config>router>policy-options>policy-statement>entry$ exit
- config>router>policy-options>policy-statement$ default-action drop
- config>router>policy-options>policy-statement>default-action$ exit
- config>router>policy-options>policy-statement$ exit
- config>router>policy-options# commit

Create a policy statement for MLD:

- config>router>policy-options# policy-statement IMPORT_MLD_JOIN
- config>router>policy-options>policy-statement$ entry 10
- config>router>policy-options>policy-statement>entry$ from prefix-list "Multicast-Source-IPv6"
- config>router>policy-options>policy-statement>entry$ action accept
- config>router>policy-options>policy-statement>entry>action$ exit
- config>router>policy-options>policy-statement>entry$ exit
- config>router>policy-options>policy-statement$ default-action drop
- config>router>policy-options>policy-statement>default-action$ exit
- config>router>policy-options>policy-statement$ exit
- config>router>policy-options# commit
- config>router>policy-options# exit all

Apply import policy to the IGMP and MLD interface: 

- configure router igmp interface "TO-CE" import "IMPORT_IGMP_JOIN"
- configure router mld interface "TO-CE" import "IMPORT_MLD_JOIN"