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V-283835

CAT III (Low)

The Nokia Multicast Source Discovery Protocol (MSDP) router must be configured to filter source-active multicast advertisements to external MSDP peers to avoid global visibility of local-only multicast sources and groups.

Rule ID

SV-283835r1203754_rule

STIG

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

Version

V1R1

CCIs

CCI-001368

Discussion

To avoid global visibility of local information, a number of source-group (S, G) states in a Protocol Independent Multicast - Sparse Mode (PIM-SM) domain must not be leaked to another domain, such as multicast sources with private address, administratively scoped multicast addresses, and the Automatic Rendezvous Point (auto-RP) groups (224.0.1.39 and 224.0.1.40). Allowing a multicast distribution tree, local to the core, to extend beyond its boundary could enable local multicast traffic to leak into other autonomous systems and customer networks.

Check Content

Review the Nokia router configuration to determine if there is export policy to block local source-active multicast advertisements.

Verify the export policy, as shown in the example below: 

- show router msdp peer 1.1.1.1 detail | match "Export Policy"
Export Policy      : MSDP-EXPORT-SA

If the router is not configured with an export policy to filter local source-active multicast advertisements, this is a finding.

Fix Text

Ensure an export policy is implemented on all MSDP routers to avoid global visibility of local multicast (S, G) states. Create an export policy.

Configure prefix-list, as shown in the example below: 

- configure router policy-options
- config>router>policy-options# begin
- config>router>policy-options# prefix-list "Multicast-Group-Source"
- config>router>policy-options>prefix-list# prefix 233.0.0.0/8 exact
- config>router>policy-options>prefix-list# prefix 172.200.200.2/32 exact
- config>router>policy-options>prefix-list# exit

Configure policy, as shown in the example below:

- config>router>policy-options# policy-statement "MSDP-EXPORT-SA"
- config>router>policy-options>policy-statement# entry 10
- config>router>policy-options>policy-statement>entry# from prefix-list "Multicast-Group-Source"
- config>router>policy-options>policy-statement>entry# action drop
- 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 accept
- 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 the export policy to the MSDP peer:

- configure router msdp peer 1.1.1.1 export "MSDP-EXPORT-SA"