Protocol Independent Multicast (PIM) register messages received from a downstream multicast Designated Routers (DR) must be filtered for any reserved or any other undesirable multicast groups.
Customer networks that do not maintain a multicast domain and only require the IP multicast service will be required to stand up a PIM-SM router that will be incorporated into the JIE shared tree structure by establishing a peering session with an RP router. Both of these implementations expose several risks that must be mitigated to provide a secured IP core network. All RP routers that are peering with customer PIM-SM routers must implement a PIM import policy to block multicast registration requests for reserved or any other undesirable multicast groups.
Verify that the RP router is configured to filter PIM register messages using the ip pim accept-register global command as shown in the example below. This command can reference either an ACL or a route-map to identify and prevent unauthorized sources or groups from registering with the RP.
ip pim accept-register list PIM_REGISTER_FILTER ! ip access-list extended PIM_REGISTER_FILTER deny ip any 18.104.22.168 0.0.0.255 deny ip 0.0.0.0 0.255.255.255 any deny ip 22.214.171.124 0.255.255.255 any deny ip 126.96.36.199 0.255.255.255 any deny ip 188.8.131.52 0.255.255.255 any deny ip 184.108.40.206 0.255.255.255 any deny ip 10.0.0.0 0.255.255.255 any deny ip 220.127.116.11 0.255.255.255 any deny ip 18.104.22.168 0.255.255.255 any ... ... ... deny ip 172.16.0.0 0.15.255.255 any deny ip 192.168.0.0 0.0.255.255 any deny ip 22.214.171.124 0.255.255.255 any deny ip 126.96.36.199 0.255.255.255 any deny ip 188.8.131.52 184.108.40.206 any permit ip any any
If the RP router peering with customer PIM-SM routers is not configured with a PIM import policy to block registration messages for reserved multicast groups, this is a finding.
Fix Text (F-72449r1_fix)
Configure RP routers to filter PIM register messages received from a tenant multicast DR for any reserved or any other undesirable multicast groups.