V-253994

Discussion

Real-time multicast traffic can entail multiple large flows of data. An attacker can flood a network segment with multicast packets, over-using the available bandwidth and thereby creating a denial-of-service (DoS) condition. Hence, it is imperative that register messages are accepted only for authorized multicast groups and sources.

Check Content

Verify that the RP router is configured to filter PIM register messages from unauthorized multicast groups and sources.
[edit policy-options]
policy-statement <name> {
    term filter_groups {
        from {
            route-filter <multicast address>/<mask> orlonger;
            route-filter <multicast address>/<mask> exact;
            <additional groups to filter>
        }
        then reject;
    }
    term filter_sources {
        from {
            source-address-filter <source host address>/32 exact;
            source-address-filter <source subnet address>/<mask> orlonger;
            <additional source addresses to filter>
        }
        then reject;
    }
    term accept_others {
        then accept;
    }
}

[edit protocols pim]
rp {
    rp-register-policy <policy name>;
} 

If the RP router peering with PIM-SM routers is not configured with a PIM import policy to block registration messages for any undesirable multicast groups and sources, this is a finding.