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CISC-RT-000840 - The Cisco multicast Rendezvous Point (RP) router must be configured to filter Protocol Independent Multicast (PIM) Join messages received from the Designated Router (DR) for any undesirable multicast groups.

Information

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 join messages are only accepted for authorized multicast groups.

Solution

Configure the RP to filter PIM join messages for any undesirable multicast groups as shown in the example below.

RP/0/0/CPU0:R2(config)#ipv4 access-list FILTER_PIM_JOINS
RP/0/0/CPU0:R2(config-ipv4-acl)#deny 239.8.0.0 0.0.255.255
RP/0/0/CPU0:R2(config-ipv4-acl)#permit any
RP/0/0/CPU0:R2(config-ipv4-acl)#exit
RP/0/0/CPU0:R2(config)#router pim
RP/0/0/CPU0:R2(config-pim)#address-family ipv4
RP/0/0/CPU0:R2(config-pim-default-ipv4)#allow-rp group-list FILTER_PIM_JOINS
RP/0/0/CPU0:R2(config-pim-default-ipv4)#end

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XR_Router_Y26M01_STIG.zip

Item Details

Category: ACCESS CONTROL

References: 800-53|AC-4, CAT|III, CCI|CCI-001414, Rule-ID|SV-216812r1117237_rule, STIG-ID|CISC-RT-000840, STIG-Legacy|SV-105969, STIG-Legacy|V-96831, Vuln-ID|V-216812

Plugin: Cisco

Control ID: f69798775c2c72bb753e84c4ef85c8339936d6d312ed20c2528e0d183f2c82d3