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V-220462

CAT II (Medium)

The Cisco multicast switch must be configured to bind a Protocol Independent Multicast (PIM) neighbor filter to interfaces that have PIM enabled.

Rule ID

SV-220462r1137911_rule

STIG

Cisco IOS Switch RTR Security Technical Implementation Guide

Version

V3R3

CCIs

CCI-001414

Discussion

PIM is a routing protocol used to build multicast distribution trees for forwarding multicast traffic across the network infrastructure. PIM traffic must be limited to only known PIM neighbors by configuring and binding a PIM neighbor filter to interfaces that have PIM enabled. If a PIM neighbor filter is not applied to interfaces that have PIM enabled, unauthorized switches can join the PIM domain, discover and use the rendezvous points, and advertise their rendezvous points into the domain. This can result in a denial of service by traffic flooding or in the unauthorized transfer of data.

Check Content

Step 1: Verify that all interfaces enabled for PIM have a neighbor access control list (ACL) bound to the interface as shown in the example below: 

interface GigabitEthernet1/1 
 no switchport 
 ip address 10.1.2.2 255.255.255.0 
 ip pim neighbor-filter PIM_NEIGHBORS 
 ip pim sparse-mode 

Step 2: Review the configured ACL for filtering PIM neighbors as shown in the example below: 

ip access-list standard PIM_NEIGHBORS 
 permit 10.1.2.6 

If PIM neighbor ACLs are not bound to all interfaces that have PIM enabled, this is a finding.

Fix Text

Configure neighbor ACLs to only accept PIM control plane traffic from documented PIM neighbors. Bind neighbor ACLs to all PIM-enabled interfaces. 

Step 1: Configure ACL for PIM neighbors. 

SW2(config)#ip access-list standard PIM_NEIGHBORS 
SW2(config-std-nacl)#permit 10.1.2.6 
SW2(config-std-nacl)#exit 

Step 2: Apply the ACL to all interfaces enabled for PIM. 

SW2(config)#int g1/1 
SW2(config-if)#ip pim neighbor-filter PIM_NEIGHBORS