CISC-RT-000250 - The Cisco perimeter router must be configured to enforce approved authorizations for controlling the flow of information between interconnected networks in accordance with applicable policy.
Information flow control regulates authorized information to travel within a network and between interconnected networks. Controlling the flow of network traffic is critical so it does not introduce any unacceptable risk to the network infrastructure or data. An example of a flow control restriction is blocking outside traffic claiming to be from within the organization. For most routers, internal information flow control is a product of system design. NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
This requirement is not applicable for the DODIN Backbone. Step 1: Configure an ACL to allow or deny traffic as shown in the example below. R1(config)#ip access-list extended FILTER_PERIMETER R1(config-ext-nacl)#permit tcp any any established R1(config-ext-nacl)#permit tcp host x.12.1.9 host x.12.1.10 eq bgp R1(config-ext-nacl)#permit tcp host x.12.1.9 eq bgp host x.12.1.10 R1(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo R1(config-ext-nacl)#permit icmp host x.12.1.9 host x.12.1.10 echo-reply R1(config-ext-nacl)#permit tcp any host x.12.1.22 eq www R1(config-ext-nacl)#deny ip any any log-input R1(config-ext-nacl)#exit Step 2: Apply the ACL inbound on all external interfaces. R2(config)#int g0/0 R1(config-if)#ip access-group FILTER_PERIMETER in