Information
If the static routes to the alternate gateway are being redistributed into an Exterior Gateway Protocol or Interior Gateway Protocol to a NIPRNet gateway, this could make traffic on NIPRNet flow to that particular router and not to the Internet Access Point routers. This could not only wreak havoc with traffic flows on NIPRNet, but it could overwhelm the connection from the router to the NIPRNet gateway(s) and also cause traffic destined for outside of NIPRNet to bypass the defenses of the Internet Access Points.
NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.
Solution
This requirement is not applicable for the DODIN Backbone.
Configure the router so that static routes are not redistributed to an alternate gateway into either a BGP or any IGP peering with the NIPRNet or to any other autonomous systems. This can be done by excluding that route in the route-map as shown in the example below.
Step 1: Configure a prefix list for any static routes with the alternate gateway as the next-hop address
R5(config)#ip prefix-list ISP_PREFIX permit x.x.x.0/24
Step 2: Configure a route map that will deny the state routes to the ISP
R5(config)#route-map FILTER_ISP_STATIC deny 10
R5(config-route-map)#match ip address prefix-list ISP_PREFIX
R5(config-route-map)#exit
R5(config)#route-map FILTER_ISP_STATIC permit 20
R5(config-route-map)#exit
Step 3: Apply the route-map to the IGP and BGP redistribute static commands as shown in the EIGRP example.
R5(config)#router eigrp 1
R5(config-router)#redistribute static route-map FILTER_ISP_STATIC