V-253990

Discussion

ISPs use BGP to share route information with other autonomous systems (i.e., other ISPs and corporate networks). If the perimeter router was configured to BGP peer with an ISP, NIPRNet routes could be advertised to the ISP; thereby creating a backdoor connection from the internet to the NIPRNet.

Check Content

This requirement is not applicable for the DODIN Backbone.

Review the configuration of the router connecting to the alternate gateway.

Review the [edit protocols bgp] hierarchy and verify there are no BGP neighbors configured to the remote AS that belongs to the alternate gateway service provider. For example:
[edit protocols bgp]
group eBGP {
    type external;
    peer-as 2;
    neighbor <address-1> {
        <bgp neighbor configuration>;
    }
    neighbor <address-2> {
        <bgp neighbor configuration>;
    }
}

Note: Neither neighbor can belong to a peer AS belonging to the alternate gateway service provider.

Verify static routing to the peer AS belonging to the alternate gateway service provider. For example:
[edit routing-options]
rib inet6.0 {
    static {
        route <peer AS IPv6 subnet>/<prefix> next-hop <peer AS router>;
    }
}
static {
    route <peer AS IPv4 subnet>/<mask> next-hop <peer AS router>;
}

If there are BGP neighbors connecting the remote AS of the alternate gateway service provider, this is a finding.