Title

The BGP router must be configured to reject outbound route advertisements for any prefixes belonging to the IP core. (Cat II impact)

Discussion

Outbound route advertisements belonging to the core can result in traffic either looping or being black holed, or at a minimum, using a non-optimized path.

Check Content

Review the router configuration to verify that there is a filter defined to block route advertisements for prefixes that belong to the IP core. The prefix filter must be referenced outbound on the appropriate BGP neighbor statements. If the router is not configured to reject outbound route advertisements that belong to the IP core, this is a finding.

Fix Text

Configure all eBGP routers to filter outbound route advertisements belonging to the IP core.

Additional Identifiers

Rule ID: SV-207138r604135_rule

Vulnerability ID: V-207138

Group Title: SRG-NET-000205

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.