The router must restrict BGP connections to known IP addresses of neighbor routers from trusted Autonomous Systems (AS).

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-55775	SRG-NET-000195-RTR-000086	SV-70029r1_rule		Medium

Description
Advertisement of routes by an Autonomous System for networks that do not belong to any of its trusted peers pulls traffic away from the authorized network. This causes a DoS on the network that allocated the block of addresses and may cause a DoS on the network that is inadvertently advertising it as the originator. It is also possible that a misconfigured or compromised router within the network could redistribute Interior Gateway Protocol routes into Border Gateway Protocol, thereby leaking internal routes.

Description

Advertisement of routes by an Autonomous System for networks that do not belong to any of its trusted peers pulls traffic away from the authorized network. This causes a DoS on the network that allocated the block of addresses and may cause a DoS on the network that is inadvertently advertising it as the originator. It is also possible that a misconfigured or compromised router within the network could redistribute Interior Gateway Protocol routes into Border Gateway Protocol, thereby leaking internal routes.

STIG	Date
Router Security Requirements Guide	2015-09-28

Details

Check Text ( C-56341r1_chk )
Review the router configuration to verify that Border Gateway Protocol connections are only from known neighbors in a trusted AS by restricting TCP port 179 to specific IP addresses. If the router is not configured to restrict TCP port 179 to specific IP addresses, this is a finding.

Fix Text (F-60645r1_fix)
Configure an ingress filter to block any unauthorized BGP connection attempts by restricting TCP port 179 to specific IP addresses (authorized BGP peers).