UCF STIG Viewer Logo
Changes are coming to https://stigviewer.com. Take our survey to help us understand your usage and how we can better serve you in the future.
Take Survey

The Cisco BGP switch must be configured to reject route advertisements from BGP peers that do not list their autonomous system (AS) number as the first AS in the AS_PATH attribute.


Overview

Finding ID Version Rule ID IA Controls Severity
V-101773 CISC-RT-000540 SV-110877r1_rule Low
Description
Verifying the path a route has traversed will ensure the IP core is not used as a transit network for unauthorized or possibly even internet traffic. All autonomous system boundary switches (ASBRs) must ensure updates received from eBGP peers list their AS number as the first AS in the AS_PATH attribute.
STIG Date
Cisco IOS-XE Switch RTR Security Technical Implementation Guide 2020-05-20

Details

Check Text ( C-100661r1_chk )
Review the switch configuration to verify the switch is configured to deny updates received from eBGP peers that do not list their AS number as the first AS in the AS_PATH attribute.

By default, Cisco IOS enforces the first AS in the AS_PATH attribute for all route advertisements. Review the switch configuration to verify that the command no bgp enforce-first-as is not configured.

router bgp xx
no synchronization
no bgp enforce-first-as

If the switch is not configured to reject updates from peers that do not list their AS number as the first AS in the AS_PATH attribute, this is a finding.
Fix Text (F-107457r1_fix)
Configure the switch to deny updates received from eBGP peers that do not list their AS number as the first AS in the AS_PATH attribute.

SW1(config)#router bgp xx
SW1(config-switch)#bgp enforce-first-as