The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to limit the amount of source-active messages it accepts on a per-peer basis.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-216822	CISC-RT-000940	SV-216822r531087_rule	CCI-001368	low
Description
To reduce any risk of a denial-of-service (DoS) attack from a rogue or misconfigured MSDP router, the router must be configured to limit the number of source-active messages it accepts from each peer.
STIG			Date
Cisco IOS XR Router RTR Security Technical Implementation Guide			2024-08-22

Details

Check Text (C-216822r531087_chk)

Review the router configuration to determine if it is configured to limit the amount of source-active messages it accepts on a per-peer basis. router msdp … … … peer 4.4.4.4 remote-as 33 maximum external-sa 555 ! peer 5.5.5.5 remote-as 44 maximum external-sa 555 ! ! If the router is not configured to limit the source-active messages it accepts, this is a finding.

Fix Text (F-18052r288841_fix)

Configure the router to limit the amount of source-active messages it accepts from each peer. RP/0/0/CPU0:R2(config)#router msdp RP/0/0/CPU0:R2(config-msdp)#peer x.14.2.1 RP/0/0/CPU0:R2(config-msdp-peer)#maximum external-sa nnn RP/0/0/CPU0:R2(config-msdp-peer)#exit RP/0/0/CPU0:R2(config-msdp)#peer x.15.3.5 RP/0/0/CPU0:R2(config-msdp-peer)#maximum external-sa nnn RP/0/0/CPU0:R2(config-msdp-peer)#end