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V-216802

CAT II (Medium)

The Cisco PE router must be configured with Unicast Reverse Path Forwarding (uRPF) loose mode enabled on all CE-facing interfaces.

Rule ID

SV-216802r531087_rule

STIG

Cisco IOS XR Router RTR Security Technical Implementation Guide

Version

V3R3

CCIs

CCI-001097

Discussion

The uRPF feature is a defense against spoofing and denial-of-service (DoS) attacks by verifying if the source address of any ingress packet is reachable. To mitigate attacks that rely on forged source addresses, all provider edge routers must enable uRPF loose mode to guarantee that all packets received from a CE router contain source addresses that are in the route table.

Check Content

Review the router configuration to determine if uRPF loose mode is enabled on all CE-facing interfaces.

interface GigabitEthernet1/1/0/0
 ip address x.1.12.2 255.255.255.252
 ipv4 verify unicast source reachable-via any

If uRPF loose mode is not enabled on all CE-facing interfaces, this is a finding.

Fix Text

Configure uRPF loose mode on all CE-facing interfaces as shown in the example

RP/0/0/CPU0:R3(config)#int g1/1/0/0
RP/0/0/CPU0:R3(config-if)#ipv4 verify unicast source reachable-via any