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V-217009

CAT II (Medium)

The Cisco PE router must be configured to ignore or block all packets with any IP options.

Rule ID

SV-217009r945860_rule

STIG

Cisco IOS XR Router RTR Security Technical Implementation Guide

Version

V3R3

CCIs

CCI-002403

Discussion

Packets with IP options are not fast switched and therefore must be punted to the router processor. Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of packets with IP options. Dropping the packets with IP options reduces the load of IP options packets on the router. The end result is a reduction in the effects of the DoS attack on the router and on downstream routers.

Check Content

In Cisco IOS XR, all IPv4 packets with any header option other than the "source-route" header options are dropped. By default, ipv4 source routing is disabled. 

Verify that the following command is not configured:

 ipv4 source-route

If the router is not configured to drop all packets with IP options, this is a finding.

Fix Text

Configure the router to drop all packets with ipv4 source-route as shown below.

RP/0/0/CPU0:R3(config)#no ipv4 source-route