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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-256061	ARST-RT-000840	SV-256061r882525_rule		Medium

Description
Packets with IP options are not fast routered 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.

Description

Packets with IP options are not fast routered 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.

STIG	Date
Arista MLS EOS 4.2x Router Security Technical Implementation Guide	2023-01-17

Details

Check Text ( C-59737r882523_chk )
Verify the PE router is configured to block all packets with any IP options with the following command: router#show run \| section IP_Option_ACL IP Access List IP_Option_ACL 10 deny ip any any ip-length gt 5 20 deny any log ! interface Ethernet25 description STIG_IP_Option_ACL ip access-group IP_Option_ACL in ! If the perimeter router is not configured to block packets with IP options, this is a finding.

Check Text ( C-59737r882523_chk )

Verify the PE router is configured to block all packets with any IP options with the following command:

router#show run | section IP_Option_ACL
IP Access List IP_Option_ACL
10 deny ip any any ip-length gt 5
20 deny any log
!
interface Ethernet25
description STIG_IP_Option_ACL
ip access-group IP_Option_ACL in
!

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

Fix Text (F-59680r882524_fix)
Configure the PE router to block packets with IP options with the following commands: router#config router(config)# ip access-list IP_Option_ACL 10 deny ip any any ip-length gt 5 ! router(config)#interface Ethernet25 ip access-group IP_Option_ACL in !