V-283846

Discussion

The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers they cannot recognize, which could cause a denial of service on the target device. In addition, the type, length, value (TLV) formatting enables headers to be very large. This option type is associated with the Nimrod Routing system and has no defining RFC document.

Check Content

This requirement is not applicable for the DODIN Backbone. 

Review the router switch configuration and determine if filters are bound to the applicable interfaces to drop IPv6 packets containing an option type value of 0x8A (Endpoint Identification) regardless of whether it appears in a Hop-by-Hop or Destination Option header. 

Verify the IPv6 filter has the HopByHop option set to "True", as shown in the example below: 

- show filter ipv6 40

Entry               : 10 (Inactive)
Description         : (Not Specified)
Log Id              : n/a
Src. IP             : ::/0
Src. Port           : n/a
Dest. IP            : ::/0
Dest. Port          : n/a
Next Header         : Undefined
Dscp                : Undefined
ICMP Type           : Undefined                    ICMP Code      : Undefined
Sampling            : Off                          Int. Sampling  : On
Tcp-flag            : (Not Specified)
Fragment            : Off
HopByHop Opt        : True                         Routing Type0  : Off

Verify an "Ing IPv6 Flt" has been applied to the interface, as shown in the example below:

- show router interface "TO-PE2" detail | match "Ingr IPv6 Flt"
Egr IPv6 Flt     : none                 Ingr IPv6 Flt     : 40

If the router is not configured to drop IPv6 packets containing an extension header with the Endpoint Identification option, this is a finding.