V-283847

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, and hence 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 from RFC 1888 (Open Systems Interconnection [OSI] NSAPs and IPv6) has been deprecated by RFC 4048.

Check Content

This requirement is not applicable for the DODIN Backbone. 

Review the router configuration and determine if filters are bound to the applicable interfaces to drop IPv6 packets containing a Destination Option header with option type value of 0xC3 (NSAP address). 

Verify the IPv6 filter has the Next Header value set to "60", as shown in the example below: 

- show filter ipv6 40

Entry               : 10
Description         : (Not Specified)
Log Id              : n/a
Src. IP             : ::/0
Src. Port           : n/a
Dest. IP            : ::/0
Dest. Port          : n/a
Next Header         : 60

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 the NSAP address option within the Destination Option header, this is a finding.