V-283837

Discussion

These options are intended to be for the Destination Option header only. The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that can be recognized. This could cause a denial of service on the target device. In addition, the type, length, value (TLV) formatting provides the ability for headers to be very large.

Check Content

This requirement is not applicable for the DODIN Backbone. 

Review the router configuration to determine if filters are bound to the applicable interfaces to drop IPv6 packets containing a Hop-by-Hop header with option type values of 0x04 (Tunnel Encapsulation Limit), 0xC9 (Home Address Destination), or 0xC3 (NSAP Address). 

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 a Hop-by-Hop header with invalid option type values, this is a finding.