Information
The optional and extensible natures of the IPv6 extension headers require higher scrutiny since many implementations do not always drop packets with headers that it cannot recognize, and hence 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.
Solution
Configure the router to drop all inbound IPv6 packets containing an undefined option type value regardless of whether they appear in a Hop-by-Hop or Destination Option header as shown in the example below.
R1(config)#ipv6 access-list FILTER_IPV6
R1(config-ipv6-acl)#deny any any dest-option-type 2
R1(config-ipv6-acl)#deny any any dest-option-type 3
R1(config-ipv6-acl)#deny any any dest-option-type 6
R1(config-ipv6-acl)#deny any any dest-option-type 9
R1(config-ipv6-acl)#deny any any dest-option-type 10
R1(config-ipv6-acl)#deny any any dest-option-type 11
R1(config-ipv6-acl)#deny any any dest-option-type 12
R1(config-ipv6-acl)#deny any any dest-option-type 13
R1(config-ipv6-acl)#deny any any dest-option-type 14
R1(config-ipv6-acl)#deny any any dest-option-type 16
...
R1(config-ipv6-acl)#deny any any dest-option-type 34
R1(config-ipv6-acl)#deny any any dest-option-type 36
R1(config-ipv6-acl)#deny any any dest-option-type 37
R1(config-ipv6-acl)#deny any any dest-option-type 39
...
R1(config-ipv6-acl)#deny any any dest-option-type 47
R1(config-ipv6-acl)#deny any any dest-option-type 49
...
R1(config-ipv6-acl)#deny any any dest-option-type 255
R1(config-ipv6-acl)#permit ...
...
...
...
R1(config-ipv6-acl)#deny ipv6 any any log
R1(config-ipv6-acl)#exit
R1(config)#int g1/0
R1(config-if)#ipv6 traffic-filter FILTER_IPV6