validity
Click on the red underlined text to get to the source
... beyond the 128th octet of the original datagram field and then only
when the extensions approximate a valid TCP header.
...
... payload contains 144 octets or more, the application
must examine the 137th octet to determine whether it represents a
valid ICMPv4 Extension Header. In order to represent a valid ...
... valid ICMPv4 Extension Header. In order to represent a valid
Extension Header, it must contain a valid ...
... compliant mode receives a sufficiently long ICMP message that does
not specify a length attribute, it will parse for a valid extension
header at a fixed location, assuming a 128-octet "original datagram"
...
... extension
header at a fixed location, assuming a 128-octet "original datagram"
field. If the application detects a valid version and checksum, it
...
...
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
...