draft-hubert-ulevitch-edns-ping-00.txt should mention the PING EDNS0
option is a first class cover channel in its "Security Considerations".
PS: I don't say it is a bad thing...
to unsubscribe send a message to [email]firstname.lastname@example.org[/email] with
the word 'unsubscribe' in a single line as the message text body.