Indeed it is. Team Cymru are (afaik) one of the best sources for this currently: <a href="http:&#x2F;&#x2F;www.team-cymru.org&#x2F;bogon-reference.html" rel="nofollow">http:&#x2F;&#x2F;www.team-cymru.org&#x2F;bogon-reference.html</a>