On 3/30/2014 5:38 PM, Ted Lemon wrote:
On Mar 30, 2014, at 6:44 PM, John C Klensin <john-ietf(_at_)jck(_dot_)com>
wrote:
Whether one accepts it or not, "been here already" tests are not
about debugging. They are about loop detection and DoS attacks.
Are there MTAs that make use of the Received: header for loop detection?
MMDF had it, probably from the early 1980s, but certainly sometime
during the 80s.
I have a vague recollection of adding it to the code, though that could
be an invented memory. The Received header field was not in RFC 733,
and was standardized in late 1982 (RFC 822), just before I stopped doing
MMDF work.
More likely, it was added by the folk who did the follow-on work for
MMDF II, but still probably early/mid 1980s.
Back then, passing through the same host more than a couple of times
would be a good indication of looping.
d/
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net