On Sat, 6 Oct 2001, James M Galvin wrote:
Also, although I do maintain a Message-ID: database for recent messages
for loop control, the most common looping problem I encounter is sites
that set their address or their MX to 127.0.0.1.
Any ideas on how to deal with that?
I added a feature to Exim that lets you specify that any A records you
look up in the DNS whose rhs is 127.0.0.1 should be ignored. You then
get "unknown domain" errors for those sites. (In fact it's more general.
You can set it to 127.0.0.0/8 for example.)
Even if you don't set that option, an A record pointing to 127.0.0.1
does not cause loops in Exim. It notices it is trying to send to itself,
and stops trying to deliver the message. (There is an option to
override, but that's the default action.)
I am trying to promote an RFC that says "Thou shalt not put records in
the public DNS that point to private addresses". I don't know how far it
will get. See
draft-ietf-dnsop-dontpublish-unreachable-01.txt
Philip
--
Philip Hazel University of Cambridge Computing Service,
ph10(_at_)cus(_dot_)cam(_dot_)ac(_dot_)uk Cambridge, England. Phone: +44
1223 334714.