Date: Wed, 23 Aug 2000 10:51:03 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: Mike Smith <msmith@freebsd.org> Cc: Brian Fundakowski Feldman <green@freebsd.org>, Darren Reed <darrenr@reed.wattle.id.au>, "Jordan K. Hubbard" <jkh@zippy.osd.bsdi.com>, root@ihack.net, freebsd-sparc@freebsd.org, freebsd-arch@freebsd.org Subject: Re: Competition Message-ID: <Pine.NEB.3.96L.1000823104217.19441C-100000@fledge.watson.org> In-Reply-To: <200008221832.LAA20960@mass.osd.bsdi.com>
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On Tue, 22 Aug 2000, Mike Smith wrote:
> Actually, "ihack.net" *is* being blocked. Because it's not set up
> correctly.
>
> Aug 22 00:21:34 hub postfix/smtpd[42146]: connect from r94aag002979.sbo-smr.ma.c
> able.rcn.com[209.6.183.136]
> Aug 22 00:21:35 hub postfix/smtpd[42146]: 5567A37B42C: client=r94aag002979.sbo-s
> mr.ma.cable.rcn.com[209.6.183.136]
> Aug 22 00:21:37 hub postfix/smtpd[42146]: reject: RCPT from r94aag002979.sbo-smr
> .ma.cable.rcn.com[209.6.183.136]: 450 <lop-nor.ihack.net>: Helo command rejected
> : Host not found; from=<root@ihack.net> to=<freebsd-sparc@FreeBSD.ORG>
Actually, the check of the "helo" field is something I'd like removed: it
makes life very difficult for hosts behind NATs without proper SMTP
proxies (such as default installs of our natd, which does not include an
SMTP proxy :-). It's not possible to send-pr from internal machines
behind my NAT without having world-visible DNS names for all my internal
machines. RFC 821 doesn't specify criteria under which HELO should be
rejected, although it does allow for that possibility with the following
errors:
HELO
S: 250
E: 500, 501, 504, 421
It's useful also to note that 450 is not among them :-). While part of
RFC 821 refers to it as a "domain name", the text also refers to it as the
"host name" of the sender. I have a rather dim view of NATs based on this
kind of problem, but unfortunately NATs are a reality, and there are many
hosts mail-delivering behind NATs. :-)
I'm fine with the other legitimacy tests--sender email address must
resolve, sender host must have a valid reverse/forward lookup pair, etc,
but the HELO check causes me a lot of trouble, and no doubt others.
Robert N M Watson
robert@fledge.watson.org http://www.watson.org/~robert/
PGP key fingerprint: AF B5 5F FF A6 4A 79 37 ED 5F 55 E9 58 04 6A B1
TIS Labs at Network Associates, Safeport Network Services
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