Date: Thu, 11 Sep 1997 09:35:47 -0700 (PDT) From: Dave Babler <dbabler@Rigel.orionsys.com> To: Greg Lehey <grog@lemis.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Help with Sendmail/DNS Message-ID: <Pine.BSI.3.95.970911092636.3940C-100000@Rigel.orionsys.com> In-Reply-To: <19970911114923.00050@lemis.com>
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On Thu, 11 Sep 1997, Greg Lehey wrote: > On Wed, Sep 10, 1997 at 06:08:59PM -0700, Dave Babler wrote: > > > > I seem to be banging my head against the wall trying to solve a problem > > and I'm hoping somebody can give me a push in the right direction. > > > > My domain is fairly simple and handles mail straightforwardly. The FBSD > > system is Rigel.orionsys.com and I run a BBS on a machine named > > bbs.orionsys.com (which responds to orionsys.com as well). The BBS can > > send and receive email directly, as can the FBSD machine. The BBS's MX > > records currently look like: > > > > orionsys.com. IN MX 10 orionsys.com. > > IN MX 20 other.host.com. > > IN MX 30 another.host.com. > > You don't have to change the names of the other systems. This is > public knowledge: > > orionsys.com preference = 10, mail exchanger = orionsys.com > orionsys.com preference = 20, mail exchanger = portal.dx.net > orionsys.com preference = 30, mail exchanger = news.dx.net > > > The problem is that the BBS software is completely fixed and we're getting > > increasing complaints about spam, so what I'd like to do is to have all > > email going to the BBS users to be delivered to Rigel (the Unix machine), > > passed thru anti-spam filters and then forwarded to the BBS. The BBS would > > still send email directly. To accomplish this, I tried to test the > > concept with another machine in the domain, named Altair: > > > > rigel.orionsys.com. IN MX 10 rigel...orionsys.com. > > altair.orionsys.com IN MX 10 rigel.orionsys.com. > > > > This produced a DSN error with sendmail "MX list for altair loops back to > > rigel" for mail sent to user@altair.orionsys.com. > > Yes, it would. Your DNS records are saying "send all mail to altair > by preference to rigel, he'll know what to do with it". But he > doesn't, and that's the message. > > > The examples in the O'Reilly 'DNS and Bind' book don't seem to deal > > directly with the setup I'm trying to do and the Sendmail book > > doesn't specifically over this exact error (although I'm assuming it > > is a looping reference). > > I find this book rather unhelpful, in fact. > > > Is this idea doomed, or am I just not seeing the right way to > > configure it? > > You say that bbs (CNAME for orionsys.com) is the BBS system. Why do > you want to send mail to altair at all? I would recommend having MXs > only for orionsys.com (which I wouldn't associate with an A record). > You could then set the MXs to point to rigel, and it could forward to > any of the other systems. > Altair is a test system, running the same BBS software - I don't want to effect email for users until I know it works. Mail also has to be received for Rigel itself (this system) and it, in turn, has no way of redirecting email by recipient - it has no way of knowing who is a valid user on the other systems, is would simply (?) be forwarding all mail sent to either orionsys.com or bbs.orionsys.com to the BBS machine, any mail sent to rigel.orionsys.com would be delivered locally. > Note that this won't be complete protection against spammers. They > can always go by the IP address. But it'll be a while before they're > that sophisticated. > True. The initial protection that was installed was to keep the BBS from forwarding - we were recently attacked and used to forward spam to AOL. Users now use the FBSD system to send SMTP mail and receive mail via POP3 from the BBS machine, which is set now to refuse to relay mail to non-local users. -Dave
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