Date: Sun, 15 Feb 1998 11:48:49 -0600 (CST) From: Bruce Albrecht <bruce@zuhause.mn.org> To: Brian Somers <brian@Awfulhak.org> Cc: questions@FreeBSD.ORG Subject: Re: ppp.linkdown, sendmail and named Message-ID: <199802151748.LAA02468@zuhause.mn.org> In-Reply-To: <199802151007.KAA10714@awfulhak.org> References: <199802150309.VAA00754@zuhause.mn.org> <199802151007.KAA10714@awfulhak.org>
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Brian Somers writes: > > It looks to me like sendmail is trying to do a reverse DNS lookup on my > > PPP gateway, which causes my system to dial up the ISP when I receive > > mail through UUCP. Is there anything I can put in the ppp.linkdown > > that might prevent this from happening? > > There's some stuff in http://www.FreeBSD.org/FAQ/userppp.html about > this. Your options are limited. The only real way is to create your > own DNS and resolve stuff like this for sendmail. > > You may also want to use ``deferred'' delivery mode in sendmail, but > this will screw up any spam filtering you've got, and will also avoid > processing incoming mail (which is ok if you're popping it anyway). I think I figured out a solution. I had the following two commands in the setup for the -auto system: set ifaddr 10.0.2.15/0 128.128.128.128/0 add 0 0 128.128.128.128 and 128.128.128.128 was not an address for which my name server was authoritative. I added a dummy entry for 10.0.2.20 to my name server db, and then changed the two lines to: set ifaddr 10.0.2.15/0 10.0.2.20/0 add 0 0 10.0.2.20 and all is well. Even after reading most of the O'Reilly cricket book, it took a bunch of debugging of my errors in my DNS database, and changing my a few things in my ppp configuration. Basically, the couple of rules one needs to know (and I hadn't seen explained in any of the FAQs): When you're setting up the rules for an auto-dial system with dynamic IP addressing in ppp.conf, and it's bringing up the link every time sendmail runs because it's doing name lookups, you need to create a local nameserver, and make sure you have the following specified in your ppp.conf file for the system: set ifaddr <myaddr>/0 <remoteaddr>/0 add 0 0 <remoteaddr> where <myaddr> and <remoteaddr> are 4 octect addresses which are authoratively defined in your local name server's databases, and the following should be in the ppp.linkup: MYADDR: delete ALL add 0 0 HISADDR and the following should be in the ppp.linkdown to remove the reverse DNS lookup by sendmail for the old gateway after the link goes down. <myaddr> and <remoteaddr> should be the same as the ones specified in ppp.conf. MYADDR: delete ALL set ifaddr <myaddr>/0 <remoteaddr>/0 add 0 0 <remoteaddr> I've found that it's invaluable to turn on logging for named as well as ppp when debugging this. My first problem for unexpected ppp linkups was that named was not finding authoritative answers for machines in my subdomain, and then after I fixed the errors in by named databases, I realized sendmail was doing reverse name lookups of the gateway, and modified my ppp configuration so that the dummy address for the gateway was something (a non-existant machine, in my case) in my domain. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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