From owner-freebsd-isp Mon Apr 28 11:31:20 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id LAA29793 for isp-outgoing; Mon, 28 Apr 1997 11:31:20 -0700 (PDT) Received: from terminus.galaxia.com (root@terminus.galaxia.com [204.255.210.97]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id LAA29787 for ; Mon, 28 Apr 1997 11:31:16 -0700 (PDT) Received: from localhost (dave@localhost) by terminus.galaxia.com (8.8.5/8.6.6) with SMTP id OAA06118 for ; Mon, 28 Apr 1997 14:31:01 -0400 (EDT) Date: Mon, 28 Apr 1997 14:31:01 -0400 (EDT) From: "David H. Brierley" X-Sender: dave@terminus To: freebsd-isp@FreeBSD.org Subject: Re: SMTP gateway clients In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-isp@FreeBSD.org X-Loop: FreeBSD.org Precedence: bulk > > It's called ETRN. > > telnet to port 25 and enter the command > > > > ETRN domain.name > > QUIT > > but it only works with a fixed IP address for the relay. The original > question was how to use dynamic IP address for the relay. What I did was to write a short program that would modify the sendmail configuration files to reflect the "current" IP address for the domain. Create a special login/password combination which runs the program, have the program prompt for a domain name and a second password, query the system to find the IP address of the incoming connection, rewrite the files. When the customer then connects a few seconds later and gives the "ETRN" comand it will deliver the mail just fine. The biggest problem is making sure that the host at IP address x.y.z.z is still the same host 5 minutes later, otherwise you end up delivering the mail to the wrong machine. This is probably best handled by having the original program maintain some form of connection to the customers machine and reset the sendmail configuration files when the connection drops. Before anybody asks, I no longer work for the ISP that I did all of this for so I no longer have access to the code. On the other hand, if anybody wants to hire me to come up with a solution for them I am available at reasonable rates. -- David H. Brierley UNIX System Consultant dave@galaxia.com