From owner-freebsd-questions Mon Nov 1 6:48:20 1999 Delivered-To: freebsd-questions@freebsd.org Received: from europe.std.com (europe.std.com [199.172.62.20]) by hub.freebsd.org (Postfix) with ESMTP id 6EC1914BC2 for ; Mon, 1 Nov 1999 06:48:13 -0800 (PST) (envelope-from lowell@world.std.com) Received: from world.std.com (lowell@world-f.std.com [199.172.62.5]) by europe.std.com (8.9.3/8.9.3) with ESMTP id JAA20542; Mon, 1 Nov 1999 09:48:01 -0500 (EST) Received: (from lowell@localhost) by world.std.com (8.9.3/8.9.3) id JAA22235; Mon, 1 Nov 1999 09:48:00 -0500 (EST) To: Erik Stainsby , freebsd-questions@freebsd.org Subject: Re: read lease length on DHCP license? References: From: Lowell Gilbert Date: 01 Nov 1999 09:47:59 -0500 In-Reply-To: Erik Stainsby's message of Sat, 30 Oct 1999 14:43:42 -2300 (/usr/i) Message-ID: Lines: 26 X-Mailer: Gnus v5.5/Emacs 20.2 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Erik Stainsby writes: > I am about to be using ADSL as my primary connection from home to my > production environment and want to be able to setup a VPN of sorts between > the home box and the working static network. ADSL as provided by the > telco is DHCP only. What I'd like to be able to do is establish the lease > duration sa given by the telco when I connect, and ship this as a TTL with > the IP assigned to my nameserver, register that in the name tables, > restart the nameservice and voila! I'm a member of my named space. > > Am I insane? Is there any clearly foreseeable flaw? Any pointers? Very ugly, but it should work. I do see a problem with setting the TTL from the lease duration. You actually want to set the lease duration a lot shorter, and you're still going to have race conditions where people who cached your address will continue to use the old address for the TTL. Not that there Is No Way to avoid that without cooperation between the DNS master and the DHCP server, though. As a rough estimate and for most purposes, I'd set the TTL at the shorter of a) half the remaining time to lease *renewal* and b) one hour, but that's mostly because it's going to mimic typical practice. Be well. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message