Date: Thu, 14 Sep 2000 00:40:34 -0700 From: "Crist J . Clark" <cjclark@reflexnet.net> To: Tom Duffey <tduffey@wi.rr.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Help! Configuring for two IP addresses => one interface, and NATD Message-ID: <20000914004034.T69158@149.211.6.64.reflexcom.com> In-Reply-To: <Pine.LNX.4.21.0009140007390.1982-100000@linuxpower.p00t.net>; from tduffey@wi.rr.com on Thu, Sep 14, 2000 at 12:10:05AM -0500 References: <002a01c01e05$f05e8550$1200a8c0@zircon> <Pine.LNX.4.21.0009140007390.1982-100000@linuxpower.p00t.net>
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On Thu, Sep 14, 2000 at 12:10:05AM -0500, Tom Duffey wrote: > > Change the netmask of the alias from 255.255.255.0 to 255.255.255.255. I > > know it doesn't seem right, but all the FreeBSD machines I've worked on > > require aliases to have 255.255.255.255 as their netmask. > > Continuing this just a bit further... as far as I can tell, an alias > should always have 255.255.255.255 as it's netmask *unless* it is not on > the same network as your primary IP. When this is the case, use the > netmask of the alias' network. Please correct me if I'm wrong. You are not really wrong, but I thought I would point out that when you have more than one address on a single interface where each lies on a different logical network there is no "real" address and none are aliases. All of the addresses are on equal footing. You only really have "aliases" when you have multiple addresses in a single logical network. In that case, only one address, the "real" address on the network, should have the actual netmask for the network. All of the others should have a 32 bit mask (255.255.255.255). One reason you want to do this is for when your machine wants to initiate communication with a machine on that logical network. If you have multiple machines on one logical net, which IP address your machine should use becomes ambigious. Computers do not like ambigious. For similar reasons, it can break other things. -- Crist J. Clark cjclark@alum.mit.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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