From owner-freebsd-net Tue Feb 27 19:58:49 2001 Delivered-To: freebsd-net@freebsd.org Received: from xena.gsicomp.on.ca (cr677933-a.ktchnr1.on.wave.home.com [24.43.230.149]) by hub.freebsd.org (Postfix) with ESMTP id 19C9A37B71A for ; Tue, 27 Feb 2001 19:58:44 -0800 (PST) (envelope-from matt@gsicomp.on.ca) Received: from hermes (hermes.gsicomp.on.ca [192.168.0.18]) by xena.gsicomp.on.ca (8.11.1/8.9.3) with SMTP id f1S3tgi16924; Tue, 27 Feb 2001 22:55:42 -0500 (EST) (envelope-from matt@gsicomp.on.ca) Message-ID: <007901c0a13a$b4480dd0$1200a8c0@gsicomp.on.ca> From: "Matthew Emmerton" To: "Luigi Rizzo" , "Josef Karthauser" Cc: "Rogier R. Mulhuijzen" , "Jonathan Graehl" , References: <200102280156.CAA29214@info.iet.unipi.it> Subject: Re: Quick question about IP aliasing Date: Tue, 27 Feb 2001 22:58:15 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > On Tue, Feb 27, 2001 at 07:16:14AM +0100, Rogier R. Mulhuijzen wrote: > > > > > > > [ Matt Emmerton wrote: ] > > > >The point is that you need to use a netmask of 255.255.255.255 for aliased > > > >IPs on FreeBSD, regardless of the alias of the primary (non-alias) IP. > > no this is incorrect. you just have to make sure that the aliased > IP&mask do not generate info which is already in the routing table. > E.g. if your primary addr is 1.2.3.4/24 , an alias of 1.2.3.5/24 will > give a warning, but an alias of 1.2.4.4/24 will not, and most likely even > 1.2.3.5/25 will not. I'm just reiterating what I was told 1.5 years ago when I complained that the following setup wouldn't work: Primary IP: 192.168.0.1/255.255.255.0 Aliased IP: 192.168.0.10/255.255.255.0 With this setup, I could not ping, traceroute or connect to the aliased IP. In order to make the aliased IP functional, I had to use a netmask of 255.255.255.255 -- a fact which I find totally confusing and counter-intuitive, but one that seems to work. > > > Everybody is saying use 255.255.255.255 for an alias. Noone is giving > > > reasons why. Exactly. I never got a good answer to this when I first stumbled upon it, and I still haven't. All I know is that this is the way it needs to be done in order for things to work properly. -- Matt Emmerton To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message