From owner-freebsd-questions@FreeBSD.ORG Tue Jan 29 03:01:23 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D3C4716A46E for ; Tue, 29 Jan 2008 03:01:23 +0000 (UTC) (envelope-from on@cs.ait.ac.th) Received: from mail.cs.ait.ac.th (mail.cs.ait.ac.th [192.41.170.16]) by mx1.freebsd.org (Postfix) with ESMTP id 0FB9D13C459 for ; Tue, 29 Jan 2008 03:01:22 +0000 (UTC) (envelope-from on@cs.ait.ac.th) Received: from banyan.cs.ait.ac.th (banyan.cs.ait.ac.th [192.41.170.5]) by mail.cs.ait.ac.th (8.13.1/8.12.11) with ESMTP id m0T31AWi003553 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 29 Jan 2008 10:01:11 +0700 (ICT) Received: (from on@localhost) by banyan.cs.ait.ac.th (8.13.6/8.12.11) id m0T2YtLn074403; Tue, 29 Jan 2008 09:34:55 +0700 (ICT) Date: Tue, 29 Jan 2008 09:34:55 +0700 (ICT) Message-Id: <200801290234.m0T2YtLn074403@banyan.cs.ait.ac.th> From: Olivier Nicole To: siraj.shaikh@gmail.com In-reply-to: <3b2ddd940801280627m6d747cd1g27682bcd9e50ceb7@mail.gmail.com> (siraj.shaikh@gmail.com) References: <3b2ddd940801280627m6d747cd1g27682bcd9e50ceb7@mail.gmail.com> X-Virus-Scanned: on CSIM by amavisd-milter (http://www.amavis.org/) Cc: freebsd-questions@freebsd.org Subject: Re: IP Aliasing X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 29 Jan 2008 03:01:23 -0000 > 1) is there an upper limit to configuring a number of alias addresses? I have a machine with 200+ IP without any problem. > 2) if an interface is configured with an alias address, then what > address is shown on the traffic leaving this interface? So, for > example, if I were to ping this machine on its primary address, I > expect to get a response from the primary address of the interface. > What happens if I ping an alias address, would I get a response from By default exiting traffic is using the primary address (the one defined with no keyword alias in the ifconfig). I think there is a way to choose the exiting IP. When a paket is responding, it use the same IP that was used in the query (else any firewall would be confused in the way). > 3) In the above scenario, all traffic leaving the interface > (regardless of the source IP on it) will have the same MAC address > (the one of the interface) - is that right? Right except maybe some NIC that allow several MAC addresses? That could be used in hi availability? > 4) Does anyone know if there are there any other network > characteristics or behaviour by which we can distinguish a machine > having more than one IP address (primary plus alias) configued on one > of its interface? Once you cross a router, you don't see the MAC of the machine anymore, MAC is local to your LAN anyway. Olivier