From owner-freebsd-questions  Fri Jan 23 13:04:12 1998
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Received: (from majordom@localhost)
          by hub.freebsd.org (8.8.8/8.8.8) id NAA13494
          for questions-outgoing; Fri, 23 Jan 1998 13:04:12 -0800 (PST)
          (envelope-from owner-freebsd-questions@FreeBSD.ORG)
Received: from gdi.uoregon.edu (gdi.uoregon.edu [128.223.170.30])
          by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id NAA13455
          for <questions@FreeBSD.ORG>; Fri, 23 Jan 1998 13:04:00 -0800 (PST)
          (envelope-from dwhite@gdi.uoregon.edu)
Received: from localhost (dwhite@localhost)
          by gdi.uoregon.edu (8.8.7/8.8.8) with SMTP id NAA08343;
          Fri, 23 Jan 1998 13:03:47 -0800 (PST)
          (envelope-from dwhite@gdi.uoregon.edu)
Date: Fri, 23 Jan 1998 13:03:47 -0800 (PST)
From: Doug White <dwhite@gdi.uoregon.edu>
Reply-To: Doug White <dwhite@resnet.uoregon.edu>
To: Satish Bommareddy <satish@x.Holontech.com>
cc: "'questions@freebsd.org'" <questions@FreeBSD.ORG>,
        "'satish@holontech.com'" <satish@holontech.com>
Subject: Re: arp handling of freeBSD
In-Reply-To: <1162BE4AB70ED111A648006097BDDB852473DA@mom.holontech.com>
Message-ID: <Pine.BSF.3.96.980123130219.8161i-100000@gdi.uoregon.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-freebsd-questions@FreeBSD.ORG
Precedence: bulk

On Wed, 21 Jan 1998, Satish Bommareddy wrote:

> hi,
> i am interested to find out how freeBSD handles arp requests
> especially when we have multiple IP addresses configured
> per interface.
> 
> if i have the primary IP as x.x.x.x
> and the secondary IP as y.y.y.y
> and so on 
> and there is an arp request for the primary IP
> what does it respond back with.

The ethernet address of the primary IP, of course.

> and in the same scenario
> when it does a arp request.
> for an different ip address say.. a.b.c.d

If it's not on the system and the system's never seen it, then it ignores
it.

> what is the source address of the arp request.
> is it always the primary IP address???

it doesn't matter; the reply says `IP x.y.z.q (the one you asked about)
has MAC address a.b.c.d.e.f.'  Run tcpdump sometime and watch the arp
requests come by.  

Doug White                              | University of Oregon  
Internet:  dwhite@resnet.uoregon.edu    | Residence Networking Assistant
http://gladstone.uoregon.edu/~dwhite    | Computer Science Major