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Date:      Tue, 27 Feb 2001 23:23:59 -0700
From:      Wes Peters <wes@softweyr.com>
To:        Josef Karthauser <joe@tao.org.uk>
Cc:        "Rogier R. Mulhuijzen" <drwilco@drwilco.nl>, Matthew Emmerton <matt@gsicomp.on.ca>, Jonathan Graehl <jonathan@graehl.org>, freebsd-net@FreeBSD.ORG
Subject:   Re: Quick question about IP aliasing
Message-ID:  <3A9C997F.51F81F8D@softweyr.com>
References:  <NCBBLOALCKKINBNNEDDLAEJIDLAA.jonathan@graehl.org> <001501c0a070$3a14d900$1200a8c0@gsicomp.on.ca> <4.3.2.7.0.20010227070424.00d25c10@mail.bsdchicks.com> <20010227194556.C737@tao.org.uk>

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Josef Karthauser wrote:
> 
> On Tue, Feb 27, 2001 at 07:16:14AM +0100, Rogier R. Mulhuijzen 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.
> >
> > Everybody is saying use 255.255.255.255 for an alias. Noone is giving
> > reasons why.
> 
> I don't understand this either.  To my mind it's a bug if it doesn't
> work with the full netmask for an IP alias address.

Because if you don't, it won't work.  ifconfig(8) may not be telling the
entire truth here:

     alias   Establish an additional network address for this interface.  This
             is sometimes useful when changing network numbers, and one wishes
             to accept packets addressed to the old interface.  If the address
             is on the same subnet as the first network address for this in-
             terface, a netmask of 0xffffffff has to be specified.

Somebody should look to see if the man page is true, or if you have to use
a netmask of 0xffffffff for all aliases.

-- 
            "Where am I, and what am I doing in this handbasket?"

Wes Peters                                                         Softweyr LLC
wes@softweyr.com                                           http://softweyr.com/

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