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Date:      Sat, 23 Jun 2001 18:47:38 -0400 (EDT)
From:      Joe Clarke <marcus@marcuscom.com>
To:        Francisco Reyes <freyes@drf.com>
Cc:        "freebsd-questions@freebsd.org" <freebsd-questions@FreeBSD.ORG>
Subject:   Re: Retaining same MAC (Re: Need help configuring ethernet DSL modem)
Message-ID:  <20010623183357.X8873-100000@shumai.marcuscom.com>
In-Reply-To: <200106232228.SAA06370@mx3.drf.com>

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The MAC is usually burned into a chip on your ethernet card.  If you have
an ethernet card on your motherboard, then you're even more restricted.
Some cards allow you to replace the MAC component.  Sun, for instance,
allows you to do this since the MAC address is tied to so many things in
Solaris....

Good rule of thumb is if you switch your ethernet card, your MAC changes.
However, you can use ifconfig to change your MAC address to whatever you
like.  As you can imagine, this can be quite bad if you choose one that is
not unique on your broadcast domain.  However, this can be useful if you
have to replace your ethernet card with a new one, but need to keep your
same MAC.  To do this, do the following while in a fairly idle network
state (like SU mode):

ifconfig <interface> ether <address>
arp -a -d

Now, when your ARP cache refreshes, your IP address will be bound to the
given MAC address.

Joe Clarke

On Sat, 23 Jun 2001, Francisco Reyes wrote:

> On Sat, 23 Jun 2001 13:23:20 -0400, Francisco Reyes wrote:
>
> >I just got a Wiltell Wirespeed DSL modem yesterday.
> >I tried with windows first: configured the machine with the IP as per the instructions and set the proper gateway. It worked.
> >
> >I then tried to do the same with FreeBSD, but it is not working. I thought maybe it was PPPoE. Wrote to the ISP and they wrote back saying
> >
> >ISP->No. Its straight ethernet. Just plug in your modem, and configure IP
> >ISP->address you were given to your ethernet interface.
> >ISP->ifconfig xx0 66.114.xx.xx netmask 255.255.255.0
>
> After many, many hours troubleshooting  why a FreeBSD
> machine could not connect it turns out the ISP uses MAC
> based authentication. I had first connected the DSL modem
> to a different machine so the authentication was failing.
>
> Does the MAC address ever change unless I change the
> hardware?
>
>
>
> Francisco Reyes
> Daily Racing Form
> Technical Support Manager
> freyes@drf.com
> (212) 366-7752
>
>
>
>
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>


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