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Date:      Thu, 15 Mar 2001 09:08:09 +1300
From:      David Preece <davep@afterswish.com>
To:        Lowell Gilbert <lowell@world.std.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Adding route using mac address
Message-ID:  <5.0.2.1.1.20010315085251.02281748@pop3.paradise.net.nz>
In-Reply-To: <44ae6odui3.fsf@lowellg.ne.mediaone.net>
References:  <amour@bugs.elitsat.net's message of "14 Mar 2001 15:20:00 %2B0100"> <Pine.BSF.4.21.0103141618360.21300-100000@bugs.elitsat.net>

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At 14:24 14/03/2001 -0500, you wrote:
>amour@bugs.elitsat.net (Alexander) writes:
>
> > How can I add route for host using the mac address.
>
>You can't.  Routes have nothing to do with media layer information.

Okay, I realise I'm on shaky ground here, but would like to disagree. 
Routes - next hop ones at least - have everything to do with layer 2. Say 
my machine is 1.2.3.8 on a class C, and my default router is 1.2.3.1. What 
we are effectively saying here is that I am layer 2 connected to 
1.2.3.everything, and that if I want to get a packet outside of that I have 
to use the machine at 1.2.3.1. So when a packet goes off to 3.4.5.6, on 
layer 2 the packet is addressed over to the router.

Conceptually it may be truer to describe a default route in terms of mac 
address. "The route out of the layer 2 network is at this address". 
However, it would be a pain in the arse, so we give routers an IP address 
and rely on arp to convert it to a mac address for us.

> > Because on the LAN some ppl are changing IPs to skip the traffic counters
> > for them.

Oh. This isn't really a routing question then. Perhaps go to a dhcp network 
and set up the dhcpd.config (or whatever it's called) with very very long 
leases so everyone gets the same IP every time. Hmmm, no, I guess that 
wouldn't help.

Perhaps we need a mac layer accounting daemon that could sit off a tee 
socket. This wouldn't be too hard, and yes, I might be volunteering. Is 
this something the community in general might find useful?

>You should also, in my opinion, consider non-technical solutions, like
>terminating these people's accounts, firing them, failing them in your
>course, slapping their wrists with #6 linguine, whatever's appropriate
>in your environment.

Might also prove appropriate. However, you're still facing the ultimate 
problem of catching the bastards. Perhaps we need something that just 
correlates mac addresses to IP's? Maybe just leaving running for 24hrs off 
a bpf then compare the answers to what you should've seen.

Dave




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