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Re: ARP spoofing attacks
From: Markus Schabel <markus.schabel () tgm ac at>
Date: Thu, 15 Apr 2004 22:47:40 +0200

David Gillett wrote:
  The short, sharp, general answer is that you can't.
Layer two security measures are going to see a packet
(it happens to be an ARP reply) from the miscreant's port, but since its source MAC address is what they expect, they'll let it through. Layer three measures won't see it either, because it's a unicast within the same vlan/subnet and so never needs to hit a layer 3
device.

  About all you can do proactively, if this is a serious
concern, is add a static ARP table entry to every host so they never need to send out an ARP request for the
gateway.

which is definitly no option if you use roaming clients, e.g. in an
wireless network, where you have different gateways depending on the
location where you are. sure, you can add static entries for _each_
gateway in _each_ host, but if you have "some" networks and "some"
hosts, this will soon be unmanagable.

we're currently thinking about an solution in wireless networks, since
we found out that wireless encryption doesn't save you from being
sniffed via ARP spoofing.

you surely can watch your networks for some spoofed ARP packets, but if
your network is not the smallest one, maybe with a lot of subnets, this
is also not an easy solution...

best regards
--
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