Re: Static ARP Replies?

[Darren Bounds <dbounds () intrusense com>]

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Hi Dan,

What does it prevent exactly? It certainly doesn't prevent gratuitous 
ARPs nor does it prevent someone from responding with their own ARP 
replies. As far as I can tell, it's nothing more than a feeble attempt 
to route *ALL* traffic through the gateway including local subnet 
traffic. Easily subverted.


Thanks,

Darren Bounds, CISSP

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Intrusense - Securing Business As Usual



On Aug 5, 2004, at 11:15 PM, Dan Taylor, Jr. wrote:

> I have encountered a few 802.11b public access points (I can't
> remember the vendors, but they were for hotels) that seem to have
> built-in ARP cache poisoning prevention.  I found it nonetheless
> impressive and am looking for solutions to implement it (presumably
> with my own wireless card and hostap drivers).
>
> Here's what happens on one of these networks:
>
> Say the AP's MAC address is DE:AD:C0:DE:CA:FE, with the IP of
> 192.168.1/255.255.255.0, and I send out an ARP request for hosts
> 192.168.1.2-254.
>
> Say my MAC address is FE:ED:FA:CE:BE:EF, with the IP address of 
> 192.168.1.100
> --> ARP broadcast (source FE:ED:FA:CE:BE:EF destination 
> FF:FF:FF:FF:FF:FF)
> --> Who has 192.168.1.2?  Tell 192.168.1.100
>
> --< ARP Reply (source DE:AD:C0:DE:CA:FE, destination FE:ED:FA:CE:BE:EF)
> --< 192.168.1.2 is at DE:AD:C0:DE:CA:FE
>
> I'm assuming this is a rather effective way of not only preventing ARP
> poisoning attacks, but making it so that all communication is
> virtually done between the client and the access point).
> Has anyone seen this feature implemented in any other access points?
> To what extent does this work and/or it's behavior on layer-2
> broadcasting or client to client (mac address to mac address)
> communications?
>
> Thanks.
>
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