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Re: Bellovin's and Ahar's attacks

>  4. When receiving a UDP message, examine the time stamp, discard any message
>     that is too old (e.g., more than twice the network latency).

How can you make an arbitrary decision like this?  What happens if
there is a network burp on the nice fiber I use, and my packet gets
routed across a satellite link instead?  Are you proposing that my
packet be ignored because it took an alternate route?

I thought that alternate routing was one of the features of TCP/IP,
and you're proposing we throw that away?  I would hope not.

Perhaps instead of using network latency, you use some other measure
to time out a packet.  You could use some arbitrary time measurement
like 5 minutes, or you could use some other method.  But just using
the network latency, which can be very dynamic over congested or
long-distance paths, is probably a sub-optimal solution.

-derek

         Derek Atkins, SB '93 MIT EE, G MIT Media Laboratory
       Member, MIT Student Information Processing Board (SIPB)
    Home page: http://www.mit.edu:8001/people/warlord/home_page.html
       warlord@MIT.EDU    PP-ASEL     N1NWH    PGP key available
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