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Re: [GNUnet-developers] Topology
From: |
Christian Grothoff |
Subject: |
Re: [GNUnet-developers] Topology |
Date: |
Thu, 25 Apr 2002 20:32:26 -0500 |
Well, you are right, we don't need what traceroute would give us. For GNUnet,
a combination of delay (link-to-link) and bandwidth would be required.
Sending probe-messages to measure delay should not be too much of a problem,
and for bandwidth we could even rely on the specs given by the local users
(after all, they will usually want to limit the amount of bandwidth the
client uses).
Much trickier is the question of
a) how to use that information (ok, now we know the shortest path to X, so
what?)
b) how to handle with this securely (the topology must be
computed assuming that there are malicious hosts in the
network supplying false information; furthermore, even the
good guys can not just publish their routing knowledge since
it would make it much easier for the malicious guys to
which hosts they should attack in order to isolate a victim
(or do other harm).
Essentially, we need some form of secure multiparty computation with
untrusted participants to extract some information that would then be still
useful to optimzize routing, very tough.
So please, before you start hacking up 'something', first consider all
implications, from what you can do better if you have the information to
which security implications the computation would have. It is not 'just'
traceroute...
Christian
On Thursday 25 April 2002 07:46 pm, you wrote:
> Unfortunatly a bunch of traceroutes doesn't neccesarily help you
> know the topology of a system. Take this sample traceroute from
> my machine on a cable modem:
> traceroute to google.com (216.239.35.100), 30 hops max, 40 byte packets
> 1 10.10.10.254 0.511 ms 0.311 ms 0.336 ms
> 2 10.9.88.1 11.436 ms 103.969 ms 12.519 ms
> 3 12.220.5.33 39.701 ms 14.783 ms 103.660 ms
> 4 12.220.1.70 124.129 ms 12.220.1.74 87.233 ms 65.619 ms
> 5 12.220.0.18 27.632 ms 82.583 ms 28.329 ms
> 6 12.123.5.78 29.869 ms 103.654 ms
> What does that really tell me? From an outsider that doesn't tell
> me anything. I know that 10.10.10.254 is my firewalls internal IP
> address, and that 10.9.88.1 is my cable providers cisco router,
> but there is no way that you could know this. All of the
> methods I have found on doing intelligent topology discovery are
> generally more invasive then most administrators would like, and
> almost certainly give more information then GNUnet would like.
> Anyonw have any other ideas? GNUnet knowing the network topology
> would have several excellent advantages (speed, qos, etc).
>
> -Blake
>
> Whatchu talkin' 'bout, Willis?
>
> > --
> > This would require the network to know the topology in the first place.
> > Code to do that discovery would be great for GNUnet, too. --
> >
> > this sounds a lot like a bunch of traceroutes to me, with the results
> > being cached. unfortunatelly, my skills aren't anywhere near working
> > with this stuff yet.
> >
> > --nathan
> >
> > --
> >
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--
______________________________________________________
|Christian Grothoff |
|650-2 Young Graduate House, West Lafayette, IN 47906|
|http://gecko.cs.purdue.edu/ address@hidden|
|____________________________________________________|
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