BugTraq
Re: ICMP spoofed source tunneling Sep 24 2004 01:43PM
raiblehugo hotmail com
In-Reply-To: <20040922203047.GA16153 (at) nenya (dot) lan [email concealed]>

>On Wed, Sep 22, 2004 at 10:06:40AM -1000, Tim Newsham wrote:

>> How does this give anonymity? When sending to the server, I must use the

>> servers address as a source address. When the server replies to me, it

>> must use my address as a source address.

>

>Yes - you cannot use this in both directions:

>

> - In the server->client direction, the server can spoof IP source

> addresses.

>

> - In the client->server direction, you need to use multi-level "anonymous

> proxying", as used by several current P2P implementations (Gnutella for

> queries, Freenet, GNUnet etc).

>

>The advantage of this is that the available bandwidth can be fully utilized

>in the server->client direction, but at the same time the server IP address

>can remain unknown to the client. With current P2P systems, server->client

>proxying significantly reduces the download bandwidth.

>

>In practice, implementing this will be fairly complicated because you end

>up re-implementing TCP over a highly asymmetric connection.

I remember a discussion (in German) about this some time ago, also discussing congestion problems. See http://www.heise.de/newsticker/foren/go.shtml?read=1&msg_id=2617169&foru
m_id=36041

Babelfish translated: http://babelfish.altavista.com/babelfish/trurl_pagecontent?url=http%3A%2
F%2Fwww.heise.de%2Fnewsticker%2Fforen%2Fgo.shtml%3Fread%3D1%26msg_id%3D2
617169%26forum_id%3D36041&lp=de_en

Enjoy!

Hugo

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