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@@ -1616,8 +1616,8 @@ with a session key shared by Alice and Bob.
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As of mid-January 2004, the Tor network consists of 16 nodes
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(14 in the US, 2 in Europe), and more are joining each week as the code
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matures.\footnote{For comparison, the current remailer network
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-has about 30 reliable nodes.} Each node has at least a 768k/768k connection,
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-and
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+has about 30 reliable nodes.} Each node has at least a 768Kb/768Kb
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+connection, and
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most have 10Mb. The number of users varies (and of course, it's hard to
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tell for sure), but we sometimes have several hundred users---admins at
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several companies have started putting their entire department's web
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@@ -1625,23 +1625,28 @@ traffic through Tor, to block snooping admins in other divisions of
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their company from reading the traffic. Tor users have reported using
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the network for web browsing, ftp, IRC, AIM, Kazaa, and ssh.
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-Each Tor currently node currently processes roughly 800,000 relay
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+Each Tor node currently processes roughly 800,000 relay
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cells (a bit under half a gigabyte) per week. On average, about 80\%
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of each 500-byte payload is full for cells going back to the client,
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whereas about 40\% is full for cells coming from the client. (The difference
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arises because most of the network's traffic is web browsing.) Interactive
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traffic like ssh brings down the average a lot---once we have more
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experience, and assuming we can resolve the anonymity issues, we may
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-consider partitioning traffic into two relay cell sizes: one to handle
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+partition traffic into two relay cell sizes: one to handle
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bulk traffic and one for interactive traffic.
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-We haven't asked to use PlanetLab \cite{planetlab} to provide more nodes,
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-because their AUP excludes projects like Tor (see also \cite{darkside}).
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+%We haven't asked to use PlanetLab \cite{planetlab} to provide more nodes,
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+%because their AUP excludes projects like Tor (see also \cite{darkside}).
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% I'm confused. Why are we mentioning PlanetLab at all? Could we perhaps
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% be more generic? -NM
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-On the other hand, we have had no abuse issues since the network was
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-deployed in October 2003. Our default exit policy rejects SMTP requests,
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-to avoid spam issues. Our slow growth rate gives us time to add features,
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+%We have had no abuse issues since the network was deployed in October
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+%2003. Our default exit policy rejects SMTP requests, to proactively
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+%avoid spam issues.
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+Based in part on our restrictive default exit policy (we
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+% proactively chose to
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+reject SMTP requests) and our low profile, we have had no abuse
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+issues since the network was deployed in October
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+2003. Our slow growth rate gives us time to add features,
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resolve bugs, and get a feel for what users actually want from an
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anonymity system. Even though having more users would bolster our
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anonymity sets, we are not eager to attract the Kazaa or warez
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@@ -1655,7 +1660,7 @@ to two factors. First, network latency is critical: we are
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intentionally bouncing traffic around the world several times. Second,
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our end-to-end congestion control algorithm focuses on protecting
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volunteer servers from accidental DoS rather than optimizing
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-performance. Right now the first $500 \times 500\mbox{B}=250\mbox{KB}$
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+performance. Right now the first $500 \times 500\mbox{B}=250\mbox{KB}$
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of the stream arrives
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quickly, and after that throughput depends on the rate that \emph{relay
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sendme} acknowledgments arrive. We can tweak the congestion control
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@@ -1669,16 +1674,15 @@ right balance.
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%transport alternative?
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With the current network's topology and load, users can typically get 1-2
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-megabits sustained transfer rate. Overall, this performance is sufficient
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-for most of our users. The Tor design aims foremost for security;
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-performance is secondary.
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+megabits sustained transfer rate, which is good enough for now. The Tor
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+design aims foremost to provide a security research platform; performance
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+just needs to be sufficient to not shed users \cite{econymics,back01}.
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Although Tor's clique topology and full-visibility directories present
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-scaling problems, we still expect the network to a few hundred nodes and
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-perhaps 10,000 users, before we're forced to change topologies to become
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-more distributed. With luck, the experience we gained running the
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-current topology will help us choose among alternatives when the time
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-comes.
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+scaling problems, we still expect the network to support a few hundred
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+nodes and perhaps 10,000 users, before we're forced to make the network
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+more distributed. With luck, the experience we gain running the current
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+topology will help us choose among alternatives when the time comes.
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\Section{Open Questions in Low-latency Anonymity}
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\label{sec:maintaining-anonymity}
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