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en/volunteer.wml    1) ## translation metadata

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volunteer.html      3) 

en/volunteer.wml    4) #include "head.wmi" TITLE="Tor: Volunteer"

volunteer.html      5) 
volunteer.html      6) <div class="main-column">
volunteer.html      7) 
volunteer.html      8) <!-- PUT CONTENT AFTER THIS TAG -->

en/volunteer.wml    9) <h2>Three things everyone can do now:</h2>

volunteer.html     10) <ol>

en/volunteer.wml   11) <li>Please consider <a href="<page docs/tor-doc-relay>">running
en/volunteer.wml   12) a relay</a> to help the Tor network grow.</li>
en/volunteer.wml   13) <li>Tell your friends! Get them to run relays. Get them to run hidden

volunteer.html     14) services. Get them to tell their friends.</li>

en/volunteer.wml   15) <li>We are looking for funding and sponsors. If you like Tor's goals, please

en/volunteer.wml   16)   <a href="<page donate>">take a moment to donate to support further
en/volunteer.wml   17)   Tor development</a>. Also, if you know any

en/volunteer.wml   18)   companies, NGOs, agencies, or other organizations that want communications

en/volunteer.wml   19)   security, let them know about us.</li>

volunteer.html     20) </ol>
volunteer.html     21) 

en/volunteer.wml   22) <a id="Usability"></a>

en/volunteer.wml   23) <h2><a class="anchor" href="#Usability">Supporting Applications</a></h2>

volunteer.html     24) <ol>

en/volunteer.wml   25) <li>We need more good ways to intercept DNS requests so they don't "leak" their

en/volunteer.wml   26) request to a local observer while we're trying to be anonymous. (This
en/volunteer.wml   27) happens because the application does the DNS resolve before going to
en/volunteer.wml   28) the SOCKS proxy.)</li>

en/volunteer.wml   29) <li>Tsocks/dsocks items:

en/volunteer.wml   30) <ul>
en/volunteer.wml   31) <li>We need to <a

en/volunteer.wml   32) href="https://wiki.torproject.org/noreply/TheOnionRouter/TSocksPatches">apply

en/volunteer.wml   33) all our tsocks patches</a> and maintain a new fork. We'll host it if
en/volunteer.wml   34) you want.</li>
en/volunteer.wml   35) <li>We should patch Dug Song's "dsocks" program to use Tor's
en/volunteer.wml   36) <i>mapaddress</i> commands from the controller interface, so we
en/volunteer.wml   37) don't waste a whole round-trip inside Tor doing the resolve before
en/volunteer.wml   38) connecting.</li>
en/volunteer.wml   39) <li>We need to make our <i>torify</i> script detect which of tsocks or
en/volunteer.wml   40) dsocks is installed, and call them appropriately. This probably means
en/volunteer.wml   41) unifying their interfaces, and might involve sharing code between them
en/volunteer.wml   42) or discarding one entirely.</li>
en/volunteer.wml   43) </ul>

en/volunteer.wml   44) </li>

en/volunteer.wml   45) <li>People running relays tell us they want to have one BandwidthRate

en/volunteer.wml   46) during some part of the day, and a different BandwidthRate at other
en/volunteer.wml   47) parts of the day. Rather than coding this inside Tor, we should have a
en/volunteer.wml   48) little script that speaks via the <a href="<page gui/index>">Tor
en/volunteer.wml   49) Controller Interface</a>, and does a setconf to change the bandwidth

en/volunteer.wml   50) rate. There is one for Unix and Mac already (it uses bash and cron),

en/volunteer.wml   51) but Windows users still need a solution.

en/volunteer.wml   52) </li>

en/volunteer.wml   53) <li>Tor can <a

en/volunteer.wml   54) href="https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#ChooseEntryExit">exit

en/volunteer.wml   55) the Tor network from a particular exit node</a>, but we should be able
en/volunteer.wml   56) to specify just a country and have something automatically pick. The
en/volunteer.wml   57) best bet is to fetch Blossom's directory also, and run a local Blossom
en/volunteer.wml   58) client that fetches this directory securely (via Tor and checking its
en/volunteer.wml   59) signature), intercepts <tt>.country.blossom</tt> hostnames, and does
en/volunteer.wml   60) the right thing.</li>

volunteer.html     61) <li>Speaking of geolocation data, somebody should draw a map of the Earth

en/volunteer.wml   62) with a pin-point for each Tor relay. Bonus points if it updates as the

en/volunteer.wml   63) network grows and changes. Unfortunately, the easy ways to do this involve
en/volunteer.wml   64) sending all the data to Google and having them draw the map for you. How
en/volunteer.wml   65) much does this impact privacy, and do we have any other good options?</li>

volunteer.html     66) </ol>
volunteer.html     67) 

en/volunteer.wml   68) <a id="Documentation"></a>
en/volunteer.wml   69) <h2><a class="anchor" href="#Documentation">Documentation</a></h2>

volunteer.html     70) <ol>

en/volunteer.wml   71) <li>Please help Matt Edman with the documentation and how-tos for his

en/volunteer.wml   72) Tor controller,
en/volunteer.wml   73) <a href="http://vidalia-project.net/">Vidalia</a>.</li>

en/volunteer.wml   74) <li>Evaluate and document

en/volunteer.wml   75) <a href="https://wiki.torproject.org/wiki/TheOnionRouter/TorifyHOWTO">our

en/volunteer.wml   76) list of programs</a> that can be configured to use Tor.</li>

volunteer.html     77) <li>We need better documentation for dynamically intercepting

en/volunteer.wml   78) connections and sending them through Tor. tsocks (Linux), dsocks (BSD),

en/volunteer.wml   79) and freecap (Windows) seem to be good candidates, as would better
en/volunteer.wml   80) use of our new TransPort feature.</li>

en/volunteer.wml   81) <li>We have a huge list of <a href="https://wiki.torproject.org/noreply/TheOnionRouter/SupportPrograms">potentially useful

volunteer.html     82) programs that interface to Tor</a>. Which ones are useful in which
volunteer.html     83) situations? Please help us test them out and document your results.</li>

en/volunteer.wml   84) <li>Help translate the web page and documentation into other
en/volunteer.wml   85) languages. See the <a href="<page translation>">translation

en/volunteer.wml   86) guidelines</a> if you want to help out. We especially need Arabic or
en/volunteer.wml   87) Farsi translations, for the many Tor users in censored areas.</li>

volunteer.html     88) </ol>
volunteer.html     89) 

en/volunteer.wml   90) <a id="Coding"></a>

en/volunteer.wml   91) <a id="Summer"></a>
en/volunteer.wml   92) <a id="Projects"></a>

en/volunteer.wml   93) <h2><a class="anchor" href="#Projects">Good Coding Projects</a></h2>

en/volunteer.wml   94) 
en/volunteer.wml   95) <p>
en/volunteer.wml   96) You may find some of these projects to be good <a href="<page
en/volunteer.wml   97) gsoc>">Google Summer of Code 2008</a> ideas. We have labelled each idea

en/volunteer.wml   98) with how useful it would be to the overall Tor project

en/volunteer.wml   99) (priority), how much work we expect it would be (effort level), how much
en/volunteer.wml  100) clue you should start with (skill level), and which of our <a href="<page

en/volunteer.wml  101) people>#Core">core developers</a> would be good mentors. There are plenty
en/volunteer.wml  102) of other good ideas to work on too &mdash; see for example the <a
en/volunteer.wml  103) href="<svnsandbox>doc/spec/proposals/">current proposals</a> list, or
en/volunteer.wml  104) just make up your own ideas.

en/volunteer.wml  105) </p>
en/volunteer.wml  106) 

en/volunteer.wml  107) <ol>
en/volunteer.wml  108) 

en/volunteer.wml  109) <li>

en/volunteer.wml  110) <b>Tor Exit Scanner improvements</b>

en/volunteer.wml  111) <br />

en/volunteer.wml  112) Priority: <i>High</i>
en/volunteer.wml  113) <br />
en/volunteer.wml  114) Effort Level: <i>High</i>
en/volunteer.wml  115) <br />

en/volunteer.wml  116) Skill Level: <i>High</i>
en/volunteer.wml  117) <br />

en/volunteer.wml  118) Likely Mentors: <i>Mike</i>

en/volunteer.wml  119) <br />

en/volunteer.wml  120) Applications as of 1 Apr 00:00 UTC: <i>5</i>

en/volunteer.wml  121) <br />

en/volunteer.wml  122) The Tor exit node scanner 'SoaT', part of the <a
en/volunteer.wml  123) href="<svnsandbox>torflow/">Torflow project</a>, makes connections out
en/volunteer.wml  124) of each Tor exit node and compares the content it gets back with what it
en/volunteer.wml  125) "should" get back. The goal is to notice misconfigured, broken, and even
en/volunteer.wml  126) malicious exit relays. Alas, the code is
en/volunteer.wml  127) currently written in rather rickety perl and relies on MD5sums of
en/volunteer.wml  128) entire documents in order to determine if exit nodes are modifying
en/volunteer.wml  129) content. The problem with this is threefold: 1) Perl sucks at life.
en/volunteer.wml  130) 2) The scanner can't verify pages that are dynamic, and attackers can
en/volunteer.wml  131) focus malicious content injection on only those dynamic pages. 3)
en/volunteer.wml  132) Pages change after a while (or based on GeoIP) and begin generating
en/volunteer.wml  133) false positives.

en/volunteer.wml  134) <br />

en/volunteer.wml  135) Ideally, soat.pl would be reimplemented in a sane language with a
en/volunteer.wml  136) robust html parser library (since the rest of Torflow is in Python
en/volunteer.wml  137) that would be nice, but it is not required), and calculate signatures only for
en/volunteer.wml  138) tags and content likely to be targeted by a malicious attacker (script
en/volunteer.wml  139) tags, object links, images, css). It should also be robust in the face of
en/volunteer.wml  140) changes to content outside of Tor, and ultimately even GeoIP localized
en/volunteer.wml  141) content.
en/volunteer.wml  142) <br />
en/volunteer.wml  143) This scanner would likely be run by the Directory Authorities and
en/volunteer.wml  144) report its results to the control port via the AuthDirBadExit config
en/volunteer.wml  145) setting.

en/volunteer.wml  146) <br />
en/volunteer.wml  147) </li>
en/volunteer.wml  148) 
en/volunteer.wml  149) <li>

en/volunteer.wml  150) <b>Tor Node Scanner improvements</b>

en/volunteer.wml  151) <br />

en/volunteer.wml  152) Priority: <i>High</i>

en/volunteer.wml  153) <br />

en/volunteer.wml  154) Effort Level: <i>Medium to High</i>

en/volunteer.wml  155) <br />
en/volunteer.wml  156) Skill Level: <i>Medium to High</i>
en/volunteer.wml  157) <br />

en/volunteer.wml  158) Likely Mentors: <i>Mike</i>

en/volunteer.wml  159) <br />

en/volunteer.wml  160) Applications as of 1 Apr 00:00 UTC: <i>1</i>

en/volunteer.wml  161) <br />

en/volunteer.wml  162) Similar to the exit scanner (or perhaps even during exit scanning),
en/volunteer.wml  163) statistics can be gathered about the reliability of nodes. Nodes that
en/volunteer.wml  164) fail too high a percentage of their circuits should not be given
en/volunteer.wml  165) Guard status. Perhaps they should have their reported bandwidth
en/volunteer.wml  166) penalized by some ratio as well, or just get marked as Invalid. In
en/volunteer.wml  167) addition, nodes that exhibit a very low average stream capacity but
en/volunteer.wml  168) advertise a very high node bandwidth can also be marked as Invalid.
en/volunteer.wml  169) Much of this statistics gathering is already done, it just needs to be
en/volunteer.wml  170) transformed into something that can be reported to the Directory
en/volunteer.wml  171) Authorities to blacklist/penalize nodes in such a way that clients
en/volunteer.wml  172) will listen.

en/volunteer.wml  173) <br />

en/volunteer.wml  174) In addition, these same statistics can be gathered about the traffic
en/volunteer.wml  175) through a node. Events can be added to the <a
en/volunteer.wml  176) href="https://www.torproject.org/svn/torctl/doc/howto.txt">Tor Control
en/volunteer.wml  177) Protocol</a> to
en/volunteer.wml  178) report if a circuit extend attempt through the node succeeds or fails, and
en/volunteer.wml  179) passive statistics can be gathered on both bandwidth and reliability
en/volunteer.wml  180) of other nodes via a node-based monitor using these events. Such a
en/volunteer.wml  181) scanner would also report information on oddly-behaving nodes to
en/volunteer.wml  182) the Directory Authorities, but a communication channel for this
en/volunteer.wml  183) currently does not exist and would need to be developed as well.
en/volunteer.wml  184) </li>
en/volunteer.wml  185) 
en/volunteer.wml  186) <li>
en/volunteer.wml  187) <b>Help track the overall Tor Network status</b>

en/volunteer.wml  188) <br />

en/volunteer.wml  189) Priority: <i>High</i>
en/volunteer.wml  190) <br />
en/volunteer.wml  191) Effort Level: <i>Medium</i>
en/volunteer.wml  192) <br />
en/volunteer.wml  193) Skill Level: <i>Medium</i>
en/volunteer.wml  194) <br />
en/volunteer.wml  195) Likely Mentors: <i>Roger, Nick, Mike</i>
en/volunteer.wml  196) <br />
en/volunteer.wml  197) It would be great to set up an automated system for tracking network
en/volunteer.wml  198) health over time, graphing it, etc. Part of this project would involve
en/volunteer.wml  199) inventing better metrics for assessing network health and growth. Is the
en/volunteer.wml  200) average uptime of the network increasing? How many relays are qualifying
en/volunteer.wml  201) for Guard status this month compared to last month? What's the turnover
en/volunteer.wml  202) in terms of new relays showing up and relays shutting off? Periodically
en/volunteer.wml  203) people collect brief snapshots, but where it gets really interesting is
en/volunteer.wml  204) when we start tracking data points over time.
en/volunteer.wml  205) <br />
en/volunteer.wml  206) Data could be collected from the "Tor Node Scanner" item above, from
en/volunteer.wml  207) the server descriptors that each relay publishes, and from other
en/volunteer.wml  208) sources. Results over time could be integrated into one of the <a
en/volunteer.wml  209) href="https://torstatus.blutmagie.de/">Tor Status</a> web pages, or be
en/volunteer.wml  210) kept separate. Speaking of the Tor Status pages, take a look at Roger's
en/volunteer.wml  211) <a href="http://archives.seul.org/or/talk/Jan-2008/msg00300.html">Tor
en/volunteer.wml  212) Status wish list</a>.
en/volunteer.wml  213) </li>
en/volunteer.wml  214) 
en/volunteer.wml  215) <li>
en/volunteer.wml  216) <b>Tor path selection improvements</b>
en/volunteer.wml  217) <br />
en/volunteer.wml  218) Priority: <i>High</i>
en/volunteer.wml  219) <br />
en/volunteer.wml  220) Effort Level: <i>Low to Medium</i>
en/volunteer.wml  221) <br />
en/volunteer.wml  222) Skill Level: <i>High</i>
en/volunteer.wml  223) <br />
en/volunteer.wml  224) Likely Mentors: <i>Roger, Nick, Mike</i>
en/volunteer.wml  225) <br />

en/volunteer.wml  226) Applications as of 1 Apr 00:00 UTC: <i>3</i>

en/volunteer.wml  227) <br />

en/volunteer.wml  228) Some simple improvements can be made to Tor's path selection to vastly
en/volunteer.wml  229) improve Tor speed. For instance, some of the (unofficial) <a
en/volunteer.wml  230) href="http://wiki.noreply.org/noreply/TheOnionRouter/FireFoxTorPerf">Tor
en/volunteer.wml  231) Performance Recommendations</a> on the wiki are to increase the number of
en/volunteer.wml  232) guards and decrease the CircuitBuildTimeout. Ideally, the client would
en/volunteer.wml  233) <a href="http://archives.seul.org/or/talk/Feb-2008/msg00012.html">learn
en/volunteer.wml  234) these values by gathering statistics on circuit construction
en/volunteer.wml  235) time</a> (and/or using values gained from Torflow), and set the timeouts
en/volunteer.wml  236) low enough such that some high percentile (75%, 90%, 1-stddev?) of
en/volunteer.wml  237) circuits succeed, yet extremely slow nodes are avoided. This would
en/volunteer.wml  238) involve some statistics gathering+basic research, and some changes to
en/volunteer.wml  239) Tor path selection code.
en/volunteer.wml  240) <br />
en/volunteer.wml  241) In addition, to improve path security, some elements from the <a
en/volunteer.wml  242) href="http://www.torproject.org/svn/trunk/doc/spec/proposals/115-two-hop-paths.txt">Two
en/volunteer.wml  243) Hop Paths proposal</a> could be done as part of this (since it will
en/volunteer.wml  244) likely touch the same code anyways), regardless of the adoption of
en/volunteer.wml  245) that proposal. In particular, clients probably should avoid guards that
en/volunteer.wml  246) seem to fail an excessive percentage of their circuits through them,
en/volunteer.wml  247) and non-firewalled clients should issue a warning if they are only able
en/volunteer.wml  248) to connect to a limited set of guard nodes. See also
en/volunteer.wml  249) <a href="http://archives.seul.org/or/dev/Feb-2008/msg00003.html">this
en/volunteer.wml  250) or-dev post</a>.

en/volunteer.wml  251) </li>
en/volunteer.wml  252) 
en/volunteer.wml  253) <li>

en/volunteer.wml  254) <b>Translation Wiki</b>
en/volunteer.wml  255) <br />
en/volunteer.wml  256) Priority: <i>High</i>
en/volunteer.wml  257) <br />
en/volunteer.wml  258) Effort Level: <i>Medium</i>
en/volunteer.wml  259) <br />
en/volunteer.wml  260) Skill Level: <i>Medium</i>
en/volunteer.wml  261) <br />
en/volunteer.wml  262) Likely Mentors: <i>Jacob</i>
en/volunteer.wml  263) <br />
en/volunteer.wml  264) We need a way to edit and translate sections of the website. Currently
en/volunteer.wml  265) the website is made up of a bunch of <a href="<svnwebsite>en/">wml
en/volunteer.wml  266) files</a>, and <a href="<page translation>">translators</a> fetch these
en/volunteer.wml  267) wml files, translate them in an editor, and either send us the translation
en/volunteer.wml  268) or use svn to commit them back. The current "cost" of publication of
en/volunteer.wml  269) website changes is quite high even for English language users. For a
en/volunteer.wml  270) single word change or any type of
en/volunteer.wml  271) minor change, the page may never be corrected or translated. It would
en/volunteer.wml  272) be nice to have a wiki that was specifically geared towards translation
en/volunteer.wml  273) and would somehow track the upstream (English) versions to indicate when
en/volunteer.wml  274) a fresh translation is needed, like our current
en/volunteer.wml  275) <a href="<page translation-status>">translation status page</a>. This
en/volunteer.wml  276) seems mostly like a job for a wiki
en/volunteer.wml  277) integrator or wiki software author. Certainly the person would need to
en/volunteer.wml  278) be interested in human languages and translation. They should at least
en/volunteer.wml  279) be minimally familiar with what Tor is; but they would not have to interact
en/volunteer.wml  280) with the software, only the documentation and the website.
en/volunteer.wml  281) </li>
en/volunteer.wml  282) 
en/volunteer.wml  283) <li>
en/volunteer.wml  284) <b>Better Debian/Ubuntu Packaging for Tor+Vidalia</b>

en/volunteer.wml  285) <br />

en/volunteer.wml  286) Priority: <i>High</i>
en/volunteer.wml  287) <br />
en/volunteer.wml  288) Effort Level: <i>Medium</i>
en/volunteer.wml  289) <br />
en/volunteer.wml  290) Skill Level: <i>Medium</i>
en/volunteer.wml  291) <br />

en/volunteer.wml  292) Likely Mentors: <i>Peter, Matt</i>

en/volunteer.wml  293) <br />

en/volunteer.wml  294) Applications as of 1 Apr 00:00 UTC: <i>1</i>

en/volunteer.wml  295) <br />

en/volunteer.wml  296) Vidalia currently doesn't play nicely on Debian and Ubuntu with the
en/volunteer.wml  297) default Tor packages. The current Tor packages automatically start Tor
en/volunteer.wml  298) as a daemon running as the debian-tor user and (sensibly) do not have a

en/volunteer.wml  299) <a href="<svnsandbox>doc/spec/control-spec.txt">ControlPort</a> defined
en/volunteer.wml  300) in the default torrc. Consequently, Vidalia will try

en/volunteer.wml  301) to start its own Tor process since it could not connect to the existing

en/volunteer.wml  302) Tor, and Vidalia's Tor process will then exit with an error message

en/volunteer.wml  303) the user likely doesn't understand since Tor cannot bind its listening

en/volunteer.wml  304) ports — they're already in use by the original Tor daemon.

en/volunteer.wml  305) <br />
en/volunteer.wml  306) The current solution involves either telling the user to stop the
en/volunteer.wml  307) existing Tor daemon and let Vidalia start its own Tor process, or
en/volunteer.wml  308) explaining to the user how to set a control port and password in their
en/volunteer.wml  309) torrc. A better solution on Debian would be to use Tor's ControlSocket,
en/volunteer.wml  310) which allows Vidalia to talk to Tor via a Unix domain socket, and could
en/volunteer.wml  311) possibly be enabled by default in Tor's Debian packages. Vidalia can

en/volunteer.wml  312) then authenticate to Tor using filesystem-based (cookie) authentication
en/volunteer.wml  313) if the user running Vidalia is also in the debian-tor group.

en/volunteer.wml  314) <br />
en/volunteer.wml  315) This project will first involve adding support for Tor's ControlSocket
en/volunteer.wml  316) to Vidalia. The student will then develop and test Debian and Ubuntu
en/volunteer.wml  317) packages for Vidalia that conform to Debian's packaging standards and

en/volunteer.wml  318) make sure they work well with the existing Tor packages. We can also

en/volunteer.wml  319) set up an apt repository to host the new Vidalia packages.
en/volunteer.wml  320) <br />

en/volunteer.wml  321) The next challenge would be to find an intuitive usable way for Vidalia
en/volunteer.wml  322) to be able to change Tor's configuration (torrc) even though it is
en/volunteer.wml  323) located in <code>/etc/tor/torrc</code> and thus immutable. The best
en/volunteer.wml  324) idea we've come up with so far is to feed Tor a new configuration via
en/volunteer.wml  325) the ControlSocket when Vidalia starts, but that's bad because Tor starts

en/volunteer.wml  326) each boot with a different configuration than the user wants. The second
en/volunteer.wml  327) best idea

en/volunteer.wml  328) we've come up with is for Vidalia to write out a temporary torrc file
en/volunteer.wml  329) and ask the user to manually move it to <code>/etc/tor/torrc</code>,
en/volunteer.wml  330) but that's bad because users shouldn't have to mess with files directly.
en/volunteer.wml  331) <br />

en/volunteer.wml  332) A student undertaking this project should have prior knowledge of
en/volunteer.wml  333) Debian package management and some C++ development experience. Previous
en/volunteer.wml  334) experience with Qt is helpful, but not required.
en/volunteer.wml  335) </li>
en/volunteer.wml  336) 

en/volunteer.wml  337) <li>
en/volunteer.wml  338) <b>Improving Tor's ability to resist censorship</b>
en/volunteer.wml  339) <br />
en/volunteer.wml  340) Priority: <i>High</i>
en/volunteer.wml  341) <br />
en/volunteer.wml  342) Effort Level: <i>High</i>
en/volunteer.wml  343) <br />
en/volunteer.wml  344) Skill Level: <i>High</i>
en/volunteer.wml  345) <br />
en/volunteer.wml  346) Likely Mentors: <i>Nick</i>
en/volunteer.wml  347) <br />
en/volunteer.wml  348) The Tor 0.2.0.x series makes <a
en/volunteer.wml  349) href="<svnsandbox>doc/design-paper/blocking.html">significant
en/volunteer.wml  350) improvements</a> in resisting national and organizational censorship.
en/volunteer.wml  351) But Tor still needs better mechanisms for some parts of its
en/volunteer.wml  352) anti-censorship design.  For example, current Tors can only listen on a
en/volunteer.wml  353) single address/port combination at a time.  There's
en/volunteer.wml  354) <a href="<svnsandbox>doc/spec/proposals/118-multiple-orports.txt">a
en/volunteer.wml  355) proposal to address this limitation</a> and allow clients to connect
en/volunteer.wml  356) to any given Tor on multiple addresses and ports, but it needs more
en/volunteer.wml  357) work.  Another anti-censorship project (far more difficult) is to try
en/volunteer.wml  358) to make Tor more scanning-resistant.  Right now, an adversary can identify
en/volunteer.wml  359) <a href="<svnsandbox>doc/spec/proposals/125-bridges.txt">Tor bridges</a>
en/volunteer.wml  360) just by trying to connect to them, following the Tor protocol, and
en/volunteer.wml  361) seeing if they respond.  To solve this, bridges could
en/volunteer.wml  362) <a href="<svnsandbox>doc/design-paper/blocking.html#tth_sEc9.3">act like
en/volunteer.wml  363) webservers</a> (HTTP or HTTPS) when contacted by port-scanning tools,
en/volunteer.wml  364) and not act like bridges until the user provides a bridge-specific key.
en/volunteer.wml  365) <br />
en/volunteer.wml  366) This project involves a lot of research and design. One of the big
en/volunteer.wml  367) challenges will be identifying and crafting approaches that can still
en/volunteer.wml  368) resist an adversary even after the adversary knows the design, and
en/volunteer.wml  369) then trading off censorship resistance with usability and robustness.
en/volunteer.wml  370) </li>
en/volunteer.wml  371) 
en/volunteer.wml  372) <li>
en/volunteer.wml  373) <b>Tor/Polipo/Vidalia Auto-Update Framework</b>
en/volunteer.wml  374) <br />
en/volunteer.wml  375) Priority: <i>Medium</i>
en/volunteer.wml  376) <br />
en/volunteer.wml  377) Effort Level: <i>High</i>
en/volunteer.wml  378) <br />
en/volunteer.wml  379) Skill Level: <i>High</i>
en/volunteer.wml  380) <br />
en/volunteer.wml  381) Likely Mentors: <i>Matt, Jacob</i>
en/volunteer.wml  382) <br />
en/volunteer.wml  383) We're in need of a good authenticated-update framework.
en/volunteer.wml  384) Vidalia already has the ability to notice when the user is running an
en/volunteer.wml  385) outdated or unrecommended version of Tor, using signed statements inside
en/volunteer.wml  386) the Tor directory information. Currently, Vidalia simply pops
en/volunteer.wml  387) up a little message box that lets the user know they should manually
en/volunteer.wml  388) upgrade. The goal of this project would be to extend Vidalia with the
en/volunteer.wml  389) ability to also fetch and install the updated Tor software for the
en/volunteer.wml  390) user. We should do the fetches via Tor when possible, but also fall back
en/volunteer.wml  391) to direct fetches in a smart way. Time permitting, we would also like
en/volunteer.wml  392) to be able to update other
en/volunteer.wml  393) applications included in the bundled installers, such as Polipo and
en/volunteer.wml  394) Vidalia itself.
en/volunteer.wml  395) <br />
en/volunteer.wml  396) To complete this project, the student will first need to first investigate
en/volunteer.wml  397) the existing auto-update frameworks (e.g., Sparkle on OS X) to evaluate
en/volunteer.wml  398) their strengths, weaknesses, security properties, and ability to be
en/volunteer.wml  399) integrated into Vidalia. If none are found to be suitable, the student
en/volunteer.wml  400) will design their own auto-update framework, document the design, and
en/volunteer.wml  401) then discuss the design with other developers to assess any security
en/volunteer.wml  402) issues. The student will then implement their framework (or integrate
en/volunteer.wml  403) an existing one) and test it.
en/volunteer.wml  404) <br />
en/volunteer.wml  405) A student undertaking this project should have good C++ development
en/volunteer.wml  406) experience. Previous experience with Qt is helpful, but not required. The
en/volunteer.wml  407) student should also have a good understanding of common security
en/volunteer.wml  408) practices, such as package signature verification. Good writing ability
en/volunteer.wml  409) is also important for this project, since a vital step of the project
en/volunteer.wml  410) will be producing a design document for others to review and discuss
en/volunteer.wml  411) with the student prior to implementation.
en/volunteer.wml  412) </li>
en/volunteer.wml  413) 
en/volunteer.wml  414) <li>
en/volunteer.wml  415) <b>An Improved and More Usable Network Map in Vidalia</b>
en/volunteer.wml  416) <br />
en/volunteer.wml  417) Priority: <i>Medium</i>
en/volunteer.wml  418) <br />
en/volunteer.wml  419) Effort Level: <i>Medium</i>
en/volunteer.wml  420) <br />
en/volunteer.wml  421) Skill Level: <i>Medium to High</i>
en/volunteer.wml  422) <br />
en/volunteer.wml  423) Likely Mentors: <i>Matt</i>
en/volunteer.wml  424) <br />
en/volunteer.wml  425) One of Vidalia's existing features is a network map that shows the user
en/volunteer.wml  426) the approximate geographic location of relays in the Tor network and
en/volunteer.wml  427) plots the paths the user's traffic takes as it is tunneled through the
en/volunteer.wml  428) Tor network. The map is currently not very interactive and has rather
en/volunteer.wml  429) poor graphics. Instead, we would like to leverage KDE's Marble widget
en/volunteer.wml  430) that gives us a better quality map and enables improved interactivity,
en/volunteer.wml  431) such as allowing the user to click on individual relays or circuits to
en/volunteer.wml  432) display additional information. We might also consider adding the ability
en/volunteer.wml  433) for users to click on a particular relay or a country containing one or
en/volunteer.wml  434) more Tor exit relays and say, "I want my connections to foo.com to exit
en/volunteer.wml  435) from here."
en/volunteer.wml  436) <br />
en/volunteer.wml  437) This project will first involve the student getting familiar with Vidalia
en/volunteer.wml  438) and the Marble widget's API. The student will then integrate the widget
en/volunteer.wml  439) into Vidalia and customize Marble to be better suited for our application,
en/volunteer.wml  440) such as making circuits clickable, storing cached map data in Vidalia's
en/volunteer.wml  441) own data directory, and customizing some of the widget's dialogs.
en/volunteer.wml  442) <br />
en/volunteer.wml  443) A student undertaking this project should have good C++ development
en/volunteer.wml  444) experience. Previous experience with Qt and CMake is helpful, but not
en/volunteer.wml  445) required.
en/volunteer.wml  446) </li>
en/volunteer.wml  447) 

en/volunteer.wml  448) <li>

en/volunteer.wml  449) <b>Tor Controller Status Event Interface</b>

en/volunteer.wml  450) <br />

en/volunteer.wml  451) Priority: <i>Medium</i>
en/volunteer.wml  452) <br />
en/volunteer.wml  453) Effort Level: <i>Medium</i>
en/volunteer.wml  454) <br />
en/volunteer.wml  455) Skill Level: <i>Medium</i>
en/volunteer.wml  456) <br />

en/volunteer.wml  457) Likely Mentors: <i>Matt, Roger</i>

en/volunteer.wml  458) <br />

en/volunteer.wml  459) There are a number of status changes inside Tor of which the user may need

en/volunteer.wml  460) to be informed. For example, if the user is trying to set up his Tor as a
en/volunteer.wml  461) relay and Tor decides that its ports are not reachable from outside

en/volunteer.wml  462) the user's network, we should alert the user. Currently, all the user

en/volunteer.wml  463) gets is a couple log messages in Vidalia's 'message log' window, which they

en/volunteer.wml  464) likely never see since they don't receive a notification that something
en/volunteer.wml  465) has gone wrong. Even if the user does actually look at the message log,
en/volunteer.wml  466) most of the messages make little sense to the novice user.
en/volunteer.wml  467) <br />
en/volunteer.wml  468) Tor has the ability to inform Vidalia of many such status changes, and
en/volunteer.wml  469) we recently implemented support for a couple of these events. Still,
en/volunteer.wml  470) there are many more status events the user should be informed of and we
en/volunteer.wml  471) need a better UI for actually displaying them to the user.
en/volunteer.wml  472) <br />
en/volunteer.wml  473) The goal of this project then is to design and implement a UI for
en/volunteer.wml  474) displaying Tor status events to the user. For example, we might put a
en/volunteer.wml  475) little badge on Vidalia's tray icon that alerts the user to new status
en/volunteer.wml  476) events they should look at. Double-clicking the icon could bring up a
en/volunteer.wml  477) dialog that summarizes recent status events in simple terms and maybe

en/volunteer.wml  478) suggests a remedy for any negative events if they can be corrected by

en/volunteer.wml  479) the user. Of course, this is just an example and the student is free to
en/volunteer.wml  480) suggest another approach.
en/volunteer.wml  481) <br />
en/volunteer.wml  482) A student undertaking this project should have good UI design and layout

en/volunteer.wml  483) and some C++ development experience. Previous experience with Qt and

en/volunteer.wml  484) Qt's Designer will be very helpful, but are not required. Some

en/volunteer.wml  485) English writing ability will also be useful, since this project will
en/volunteer.wml  486) likely involve writing small amounts of help documentation that should
en/volunteer.wml  487) be understandable by non-technical users. Bonus points for some graphic
en/volunteer.wml  488) design/Photoshop fu, since we might want/need some shiny new icons too.
en/volunteer.wml  489) </li>
en/volunteer.wml  490) 

en/volunteer.wml  491) <li>

en/volunteer.wml  492) <b>Improvements on our active browser configuration tester</b> -

en/volunteer.wml  493) <a href="https://check.torproject.org/">https://check.torproject.org/</a>

en/volunteer.wml  494) <br />

en/volunteer.wml  495) Priority: <i>Medium</i>
en/volunteer.wml  496) <br />
en/volunteer.wml  497) Effort Level: <i>Low</i>
en/volunteer.wml  498) <br />
en/volunteer.wml  499) Skill Level: <i>Low to Medium</i>
en/volunteer.wml  500) <br />

en/volunteer.wml  501) Likely Mentors: <i>Jacob, Steven</i>

en/volunteer.wml  502) <br />

en/volunteer.wml  503) Applications as of 1 Apr 00:00 UTC: <i>1</i>
en/volunteer.wml  504) <br />

en/volunteer.wml  505) We currently have a functional web page to detect if Tor is working. It

en/volunteer.wml  506) has a few places where it falls short. It requires improvements with

en/volunteer.wml  507) regard to default languages and functionality. It currently only responds
en/volunteer.wml  508) in English. In addition, it is a hack of a perl script that should have
en/volunteer.wml  509) never seen the light of day. It should probably be rewritten in python

en/volunteer.wml  510) with multi-lingual support in mind. It currently uses the <a
en/volunteer.wml  511) href="http://exitlist.torproject.org/">Tor DNS exit list</a>
en/volunteer.wml  512) and should continue to do so in the future. It currently result in certain

en/volunteer.wml  513) false positives and these should be discovered, documented, and fixed
en/volunteer.wml  514) where possible. Anyone working on this project should be interested in

en/volunteer.wml  515) DNS, basic perl or preferably python programming skills, and will have

en/volunteer.wml  516) to interact minimally with Tor to test their code.

en/volunteer.wml  517) <br />
en/volunteer.wml  518) If you want to make the project more exciting
en/volunteer.wml  519) and involve more design and coding, take a look at <a
en/volunteer.wml  520) href="<svnsandbox>doc/spec/proposals/131-verify-tor-usage.txt">proposal
en/volunteer.wml  521) 131-verify-tor-usage.txt</a>.

en/volunteer.wml  522) </li>
en/volunteer.wml  523) 
en/volunteer.wml  524) <li>

en/volunteer.wml  525) <b>Improvements on our DNS Exit List service</b> -

en/volunteer.wml  526) <a href="http://exitlist.torproject.org/">http://exitlist.torproject.org/</a>

en/volunteer.wml  527) <br />

en/volunteer.wml  528) Priority: <i>Medium</i>
en/volunteer.wml  529) <br />
en/volunteer.wml  530) Effort Level: <i>Low</i>
en/volunteer.wml  531) <br />
en/volunteer.wml  532) Skill Level: <i>Low</i>
en/volunteer.wml  533) <br />

en/volunteer.wml  534) Likely Mentors: <i>Jacob, Tup</i>

en/volunteer.wml  535) <br />

en/volunteer.wml  536) The <a href="http://p56soo2ibjkx23xo.onion/">exitlist software</a>
en/volunteer.wml  537) is written by our fabulous anonymous

en/volunteer.wml  538) contributer Tup. It's a DNS server written in Haskell that supports part of our <a

en/volunteer.wml  539) href="https://www.torproject.org/svn/trunk/doc/contrib/torel-design.txt">exitlist

en/volunteer.wml  540) design document</a>. Currently, it is functional and it is used by

en/volunteer.wml  541) check.torproject.org and other users. The issues that are outstanding
en/volunteer.wml  542) are mostly aesthetic. This wonderful service could use a much better
en/volunteer.wml  543) website using the common Tor theme. It would be best served with better
en/volunteer.wml  544) documentation for common services that use an RBL. It could use more
en/volunteer.wml  545) publicity. A person working on this project should be interested in DNS,
en/volunteer.wml  546) basic RBL configuration for popular services, and writing documentation.
en/volunteer.wml  547) The person would require minimal Tor interaction — testing their
en/volunteer.wml  548) own documentation at the very least. Furthermore, it would be useful

en/volunteer.wml  549) if they were interested in Haskell and wanted to implement more of the

en/volunteer.wml  550) torel-design.txt suggestions.
en/volunteer.wml  551) </li>
en/volunteer.wml  552) 
en/volunteer.wml  553) <li>

en/volunteer.wml  554) <b>Testing integration of Tor with web browsers for our end users</b>

en/volunteer.wml  555) <br />

en/volunteer.wml  556) Priority: <i>Medium</i>
en/volunteer.wml  557) <br />
en/volunteer.wml  558) Effort Level: <i>Medium</i>
en/volunteer.wml  559) <br />
en/volunteer.wml  560) Skill Level: <i>Medium</i>
en/volunteer.wml  561) <br />

en/volunteer.wml  562) Likely Mentors: <i>Jacob, Mike, Greg</i>

en/volunteer.wml  563) <br />

en/volunteer.wml  564) Applications as of 1 Apr 00:00 UTC: <i>1</i>
en/volunteer.wml  565) <br />

en/volunteer.wml  566) The Tor project currently lacks a solid test suite to ensure that a
en/volunteer.wml  567) user has a properly and safely configured web browser. It should test for as

en/volunteer.wml  568) many known issues as possible. It should attempt to decloak the

en/volunteer.wml  569) user in any way possible. Two current webpages that track these

en/volunteer.wml  570) kinds of issues are run by Greg Fleischer and HD Moore. Greg keeps a nice <a

en/volunteer.wml  571) href="http://pseudo-flaw.net/tor/torbutton/">list of issues along
en/volunteer.wml  572) with their proof of concept code, bug issues, etc</a>. HD Moore runs

en/volunteer.wml  573) the <a href="http://metasploit.com/research/projects/decloak/">metasploit

en/volunteer.wml  574) decloak website</a>. A student interested in defending Tor could start

en/volunteer.wml  575) by collecting as many workable and known methods for decloaking a

en/volunteer.wml  576) Tor user. (<a href="https://torcheck.xenobite.eu/">This page</a> may
en/volunteer.wml  577) be helpful as a start.) The student should be familiar with the common
en/volunteer.wml  578) pitfalls but

en/volunteer.wml  579) possibly have new methods in mind for implementing decloaking issues. The
en/volunteer.wml  580) website should ensure that it tells a user what their problem is. It
en/volunteer.wml  581) should help them to fix the problem or direct them to the proper support

en/volunteer.wml  582) channels. The student should be closely familiar with using Tor and how
en/volunteer.wml  583) to prevent Tor information leakage.

en/volunteer.wml  584) </li>
en/volunteer.wml  585) 

en/volunteer.wml  586) <li>

en/volunteer.wml  587) <b>Libevent and Tor integration improvements</b>
en/volunteer.wml  588) <br />

en/volunteer.wml  589) Priority: <i>Medium</i>
en/volunteer.wml  590) <br />
en/volunteer.wml  591) Effort Level: <i>High</i>
en/volunteer.wml  592) <br />
en/volunteer.wml  593) Skill Level: <i>Medium to High</i>
en/volunteer.wml  594) <br />

en/volunteer.wml  595) Likely Mentors: <i>Nick</i>

en/volunteer.wml  596) <br />

en/volunteer.wml  597) Tor should make better use of the more recent features of Niels
en/volunteer.wml  598) Provos's <a href="http://monkey.org/~provos/libevent/">Libevent</a>

en/volunteer.wml  599) library.  Tor already uses Libevent for its low-level asynchronous IO

en/volunteer.wml  600) calls, and could also use Libevent's increasingly good implementations

en/volunteer.wml  601) of network buffers and of HTTP.  This wouldn't be simply a matter of

en/volunteer.wml  602) replacing Tor's internal calls with calls to Libevent: instead, we'll

en/volunteer.wml  603) need to refactor Tor to use Libevent calls that do not follow the

en/volunteer.wml  604) same models as Tor's existing backends. Also, we'll need to add
en/volunteer.wml  605) missing functionality to Libevent as needed — most difficult likely
en/volunteer.wml  606) will be adding OpenSSL support on top of Libevent's buffer abstraction.
en/volunteer.wml  607) Also tricky will be adding rate-limiting to Libevent.

en/volunteer.wml  608) </li>
en/volunteer.wml  609) 
en/volunteer.wml  610) <li>

en/volunteer.wml  611) <b>Tuneup Tor!</b>
en/volunteer.wml  612) <br />

en/volunteer.wml  613) Priority: <i>Medium</i>
en/volunteer.wml  614) <br />
en/volunteer.wml  615) Effort Level: <i>Medium</i>
en/volunteer.wml  616) <br />
en/volunteer.wml  617) Skill Level: <i>Medium to High</i>
en/volunteer.wml  618) <br />

en/volunteer.wml  619) Likely Mentors: <i>Nick, Roger, Mike</i>

en/volunteer.wml  620) <br />

en/volunteer.wml  621) Right now, Tor relays measure and report their own bandwidth, and Tor
en/volunteer.wml  622) clients choose which relays to use in part based on that bandwidth.
en/volunteer.wml  623) This approach is vulnerable to
en/volunteer.wml  624) <a href="http://freehaven.net/anonbib/#bauer:wpes2007">attacks where
en/volunteer.wml  625) relays lie about their bandwidth</a>;
en/volunteer.wml  626) to address this, Tor currently caps the maximum bandwidth
en/volunteer.wml  627) it's willing to believe any relay provides.  This is a limited fix, and
en/volunteer.wml  628) a waste of bandwidth capacity to boot.  Instead,

en/volunteer.wml  629) Tor should possibly measure bandwidth in a more distributed way, perhaps
en/volunteer.wml  630) as described in the

en/volunteer.wml  631) <a href="http://freehaven.net/anonbib/author.html#snader08">"A Tune-up for
en/volunteer.wml  632) Tor"</a> paper

en/volunteer.wml  633) by Snader and Borisov. A student could use current testing code to

en/volunteer.wml  634) double-check this paper's findings and verify the extent to which they

en/volunteer.wml  635) dovetail with Tor as deployed in the wild, and determine good ways to
en/volunteer.wml  636) incorporate them into their suggestions Tor network without adding too

en/volunteer.wml  637) much communications overhead between relays and directory

en/volunteer.wml  638) authorities.

en/volunteer.wml  639) </li>
en/volunteer.wml  640) 

en/volunteer.wml  641) <!--

en/volunteer.wml  642) <li>

en/volunteer.wml  643) <b>Improving the Tor QA process: Continuous Integration for Windows builds</b>
en/volunteer.wml  644) <br />

en/volunteer.wml  645) Priority: <i>High</i>
en/volunteer.wml  646) <br />
en/volunteer.wml  647) Effort Level: <i>Medium</i>
en/volunteer.wml  648) <br />
en/volunteer.wml  649) Skill Level: <i>Medium</i>
en/volunteer.wml  650) <br />

en/volunteer.wml  651) Likely Mentors: <i>Jacob, Andrew</i>

en/volunteer.wml  652) <br />

en/volunteer.wml  653) It would be useful to have automated build processes for Windows and
en/volunteer.wml  654) probably other platforms. The purpose of having a continuous integration
en/volunteer.wml  655) build environment is to ensure that Windows isn't left behind for any of
en/volunteer.wml  656) the software projects used in the Tor project or its accompanying.<br />
en/volunteer.wml  657) Buildbot may be a good choice for this as it appears to support all of

en/volunteer.wml  658) the platforms Tor does. See the

en/volunteer.wml  659) <a href="http://en.wikipedia.org/wiki/BuildBot">wikipedia entry for

en/volunteer.wml  660) buildbot</a>.<br />
en/volunteer.wml  661) There may be better options and the person undertaking this task should
en/volunteer.wml  662) evaluate other options. Any person working on this automatic build
en/volunteer.wml  663) process should have experience or be willing to learn how to build all
en/volunteer.wml  664) of the respective Tor related code bases from scratch. Furthermore, the
en/volunteer.wml  665) person should have some experience building software in Windows
en/volunteer.wml  666) environments as this is the target audience we want to ensure we do not
en/volunteer.wml  667) leave behind. It would require close work with the Tor source code but

en/volunteer.wml  668) probably only in the form of building, not authoring.<br />
en/volunteer.wml  669) Additionally, we need to automate our performance testing for all platforms.

en/volunteer.wml  670) We've got buildbot (except on Windows — as noted above) to automate

en/volunteer.wml  671) our regular integration and compile testing already,
en/volunteer.wml  672) but we need to get our network simulation tests (as built in torflow)
en/volunteer.wml  673) updated for more recent versions of Tor, and designed to launch a test
en/volunteer.wml  674) network either on a single machine, or across several, so we can test

en/volunteer.wml  675) changes in performance on machines in different roles automatically.

en/volunteer.wml  676) </li>

en/volunteer.wml  677) -->

en/volunteer.wml  678) 

en/volunteer.wml  679) <li>

en/volunteer.wml  680) <b>Improve our unit testing process</b>
en/volunteer.wml  681) <br />

en/volunteer.wml  682) Priority: <i>Medium</i>
en/volunteer.wml  683) <br />
en/volunteer.wml  684) Effort Level: <i>Medium</i>
en/volunteer.wml  685) <br />
en/volunteer.wml  686) Skill Level: <i>Medium</i>
en/volunteer.wml  687) <br />

en/volunteer.wml  688) Likely Mentors: <i>Nick</i>

en/volunteer.wml  689) <br />

en/volunteer.wml  690) Tor needs to be far more tested. This is a multi-part effort. To start

en/volunteer.wml  691) with, our unit test coverage should rise substantially, especially in

en/volunteer.wml  692) the areas outside the utility functions. This will require significant

en/volunteer.wml  693) refactoring of some parts of Tor, in order to dissociate as much logic

en/volunteer.wml  694) as possible from globals.
en/volunteer.wml  695) <br />

en/volunteer.wml  696) Additionally, we need to automate our performance testing. We've got

en/volunteer.wml  697) buildbot to automate our regular integration and compile testing already
en/volunteer.wml  698) (though we need somebody to set it up on Windows),
en/volunteer.wml  699) but we need to get our network simulation tests (as built in TorFlow: see
en/volunteer.wml  700) the "Tor Node Scanner improvements" item)

en/volunteer.wml  701) updated for more recent versions of Tor, and designed to launch a test
en/volunteer.wml  702) network either on a single machine, or across several, so we can test

en/volunteer.wml  703) changes in performance on machines in different roles automatically.

en/volunteer.wml  704) </li>
en/volunteer.wml  705) 

en/volunteer.wml  706) <li>

en/volunteer.wml  707) <b>Help revive an independent Tor client implementation</b>

en/volunteer.wml  708) <br />

en/volunteer.wml  709) Priority: <i>Medium</i>

en/volunteer.wml  710) <br />
en/volunteer.wml  711) Effort Level: <i>High</i>
en/volunteer.wml  712) <br />
en/volunteer.wml  713) Skill Level: <i>Medium to High</i>
en/volunteer.wml  714) <br />

en/volunteer.wml  715) Likely Mentors: <i>Karsten, Nick</i>

en/volunteer.wml  716) <br />

en/volunteer.wml  717) Applications as of 1 Apr 00::00 UTC: <i>4</i>

en/volunteer.wml  718) <br />

en/volunteer.wml  719) Reanimate one of the approaches to implement a Tor client in Java,
en/volunteer.wml  720) e.g. the <a href="http://onioncoffee.sourceforge.net/">OnionCoffee
en/volunteer.wml  721) project</a>, and make it run on <a
en/volunteer.wml  722) href="http://code.google.com/android/">Android</a>. The first step
en/volunteer.wml  723) would be to port the existing code and execute it in an Android
en/volunteer.wml  724) environment. Next, the code should be updated to support the newer Tor
en/volunteer.wml  725) protocol versions like the <a href="<svnsandbox>doc/spec/dir-spec.txt">v3
en/volunteer.wml  726) directory protocol</a>. Further, support for requesting or even

en/volunteer.wml  727) providing Tor hidden services would be neat, but not required.
en/volunteer.wml  728) <br />
en/volunteer.wml  729) The student should be able to understand and write new Java code, including

en/volunteer.wml  730) a Java cryptography API. Being able to read C code would be helpful,

en/volunteer.wml  731) too. The student should be willing to read the existing documentation,

en/volunteer.wml  732) implement code based on it, and refine the documentation
en/volunteer.wml  733) when things are underdocumented. This project is mostly about coding and

en/volunteer.wml  734) to a small degree about design.
en/volunteer.wml  735) </li>
en/volunteer.wml  736) 
en/volunteer.wml  737) <li>

en/volunteer.wml  738) <b>Automatic system tests and automatically starting private Tor networks</b>

en/volunteer.wml  739) <br />

en/volunteer.wml  740) Priority: <i>Medium</i>
en/volunteer.wml  741) <br />
en/volunteer.wml  742) Effort Level: <i>Medium</i>
en/volunteer.wml  743) <br />
en/volunteer.wml  744) Skill Level: <i>Medium</i>
en/volunteer.wml  745) <br />

en/volunteer.wml  746) Likely Mentors: <i>Karsten, Nick, Roger</i>

en/volunteer.wml  747) <br />

en/volunteer.wml  748) Applications as of 1 Apr 00:00 UTC: <i>2</i>
en/volunteer.wml  749) <br />

en/volunteer.wml  750) Write a tool that runs automatic system tests in addition
en/volunteer.wml  751) to the existing unit tests. The Java-based Tor simulator <a
en/volunteer.wml  752) href="https://tor-svn.freehaven.net/svn/puppetor/trunk/">PuppeTor</a>
en/volunteer.wml  753) might be a good start for starting up a private Tor network, using it
en/volunteer.wml  754) for a while, and verifying that at least parts of it are working. This
en/volunteer.wml  755) project requires to conceive a blueprint for performing system tests
en/volunteer.wml  756) of private Tor networks, before starting to code. Typical types of
en/volunteer.wml  757) tests range from performing single requests over the private network to
en/volunteer.wml  758) manipulating exchanged messages and see if nodes handle corrupt messages

en/volunteer.wml  759) appropriately.
en/volunteer.wml  760) <br />
en/volunteer.wml  761) The student should be able to obtain a good understanding

en/volunteer.wml  762) of how Tor works and what problems and bugs could arise to design good

en/volunteer.wml  763) test cases. Understanding the existing Tor code structure and documentation is

en/volunteer.wml  764) vital. If PuppeTor is used, the student should also be able to understand
en/volunteer.wml  765) and possibly extend an existing Java application. This project is partly
en/volunteer.wml  766) about design and partly about coding.
en/volunteer.wml  767) </li>
en/volunteer.wml  768) 
en/volunteer.wml  769) <li>

en/volunteer.wml  770) <b>Bring moniTor to life</b>
en/volunteer.wml  771) <br />

en/volunteer.wml  772) Priority: <i>Medium</i>
en/volunteer.wml  773) <br />
en/volunteer.wml  774) Effort Level: <i>Medium</i>
en/volunteer.wml  775) <br />
en/volunteer.wml  776) Skill Level: <i>Low to Medium</i>
en/volunteer.wml  777) <br />

en/volunteer.wml  778) Likely Mentors: <i>Karsten, Jacob</i>

en/volunteer.wml  779) <br />

en/volunteer.wml  780) Applications as of 1 Apr 00::00 UTC: <i>2</i>

en/volunteer.wml  781) <br />

en/volunteer.wml  782) Implement a <a href="http://www.ss64.com/bash/top.html">top-like</a>
en/volunteer.wml  783) management tool for Tor relays. The purpose of such a tool would be
en/volunteer.wml  784) to monitor a local Tor relay via its control port and include useful
en/volunteer.wml  785) system information of the underlying machine. When running this tool, it
en/volunteer.wml  786) would dynamically update its content like top does for Linux processes.
en/volunteer.wml  787) <a href="http://archives.seul.org/or/dev/Jan-2008/msg00005.html">This

en/volunteer.wml  788) or-dev post</a> might be a good first read.
en/volunteer.wml  789) <br />
en/volunteer.wml  790) The student should be familiar

en/volunteer.wml  791) with or willing to learn about administering a Tor relay and configuring
en/volunteer.wml  792) it via its control port. As an initial prototype is written in Python,
en/volunteer.wml  793) some knowledge about writing Python code would be helpful, too. This

en/volunteer.wml  794) project is one part about identifying requirements to such a
en/volunteer.wml  795) tool and designing its interface, and one part lots of coding.

en/volunteer.wml  796) </li>
en/volunteer.wml  797) 

en/volunteer.wml  798) <li>
en/volunteer.wml  799) <b>Torbutton improvements</b>
en/volunteer.wml  800) <br />

en/volunteer.wml  801) Priority: <i>Medium</i>

en/volunteer.wml  802) <br />

en/volunteer.wml  803) Effort Level: <i>High</i>
en/volunteer.wml  804) <br />
en/volunteer.wml  805) Skill Level: <i>High</i>

en/volunteer.wml  806) <br />

en/volunteer.wml  807) Likely Mentors: <i>Mike</i>

en/volunteer.wml  808) <br/>
en/volunteer.wml  809) Torbutton has a number of improvements that can be made in the post-1.2
en/volunteer.wml  810) timeframe. Most of these are documented as feature requests in the <a

en/volunteer.wml  811) href="https://bugs.torproject.org/flyspray/index.php?tasks=all&project=5">Torbutton

en/volunteer.wml  812) flyspray section</a>. Good examples include: stripping off node.exit on http
en/volunteer.wml  813) headers, more fine-grained control over formfill blocking, improved referrer

en/volunteer.wml  814) spoofing based on the domain of the site (a-la <a

en/volunteer.wml  815) href="https://addons.mozilla.org/en-US/firefox/addon/953">refcontrol extension</a>),

en/volunteer.wml  816) tighter integration with Vidalia for reporting Tor status, a New Identity
en/volunteer.wml  817) button with Tor integration and multiple identity management, and anything

en/volunteer.wml  818) else you might think of.

en/volunteer.wml  819) <br />
en/volunteer.wml  820) This work would be independent coding in Javascript and the fun world of <a
en/volunteer.wml  821) href="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">XUL</a>,
en/volunteer.wml  822) with not too much involvement in the Tor internals.

en/volunteer.wml  823) </li>
en/volunteer.wml  824) 

en/volunteer.wml  825) <li>

en/volunteer.wml  826) <b>Porting Polipo to Windows</b>
en/volunteer.wml  827) <br />

en/volunteer.wml  828) Priority: <i>Medium</i>

en/volunteer.wml  829) <br />

en/volunteer.wml  830) Effort Level: <i>Medium</i>

en/volunteer.wml  831) <br />
en/volunteer.wml  832) Skill Level: <i>Medium to High</i>
en/volunteer.wml  833) <br />

en/volunteer.wml  834) Likely Mentors: <i>Andrew, Steven, Roger</i>

en/volunteer.wml  835) <br />

en/volunteer.wml  836) Help port <a
en/volunteer.wml  837) href="http://www.pps.jussieu.fr/~jch/software/polipo/">Polipo</a> to

en/volunteer.wml  838) Windows. Example topics to tackle include:
en/volunteer.wml  839) 1) handle spaces in path names and understand the filesystem
en/volunteer.wml  840) namespace — that is, where application data, personal data,

en/volunteer.wml  841) and program data typically reside in various versions of Windows. 2) the
en/volunteer.wml  842) ability to handle ipv6 communications. 3) the ability to asynchronously
en/volunteer.wml  843) query name servers, find the system nameservers, and manage netbios
en/volunteer.wml  844) and dns queries. 4) use native regex capabilities of Windows, rather
en/volunteer.wml  845) than using 3rd party GNU regex libraries. 5) manage events and buffers
en/volunteer.wml  846) natively (i.e. in Unix-like OSes, Polipo defaults to 25% of ram, in
en/volunteer.wml  847) Windows it's whatever the config specifies). 6) some sort of GUI config
en/volunteer.wml  848) and reporting tool, bonus if it has a systray icon with right clickable
en/volunteer.wml  849) menu options. Double bonus if it's cross-platform compatible.
en/volunteer.wml  850) </li>
en/volunteer.wml  851) 
en/volunteer.wml  852) <li>

en/volunteer.wml  853) <b>Make our diagrams beautiful and automated</b>

en/volunteer.wml  854) <br />

en/volunteer.wml  855) Priority: <i>Medium</i>

en/volunteer.wml  856) <br />
en/volunteer.wml  857) Effort Level: <i>Low</i>
en/volunteer.wml  858) <br />
en/volunteer.wml  859) Skill Level: <i>Low</i>
en/volunteer.wml  860) <br />

en/volunteer.wml  861) Likely Mentors: <i>Andrew</i>

en/volunteer.wml  862) <br />

en/volunteer.wml  863) We need a way to generate the website diagrams (for example, the "How
en/volunteer.wml  864) Tor Works" pictures on the <a href="<page overview>">overview page</a>
en/volunteer.wml  865) from source, so we can translate them as UTF-8 text rather than edit
en/volunteer.wml  866) them by hand with Gimp. We might want to
en/volunteer.wml  867) integrate this as an wml file so translations are easy and images are
en/volunteer.wml  868) generated in multiple languages whenever we build the website. See the
en/volunteer.wml  869) "Translation Wiki" idea above.

en/volunteer.wml  870) </li>
en/volunteer.wml  871) 

en/volunteer.wml  872) <li>
en/volunteer.wml  873) <b>Improve the LiveCD offerings for the Tor community</b>
en/volunteer.wml  874) <br />

en/volunteer.wml  875) Priority: <i>Low</i>
en/volunteer.wml  876) <br />
en/volunteer.wml  877) Effort Level: <i>Low</i>
en/volunteer.wml  878) <br />
en/volunteer.wml  879) Skill Level: <i>Medium to High</i>
en/volunteer.wml  880) <br />

en/volunteer.wml  881) Likely Mentors: <i>Anonym, Jacob, Roger</i>

en/volunteer.wml  882) <br />

en/volunteer.wml  883) How can we make the <a

en/volunteer.wml  884) href="http://anonymityanywhere.com/incognito/">Incognito LiveCD</a>

en/volunteer.wml  885) easier to maintain, improve, and document?
en/volunteer.wml  886) </li>

en/volunteer.wml  887) 

en/volunteer.wml  888) <li>
en/volunteer.wml  889) <b>Rework and extend Blossom</b>
en/volunteer.wml  890) <br />
en/volunteer.wml  891) Priority: <i>Medium</i>
en/volunteer.wml  892) <br />
en/volunteer.wml  893) Effort Level: <i>Medium to High</i>
en/volunteer.wml  894) <br />
en/volunteer.wml  895) Skill Level: <i>Medium to High</i>
en/volunteer.wml  896) <br />
en/volunteer.wml  897) Likely Mentors: <i>Goodell</i>
en/volunteer.wml  898) <br />
en/volunteer.wml  899) Rework and extend Blossom (a tool for monitoring and
en/volunteer.wml  900) selecting appropriate Tor circuits based upon exit node requirements
en/volunteer.wml  901) specified by the user) to gather data in a self-contained way, with
en/volunteer.wml  902) parameters easily configurable by the user.  Blossom is presently
en/volunteer.wml  903) implemented as a single Python script that interfaces with Tor using the
en/volunteer.wml  904) Controller interface and depends upon metadata about Tor nodes obtained
en/volunteer.wml  905) via external processes, such as a webpage indicating status of the nodes
en/volunteer.wml  906) plus publically available data from DNS, whois, etc.  This project has
en/volunteer.wml  907) two parts: (1) Determine which additional metadata may be useful and
en/volunteer.wml  908) rework Blossom so that it cleanly obtains the metadata on its own rather
en/volunteer.wml  909) than depend upon external scripts (this may, for example, involve
en/volunteer.wml  910) additional threads or inter-process communication), and (2) develop a
en/volunteer.wml  911) means by which the user can easily configure Blossom, starting with a
en/volunteer.wml  912) configuration file and possibly working up to a web configuration engine.

en/volunteer.wml  913) Knowledge of Tor and Python are important; knowledge of
en/volunteer.wml  914) TCP, interprocess communication, and Perl will also be helpful.  An
en/volunteer.wml  915) interest in network neutrality is important as well, since the
en/volunteer.wml  916) principles of evaluating and understanding internet inconsistency are at
en/volunteer.wml  917) the core of the Blossom effort.

en/volunteer.wml  918) </li>
en/volunteer.wml  919) 
en/volunteer.wml  920) <li>
en/volunteer.wml  921) <b>Improve Blossom: Allow users to qualitatively describe exit nodes they desire</b>
en/volunteer.wml  922) <br />
en/volunteer.wml  923) Priority: <i>Low</i>
en/volunteer.wml  924) <br />
en/volunteer.wml  925) Effort Level: <i>Medium</i>
en/volunteer.wml  926) <br />
en/volunteer.wml  927) Skill Level: <i>Medium</i>
en/volunteer.wml  928) <br />
en/volunteer.wml  929) Likely Mentors: <i>Goodell</i>
en/volunteer.wml  930) <br />
en/volunteer.wml  931) Develop and implement a means of affording Blossom
en/volunteer.wml  932) users the ability to qualitatively describe the exit node that they
en/volunteer.wml  933) want.  The Internet is an inconsistent place: some Tor exit nodes see
en/volunteer.wml  934) the world differently than others.  As presently implemented, Blossom (a
en/volunteer.wml  935) tool for monitoring and selecting appropriate Tor circuits based upon
en/volunteer.wml  936) exit node requirements specified by the user) lacks a sufficiently rich
en/volunteer.wml  937) language to describe how the different vantage points are different.
en/volunteer.wml  938) For example, some exit nodes may have an upstream network that filters
en/volunteer.wml  939) certain kinds of traffic or certain websites.  Other exit nodes may
en/volunteer.wml  940) provide access to special content as a result of their location, perhaps
en/volunteer.wml  941) as a result of discrimination on the part of the content providers
en/volunteer.wml  942) themselves.  This project has two parts: (1) develop a language for
en/volunteer.wml  943) describing characteristics of networks in which exit nodes reside, and
en/volunteer.wml  944) (2) incorporate this language into Blossom so that users can select Tor
en/volunteer.wml  945) paths based upon the description.

en/volunteer.wml  946) Knowledge of Tor and Python are important; knowledge of
en/volunteer.wml  947) TCP, interprocess communication, and Perl will also be helpful.  An
en/volunteer.wml  948) interest in network neutrality is important as well, since the
en/volunteer.wml  949) principles of evaluating and understanding internet inconsistency are at
en/volunteer.wml  950) the core of the Blossom effort.

en/volunteer.wml  951) </li>
en/volunteer.wml  952) 

en/volunteer.wml  953) <li>
en/volunteer.wml  954) <b>Bring up new ideas!</b>
en/volunteer.wml  955) <br />
en/volunteer.wml  956) Don't like any of these? Look at the <a

en/volunteer.wml  957) href="<svnsandbox>doc/design-paper/roadmap-future.pdf">Tor development

en/volunteer.wml  958) roadmap</a> for more ideas.
en/volunteer.wml  959) </li>
en/volunteer.wml  960) 

en/volunteer.wml  961) </ol>
en/volunteer.wml  962) 

en/volunteer.wml  963) <h2><a class="anchor" href="#Coding">Coding and Design</a></h2>

volunteer.html    964) <ol>

en/volunteer.wml  965) <li>Tor relays don't work well on Windows XP. On

en/volunteer.wml  966) Windows, Tor uses the standard <tt>select()</tt> system

en/volunteer.wml  967) call, which uses space in the non-page pool. This means

en/volunteer.wml  968) that a medium sized Tor relay will empty the non-page pool, <a

en/volunteer.wml  969) href="https://wiki.torproject.org/noreply/TheOnionRouter/WindowsBufferProblems">causing

en/volunteer.wml  970) havoc and system crashes</a>. We should probably be using overlapped IO

en/volunteer.wml  971) instead. One solution would be to teach <a
en/volunteer.wml  972) href="http://www.monkey.org/~provos/libevent/">libevent</a> how to use
en/volunteer.wml  973) overlapped IO rather than select() on Windows, and then adapt Tor to

en/volunteer.wml  974) the new libevent interface. Christian King made a
en/volunteer.wml  975) <a href="https://tor-svn.freehaven.net/svn/libevent-urz/trunk/">good

en/volunteer.wml  976) start</a> on this in the summer of 2007.</li>

en/volunteer.wml  977) <li>We need to actually start building our <a href="<page
en/volunteer.wml  978) documentation>#DesignDoc">blocking-resistance design</a>. This involves

en/volunteer.wml  979) fleshing out the design, modifying many different pieces of Tor, adapting
en/volunteer.wml  980) <a href="http://vidalia-project.net/">Vidalia</a> so it supports the
en/volunteer.wml  981) new features, and planning for deployment.</li>

en/volunteer.wml  982) <li>We need a flexible simulator framework for studying end-to-end
en/volunteer.wml  983) traffic confirmation attacks. Many researchers have whipped up ad hoc
en/volunteer.wml  984) simulators to support their intuition either that the attacks work
en/volunteer.wml  985) really well or that some defense works great. Can we build a simulator
en/volunteer.wml  986) that's clearly documented and open enough that everybody knows it's
en/volunteer.wml  987) giving a reasonable answer? This will spur a lot of new research.
en/volunteer.wml  988) See the entry <a href="#Research">below</a> on confirmation attacks for
en/volunteer.wml  989) details on the research side of this task &mdash; who knows, when it's
en/volunteer.wml  990) done maybe you can help write a paper or three also.</li>

en/volunteer.wml  991) <li>Tor 0.1.1.x and later include support for hardware crypto accelerators

en/volunteer.wml  992) via OpenSSL. Nobody has ever tested it, though. Does somebody want to get

volunteer.html    993) a card and let us know how it goes?</li>

volunteer.html    994) <li>Perform a security analysis of Tor with <a
volunteer.html    995) href="http://en.wikipedia.org/wiki/Fuzz_testing">"fuzz"</a>. Determine

en/volunteer.wml  996) if there are good fuzzing libraries out there for what we want. Win fame by

volunteer.html    997) getting credit when we put out a new release because of you!</li>

volunteer.html    998) <li>Tor uses TCP for transport and TLS for link
volunteer.html    999) encryption. This is nice and simple, but it means all cells
volunteer.html   1000) on a link are delayed when a single packet gets dropped, and
volunteer.html   1001) it means we can only reasonably support TCP streams. We have a <a

en/volunteer.wml 1002) href="https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#TransportIPnotTCP">list

en/volunteer.wml 1003) of reasons why we haven't shifted to UDP transport</a>, but it would
en/volunteer.wml 1004) be great to see that list get shorter. We also have a proposed <a

en/volunteer.wml 1005) href="<svnsandbox>doc/spec/proposals/100-tor-spec-udp.txt">specification
en/volunteer.wml 1006) for Tor and

en/volunteer.wml 1007) UDP</a> &mdash; please let us know what's wrong with it.</li>

volunteer.html   1008) <li>We're not that far from having IPv6 support for destination addresses
volunteer.html   1009) (at exit nodes). If you care strongly about IPv6, that's probably the
volunteer.html   1010) first place to start.</li>

volunteer.html   1011) </ol>
volunteer.html   1012) 

en/volunteer.wml 1013) <a id="Research"></a>
en/volunteer.wml 1014) <h2><a class="anchor" href="#Research">Research</a></h2>

volunteer.html   1015) <ol>

volunteer.html   1016) <li>The "website fingerprinting attack": make a list of a few
volunteer.html   1017) hundred popular websites, download their pages, and make a set of
volunteer.html   1018) "signatures" for each site. Then observe a Tor client's traffic. As
volunteer.html   1019) you watch him receive data, you quickly approach a guess about which
volunteer.html   1020) (if any) of those sites he is visiting. First, how effective is
volunteer.html   1021) this attack on the deployed Tor codebase? Then start exploring
volunteer.html   1022) defenses: for example, we could change Tor's cell size from 512
volunteer.html   1023) bytes to 1024 bytes, we could employ padding techniques like <a
volunteer.html   1024) href="http://freehaven.net/anonbib/#timing-fc2004">defensive dropping</a>,
volunteer.html   1025) or we could add traffic delays. How much of an impact do these have,
volunteer.html   1026) and how much usability impact (using some suitable metric) is there from
volunteer.html   1027) a successful defense in each case?</li>

volunteer.html   1028) <li>The "end-to-end traffic confirmation attack":
volunteer.html   1029) by watching traffic at Alice and at Bob, we can <a
volunteer.html   1030) href="http://freehaven.net/anonbib/#danezis:pet2004">compare
volunteer.html   1031) traffic signatures and become convinced that we're watching the same
volunteer.html   1032) stream</a>. So far Tor accepts this as a fact of life and assumes this
volunteer.html   1033) attack is trivial in all cases. First of all, is that actually true? How
volunteer.html   1034) much traffic of what sort of distribution is needed before the adversary
volunteer.html   1035) is confident he has won? Are there scenarios (e.g. not transmitting much)
volunteer.html   1036) that slow down the attack? Do some traffic padding or traffic shaping
volunteer.html   1037) schemes work better than others?</li>

en/volunteer.wml 1038) <li>A related question is: Does running a relay/bridge provide additional
en/volunteer.wml 1039) protection against these timing attacks? Can an external adversary that can't

en/volunteer.wml 1040) see inside TLS links still recognize individual streams reliably?

en/volunteer.wml 1041) Does the amount of traffic carried degrade this ability any? What if the
en/volunteer.wml 1042) client-relay deliberately delayed upstream relayed traffic to create a queue
en/volunteer.wml 1043) that could be used to mimic timings of client downstream traffic to make it
en/volunteer.wml 1044) look like it was also relayed? This same queue could also be used for masking
en/volunteer.wml 1045) timings in client upstream traffic with the techniques from <a
en/volunteer.wml 1046) href="http://www.freehaven.net/anonbib/#ShWa-Timing06">adaptive padding</a>,
en/volunteer.wml 1047) but without the need for additional traffic. Would such an interleaving of
en/volunteer.wml 1048) client upstream traffic obscure timings for external adversaries? Would the
en/volunteer.wml 1049) strategies need to be adjusted for asymmetric links? For example, on
en/volunteer.wml 1050) asymmetric links, is it actually possible to differentiate client traffic from
en/volunteer.wml 1051) natural bursts due to their asymmetric capacity? Or is it easier than
en/volunteer.wml 1052) symmetric links for some other reason?</li>

volunteer.html   1053) <li>The "routing zones attack": most of the literature thinks of
volunteer.html   1054) the network path between Alice and her entry node (and between the
volunteer.html   1055) exit node and Bob) as a single link on some graph. In practice,
volunteer.html   1056) though, the path traverses many autonomous systems (ASes), and <a
volunteer.html   1057) href="http://freehaven.net/anonbib/#feamster:wpes2004">it's not uncommon
volunteer.html   1058) that the same AS appears on both the entry path and the exit path</a>.
volunteer.html   1059) Unfortunately, to accurately predict whether a given Alice, entry,
volunteer.html   1060) exit, Bob quad will be dangerous, we need to download an entire Internet
volunteer.html   1061) routing zone and perform expensive operations on it. Are there practical
volunteer.html   1062) approximations, such as avoiding IP addresses in the same /8 network?</li>

en/volunteer.wml 1063) <li>Other research questions regarding geographic diversity consider
en/volunteer.wml 1064) the tradeoff between choosing an efficient circuit and choosing a random

en/volunteer.wml 1065) circuit. Look at Stephen Rollyson's <a

en/volunteer.wml 1066) href="http://swiki.cc.gatech.edu:8080/ugResearch/uploads/7/ImprovingTor.pdf">position
en/volunteer.wml 1067) paper</a> on how to discard particularly slow choices without hurting

en/volunteer.wml 1068) anonymity "too much". This line of reasoning needs more work and more
en/volunteer.wml 1069) thinking, but it looks very promising.</li>

en/volunteer.wml 1070) <li>Tor doesn't work very well when relays have asymmetric bandwidth

volunteer.html   1071) (e.g. cable or DSL). Because Tor has separate TCP connections between
volunteer.html   1072) each hop, if the incoming bytes are arriving just fine and the outgoing
volunteer.html   1073) bytes are all getting dropped on the floor, the TCP push-back mechanisms
volunteer.html   1074) don't really transmit this information back to the incoming streams.
volunteer.html   1075) Perhaps Tor should detect when it's dropping a lot of outgoing packets,
volunteer.html   1076) and rate-limit incoming streams to regulate this itself? I can imagine
volunteer.html   1077) a build-up and drop-off scheme where we pick a conservative rate-limit,
volunteer.html   1078) slowly increase it until we get lost packets, back off, repeat. We
volunteer.html   1079) need somebody who's good with networks to simulate this and help design
volunteer.html   1080) solutions; and/or we need to understand the extent of the performance
volunteer.html   1081) degradation, and use this as motivation to reconsider UDP transport.</li>
volunteer.html   1082) <li>A related topic is congestion control. Is our
volunteer.html   1083) current design sufficient once we have heavy use? Maybe
volunteer.html   1084) we should experiment with variable-sized windows rather
volunteer.html   1085) than fixed-size windows? That seemed to go well in an <a
volunteer.html   1086) href="http://www.psc.edu/networking/projects/hpn-ssh/theory.php">ssh
volunteer.html   1087) throughput experiment</a>. We'll need to measure and tweak, and maybe
volunteer.html   1088) overhaul if the results are good.</li>

volunteer.html   1089) <li>To let dissidents in remote countries use Tor without being blocked
volunteer.html   1090) at their country's firewall, we need a way to get tens of thousands of
volunteer.html   1091) relays, not just a few hundred. We can imagine a Tor client GUI that

en/volunteer.wml 1092) has a "Tor for Freedom" button at the top that opens a port and relays a

volunteer.html   1093) few KB/s of traffic into the Tor network. (A few KB/s shouldn't be too
volunteer.html   1094) much hassle, and there are few abuse issues since they're not being exit
volunteer.html   1095) nodes.) But how do we distribute a list of these volunteer clients to the
volunteer.html   1096) good dissidents in an automated way that doesn't let the country-level

en/volunteer.wml 1097) firewalls intercept and enumerate them? This probably needs to work on a

en/volunteer.wml 1098) human-trust level. See our <a href="<page documentation>#DesignDoc">early
en/volunteer.wml 1099) blocking-resistance design document</a> and our
en/volunteer.wml 1100) <a

en/volunteer.wml 1101) href="https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#BlockingResistance">FAQ

en/volunteer.wml 1102) entry</a> on this, and then read the <a
en/volunteer.wml 1103) href="http://freehaven.net/anonbib/topic.html#Communications_20Censorship">censorship
en/volunteer.wml 1104) resistance section of anonbib</a>.</li>

volunteer.html   1105) <li>Tor circuits are built one hop at a time, so in theory we have the
volunteer.html   1106) ability to make some streams exit from the second hop, some from the
volunteer.html   1107) third, and so on. This seems nice because it breaks up the set of exiting

en/volunteer.wml 1108) streams that a given relay can see. But if we want each stream to be safe,

volunteer.html   1109) the "shortest" path should be at least 3 hops long by our current logic, so
volunteer.html   1110) the rest will be even longer. We need to examine this performance / security
volunteer.html   1111) tradeoff.</li>

en/volunteer.wml 1112) <li>It's not that hard to DoS Tor relays or directory authorities. Are client

volunteer.html   1113) puzzles the right answer? What other practical approaches are there? Bonus
volunteer.html   1114) if they're backward-compatible with the current Tor protocol.</li>

en/volunteer.wml 1115) <li>Programs like <a
en/volunteer.wml 1116) href="https://torbutton.torproject.org/dev/">Torbutton</a> aim to hide
en/volunteer.wml 1117) your browser's UserAgent string by replacing it with a uniform answer for
en/volunteer.wml 1118) every Tor user. That way the attacker can't splinter Tor's anonymity set
en/volunteer.wml 1119) by looking at that header. It tries to pick a string that is commonly used
en/volunteer.wml 1120) by non-Tor users too, so it doesn't stand out. Question one: how badly
en/volunteer.wml 1121) do we hurt ourselves by periodically updating the version of Firefox
en/volunteer.wml 1122) that Torbutton claims to be? If we update it too often, we splinter the
en/volunteer.wml 1123) anonymity sets ourselves. If we don't update it often enough, then all the
en/volunteer.wml 1124) Tor users stand out because they claim to be running a quite old version
en/volunteer.wml 1125) of Firefox. The answer here probably depends on the Firefox versions seen
en/volunteer.wml 1126) in the wild. Question two: periodically people ask us to cycle through N
en/volunteer.wml 1127) UserAgent strings rather than stick with one. Does this approach help,
en/volunteer.wml 1128) hurt, or not matter? Consider: cookies and recognizing Torbutton users
en/volunteer.wml 1129) by their rotating UserAgents; malicious websites who only attack certain
en/volunteer.wml 1130) browsers; and whether the answers to question one impact this answer.
en/volunteer.wml 1131) </li>

volunteer.html   1132) </ol>
volunteer.html   1133) 

en/volunteer.wml 1134) <p>

en/volunteer.wml 1135) <a href="<page contact>">Let us know</a> if you've made progress on any
en/volunteer.wml 1136) of these!

en/volunteer.wml 1137) </p>

volunteer.html   1138) 

en/volunteer.wml 1139)   </div><!-- #main -->

volunteer.html   1140) 

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