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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.
en/volunteer.wml  102) </p>
en/volunteer.wml  103) 

en/volunteer.wml  104) <ol>
en/volunteer.wml  105) 

en/volunteer.wml  106) <li>

en/volunteer.wml  107) <b>Tor Exit Scanner improvements</b>

en/volunteer.wml  108) <br />

en/volunteer.wml  109) Priority: <i>High</i>
en/volunteer.wml  110) <br />
en/volunteer.wml  111) Effort Level: <i>High</i>
en/volunteer.wml  112) <br />

en/volunteer.wml  113) Skill Level: <i>High</i>
en/volunteer.wml  114) <br />

en/volunteer.wml  115) Likely Mentors: <i>Mike</i>

en/volunteer.wml  116) <br />

en/volunteer.wml  117) The Tor exit node scanner 'SoaT', part of the <a
en/volunteer.wml  118) href="<svnsandbox>torflow/">Torflow project</a>, makes connections out
en/volunteer.wml  119) of each Tor exit node and compares the content it gets back with what it
en/volunteer.wml  120) "should" get back. The goal is to notice misconfigured, broken, and even
en/volunteer.wml  121) malicious exit relays. Alas, the code is
en/volunteer.wml  122) currently written in rather rickety perl and relies on MD5sums of
en/volunteer.wml  123) entire documents in order to determine if exit nodes are modifying
en/volunteer.wml  124) content. The problem with this is threefold: 1) Perl sucks at life.
en/volunteer.wml  125) 2) The scanner can't verify pages that are dynamic, and attackers can
en/volunteer.wml  126) focus malicious content injection on only those dynamic pages. 3)
en/volunteer.wml  127) Pages change after a while (or based on GeoIP) and begin generating
en/volunteer.wml  128) false positives.

en/volunteer.wml  129) <br />

en/volunteer.wml  130) Ideally, soat.pl would be reimplemented in a sane language with a
en/volunteer.wml  131) robust html parser library (since the rest of Torflow is in Python
en/volunteer.wml  132) that would be nice, but it is not required), and calculate signatures only for
en/volunteer.wml  133) tags and content likely to be targeted by a malicious attacker (script
en/volunteer.wml  134) tags, object links, images, css). It should also be robust in the face of
en/volunteer.wml  135) changes to content outside of Tor, and ultimately even GeoIP localized
en/volunteer.wml  136) content.
en/volunteer.wml  137) <br />
en/volunteer.wml  138) This scanner would likely be run by the Directory Authorities and
en/volunteer.wml  139) report its results to the control port via the AuthDirBadExit config
en/volunteer.wml  140) setting.

en/volunteer.wml  141) <br />
en/volunteer.wml  142) </li>
en/volunteer.wml  143) 
en/volunteer.wml  144) <li>

en/volunteer.wml  145) <b>Tor Node Scanner improvements</b>

en/volunteer.wml  146) <br />

en/volunteer.wml  147) Priority: <i>High</i>

en/volunteer.wml  148) <br />

en/volunteer.wml  149) Effort Level: <i>Medium to High</i>

en/volunteer.wml  150) <br />
en/volunteer.wml  151) Skill Level: <i>Medium to High</i>
en/volunteer.wml  152) <br />

en/volunteer.wml  153) Likely Mentors: <i>Mike</i>

en/volunteer.wml  154) <br />

en/volunteer.wml  155) Similar to the exit scanner (or perhaps even during exit scanning),
en/volunteer.wml  156) statistics can be gathered about the reliability of nodes. Nodes that
en/volunteer.wml  157) fail too high a percentage of their circuits should not be given
en/volunteer.wml  158) Guard status. Perhaps they should have their reported bandwidth
en/volunteer.wml  159) penalized by some ratio as well, or just get marked as Invalid. In
en/volunteer.wml  160) addition, nodes that exhibit a very low average stream capacity but
en/volunteer.wml  161) advertise a very high node bandwidth can also be marked as Invalid.
en/volunteer.wml  162) Much of this statistics gathering is already done, it just needs to be
en/volunteer.wml  163) transformed into something that can be reported to the Directory
en/volunteer.wml  164) Authorities to blacklist/penalize nodes in such a way that clients
en/volunteer.wml  165) will listen.

en/volunteer.wml  166) <br />

en/volunteer.wml  167) In addition, these same statistics can be gathered about the traffic
en/volunteer.wml  168) through a node. Events can be added to the <a
en/volunteer.wml  169) href="https://www.torproject.org/svn/torctl/doc/howto.txt">Tor Control
en/volunteer.wml  170) Protocol</a> to
en/volunteer.wml  171) report if a circuit extend attempt through the node succeeds or fails, and
en/volunteer.wml  172) passive statistics can be gathered on both bandwidth and reliability
en/volunteer.wml  173) of other nodes via a node-based monitor using these events. Such a
en/volunteer.wml  174) scanner would also report information on oddly-behaving nodes to
en/volunteer.wml  175) the Directory Authorities, but a communication channel for this
en/volunteer.wml  176) currently does not exist and would need to be developed as well.
en/volunteer.wml  177) </li>
en/volunteer.wml  178) 
en/volunteer.wml  179) <li>
en/volunteer.wml  180) <b>Help track the overall Tor Network status</b>

en/volunteer.wml  181) <br />

en/volunteer.wml  182) Priority: <i>High</i>
en/volunteer.wml  183) <br />
en/volunteer.wml  184) Effort Level: <i>Medium</i>
en/volunteer.wml  185) <br />
en/volunteer.wml  186) Skill Level: <i>Medium</i>
en/volunteer.wml  187) <br />
en/volunteer.wml  188) Likely Mentors: <i>Roger, Nick, Mike</i>
en/volunteer.wml  189) <br />
en/volunteer.wml  190) It would be great to set up an automated system for tracking network
en/volunteer.wml  191) health over time, graphing it, etc. Part of this project would involve
en/volunteer.wml  192) inventing better metrics for assessing network health and growth. Is the
en/volunteer.wml  193) average uptime of the network increasing? How many relays are qualifying
en/volunteer.wml  194) for Guard status this month compared to last month? What's the turnover
en/volunteer.wml  195) in terms of new relays showing up and relays shutting off? Periodically
en/volunteer.wml  196) people collect brief snapshots, but where it gets really interesting is
en/volunteer.wml  197) when we start tracking data points over time.
en/volunteer.wml  198) <br />
en/volunteer.wml  199) Data could be collected from the "Tor Node Scanner" item above, from
en/volunteer.wml  200) the server descriptors that each relay publishes, and from other
en/volunteer.wml  201) sources. Results over time could be integrated into one of the <a
en/volunteer.wml  202) href="https://torstatus.blutmagie.de/">Tor Status</a> web pages, or be
en/volunteer.wml  203) kept separate. Speaking of the Tor Status pages, take a look at Roger's
en/volunteer.wml  204) <a href="http://archives.seul.org/or/talk/Jan-2008/msg00300.html">Tor
en/volunteer.wml  205) Status wish list</a>.
en/volunteer.wml  206) </li>
en/volunteer.wml  207) 
en/volunteer.wml  208) <li>
en/volunteer.wml  209) <b>Tor path selection improvements</b>
en/volunteer.wml  210) <br />
en/volunteer.wml  211) Priority: <i>High</i>
en/volunteer.wml  212) <br />
en/volunteer.wml  213) Effort Level: <i>Low to Medium</i>
en/volunteer.wml  214) <br />
en/volunteer.wml  215) Skill Level: <i>High</i>
en/volunteer.wml  216) <br />
en/volunteer.wml  217) Likely Mentors: <i>Roger, Nick, Mike</i>
en/volunteer.wml  218) <br />
en/volunteer.wml  219) Some simple improvements can be made to Tor's path selection to vastly
en/volunteer.wml  220) improve Tor speed. For instance, some of the (unofficial) <a
en/volunteer.wml  221) href="http://wiki.noreply.org/noreply/TheOnionRouter/FireFoxTorPerf">Tor
en/volunteer.wml  222) Performance Recommendations</a> on the wiki are to increase the number of
en/volunteer.wml  223) guards and decrease the CircuitBuildTimeout. Ideally, the client would
en/volunteer.wml  224) <a href="http://archives.seul.org/or/talk/Feb-2008/msg00012.html">learn
en/volunteer.wml  225) these values by gathering statistics on circuit construction
en/volunteer.wml  226) time</a> (and/or using values gained from Torflow), and set the timeouts
en/volunteer.wml  227) low enough such that some high percentile (75%, 90%, 1-stddev?) of
en/volunteer.wml  228) circuits succeed, yet extremely slow nodes are avoided. This would
en/volunteer.wml  229) involve some statistics gathering+basic research, and some changes to
en/volunteer.wml  230) Tor path selection code.
en/volunteer.wml  231) <br />
en/volunteer.wml  232) In addition, to improve path security, some elements from the <a
en/volunteer.wml  233) href="http://www.torproject.org/svn/trunk/doc/spec/proposals/115-two-hop-paths.txt">Two
en/volunteer.wml  234) Hop Paths proposal</a> could be done as part of this (since it will
en/volunteer.wml  235) likely touch the same code anyways), regardless of the adoption of
en/volunteer.wml  236) that proposal. In particular, clients probably should avoid guards that
en/volunteer.wml  237) seem to fail an excessive percentage of their circuits through them,
en/volunteer.wml  238) and non-firewalled clients should issue a warning if they are only able
en/volunteer.wml  239) to connect to a limited set of guard nodes. See also
en/volunteer.wml  240) <a href="http://archives.seul.org/or/dev/Feb-2008/msg00003.html">this
en/volunteer.wml  241) or-dev post</a>.

en/volunteer.wml  242) </li>
en/volunteer.wml  243) 
en/volunteer.wml  244) <li>

en/volunteer.wml  245) <b>Translation Wiki</b>
en/volunteer.wml  246) <br />
en/volunteer.wml  247) Priority: <i>High</i>
en/volunteer.wml  248) <br />
en/volunteer.wml  249) Effort Level: <i>Medium</i>
en/volunteer.wml  250) <br />
en/volunteer.wml  251) Skill Level: <i>Medium</i>
en/volunteer.wml  252) <br />
en/volunteer.wml  253) Likely Mentors: <i>Jacob</i>
en/volunteer.wml  254) <br />
en/volunteer.wml  255) We need a way to edit and translate sections of the website. Currently
en/volunteer.wml  256) the website is made up of a bunch of <a href="<svnwebsite>en/">wml
en/volunteer.wml  257) files</a>, and <a href="<page translation>">translators</a> fetch these
en/volunteer.wml  258) wml files, translate them in an editor, and either send us the translation
en/volunteer.wml  259) or use svn to commit them back. The current "cost" of publication of
en/volunteer.wml  260) website changes is quite high even for English language users. For a
en/volunteer.wml  261) single word change or any type of
en/volunteer.wml  262) minor change, the page may never be corrected or translated. It would
en/volunteer.wml  263) be nice to have a wiki that was specifically geared towards translation
en/volunteer.wml  264) and would somehow track the upstream (English) versions to indicate when
en/volunteer.wml  265) a fresh translation is needed, like our current
en/volunteer.wml  266) <a href="<page translation-status>">translation status page</a>. This
en/volunteer.wml  267) seems mostly like a job for a wiki
en/volunteer.wml  268) integrator or wiki software author. Certainly the person would need to
en/volunteer.wml  269) be interested in human languages and translation. They should at least
en/volunteer.wml  270) be minimally familiar with what Tor is; but they would not have to interact
en/volunteer.wml  271) with the software, only the documentation and the website.
en/volunteer.wml  272) </li>
en/volunteer.wml  273) 
en/volunteer.wml  274) <li>
en/volunteer.wml  275) <b>Better Debian/Ubuntu Packaging for Tor+Vidalia</b>

en/volunteer.wml  276) <br />

en/volunteer.wml  277) Priority: <i>High</i>
en/volunteer.wml  278) <br />
en/volunteer.wml  279) Effort Level: <i>Medium</i>
en/volunteer.wml  280) <br />
en/volunteer.wml  281) Skill Level: <i>Medium</i>
en/volunteer.wml  282) <br />

en/volunteer.wml  283) Likely Mentors: <i>Peter, Matt</i>

en/volunteer.wml  284) <br />

en/volunteer.wml  285) Vidalia currently doesn't play nicely on Debian and Ubuntu with the
en/volunteer.wml  286) default Tor packages. The current Tor packages automatically start Tor
en/volunteer.wml  287) as a daemon running as the debian-tor user and (sensibly) do not have a

en/volunteer.wml  288) <a href="<svnsandbox>doc/spec/control-spec.txt">ControlPort</a> defined
en/volunteer.wml  289) in the default torrc. Consequently, Vidalia will try

en/volunteer.wml  290) to start its own Tor process since it could not connect to the existing

en/volunteer.wml  291) Tor, and Vidalia's Tor process will then exit with an error message

en/volunteer.wml  292) the user likely doesn't understand since Tor cannot bind its listening

en/volunteer.wml  293) ports — they're already in use by the original Tor daemon.

en/volunteer.wml  294) <br />
en/volunteer.wml  295) The current solution involves either telling the user to stop the
en/volunteer.wml  296) existing Tor daemon and let Vidalia start its own Tor process, or
en/volunteer.wml  297) explaining to the user how to set a control port and password in their
en/volunteer.wml  298) torrc. A better solution on Debian would be to use Tor's ControlSocket,
en/volunteer.wml  299) which allows Vidalia to talk to Tor via a Unix domain socket, and could
en/volunteer.wml  300) possibly be enabled by default in Tor's Debian packages. Vidalia can

en/volunteer.wml  301) then authenticate to Tor using filesystem-based (cookie) authentication
en/volunteer.wml  302) if the user running Vidalia is also in the debian-tor group.

en/volunteer.wml  303) <br />
en/volunteer.wml  304) This project will first involve adding support for Tor's ControlSocket
en/volunteer.wml  305) to Vidalia. The student will then develop and test Debian and Ubuntu
en/volunteer.wml  306) packages for Vidalia that conform to Debian's packaging standards and

en/volunteer.wml  307) make sure they work well with the existing Tor packages. We can also

en/volunteer.wml  308) set up an apt repository to host the new Vidalia packages.
en/volunteer.wml  309) <br />

en/volunteer.wml  310) The next challenge would be to find an intuitive usable way for Vidalia
en/volunteer.wml  311) to be able to change Tor's configuration (torrc) even though it is
en/volunteer.wml  312) located in <code>/etc/tor/torrc</code> and thus immutable. The best
en/volunteer.wml  313) idea we've come up with so far is to feed Tor a new configuration via
en/volunteer.wml  314) the ControlSocket when Vidalia starts, but that's bad because Tor starts

en/volunteer.wml  315) each boot with a different configuration than the user wants. The second
en/volunteer.wml  316) best idea

en/volunteer.wml  317) we've come up with is for Vidalia to write out a temporary torrc file
en/volunteer.wml  318) and ask the user to manually move it to <code>/etc/tor/torrc</code>,
en/volunteer.wml  319) but that's bad because users shouldn't have to mess with files directly.
en/volunteer.wml  320) <br />

en/volunteer.wml  321) A student undertaking this project should have prior knowledge of
en/volunteer.wml  322) Debian package management and some C++ development experience. Previous
en/volunteer.wml  323) experience with Qt is helpful, but not required.
en/volunteer.wml  324) </li>
en/volunteer.wml  325) 

en/volunteer.wml  326) <li>
en/volunteer.wml  327) <b>Improving Tor's ability to resist censorship</b>
en/volunteer.wml  328) <br />
en/volunteer.wml  329) Priority: <i>High</i>
en/volunteer.wml  330) <br />
en/volunteer.wml  331) Effort Level: <i>High</i>
en/volunteer.wml  332) <br />
en/volunteer.wml  333) Skill Level: <i>High</i>
en/volunteer.wml  334) <br />
en/volunteer.wml  335) Likely Mentors: <i>Nick</i>
en/volunteer.wml  336) <br />
en/volunteer.wml  337) The Tor 0.2.0.x series makes <a
en/volunteer.wml  338) href="<svnsandbox>doc/design-paper/blocking.html">significant
en/volunteer.wml  339) improvements</a> in resisting national and organizational censorship.
en/volunteer.wml  340) But Tor still needs better mechanisms for some parts of its
en/volunteer.wml  341) anti-censorship design.  For example, current Tors can only listen on a
en/volunteer.wml  342) single address/port combination at a time.  There's
en/volunteer.wml  343) <a href="<svnsandbox>doc/spec/proposals/118-multiple-orports.txt">a
en/volunteer.wml  344) proposal to address this limitation</a> and allow clients to connect
en/volunteer.wml  345) to any given Tor on multiple addresses and ports, but it needs more
en/volunteer.wml  346) work.  Another anti-censorship project (far more difficult) is to try
en/volunteer.wml  347) to make Tor more scanning-resistant.  Right now, an adversary can identify
en/volunteer.wml  348) <a href="<svnsandbox>doc/spec/proposals/125-bridges.txt">Tor bridges</a>
en/volunteer.wml  349) just by trying to connect to them, following the Tor protocol, and
en/volunteer.wml  350) seeing if they respond.  To solve this, bridges could
en/volunteer.wml  351) <a href="<svnsandbox>doc/design-paper/blocking.html#tth_sEc9.3">act like
en/volunteer.wml  352) webservers</a> (HTTP or HTTPS) when contacted by port-scanning tools,
en/volunteer.wml  353) and not act like bridges until the user provides a bridge-specific key.
en/volunteer.wml  354) <br />
en/volunteer.wml  355) This project involves a lot of research and design. One of the big
en/volunteer.wml  356) challenges will be identifying and crafting approaches that can still
en/volunteer.wml  357) resist an adversary even after the adversary knows the design, and
en/volunteer.wml  358) then trading off censorship resistance with usability and robustness.
en/volunteer.wml  359) </li>
en/volunteer.wml  360) 
en/volunteer.wml  361) <li>
en/volunteer.wml  362) <b>Tor/Polipo/Vidalia Auto-Update Framework</b>
en/volunteer.wml  363) <br />
en/volunteer.wml  364) Priority: <i>Medium</i>
en/volunteer.wml  365) <br />
en/volunteer.wml  366) Effort Level: <i>High</i>
en/volunteer.wml  367) <br />
en/volunteer.wml  368) Skill Level: <i>High</i>
en/volunteer.wml  369) <br />
en/volunteer.wml  370) Likely Mentors: <i>Matt, Jacob</i>
en/volunteer.wml  371) <br />
en/volunteer.wml  372) We're in need of a good authenticated-update framework.
en/volunteer.wml  373) Vidalia already has the ability to notice when the user is running an
en/volunteer.wml  374) outdated or unrecommended version of Tor, using signed statements inside
en/volunteer.wml  375) the Tor directory information. Currently, Vidalia simply pops
en/volunteer.wml  376) up a little message box that lets the user know they should manually
en/volunteer.wml  377) upgrade. The goal of this project would be to extend Vidalia with the
en/volunteer.wml  378) ability to also fetch and install the updated Tor software for the
en/volunteer.wml  379) user. We should do the fetches via Tor when possible, but also fall back
en/volunteer.wml  380) to direct fetches in a smart way. Time permitting, we would also like
en/volunteer.wml  381) to be able to update other
en/volunteer.wml  382) applications included in the bundled installers, such as Polipo and
en/volunteer.wml  383) Vidalia itself.
en/volunteer.wml  384) <br />
en/volunteer.wml  385) To complete this project, the student will first need to first investigate
en/volunteer.wml  386) the existing auto-update frameworks (e.g., Sparkle on OS X) to evaluate
en/volunteer.wml  387) their strengths, weaknesses, security properties, and ability to be
en/volunteer.wml  388) integrated into Vidalia. If none are found to be suitable, the student
en/volunteer.wml  389) will design their own auto-update framework, document the design, and
en/volunteer.wml  390) then discuss the design with other developers to assess any security
en/volunteer.wml  391) issues. The student will then implement their framework (or integrate
en/volunteer.wml  392) an existing one) and test it.
en/volunteer.wml  393) <br />
en/volunteer.wml  394) A student undertaking this project should have good C++ development
en/volunteer.wml  395) experience. Previous experience with Qt is helpful, but not required. The
en/volunteer.wml  396) student should also have a good understanding of common security
en/volunteer.wml  397) practices, such as package signature verification. Good writing ability
en/volunteer.wml  398) is also important for this project, since a vital step of the project
en/volunteer.wml  399) will be producing a design document for others to review and discuss
en/volunteer.wml  400) with the student prior to implementation.
en/volunteer.wml  401) </li>
en/volunteer.wml  402) 
en/volunteer.wml  403) <li>
en/volunteer.wml  404) <b>An Improved and More Usable Network Map in Vidalia</b>
en/volunteer.wml  405) <br />
en/volunteer.wml  406) Priority: <i>Medium</i>
en/volunteer.wml  407) <br />
en/volunteer.wml  408) Effort Level: <i>Medium</i>
en/volunteer.wml  409) <br />
en/volunteer.wml  410) Skill Level: <i>Medium to High</i>
en/volunteer.wml  411) <br />
en/volunteer.wml  412) Likely Mentors: <i>Matt</i>
en/volunteer.wml  413) <br />
en/volunteer.wml  414) One of Vidalia's existing features is a network map that shows the user
en/volunteer.wml  415) the approximate geographic location of relays in the Tor network and
en/volunteer.wml  416) plots the paths the user's traffic takes as it is tunneled through the
en/volunteer.wml  417) Tor network. The map is currently not very interactive and has rather
en/volunteer.wml  418) poor graphics. Instead, we would like to leverage KDE's Marble widget
en/volunteer.wml  419) that gives us a better quality map and enables improved interactivity,
en/volunteer.wml  420) such as allowing the user to click on individual relays or circuits to
en/volunteer.wml  421) display additional information. We might also consider adding the ability
en/volunteer.wml  422) for users to click on a particular relay or a country containing one or
en/volunteer.wml  423) more Tor exit relays and say, "I want my connections to foo.com to exit
en/volunteer.wml  424) from here."
en/volunteer.wml  425) <br />
en/volunteer.wml  426) This project will first involve the student getting familiar with Vidalia
en/volunteer.wml  427) and the Marble widget's API. The student will then integrate the widget
en/volunteer.wml  428) into Vidalia and customize Marble to be better suited for our application,
en/volunteer.wml  429) such as making circuits clickable, storing cached map data in Vidalia's
en/volunteer.wml  430) own data directory, and customizing some of the widget's dialogs.
en/volunteer.wml  431) <br />
en/volunteer.wml  432) A student undertaking this project should have good C++ development
en/volunteer.wml  433) experience. Previous experience with Qt and CMake is helpful, but not
en/volunteer.wml  434) required.
en/volunteer.wml  435) </li>
en/volunteer.wml  436) 

en/volunteer.wml  437) <li>

en/volunteer.wml  438) <b>Tor Controller Status Event Interface</b>

en/volunteer.wml  439) <br />

en/volunteer.wml  440) Priority: <i>Medium</i>
en/volunteer.wml  441) <br />
en/volunteer.wml  442) Effort Level: <i>Medium</i>
en/volunteer.wml  443) <br />
en/volunteer.wml  444) Skill Level: <i>Medium</i>
en/volunteer.wml  445) <br />

en/volunteer.wml  446) Likely Mentors: <i>Matt, Roger</i>

en/volunteer.wml  447) <br />

en/volunteer.wml  448) There are a number of status changes inside Tor of which the user may need

en/volunteer.wml  449) to be informed. For example, if the user is trying to set up his Tor as a
en/volunteer.wml  450) relay and Tor decides that its ports are not reachable from outside

en/volunteer.wml  451) the user's network, we should alert the user. Currently, all the user

en/volunteer.wml  452) gets is a couple log messages in Vidalia's 'message log' window, which they

en/volunteer.wml  453) likely never see since they don't receive a notification that something
en/volunteer.wml  454) has gone wrong. Even if the user does actually look at the message log,
en/volunteer.wml  455) most of the messages make little sense to the novice user.
en/volunteer.wml  456) <br />
en/volunteer.wml  457) Tor has the ability to inform Vidalia of many such status changes, and
en/volunteer.wml  458) we recently implemented support for a couple of these events. Still,
en/volunteer.wml  459) there are many more status events the user should be informed of and we
en/volunteer.wml  460) need a better UI for actually displaying them to the user.
en/volunteer.wml  461) <br />
en/volunteer.wml  462) The goal of this project then is to design and implement a UI for
en/volunteer.wml  463) displaying Tor status events to the user. For example, we might put a
en/volunteer.wml  464) little badge on Vidalia's tray icon that alerts the user to new status
en/volunteer.wml  465) events they should look at. Double-clicking the icon could bring up a
en/volunteer.wml  466) dialog that summarizes recent status events in simple terms and maybe

en/volunteer.wml  467) suggests a remedy for any negative events if they can be corrected by

en/volunteer.wml  468) the user. Of course, this is just an example and the student is free to
en/volunteer.wml  469) suggest another approach.
en/volunteer.wml  470) <br />
en/volunteer.wml  471) A student undertaking this project should have good UI design and layout

en/volunteer.wml  472) and some C++ development experience. Previous experience with Qt and

en/volunteer.wml  473) Qt's Designer will be very helpful, but are not required. Some

en/volunteer.wml  474) English writing ability will also be useful, since this project will
en/volunteer.wml  475) likely involve writing small amounts of help documentation that should
en/volunteer.wml  476) be understandable by non-technical users. Bonus points for some graphic
en/volunteer.wml  477) design/Photoshop fu, since we might want/need some shiny new icons too.
en/volunteer.wml  478) </li>
en/volunteer.wml  479) 

en/volunteer.wml  480) <li>

en/volunteer.wml  481) <b>Improvements on our active browser configuration tester</b> -

en/volunteer.wml  482) <a href="https://check.torproject.org/">https://check.torproject.org/</a>

en/volunteer.wml  483) <br />

en/volunteer.wml  484) Priority: <i>Medium</i>
en/volunteer.wml  485) <br />
en/volunteer.wml  486) Effort Level: <i>Low</i>
en/volunteer.wml  487) <br />
en/volunteer.wml  488) Skill Level: <i>Low to Medium</i>
en/volunteer.wml  489) <br />

en/volunteer.wml  490) Likely Mentors: <i>Jacob, Steven</i>

en/volunteer.wml  491) <br />

en/volunteer.wml  492) We currently have a functional web page to detect if Tor is working. It

en/volunteer.wml  493) has a few places where it falls short. It requires improvements with

en/volunteer.wml  494) regard to default languages and functionality. It currently only responds
en/volunteer.wml  495) in English. In addition, it is a hack of a perl script that should have
en/volunteer.wml  496) never seen the light of day. It should probably be rewritten in python

en/volunteer.wml  497) with multi-lingual support in mind. It currently uses the <a
en/volunteer.wml  498) href="http://exitlist.torproject.org/">Tor DNS exit list</a>
en/volunteer.wml  499) and should continue to do so in the future. It currently result in certain

en/volunteer.wml  500) false positives and these should be discovered, documented, and fixed
en/volunteer.wml  501) where possible. Anyone working on this project should be interested in

en/volunteer.wml  502) DNS, basic perl or preferably python programming skills, and will have

en/volunteer.wml  503) to interact minimally with Tor to test their code.

en/volunteer.wml  504) <br />
en/volunteer.wml  505) If you want to make the project more exciting
en/volunteer.wml  506) and involve more design and coding, take a look at <a
en/volunteer.wml  507) href="<svnsandbox>doc/spec/proposals/131-verify-tor-usage.txt">proposal
en/volunteer.wml  508) 131-verify-tor-usage.txt</a>.

en/volunteer.wml  509) </li>
en/volunteer.wml  510) 
en/volunteer.wml  511) <li>

en/volunteer.wml  512) <b>Improvements on our DNS Exit List service</b> -

en/volunteer.wml  513) <a href="http://exitlist.torproject.org/">http://exitlist.torproject.org/</a>

en/volunteer.wml  514) <br />

en/volunteer.wml  515) Priority: <i>Medium</i>
en/volunteer.wml  516) <br />
en/volunteer.wml  517) Effort Level: <i>Low</i>
en/volunteer.wml  518) <br />
en/volunteer.wml  519) Skill Level: <i>Low</i>
en/volunteer.wml  520) <br />

en/volunteer.wml  521) Likely Mentors: <i>Jacob, Tup</i>

en/volunteer.wml  522) <br />

en/volunteer.wml  523) The <a href="http://p56soo2ibjkx23xo.onion/">exitlist software</a>
en/volunteer.wml  524) is written by our fabulous anonymous

en/volunteer.wml  525) contributer Tup. It's a DNS server written in Haskell that supports part of our <a

en/volunteer.wml  526) href="https://www.torproject.org/svn/trunk/doc/contrib/torel-design.txt">exitlist

en/volunteer.wml  527) design document</a>. Currently, it is functional and it is used by

en/volunteer.wml  528) check.torproject.org and other users. The issues that are outstanding
en/volunteer.wml  529) are mostly aesthetic. This wonderful service could use a much better
en/volunteer.wml  530) website using the common Tor theme. It would be best served with better
en/volunteer.wml  531) documentation for common services that use an RBL. It could use more
en/volunteer.wml  532) publicity. A person working on this project should be interested in DNS,
en/volunteer.wml  533) basic RBL configuration for popular services, and writing documentation.
en/volunteer.wml  534) The person would require minimal Tor interaction — testing their
en/volunteer.wml  535) own documentation at the very least. Furthermore, it would be useful

en/volunteer.wml  536) if they were interested in Haskell and wanted to implement more of the

en/volunteer.wml  537) torel-design.txt suggestions.
en/volunteer.wml  538) </li>
en/volunteer.wml  539) 
en/volunteer.wml  540) <li>

en/volunteer.wml  541) <b>Testing integration of Tor with web browsers for our end users</b>

en/volunteer.wml  542) <br />

en/volunteer.wml  543) Priority: <i>Medium</i>
en/volunteer.wml  544) <br />
en/volunteer.wml  545) Effort Level: <i>Medium</i>
en/volunteer.wml  546) <br />
en/volunteer.wml  547) Skill Level: <i>Medium</i>
en/volunteer.wml  548) <br />

en/volunteer.wml  549) Likely Mentors: <i>Jacob, Mike, Greg</i>

en/volunteer.wml  550) <br />

en/volunteer.wml  551) The Tor project currently lacks a solid test suite to ensure that a
en/volunteer.wml  552) user has a properly and safely configured web browser. It should test for as

en/volunteer.wml  553) many known issues as possible. It should attempt to decloak the

en/volunteer.wml  554) user in any way possible. Two current webpages that track these

en/volunteer.wml  555) kinds of issues are run by Greg Fleischer and HD Moore. Greg keeps a nice <a

en/volunteer.wml  556) href="http://pseudo-flaw.net/tor/torbutton/">list of issues along
en/volunteer.wml  557) with their proof of concept code, bug issues, etc</a>. HD Moore runs

en/volunteer.wml  558) the <a href="http://metasploit.com/research/projects/decloak/">metasploit

en/volunteer.wml  559) decloak website</a>. A student interested in defending Tor could start

en/volunteer.wml  560) by collecting as many workable and known methods for decloaking a

en/volunteer.wml  561) Tor user. (<a href="https://torcheck.xenobite.eu/">This page</a> may
en/volunteer.wml  562) be helpful as a start.) The student should be familiar with the common
en/volunteer.wml  563) pitfalls but

en/volunteer.wml  564) possibly have new methods in mind for implementing decloaking issues. The
en/volunteer.wml  565) website should ensure that it tells a user what their problem is. It
en/volunteer.wml  566) should help them to fix the problem or direct them to the proper support

en/volunteer.wml  567) channels. The student should be closely familiar with using Tor and how
en/volunteer.wml  568) to prevent Tor information leakage.

en/volunteer.wml  569) </li>
en/volunteer.wml  570) 

en/volunteer.wml  571) <li>

en/volunteer.wml  572) <b>Libevent and Tor integration improvements</b>
en/volunteer.wml  573) <br />

en/volunteer.wml  574) Priority: <i>Medium</i>
en/volunteer.wml  575) <br />
en/volunteer.wml  576) Effort Level: <i>High</i>
en/volunteer.wml  577) <br />
en/volunteer.wml  578) Skill Level: <i>Medium to High</i>
en/volunteer.wml  579) <br />

en/volunteer.wml  580) Likely Mentors: <i>Nick</i>

en/volunteer.wml  581) <br />

en/volunteer.wml  582) Tor should make better use of the more recent features of Niels
en/volunteer.wml  583) Provos's <a href="http://monkey.org/~provos/libevent/">Libevent</a>

en/volunteer.wml  584) library.  Tor already uses Libevent for its low-level asynchronous IO

en/volunteer.wml  585) calls, and could also use Libevent's increasingly good implementations

en/volunteer.wml  586) of network buffers and of HTTP.  This wouldn't be simply a matter of

en/volunteer.wml  587) replacing Tor's internal calls with calls to Libevent: instead, we'll

en/volunteer.wml  588) need to refactor Tor to use Libevent calls that do not follow the

en/volunteer.wml  589) same models as Tor's existing backends. Also, we'll need to add
en/volunteer.wml  590) missing functionality to Libevent as needed — most difficult likely
en/volunteer.wml  591) will be adding OpenSSL support on top of Libevent's buffer abstraction.
en/volunteer.wml  592) Also tricky will be adding rate-limiting to Libevent.

en/volunteer.wml  593) </li>
en/volunteer.wml  594) 
en/volunteer.wml  595) <li>

en/volunteer.wml  596) <b>Tuneup Tor!</b>
en/volunteer.wml  597) <br />

en/volunteer.wml  598) Priority: <i>Medium</i>
en/volunteer.wml  599) <br />
en/volunteer.wml  600) Effort Level: <i>Medium</i>
en/volunteer.wml  601) <br />
en/volunteer.wml  602) Skill Level: <i>Medium to High</i>
en/volunteer.wml  603) <br />

en/volunteer.wml  604) Likely Mentors: <i>Nick, Roger, Mike</i>

en/volunteer.wml  605) <br />

en/volunteer.wml  606) Right now, Tor relays measure and report their own bandwidth, and Tor
en/volunteer.wml  607) clients choose which relays to use in part based on that bandwidth.
en/volunteer.wml  608) This approach is vulnerable to
en/volunteer.wml  609) <a href="http://freehaven.net/anonbib/#bauer:wpes2007">attacks where
en/volunteer.wml  610) relays lie about their bandwidth</a>;
en/volunteer.wml  611) to address this, Tor currently caps the maximum bandwidth
en/volunteer.wml  612) it's willing to believe any relay provides.  This is a limited fix, and
en/volunteer.wml  613) a waste of bandwidth capacity to boot.  Instead,

en/volunteer.wml  614) Tor should possibly measure bandwidth in a more distributed way, perhaps
en/volunteer.wml  615) as described in the

en/volunteer.wml  616) <a href="http://freehaven.net/anonbib/author.html#snader08">"A Tune-up for
en/volunteer.wml  617) Tor"</a> paper

en/volunteer.wml  618) by Snader and Borisov. A student could use current testing code to

en/volunteer.wml  619) double-check this paper's findings and verify the extent to which they

en/volunteer.wml  620) dovetail with Tor as deployed in the wild, and determine good ways to
en/volunteer.wml  621) incorporate them into their suggestions Tor network without adding too

en/volunteer.wml  622) much communications overhead between relays and directory

en/volunteer.wml  623) authorities.

en/volunteer.wml  624) </li>
en/volunteer.wml  625) 

en/volunteer.wml  626) <!--

en/volunteer.wml  627) <li>

en/volunteer.wml  628) <b>Improving the Tor QA process: Continuous Integration for Windows builds</b>
en/volunteer.wml  629) <br />

en/volunteer.wml  630) Priority: <i>High</i>
en/volunteer.wml  631) <br />
en/volunteer.wml  632) Effort Level: <i>Medium</i>
en/volunteer.wml  633) <br />
en/volunteer.wml  634) Skill Level: <i>Medium</i>
en/volunteer.wml  635) <br />

en/volunteer.wml  636) Likely Mentors: <i>Jacob, Andrew</i>

en/volunteer.wml  637) <br />

en/volunteer.wml  638) It would be useful to have automated build processes for Windows and
en/volunteer.wml  639) probably other platforms. The purpose of having a continuous integration
en/volunteer.wml  640) build environment is to ensure that Windows isn't left behind for any of
en/volunteer.wml  641) the software projects used in the Tor project or its accompanying.<br />
en/volunteer.wml  642) Buildbot may be a good choice for this as it appears to support all of

en/volunteer.wml  643) the platforms Tor does. See the

en/volunteer.wml  644) <a href="http://en.wikipedia.org/wiki/BuildBot">wikipedia entry for

en/volunteer.wml  645) buildbot</a>.<br />
en/volunteer.wml  646) There may be better options and the person undertaking this task should
en/volunteer.wml  647) evaluate other options. Any person working on this automatic build
en/volunteer.wml  648) process should have experience or be willing to learn how to build all
en/volunteer.wml  649) of the respective Tor related code bases from scratch. Furthermore, the
en/volunteer.wml  650) person should have some experience building software in Windows
en/volunteer.wml  651) environments as this is the target audience we want to ensure we do not
en/volunteer.wml  652) leave behind. It would require close work with the Tor source code but

en/volunteer.wml  653) probably only in the form of building, not authoring.<br />
en/volunteer.wml  654) Additionally, we need to automate our performance testing for all platforms.

en/volunteer.wml  655) We've got buildbot (except on Windows — as noted above) to automate

en/volunteer.wml  656) our regular integration and compile testing already,
en/volunteer.wml  657) but we need to get our network simulation tests (as built in torflow)
en/volunteer.wml  658) updated for more recent versions of Tor, and designed to launch a test
en/volunteer.wml  659) network either on a single machine, or across several, so we can test

en/volunteer.wml  660) changes in performance on machines in different roles automatically.

en/volunteer.wml  661) </li>

en/volunteer.wml  662) -->

en/volunteer.wml  663) 

en/volunteer.wml  664) <li>

en/volunteer.wml  665) <b>Improve our unit testing process</b>
en/volunteer.wml  666) <br />

en/volunteer.wml  667) Priority: <i>Medium</i>
en/volunteer.wml  668) <br />
en/volunteer.wml  669) Effort Level: <i>Medium</i>
en/volunteer.wml  670) <br />
en/volunteer.wml  671) Skill Level: <i>Medium</i>
en/volunteer.wml  672) <br />

en/volunteer.wml  673) Likely Mentors: <i>Nick</i>

en/volunteer.wml  674) <br />

en/volunteer.wml  675) Tor needs to be far more tested. This is a multi-part effort. To start

en/volunteer.wml  676) with, our unit test coverage should rise substantially, especially in

en/volunteer.wml  677) the areas outside the utility functions. This will require significant

en/volunteer.wml  678) refactoring of some parts of Tor, in order to dissociate as much logic

en/volunteer.wml  679) as possible from globals.
en/volunteer.wml  680) <br />

en/volunteer.wml  681) Additionally, we need to automate our performance testing. We've got

en/volunteer.wml  682) buildbot to automate our regular integration and compile testing already
en/volunteer.wml  683) (though we need somebody to set it up on Windows),
en/volunteer.wml  684) but we need to get our network simulation tests (as built in TorFlow: see
en/volunteer.wml  685) the "Tor Node Scanner improvements" item)

en/volunteer.wml  686) updated for more recent versions of Tor, and designed to launch a test
en/volunteer.wml  687) network either on a single machine, or across several, so we can test

en/volunteer.wml  688) changes in performance on machines in different roles automatically.

en/volunteer.wml  689) </li>
en/volunteer.wml  690) 

en/volunteer.wml  691) <li>

en/volunteer.wml  692) <b>Help revive an independent Tor client implementation</b>

en/volunteer.wml  693) <br />

en/volunteer.wml  694) Priority: <i>Medium</i>

en/volunteer.wml  695) <br />
en/volunteer.wml  696) Effort Level: <i>High</i>
en/volunteer.wml  697) <br />
en/volunteer.wml  698) Skill Level: <i>Medium to High</i>
en/volunteer.wml  699) <br />

en/volunteer.wml  700) Likely Mentors: <i>Karsten, Nick</i>

en/volunteer.wml  701) <br />

en/volunteer.wml  702) Reanimate one of the approaches to implement a Tor client in Java,
en/volunteer.wml  703) e.g. the <a href="http://onioncoffee.sourceforge.net/">OnionCoffee
en/volunteer.wml  704) project</a>, and make it run on <a
en/volunteer.wml  705) href="http://code.google.com/android/">Android</a>. The first step
en/volunteer.wml  706) would be to port the existing code and execute it in an Android
en/volunteer.wml  707) environment. Next, the code should be updated to support the newer Tor
en/volunteer.wml  708) protocol versions like the <a href="<svnsandbox>doc/spec/dir-spec.txt">v3
en/volunteer.wml  709) directory protocol</a>. Further, support for requesting or even

en/volunteer.wml  710) providing Tor hidden services would be neat, but not required.
en/volunteer.wml  711) <br />
en/volunteer.wml  712) The student should be able to understand and write new Java code, including

en/volunteer.wml  713) a Java cryptography API. Being able to read C code would be helpful,

en/volunteer.wml  714) too. The student should be willing to read the existing documentation,

en/volunteer.wml  715) implement code based on it, and refine the documentation
en/volunteer.wml  716) when things are underdocumented. This project is mostly about coding and

en/volunteer.wml  717) to a small degree about design.
en/volunteer.wml  718) </li>
en/volunteer.wml  719) 
en/volunteer.wml  720) <li>

en/volunteer.wml  721) <b>Automatic system tests and automatically starting private Tor networks</b>

en/volunteer.wml  722) <br />

en/volunteer.wml  723) Priority: <i>Medium</i>
en/volunteer.wml  724) <br />
en/volunteer.wml  725) Effort Level: <i>Medium</i>
en/volunteer.wml  726) <br />
en/volunteer.wml  727) Skill Level: <i>Medium</i>
en/volunteer.wml  728) <br />

en/volunteer.wml  729) Likely Mentors: <i>Karsten, Nick, Roger</i>

en/volunteer.wml  730) <br />

en/volunteer.wml  731) Write a tool that runs automatic system tests in addition
en/volunteer.wml  732) to the existing unit tests. The Java-based Tor simulator <a
en/volunteer.wml  733) href="https://tor-svn.freehaven.net/svn/puppetor/trunk/">PuppeTor</a>
en/volunteer.wml  734) might be a good start for starting up a private Tor network, using it
en/volunteer.wml  735) for a while, and verifying that at least parts of it are working. This
en/volunteer.wml  736) project requires to conceive a blueprint for performing system tests
en/volunteer.wml  737) of private Tor networks, before starting to code. Typical types of
en/volunteer.wml  738) tests range from performing single requests over the private network to
en/volunteer.wml  739) manipulating exchanged messages and see if nodes handle corrupt messages

en/volunteer.wml  740) appropriately.
en/volunteer.wml  741) <br />
en/volunteer.wml  742) The student should be able to obtain a good understanding

en/volunteer.wml  743) of how Tor works and what problems and bugs could arise to design good

en/volunteer.wml  744) test cases. Understanding the existing Tor code structure and documentation is

en/volunteer.wml  745) vital. If PuppeTor is used, the student should also be able to understand
en/volunteer.wml  746) and possibly extend an existing Java application. This project is partly
en/volunteer.wml  747) about design and partly about coding.
en/volunteer.wml  748) </li>
en/volunteer.wml  749) 
en/volunteer.wml  750) <li>

en/volunteer.wml  751) <b>Bring moniTor to life</b>
en/volunteer.wml  752) <br />

en/volunteer.wml  753) Priority: <i>Medium</i>
en/volunteer.wml  754) <br />
en/volunteer.wml  755) Effort Level: <i>Medium</i>
en/volunteer.wml  756) <br />
en/volunteer.wml  757) Skill Level: <i>Low to Medium</i>
en/volunteer.wml  758) <br />

en/volunteer.wml  759) Likely Mentors: <i>Karsten, Jacob</i>

en/volunteer.wml  760) <br />

en/volunteer.wml  761) Implement a <a href="http://www.ss64.com/bash/top.html">top-like</a>
en/volunteer.wml  762) management tool for Tor relays. The purpose of such a tool would be
en/volunteer.wml  763) to monitor a local Tor relay via its control port and include useful
en/volunteer.wml  764) system information of the underlying machine. When running this tool, it
en/volunteer.wml  765) would dynamically update its content like top does for Linux processes.
en/volunteer.wml  766) <a href="http://archives.seul.org/or/dev/Jan-2008/msg00005.html">This

en/volunteer.wml  767) or-dev post</a> might be a good first read.
en/volunteer.wml  768) <br />
en/volunteer.wml  769) The student should be familiar

en/volunteer.wml  770) with or willing to learn about administering a Tor relay and configuring
en/volunteer.wml  771) it via its control port. As an initial prototype is written in Python,
en/volunteer.wml  772) some knowledge about writing Python code would be helpful, too. This

en/volunteer.wml  773) project is one part about identifying requirements to such a
en/volunteer.wml  774) tool and designing its interface, and one part lots of coding.

en/volunteer.wml  775) </li>
en/volunteer.wml  776) 

en/volunteer.wml  777) <li>
en/volunteer.wml  778) <b>Torbutton improvements</b>
en/volunteer.wml  779) <br />

en/volunteer.wml  780) Priority: <i>Medium</i>

en/volunteer.wml  781) <br />

en/volunteer.wml  782) Effort Level: <i>High</i>
en/volunteer.wml  783) <br />
en/volunteer.wml  784) Skill Level: <i>High</i>

en/volunteer.wml  785) <br />

en/volunteer.wml  786) Likely Mentors: <i>Mike</i>

en/volunteer.wml  787) <br/>
en/volunteer.wml  788) Torbutton has a number of improvements that can be made in the post-1.2
en/volunteer.wml  789) timeframe. Most of these are documented as feature requests in the <a

en/volunteer.wml  790) href="https://bugs.torproject.org/flyspray/index.php?tasks=all&project=5">Torbutton

en/volunteer.wml  791) flyspray section</a>. Good examples include: stripping off node.exit on http
en/volunteer.wml  792) headers, more fine-grained control over formfill blocking, improved referrer

en/volunteer.wml  793) spoofing based on the domain of the site (a-la <a

en/volunteer.wml  794) href="https://addons.mozilla.org/en-US/firefox/addon/953">refcontrol extension</a>),

en/volunteer.wml  795) tighter integration with Vidalia for reporting Tor status, a New Identity
en/volunteer.wml  796) button with Tor integration and multiple identity management, and anything

en/volunteer.wml  797) else you might think of.

en/volunteer.wml  798) <br />
en/volunteer.wml  799) This work would be independent coding in Javascript and the fun world of <a
en/volunteer.wml  800) href="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">XUL</a>,
en/volunteer.wml  801) with not too much involvement in the Tor internals.

en/volunteer.wml  802) </li>
en/volunteer.wml  803) 

en/volunteer.wml  804) <li>

en/volunteer.wml  805) <b>Porting Polipo to Windows</b>
en/volunteer.wml  806) <br />

en/volunteer.wml  807) Priority: <i>Medium</i>

en/volunteer.wml  808) <br />

en/volunteer.wml  809) Effort Level: <i>Medium</i>

en/volunteer.wml  810) <br />
en/volunteer.wml  811) Skill Level: <i>Medium to High</i>
en/volunteer.wml  812) <br />

en/volunteer.wml  813) Likely Mentors: <i>Andrew, Steven, Roger</i>

en/volunteer.wml  814) <br />

en/volunteer.wml  815) Help port <a
en/volunteer.wml  816) href="http://www.pps.jussieu.fr/~jch/software/polipo/">Polipo</a> to

en/volunteer.wml  817) Windows. Example topics to tackle include:
en/volunteer.wml  818) 1) handle spaces in path names and understand the filesystem
en/volunteer.wml  819) namespace — that is, where application data, personal data,

en/volunteer.wml  820) and program data typically reside in various versions of Windows. 2) the
en/volunteer.wml  821) ability to handle ipv6 communications. 3) the ability to asynchronously
en/volunteer.wml  822) query name servers, find the system nameservers, and manage netbios
en/volunteer.wml  823) and dns queries. 4) use native regex capabilities of Windows, rather
en/volunteer.wml  824) than using 3rd party GNU regex libraries. 5) manage events and buffers
en/volunteer.wml  825) natively (i.e. in Unix-like OSes, Polipo defaults to 25% of ram, in
en/volunteer.wml  826) Windows it's whatever the config specifies). 6) some sort of GUI config
en/volunteer.wml  827) and reporting tool, bonus if it has a systray icon with right clickable
en/volunteer.wml  828) menu options. Double bonus if it's cross-platform compatible.
en/volunteer.wml  829) </li>
en/volunteer.wml  830) 
en/volunteer.wml  831) <li>

en/volunteer.wml  832) <b>Make our diagrams beautiful and automated</b>

en/volunteer.wml  833) <br />

en/volunteer.wml  834) Priority: <i>Medium</i>

en/volunteer.wml  835) <br />
en/volunteer.wml  836) Effort Level: <i>Low</i>
en/volunteer.wml  837) <br />
en/volunteer.wml  838) Skill Level: <i>Low</i>
en/volunteer.wml  839) <br />

en/volunteer.wml  840) Likely Mentors: <i>Andrew</i>

en/volunteer.wml  841) <br />

en/volunteer.wml  842) We need a way to generate the website diagrams (for example, the "How
en/volunteer.wml  843) Tor Works" pictures on the <a href="<page overview>">overview page</a>
en/volunteer.wml  844) from source, so we can translate them as UTF-8 text rather than edit
en/volunteer.wml  845) them by hand with Gimp. We might want to
en/volunteer.wml  846) integrate this as an wml file so translations are easy and images are
en/volunteer.wml  847) generated in multiple languages whenever we build the website. See the
en/volunteer.wml  848) "Translation Wiki" idea above.

en/volunteer.wml  849) </li>
en/volunteer.wml  850) 

en/volunteer.wml  851) <li>
en/volunteer.wml  852) <b>Improve the LiveCD offerings for the Tor community</b>
en/volunteer.wml  853) <br />

en/volunteer.wml  854) Priority: <i>Low</i>
en/volunteer.wml  855) <br />
en/volunteer.wml  856) Effort Level: <i>Low</i>
en/volunteer.wml  857) <br />
en/volunteer.wml  858) Skill Level: <i>Medium to High</i>
en/volunteer.wml  859) <br />

en/volunteer.wml  860) Likely Mentors: <i>Anonym, Jacob, Roger</i>

en/volunteer.wml  861) <br />

en/volunteer.wml  862) How can we make the <a

en/volunteer.wml  863) href="http://anonymityanywhere.com/incognito/">Incognito LiveCD</a>

en/volunteer.wml  864) easier to maintain, improve, and document?
en/volunteer.wml  865) </li>

en/volunteer.wml  866) 

en/volunteer.wml  867) <li>
en/volunteer.wml  868) <b>Rework and extend Blossom</b>
en/volunteer.wml  869) <br />
en/volunteer.wml  870) Priority: <i>Medium</i>
en/volunteer.wml  871) <br />
en/volunteer.wml  872) Effort Level: <i>Medium to High</i>
en/volunteer.wml  873) <br />
en/volunteer.wml  874) Skill Level: <i>Medium to High</i>
en/volunteer.wml  875) <br />
en/volunteer.wml  876) Likely Mentors: <i>Goodell</i>
en/volunteer.wml  877) <br />
en/volunteer.wml  878) Rework and extend Blossom (a tool for monitoring and
en/volunteer.wml  879) selecting appropriate Tor circuits based upon exit node requirements
en/volunteer.wml  880) specified by the user) to gather data in a self-contained way, with
en/volunteer.wml  881) parameters easily configurable by the user.  Blossom is presently
en/volunteer.wml  882) implemented as a single Python script that interfaces with Tor using the
en/volunteer.wml  883) Controller interface and depends upon metadata about Tor nodes obtained
en/volunteer.wml  884) via external processes, such as a webpage indicating status of the nodes
en/volunteer.wml  885) plus publically available data from DNS, whois, etc.  This project has
en/volunteer.wml  886) two parts: (1) Determine which additional metadata may be useful and
en/volunteer.wml  887) rework Blossom so that it cleanly obtains the metadata on its own rather
en/volunteer.wml  888) than depend upon external scripts (this may, for example, involve
en/volunteer.wml  889) additional threads or inter-process communication), and (2) develop a
en/volunteer.wml  890) means by which the user can easily configure Blossom, starting with a
en/volunteer.wml  891) configuration file and possibly working up to a web configuration engine.

en/volunteer.wml  892) Knowledge of Tor and Python are important; knowledge of
en/volunteer.wml  893) TCP, interprocess communication, and Perl will also be helpful.  An
en/volunteer.wml  894) interest in network neutrality is important as well, since the
en/volunteer.wml  895) principles of evaluating and understanding internet inconsistency are at
en/volunteer.wml  896) the core of the Blossom effort.

en/volunteer.wml  897) </li>
en/volunteer.wml  898) 
en/volunteer.wml  899) <li>
en/volunteer.wml  900) <b>Improve Blossom: Allow users to qualitatively describe exit nodes they desire</b>
en/volunteer.wml  901) <br />
en/volunteer.wml  902) Priority: <i>Low</i>
en/volunteer.wml  903) <br />
en/volunteer.wml  904) Effort Level: <i>Medium</i>
en/volunteer.wml  905) <br />
en/volunteer.wml  906) Skill Level: <i>Medium</i>
en/volunteer.wml  907) <br />
en/volunteer.wml  908) Likely Mentors: <i>Goodell</i>
en/volunteer.wml  909) <br />
en/volunteer.wml  910) Develop and implement a means of affording Blossom
en/volunteer.wml  911) users the ability to qualitatively describe the exit node that they
en/volunteer.wml  912) want.  The Internet is an inconsistent place: some Tor exit nodes see
en/volunteer.wml  913) the world differently than others.  As presently implemented, Blossom (a
en/volunteer.wml  914) tool for monitoring and selecting appropriate Tor circuits based upon
en/volunteer.wml  915) exit node requirements specified by the user) lacks a sufficiently rich
en/volunteer.wml  916) language to describe how the different vantage points are different.
en/volunteer.wml  917) For example, some exit nodes may have an upstream network that filters
en/volunteer.wml  918) certain kinds of traffic or certain websites.  Other exit nodes may
en/volunteer.wml  919) provide access to special content as a result of their location, perhaps
en/volunteer.wml  920) as a result of discrimination on the part of the content providers
en/volunteer.wml  921) themselves.  This project has two parts: (1) develop a language for
en/volunteer.wml  922) describing characteristics of networks in which exit nodes reside, and
en/volunteer.wml  923) (2) incorporate this language into Blossom so that users can select Tor
en/volunteer.wml  924) paths based upon the description.

en/volunteer.wml  925) Knowledge of Tor and Python are important; knowledge of
en/volunteer.wml  926) TCP, interprocess communication, and Perl will also be helpful.  An
en/volunteer.wml  927) interest in network neutrality is important as well, since the
en/volunteer.wml  928) principles of evaluating and understanding internet inconsistency are at
en/volunteer.wml  929) the core of the Blossom effort.

en/volunteer.wml  930) </li>
en/volunteer.wml  931) 

en/volunteer.wml  932) <li>
en/volunteer.wml  933) <b>Bring up new ideas!</b>
en/volunteer.wml  934) <br />
en/volunteer.wml  935) Don't like any of these? Look at the <a

en/volunteer.wml  936) href="<svnsandbox>doc/design-paper/roadmap-future.pdf">Tor development

en/volunteer.wml  937) roadmap</a> for more ideas.
en/volunteer.wml  938) </li>
en/volunteer.wml  939) 

en/volunteer.wml  940) </ol>
en/volunteer.wml  941) 

en/volunteer.wml  942) <h2><a class="anchor" href="#Coding">Coding and Design</a></h2>

volunteer.html    943) <ol>

en/volunteer.wml  944) <li>Tor relays don't work well on Windows XP. On

en/volunteer.wml  945) Windows, Tor uses the standard <tt>select()</tt> system

en/volunteer.wml  946) call, which uses space in the non-page pool. This means

en/volunteer.wml  947) that a medium sized Tor relay will empty the non-page pool, <a

en/volunteer.wml  948) href="https://wiki.torproject.org/noreply/TheOnionRouter/WindowsBufferProblems">causing

en/volunteer.wml  949) havoc and system crashes</a>. We should probably be using overlapped IO

en/volunteer.wml  950) instead. One solution would be to teach <a
en/volunteer.wml  951) href="http://www.monkey.org/~provos/libevent/">libevent</a> how to use
en/volunteer.wml  952) overlapped IO rather than select() on Windows, and then adapt Tor to

en/volunteer.wml  953) the new libevent interface. Christian King made a
en/volunteer.wml  954) <a href="https://tor-svn.freehaven.net/svn/libevent-urz/trunk/">good

en/volunteer.wml  955) start</a> on this in the summer of 2007.</li>

en/volunteer.wml  956) <li>We need to actually start building our <a href="<page
en/volunteer.wml  957) documentation>#DesignDoc">blocking-resistance design</a>. This involves

en/volunteer.wml  958) fleshing out the design, modifying many different pieces of Tor, adapting
en/volunteer.wml  959) <a href="http://vidalia-project.net/">Vidalia</a> so it supports the
en/volunteer.wml  960) new features, and planning for deployment.</li>

en/volunteer.wml  961) <li>We need a flexible simulator framework for studying end-to-end
en/volunteer.wml  962) traffic confirmation attacks. Many researchers have whipped up ad hoc
en/volunteer.wml  963) simulators to support their intuition either that the attacks work
en/volunteer.wml  964) really well or that some defense works great. Can we build a simulator
en/volunteer.wml  965) that's clearly documented and open enough that everybody knows it's
en/volunteer.wml  966) giving a reasonable answer? This will spur a lot of new research.
en/volunteer.wml  967) See the entry <a href="#Research">below</a> on confirmation attacks for
en/volunteer.wml  968) details on the research side of this task &mdash; who knows, when it's
en/volunteer.wml  969) done maybe you can help write a paper or three also.</li>

en/volunteer.wml  970) <li>Tor 0.1.1.x and later include support for hardware crypto accelerators

en/volunteer.wml  971) via OpenSSL. Nobody has ever tested it, though. Does somebody want to get

volunteer.html    972) a card and let us know how it goes?</li>

volunteer.html    973) <li>Perform a security analysis of Tor with <a
volunteer.html    974) href="http://en.wikipedia.org/wiki/Fuzz_testing">"fuzz"</a>. Determine

en/volunteer.wml  975) if there are good fuzzing libraries out there for what we want. Win fame by

volunteer.html    976) getting credit when we put out a new release because of you!</li>

volunteer.html    977) <li>Tor uses TCP for transport and TLS for link
volunteer.html    978) encryption. This is nice and simple, but it means all cells
volunteer.html    979) on a link are delayed when a single packet gets dropped, and
volunteer.html    980) it means we can only reasonably support TCP streams. We have a <a

en/volunteer.wml  981) href="https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#TransportIPnotTCP">list

en/volunteer.wml  982) of reasons why we haven't shifted to UDP transport</a>, but it would
en/volunteer.wml  983) be great to see that list get shorter. We also have a proposed <a

en/volunteer.wml  984) href="<svnsandbox>doc/spec/proposals/100-tor-spec-udp.txt">specification
en/volunteer.wml  985) for Tor and

en/volunteer.wml  986) UDP</a> &mdash; please let us know what's wrong with it.</li>

volunteer.html    987) <li>We're not that far from having IPv6 support for destination addresses
volunteer.html    988) (at exit nodes). If you care strongly about IPv6, that's probably the
volunteer.html    989) first place to start.</li>

volunteer.html    990) </ol>
volunteer.html    991) 

en/volunteer.wml  992) <a id="Research"></a>
en/volunteer.wml  993) <h2><a class="anchor" href="#Research">Research</a></h2>

volunteer.html    994) <ol>

volunteer.html    995) <li>The "website fingerprinting attack": make a list of a few
volunteer.html    996) hundred popular websites, download their pages, and make a set of
volunteer.html    997) "signatures" for each site. Then observe a Tor client's traffic. As
volunteer.html    998) you watch him receive data, you quickly approach a guess about which
volunteer.html    999) (if any) of those sites he is visiting. First, how effective is
volunteer.html   1000) this attack on the deployed Tor codebase? Then start exploring
volunteer.html   1001) defenses: for example, we could change Tor's cell size from 512
volunteer.html   1002) bytes to 1024 bytes, we could employ padding techniques like <a
volunteer.html   1003) href="http://freehaven.net/anonbib/#timing-fc2004">defensive dropping</a>,
volunteer.html   1004) or we could add traffic delays. How much of an impact do these have,
volunteer.html   1005) and how much usability impact (using some suitable metric) is there from
volunteer.html   1006) a successful defense in each case?</li>

volunteer.html   1007) <li>The "end-to-end traffic confirmation attack":
volunteer.html   1008) by watching traffic at Alice and at Bob, we can <a
volunteer.html   1009) href="http://freehaven.net/anonbib/#danezis:pet2004">compare
volunteer.html   1010) traffic signatures and become convinced that we're watching the same
volunteer.html   1011) stream</a>. So far Tor accepts this as a fact of life and assumes this
volunteer.html   1012) attack is trivial in all cases. First of all, is that actually true? How
volunteer.html   1013) much traffic of what sort of distribution is needed before the adversary
volunteer.html   1014) is confident he has won? Are there scenarios (e.g. not transmitting much)
volunteer.html   1015) that slow down the attack? Do some traffic padding or traffic shaping
volunteer.html   1016) schemes work better than others?</li>

en/volunteer.wml 1017) <li>A related question is: Does running a relay/bridge provide additional
en/volunteer.wml 1018) protection against these timing attacks? Can an external adversary that can't

en/volunteer.wml 1019) see inside TLS links still recognize individual streams reliably?

en/volunteer.wml 1020) Does the amount of traffic carried degrade this ability any? What if the
en/volunteer.wml 1021) client-relay deliberately delayed upstream relayed traffic to create a queue
en/volunteer.wml 1022) that could be used to mimic timings of client downstream traffic to make it
en/volunteer.wml 1023) look like it was also relayed? This same queue could also be used for masking
en/volunteer.wml 1024) timings in client upstream traffic with the techniques from <a
en/volunteer.wml 1025) href="http://www.freehaven.net/anonbib/#ShWa-Timing06">adaptive padding</a>,
en/volunteer.wml 1026) but without the need for additional traffic. Would such an interleaving of
en/volunteer.wml 1027) client upstream traffic obscure timings for external adversaries? Would the
en/volunteer.wml 1028) strategies need to be adjusted for asymmetric links? For example, on
en/volunteer.wml 1029) asymmetric links, is it actually possible to differentiate client traffic from
en/volunteer.wml 1030) natural bursts due to their asymmetric capacity? Or is it easier than
en/volunteer.wml 1031) symmetric links for some other reason?</li>

volunteer.html   1032) <li>The "routing zones attack": most of the literature thinks of
volunteer.html   1033) the network path between Alice and her entry node (and between the
volunteer.html   1034) exit node and Bob) as a single link on some graph. In practice,
volunteer.html   1035) though, the path traverses many autonomous systems (ASes), and <a
volunteer.html   1036) href="http://freehaven.net/anonbib/#feamster:wpes2004">it's not uncommon
volunteer.html   1037) that the same AS appears on both the entry path and the exit path</a>.
volunteer.html   1038) Unfortunately, to accurately predict whether a given Alice, entry,
volunteer.html   1039) exit, Bob quad will be dangerous, we need to download an entire Internet
volunteer.html   1040) routing zone and perform expensive operations on it. Are there practical
volunteer.html   1041) approximations, such as avoiding IP addresses in the same /8 network?</li>

en/volunteer.wml 1042) <li>Other research questions regarding geographic diversity consider
en/volunteer.wml 1043) the tradeoff between choosing an efficient circuit and choosing a random

en/volunteer.wml 1044) circuit. Look at Stephen Rollyson's <a

en/volunteer.wml 1045) href="http://swiki.cc.gatech.edu:8080/ugResearch/uploads/7/ImprovingTor.pdf">position
en/volunteer.wml 1046) paper</a> on how to discard particularly slow choices without hurting

en/volunteer.wml 1047) anonymity "too much". This line of reasoning needs more work and more
en/volunteer.wml 1048) thinking, but it looks very promising.</li>

en/volunteer.wml 1049) <li>Tor doesn't work very well when relays have asymmetric bandwidth

volunteer.html   1050) (e.g. cable or DSL). Because Tor has separate TCP connections between
volunteer.html   1051) each hop, if the incoming bytes are arriving just fine and the outgoing
volunteer.html   1052) bytes are all getting dropped on the floor, the TCP push-back mechanisms
volunteer.html   1053) don't really transmit this information back to the incoming streams.
volunteer.html   1054) Perhaps Tor should detect when it's dropping a lot of outgoing packets,
volunteer.html   1055) and rate-limit incoming streams to regulate this itself? I can imagine
volunteer.html   1056) a build-up and drop-off scheme where we pick a conservative rate-limit,
volunteer.html   1057) slowly increase it until we get lost packets, back off, repeat. We
volunteer.html   1058) need somebody who's good with networks to simulate this and help design
volunteer.html   1059) solutions; and/or we need to understand the extent of the performance
volunteer.html   1060) degradation, and use this as motivation to reconsider UDP transport.</li>
volunteer.html   1061) <li>A related topic is congestion control. Is our
volunteer.html   1062) current design sufficient once we have heavy use? Maybe
volunteer.html   1063) we should experiment with variable-sized windows rather
volunteer.html   1064) than fixed-size windows? That seemed to go well in an <a
volunteer.html   1065) href="http://www.psc.edu/networking/projects/hpn-ssh/theory.php">ssh
volunteer.html   1066) throughput experiment</a>. We'll need to measure and tweak, and maybe
volunteer.html   1067) overhaul if the results are good.</li>

volunteer.html   1068) <li>To let dissidents in remote countries use Tor without being blocked
volunteer.html   1069) at their country's firewall, we need a way to get tens of thousands of
volunteer.html   1070) relays, not just a few hundred. We can imagine a Tor client GUI that

en/volunteer.wml 1071) has a "Tor for Freedom" button at the top that opens a port and relays a

volunteer.html   1072) few KB/s of traffic into the Tor network. (A few KB/s shouldn't be too
volunteer.html   1073) much hassle, and there are few abuse issues since they're not being exit
volunteer.html   1074) nodes.) But how do we distribute a list of these volunteer clients to the
volunteer.html   1075) good dissidents in an automated way that doesn't let the country-level

en/volunteer.wml 1076) firewalls intercept and enumerate them? This probably needs to work on a

en/volunteer.wml 1077) human-trust level. See our <a href="<page documentation>#DesignDoc">early
en/volunteer.wml 1078) blocking-resistance design document</a> and our
en/volunteer.wml 1079) <a

en/volunteer.wml 1080) href="https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#BlockingResistance">FAQ

en/volunteer.wml 1081) entry</a> on this, and then read the <a
en/volunteer.wml 1082) href="http://freehaven.net/anonbib/topic.html#Communications_20Censorship">censorship
en/volunteer.wml 1083) resistance section of anonbib</a>.</li>

volunteer.html   1084) <li>Tor circuits are built one hop at a time, so in theory we have the
volunteer.html   1085) ability to make some streams exit from the second hop, some from the
volunteer.html   1086) third, and so on. This seems nice because it breaks up the set of exiting

en/volunteer.wml 1087) streams that a given relay can see. But if we want each stream to be safe,

volunteer.html   1088) the "shortest" path should be at least 3 hops long by our current logic, so
volunteer.html   1089) the rest will be even longer. We need to examine this performance / security
volunteer.html   1090) tradeoff.</li>

en/volunteer.wml 1091) <li>It's not that hard to DoS Tor relays or directory authorities. Are client

volunteer.html   1092) puzzles the right answer? What other practical approaches are there? Bonus
volunteer.html   1093) if they're backward-compatible with the current Tor protocol.</li>

volunteer.html   1094) </ol>
volunteer.html   1095) 

en/volunteer.wml 1096) <p>

en/volunteer.wml 1097) <a href="<page contact>">Let us know</a> if you've made progress on any
en/volunteer.wml 1098) of these!

en/volunteer.wml 1099) </p>

volunteer.html   1100) 

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