tor-webwml.git

1) ## translation metadata

2) # Revision: $Revision$

3) # Translation-Priority: 4-optional
4) 
5) #include "head.wmi" TITLE="Tor: Volunteer" CHARSET="UTF-8"
6) <div id="content" class="clearfix">
7)   <div id="breadcrumbs">

8)     <a href="<page index>">Home &raquo; </a>

9)     <a href="<page getinvolved/volunteer>">Volunteer</a>
10)   </div>

11)   <div id="maincol">

12)     <!-- PUT CONTENT AFTER THIS TAG -->
13)     <h1>A few things everyone can do now:</h1>
14)     <ol>
15)     <li>Please consider <a href="<page docs/tor-doc-relay>">running
16)     a relay</a> to help the Tor network grow.</li>

17)     <li>Do you have an Amazon account? Are you willing to spend up to $3 a

18)     month? Then spin up your own Tor <a href="<page
19)     docs/bridges>">bridge</a> in less than 10 minutes with <a

20)     href="https://cloud.torproject.org/">tor cloud</a>!</li>

21)     <li>Tell your friends! Get them to run relays. Get them to run hidden
22)     services. Get them to tell their friends.</li>
23)     <li>If you like Tor's goals, please <a href="<page donate/donate>">take a moment
24)     to donate to support further Tor development</a>. We're also looking
25)     for more sponsors &mdash; if you know any companies, NGOs, agencies,
26)     or other organizations that want anonymity / privacy / communications
27)     security, let them know about us.</li>
28)     <li>We're looking for more <a href="<page about/torusers>">good examples of Tor
29)     users and Tor use cases</a>. If you use Tor for a scenario or purpose not
30)     yet described on that page, and you're comfortable sharing it with us,
31)     we'd love to hear from you.</li>
32)     </ol>

33) 

34)     <a id="Documentation"></a>
35)     <h2><a class="anchor" href="#Documentation">Documentation</a></h2>
36)     <ol>

37)     <li>Help translate the
38) <!-- web page and -->
39)     documentation into other

40)     languages. See the <a href="<page getinvolved/translation>">translation
41)     guidelines</a> if you want to help out. We especially need Arabic or
42)     Farsi translations, for the many Tor users in censored areas.</li>
43)     <li>Evaluate and document

44)     <a href="<wiki>doc/TorifyHOWTO">our

45)     list of programs</a> that can be configured to use Tor.</li>
46)     <li>We have a huge list of <a

47)     href="<wiki>doc/SupportPrograms">potentially useful

48)     programs that interface to Tor</a>. Which ones are useful in which
49)     situations? Please help us test them out and document your results.</li>
50)     </ol>

51) 

52)     <a id="Advocacy"></a>
53)     <h2><a class="anchor" href="#Advocacy">Advocacy</a></h2>
54)     <ol>

55)     <li>Create a presentation that can be used for various user group
56) meetings around the world.</li>

57)     <li>Create a video about the positive uses of Tor, what Tor is,
58)     or how to use it.  Some have already started on <a

59)     href="https://media.torproject.org/video/">Tor's Media server</a>,

60)     <a

61)     href="http://www.howcast.com/videos/90601-How-To-Circumvent-an-Internet-Proxy">Howcast</a>,

62)     and <a href="http://www.youtube.com/thetorproject">YouTube</a>.</li>

63)     <li>Create a poster, or a set of posters, around a theme,

64)     such as "Tor for Freedom!"</li>
65)     <li>Create a t-shirt design that incorporates "<a
66)     href="https://check.torproject.org/">Congratulations! You are using
67)     Tor!</a>" in any language.</li>

68)     </ol>

69) 

70) <!--

71)     <a id="gsoc"></a>
72)     <h2><a class="anchor" href="#gsoc">Google Summer of Code</a></h2>
73) 
74)     <p>
75)     Tor is also taking part in this year's <a
76)     href="https://www.google-melange.com/gsoc/homepage/google/gsoc2013">Google
77)     Summer of Code</a>! The criteria for this is a little different - either
78)     gender can apply but you need to be either <a
79)     href="https://www.google-melange.com/gsoc/document/show/gsoc_program/google/gsoc2013/help_page#2._Whos_eligible_to_participate_as_a">a
80)     present student or just graduated</a>.
81)     </p>
82) 
83)     <p>
84)     As mentioned above if you're eligible for either program then please apply
85)     for both! Google Summer of Code is a far, far larger program for us than
86)     OPW so your chances of being applied that way are considerably better.
87)     </p>
88) 
89)     <p>
90)     <b>See our page for <a href="<page about/gsoc>">Google Summer of Code</a>
91)     for more information.</b>
92)     </p>

93) -->

94) 

95)     <a id="Projects"></a>
96)     <h2><a class="anchor" href="#Projects">Projects</a></h2>

97) 

98)     <p>
99)     Below are a list of Tor related projects we're developing and/or
100)     maintaining. Most discussions happen on IRC so if you're interested in any
101)     of these (or you have a project idea of your own), then please <a

102)     href="<page about/contact>#irc">join us in #tor-dev</a>. Don't be shy
103)     to ask questions, and don't hesitate to ask even if the main contributors
104)     aren't active at that moment.

105)     </p>

106) 

107)     <table id="projects">
108)       <tr>
109)         <th>Name</th>
110)         <th>Category</th>
111)         <th>Language</th>
112)         <th>Activity</th>
113)         <th>Contributors</th>
114)       </tr>

115) 

116)       <tr>
117)         <td><a href="#project-tor">Tor</a></td>
118)         <td>Core</td>
119)         <td>C</td>
120)         <td>Heavy</td>

121)         <td>nickm, athena, arma</td>

122)       </tr>

123) 

124)       <tr>

125)         <td>*<a href="#project-jtor">JTor</a></td>
126)         <td>Core</td>
127)         <td>Java</td>

128)         <td>Moderate</td>

129)         <td>bleidl</td>
130)       </tr>
131) 
132)       <tr>

133)         <td><a href="#project-torbrowser">Tor Browser</a></td>

134)         <td>Bundle</td>

135)         <td>C, Scripting</td>

136)         <td>Moderate</td>

137)         <td>mikeperry, Erinn</td>

138)       </tr>

139) 

140)       <tr>

141)         <td><a href="#project-torbutton">Torbutton</a></td>
142)         <td>Browser Add-on</td>
143)         <td>Javascript</td>
144)         <td>Moderate</td>
145)         <td>mikeperry</td>

146)       </tr>

147) 

148)       <tr>

149)         <td><a href="#project-httpseverywhere">HTTPS Everywhere</a></td>
150)         <td>Browser Add-on</td>
151)         <td>Javascript</td>

152)         <td>Heavy</td>

153)         <td>pde, mikeperry</td>

154)       </tr>

155) 

156)       <tr>

157)         <td><a href="#project-vidalia">Vidalia</a></td>
158)         <td>User Interface</td>
159)         <td>C++, Qt</td>

160)         <td>None</td>

161)         <td>chiiph</td>
162)       </tr>

163) 

164)       <tr>

165)         <td><a href="#project-arm">Arm</a></td>
166)         <td>User Interface</td>
167)         <td>Python, Curses</td>

168)         <td>Light</td>

169)         <td>atagar</td>
170)       </tr>

171) 

172)       <tr>

173)         <td><a href="#project-orbot">Orbot</a></td>
174)         <td>User Interface</td>
175)         <td>Java</td>

176)         <td>Light</td>

177)         <td>n8fr8</td>

178)       </tr>

179) 

180)       <tr>

181)         <td><a href="#project-tails">Tails</a></td>
182)         <td>OS image</td>
183)         <td>Sys Admin</td>
184)         <td>Heavy</td>
185)         <td><a href="https://tails.boum.org/">#tails</a></td>

186)       </tr>

187) 

188)       <tr>

189)         <td><a href="#project-torramdisk">tor-ramdisk</a></td>
190)         <td>OS image</td>
191)         <td>Sys Admin</td>

192)         <td>None</td>

193)         <td>blueness</td>
194)       </tr>
195) 

196)       <tr>

197)         <td>*<a href="#project-torouter">Torouter</a></td>
198)         <td>OS image</td>
199)         <td>Sys Admin</td>

200)         <td>None</td>

201)         <td>ioerror</td>
202)       </tr>
203) 

204)       <tr>

205)         <td><a href="#project-torsocks">Torsocks</a></td>
206)         <td>Usability</td>
207)         <td>C</td>

208)         <td>Light</td>

209)         <td>ioerror, nickm</td>
210)       </tr>
211) 

212)       <tr>

213)         <td><a href="#project-torbirdy">TorBirdy</a></td>
214)         <td>Browser Add-on</td>
215)         <td>JavaScript</td>
216)         <td>Heavy</td>

217)         <td>Sukhbir (sukhe)</td>

218)       </tr>

219) 

220)       <tr>

221)         <td><a href="#project-obfsproxy">Obfsproxy</a></td>
222)         <td>Client Add-on</td>

223)         <td>Python</td>

224)         <td>Moderate</td>

225)         <td>asn</td>

226)       </tr>
227) 

228)       <tr>

229)         <td><a href="#project-flash-proxy">Flash Proxy</a></td>
230)         <td>Client Add-on</td>
231)         <td>Python, JavaScript, Go</td>

232)         <td>Heavy</td>

233)         <td>dcf, aallai, jct</td>
234)       </tr>

235) 

236)       <tr>

237)         <td><a href="#project-shadow">Shadow</a></td>

238)         <td>Simulator</td>

239)         <td>C, Python</td>

240)         <td>Heavy</td>

241)         <td>robgjansen</td>
242)       </tr>

243) 

244)       <tr>

245)         <td><a href="#project-stem">Stem</a></td>

246)         <td>Library</td>
247)         <td>Python</td>
248)         <td>Heavy</td>

249)         <td>atagar</td>

250)       </tr>

251) 

252)       <tr>

253)         <td><a href="#project-txtorcon">Txtorcon</a></td>
254)         <td>Library</td>
255)         <td>Python, Twisted</td>

256)         <td>Moderate</td>

257)         <td>meejah</td>
258)       </tr>

259) 

260)       <tr>

261)         <td><a href="#project-tlsdate">Tlsdate</a></td>
262)         <td>Utility</td>
263)         <td>C</td>

264)         <td>Moderate</td>

265)         <td>ioerror</td>
266)       </tr>

267) 

268)       <tr>

269)         <td><a href="#project-metrics">Metrics</a></td>
270)         <td>Client Service</td>
271)         <td>Java</td>

272)         <td>Moderate</td>

273)         <td>karsten</td>
274)       </tr>

275) 

276)       <tr>

277)         <td><a href="#project-atlas">Atlas</a></td>
278)         <td>Client Service</td>
279)         <td>JavaScript</td>

280)         <td>Light</td>

281)         <td>hellais, karsten</td>

282)       </tr>

283) 

284)       <tr>
285)         <td><a href="#project-globe">Globe</a></td>
286)         <td>Client Service</td>
287)         <td>JavaScript</td>
288)         <td>Heavy</td>
289)         <td>Christian</td>
290)       </tr>
291) 

292)       <tr>

293)         <td><a href="#project-compass">Compass</a></td>
294)         <td>Client Service</td>
295)         <td>Python</td>

296)         <td>Light</td>

297)         <td>gsathya, karsten, cwacek</td>

298)       </tr>

299) 

300)       <tr>

301)         <td><a href="#project-onionoo">Onionoo</a></td>
302)         <td>Backend Service</td>
303)         <td>Java, Python</td>

304)         <td>Moderate</td>

305)         <td>karsten, gsathya</td>
306)       </tr>
307) 

308)       <tr>

309)         <td><a href="#project-weather">Weather</a></td>
310)         <td>Client Service</td>
311)         <td>Python</td>

312)         <td>None</td>

313)         <td>kaner</td>
314)       </tr>

315) 

316)       <tr>

317)         <td><a href="#project-gettor">GetTor</a></td>
318)         <td>Client Service</td>
319)         <td>Python</td>

320)         <td>None</td>

321)         <td>kaner</td>

322)       </tr>

323) 

324)       <tr>

325)         <td><a href="#project-torcheck">TorCheck</a></td>
326)         <td>Client Service</td>
327)         <td>Python, Perl</td>
328)         <td>None</td>

329)         <td>ioerror</td>

330)       </tr>

331) 

332)       <tr>

333)         <td><a href="#project-bridgedb">BridgeDB</a></td>
334)         <td>Backend Service</td>
335)         <td>Python</td>

336)         <td>Light</td>

337)         <td>kaner, nickm</td>

338)       </tr>

339) 

340)       <tr>

341)         <td><a href="#project-ooni-probe">Ooni Probe</a></td>

342)         <td>Scanner</td>
343)         <td>Python</td>

344)         <td>Moderate</td>

345)         <td>hellais, isis, ioerror</td>
346)       </tr>
347) 

348)       <tr>
349)         <td><a href="#project-torps">TorPS</a></td>
350)         <td>Backend Service</td>
351)         <td>Python</td>
352)         <td>Light</td>
353)         <td>Aaron Johnson</td>
354)       </tr>
355) 

356)       <tr>

357)         <td><a href="#project-torflow">TorFlow</a></td>
358)         <td>Backend Service</td>
359)         <td>Python</td>

360)         <td>None</td>

361)         <td>aagbsn, mikeperry</td>

362)       </tr>

363) 

364)       <tr>

365)         <td>*<a href="#project-torbel">TorBEL</a></td>
366)         <td>Backend Service</td>
367)         <td>Python</td>
368)         <td>None</td>
369)         <td>Sebastian</td>
370)       </tr>

371) 

372)       <tr>

373)         <td><a href="#project-tor2web">Tor2web</a></td>
374)         <td>Client Service</td>

375)         <td>Python</td>

376)         <td>Moderate</td>

377)         <td>hellais</td>

378)       </tr>

379) 

380)       <tr>

381)         <td><a href="#project-anonbib">Anonbib</a></td>
382)         <td>Website</td>

383)         <td>Python</td>

384)         <td>Light</td>
385)         <td>arma, nickm</td>
386)       </tr>
387) 

388)     </table>

389) 

390)     <sub>
391)     * Project is still in an alpha state.
392)     </sub>

393) 

394)     <br /><br />

395) 

396)     <a id="project-tor"></a>
397)     <h3>Tor (<a href="https://gitweb.torproject.org/tor.git">code</a>, <a

398)     href="https://trac.torproject.org/projects/tor/report/12">bug

399)     tracker</a>)</h3>

400) 

401)     <p>
402)     Central project, providing the core software for using and participating in
403)     the Tor network. Numerous people contribute to the project to varying
404)     extents, but the chief architects are Nick Mathewson and Roger Dingledine.
405)     </p>

406) 

407)     <p>
408)     <b>Project Ideas:</b><br />

409)     <i><a href="#limitCapabilities">Run With Limited Capabilities</a></i><br />
410)     <i><a href="#torCleanup">Tor Codebase Cleanup</a></i><br />

411)     <i><a href="#httpsImpersonation">HTTPS Server Impersonation</a></i><br />

412)     <i><a href="#chutneyExpansion">Make Chutney Do More, More Reliably</a></i>

413)     </p>

414) 

415)     <a id="project-jtor"></a>
416)     <h3><a href="https://github.com/brl/JTor/wiki">JTor</a> (<a

417)     href="https://gitweb.torproject.org/jtor.git">code</a>, <a

418)     href="https://github.com/brl/JTor/issues">bug
419)     tracker</a>)</h3>

420) 

421)     <p>
422)     Java implementation of Tor and successor to <a
423)     href="http://onioncoffee.sourceforge.net/">OnionCoffee</a>. This project
424)     isn't yet complete, and has been inactive since Fall 2010.
425)     </p>

426) 

427)     <a id="project-torbrowser"></a>

428)     <h3><a href="<page projects/torbrowser>">Tor Browser Bundle</a> (<a
429)     href="https://gitweb.torproject.org/torbrowser.git">code</a>, <a
430)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Tor+bundles/installation&order=priority">bug

431)     tracker</a>, <a href="https://www.torproject.org/projects/torbrowser/design/">design doc</a>)</h3>
432) 

433)     <p>
434)     The Tor Browser Bundle is an easy-to-use portable package of Tor, Vidalia,

435)     Torbutton, and a Firefox fork preconfigured to work together out of

436)     the box. It contains a modified copy of Firefox that aims to resolve the
437)     privacy and security issues in mainline version.

438)     </p>

439) 
440)     <a id="project-torbutton"></a>
441)     <h3><a href="<page torbutton/index>">Torbutton</a> (<a
442)     href="https://gitweb.torproject.org/torbutton.git">code</a>, <a
443)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Torbutton&order=priority">bug

444)     tracker</a>)</h3>

445) 

446)     <p>

447)     Firefox addon that addresses many of the client-side threats to browsing
448)     the Internet anonymously. Mike has since continued to adapt it to new
449)     threats, updated versions of Firefox, and possibly <a
450)     href="https://blog.torproject.org/blog/google-chrome-incognito-mode-tor-and-fingerprinting">Chrome
451)     as well</a>.

452)     </p>

453) 
454)     <a id="project-httpseverywhere"></a>
455)     <h3><a href="https://www.eff.org/https-everywhere">HTTPS Everywhere</a> (<a
456)     href="https://gitweb.torproject.org/https-everywhere.git">code</a>, <a
457)     href="https://trac.torproject.org/projects/tor/report/19">bug

458)     tracker</a>)</h3>

459) 

460)     <p>

461)     HTTPS Everywhere is a Firefox and Chrome extension that encrypts
462)     your communications with many major websites, making your browsing
463)     more secure.

464)     </p>

465) 

466)     <a id="project-vidalia"></a>
467)     <h3><a href="<page projects/vidalia>">Vidalia</a> (<a

468)     href="https://gitweb.torproject.org/vidalia.git">code</a>, <a

469)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Vidalia&order=priority">bug
470)     tracker</a>)</h3>

471) 

472)     <p>
473)     The most commonly used user interface for Tor. Matt Edman started the
474)     project in 2006 and brought it to its current stable state. Development

475)     slowed for several years, though Tomás Touceda has since taken the
476)     lead with pushing the project forward.

477)     </p>

478) 

479)     <a id="project-arm"></a>

480)     <h3><a href="https://www.atagar.com/arm/">Arm</a> (<a

481)     href="https://gitweb.torproject.org/arm.git">code</a>, <a

482)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=arm&order=priority">bug
483)     tracker</a>)</h3>

484) 

485)     <p>

486)     The anonymizing relay monitor (arm) is a terminal status monitor for Tor,
487)     intended for command-line aficionados, ssh connections, and anyone with a
488)     tty terminal. This works much like top does for system usage, providing
489)     real time statistics for bandwidth, resource usage, connections, and quite
490)     a bit more.

491)     </p>

492) 

493)     <a id="project-orbot"></a>
494)     <h3><a href="https://guardianproject.info/apps/orbot/">Orbot</a> (<a

495)     href="https://gitweb.torproject.org/orbot.git">code</a>, <a

496)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Orbot&order=priority">bug
497)     tracker</a>)</h3>

498) 
499)     <p>
500)     Provides Tor on the Android platform. This was under very active
501)     development up through Fall 2010, after which things have been quiet.
502)     </p>
503) 
504)     <a id="project-tails"></a>
505)     <h3><a href="https://tails.boum.org/">The Amnesic Incognito Live System</a> (<a

506)     href="https://git-tails.immerda.ch/tails/">code</a>, <a
507)     href="https://labs.riseup.net/code/projects/tails">bug

508)     tracker</a>)</h3>
509) 
510)     <p>
511)     The Amnesic Incognito Live System is a live CD/USB distribution
512)     preconfigured so that everything is safely routed through Tor and leaves no
513)     trace on the local system. This is a merger of the Amnesia and <a
514)     href="http://www.anonymityanywhere.com/incognito/">Incognito</a> projects,
515)     and still under very active development.
516)     </p>
517) 

518)     <a id="project-torramdisk"></a>
519)     <h3><a href="http://opensource.dyc.edu/tor-ramdisk">Tor-ramdisk</a> (<a

520)     href="https://gitweb.torproject.org/tor-ramdisk.git">code</a>, <a

521)     href="http://opensource.dyc.edu/tor-ramdisk-documentation">documentation</a>)</h3>

522) 
523)     <p>

524)     Tor-ramdisk is a uClibc-based micro Linux distribution whose sole
525)     purpose is to securely host a Tor server purely in RAM.

526)     </p>
527) 

528)     <a id="project-torouter"></a>
529)     <h3><a
530)     href="<wiki>doc/Torouter">Torouter</a> (<a

531)     href="https://gitweb.torproject.org/torouter.git">code</a>, <a

532)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Torouter&order=priority">bug
533)     tracker</a>)</h3>
534) 
535)     <p>
536)     Project to provide an easy-to-use, embedded Tor instance for routers. This
537)     had high activity in late 2010, but has since been rather quiet.
538)     </p>
539) 
540)     <a id="project-torsocks"></a>

541)     <h3>Torsocks (<a

542)     href="https://gitweb.torproject.org/torsocks.git">code</a>, <a
543)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Torify&order=priority">bug
544)     tracker</a>)</h3>
545) 

546)     <p>

547)     Utility for adapting other applications to work with Tor. Development has
548)     slowed and compatibility issues remain with some platforms, but it's
549)     otherwise feature complete.

550)     </p>

551) 

552)     <a id="project-torbirdy"></a>
553)     <h3>TorBirdy (<a
554)     href="https://github.com/ioerror/torbirdy">code</a>, <a
555)     href="https://trac.torproject.org/projects/tor/wiki/torbirdy/dev">bug
556)     tracker</a>)</h3>

557) 

558)     <p>
559)     TorBirdy is Torbutton for Thunderbird and related Mozilla mail clients.
560)     </p>

561) 

562)     <a id="project-obfsproxy"></a>

563)     <h3><a href="<page projects/obfsproxy>">Obfsproxy</a> (<a

564)     href="https://gitweb.torproject.org/pluggable-transports/obfsproxy.git">code</a>,
565)     <a href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Pluggable+transport&order=priority">bug

566)     tracker</a>)</h3>

567) 

568)     <p>
569)     A proxy that shapes Tor traffic, making it harder for censors to detect and

570)     block Tor. This has both a C and python implementation.

571)     </p>

572) 

573)     <p>
574)     <b>Project Ideas:</b><br />
575)     <i><a href="#betterPluggableTransports">Build Better Pluggable Transports</a></i>
576)     </p>
577) 

578)     <a id="project-flash-proxy"></a>
579)     <h3><a href="https://crypto.stanford.edu/flashproxy/">Flash Proxy</a> (<a
580)     href="https://gitweb.torproject.org/flashproxy.git">code</a>, <a
581)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_information&status=needs_review&status=needs_revision&status=new&status=reopened&component=Flashproxy">bug
582)     tracker</a>)</h3>

583) 

584)     <p>
585)     Pluggable transport using proxies running in web browsers to defeat
586)     address-based blocking.
587)     </p>

588) 

589)     <a id="project-shadow"></a>
590)     <h3><a href="https://shadow.cs.umn.edu/">Shadow</a> (<a
591)     href="https://github.com/shadow">code</a>, <a
592)     href="https://github.com/shadow/shadow/issues">bug
593)     tracker</a>)</h3>

594) 

595)     <p>
596)     Shadow is a discrete-event network simulator that runs the real
597)     Tor software as a plug-in. Shadow is open-source software that enables
598)     accurate, efficient, controlled, and repeatable Tor experimentation.

599)     For another simulator, see <a
600)     href="http://crysp.uwaterloo.ca/software/exptor/">ExperimenTor</a>.

601)     </p>

602) 

603)     <a id="project-stem"></a>

604)     <h3><a href="https://stem.torproject.org/">Stem</a> (<a

605)     href="https://gitweb.torproject.org/stem.git">code</a>, <a

606)     href="https://trac.torproject.org/projects/tor/wiki/doc/stem/bugs">bug

607)     tracker</a>)</h3>

608) 

609)     <p>

610)     Python controller library for scripts and controller applications using
611)     Tor.

612)     </p>

613) 

614)     <p>
615)     <b>Project Ideas:</b><br />

616)     <i><a href="#txtorcon-stemIntegration">Txtorcon/Stem Integration</a></i><br />

617)     <i><a href="#stemUsability">Stem Usability and Porting</a></i><br />
618)     <i><a href="#stemTestingForTor">Stem Tests for Tor</a></i>

619)     </p>

620) 

621)     <a id="project-txtorcon"></a>

622)     <h3><a href="https://txtorcon.readthedocs.org">Txtorcon</a> (<a

623)     href="https://github.com/meejah/txtorcon">code</a>, <a

624)     href="https://github.com/meejah/txtorcon/issues">bug tracker</a>)</h3>

625) 

626)     <p>
627)     Twisted-based asynchronous Tor control protocol implementation. Includes
628)     unit-tests, examples, state-tracking code and configuration abstraction.
629)     Used by OONI and APAF.
630)     </p>

631) 

632)     <p>
633)     <b>Project Ideas:</b><br />
634)     <i><a href="#txtorcon-stemIntegration">Txtorcon/Stem Integration</a></i>
635)     </p>
636) 

637)     <a id="project-tlsdate"></a>
638)     <h3>Tlsdate (<a href="https://github.com/ioerror/tlsdate">code</a>)</h3>

639) 

640)     <p>
641)     tlsdate: secure parasitic rdate replacement
642)     </p>

643) 

644)     <p>
645)     tlsdate sets the local clock by securely connecting with TLS to remote
646)     servers and extracting the remote time out of the secure handshake. Unlike
647)     ntpdate, tlsdate uses TCP, for instance connecting to a remote HTTPS or TLS
648)     enabled service, and provides some protection against adversaries that try
649)     to feed you malicious time information.
650)     </p>

651) 

652)     <a id="project-metrics"></a>
653)     <h3><a href="https://metrics.torproject.org/">Metrics</a> (code: <a
654)     href="https://gitweb.torproject.org/metrics-db.git">db</a>, <a
655)     href="https://gitweb.torproject.org/metrics-utils.git">utils</a>, <a

656)     href="https://gitweb.torproject.org/metrics-web.git">web</a>)</h3>

657) 

658)     <p>
659)     Processing and analytics of consensus data, provided to users via the
660)     metrics portal. This has been under active development for several years by

661)     Karsten Loesing. See also <a
662)     href="https://gitweb.torproject.org/torperf.git">TorPerf</a>.

663)     </p>

664) 

665)     <p>
666)     <b>Project Ideas:</b><br />
667)     <i><a href="#metricsSearch">Searchable Tor descriptor and Metrics data archive</a></i> (Python/Django?)
668)     </p>

669) 

670)     <a id="project-atlas"></a>
671)     <h3><a href="https://atlas.torproject.org/">Atlas</a> (<a
672)     href="https://gitweb.torproject.org/atlas.git">code</a>)</h3>

673) 

674)     <p>
675)     Atlas is a web application to discover Tor relays and bridges. It provides
676)     useful information on how relays are configured along with graphics about

677)     their past usage.

678)     </p>

679) 

680)     <p>

681)     This is the spiritual successor to <a
682)     href="https://gitweb.torproject.org/torstatus.git">TorStatus</a>, the <a

683)     href="https://svn.torproject.org/svn/torstatus/trunk/">original

684)     codebase</a> for which was written in PHP, and rewritten by students from
685)     Wesleyan as Django.

686)     </p>

687) 

688)     <a id="project-globe"></a>
689)     <h3><a href="http://globe.rndm.de/">Globe</a> (<a
690)     href="https://github.com/makepanic/globe">code</a>, <a
691)     href="https://github.com/makepanic/globe/issues">bug tracker</a>)</h3>
692) 
693)     <p>
694)     Globe is a web application that allows you to search for Tor relays and
695)     bridges. It gives you a detailed overview of properties and configurations
696)     of a relay or bridge.
697)     </p>
698) 

699)     <a id="project-compass"></a>
700)     <h3><a href="https://compass.torproject.org/">Compass</a> (<a
701)     href="https://gitweb.torproject.org/compass.git">code</a>, <a
702)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Compass&order=priority">bug
703)     tracker</a>)</h3>

704) 

705)     <p>
706)     Compass is a web and command line application that filters and
707)     aggregates the Tor relays based on various attributes.
708)     </p>

709) 
710)     <a id="project-onionoo"></a>
711)     <h3><a href="<page projects/onionoo>">Onionoo</a> (<a
712)     href="https://gitweb.torproject.org/onionoo.git">java codebase</a>, <a
713)     href="https://gitweb.torproject.org/pyonionoo.git">python

714)     codebase</a>, <a href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Onionoo&order=priority">bug tracker</a>)</h3>

715) 
716)     <p>
717)     Onionoo is a JSON based protocol to learn information about currently
718)     running Tor relays and bridges.
719)     </p>
720) 

721)     <a id="project-weather"></a>

722)     <h3><a href="https://trac.torproject.org/projects/tor/wiki/org/roadmaps/Weather">Weather</a> (<a

723)     href="https://gitweb.torproject.org/weather.git">code</a>, <a
724)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Tor+Weather&order=priority">bug
725)     tracker</a>)</h3>

726) 

727)     <p>
728)     Provides automatic notification to subscribed relay operators when their
729)     relay's unreachable. This underwent a rewrite by the <a
730)     href="http://hfoss.wesleyan.edu/">Wesleyan HFOSS team</a>, which went live
731)     in early 2011.
732)     </p>

733) 

734)     <a id="project-gettor"></a>

735)     <h3><a href="https://trac.torproject.org/projects/tor/wiki/org/roadmaps/GetTor">GetTor</a> (<a

736)     href="https://gitweb.torproject.org/gettor.git">code</a>, <a

737)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=GetTor&order=priority">bug
738)     tracker</a>)</h3>

739) 

740)     <p>
741)     E-mail autoresponder providing Tor's packages over SMTP. This has been
742)     relatively unchanged for quite a while.
743)     </p>

744) 

745)     <a id="project-torcheck"></a>

746)     <h3><a href="https://trac.torproject.org/projects/tor/wiki/org/roadmaps/TorCheck">TorCheck</a> (<a

747)     href="https://svn.torproject.org/svn/check/trunk/">code</a>, <a
748)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Tor+Check&order=priority">bug
749)     tracker</a>)</h3>

750) 

751)     <p>
752)     Provides a simple site for determining if the visitor is using Tor or not.
753)     This has been relatively unchanged for quite a while.
754)     </p>

755) 

756)     <a id="project-bridgedb"></a>

757)     <h3><a href="https://trac.torproject.org/projects/tor/wiki/org/roadmaps/BridgeDB">BridgeDB</a> (<a

758)     href="https://gitweb.torproject.org/bridgedb.git">code</a>, <a
759)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=BridgeDB&order=priority">bug
760)     tracker</a>)</h3>

761) 

762)     <p>
763)     Backend bridge distributor, handling the various pools they're distributed
764)     in. This was actively developed until Fall of 2010.
765)     </p>

766) 
767)     <a id="project-ooni-probe"></a>

768)     <h3><a href="https://ooni.torproject.org/">Ooni Probe</a> (<a

769)     href="https://gitweb.torproject.org/ooni-probe.git">code</a>, <a
770)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Ooni&order=priority">bug
771)     tracker</a>)</h3>
772) 
773)     <p>
774)     Censorship scanner, checking your local connection for blocked or modified
775)     content.
776)     </p>
777) 

778)     <p>
779)     <b>Project Ideas:</b><br />

780)     <i><a href="#ooniprobeSimulator">Create an Internet Censorship Virtual Machine Based Simulator</a></i><br />
781)     <i><a href="#censorshipAnalyzer">Develop a Censorship Analyzer</a></i>

782)     </p>
783) 

784)     <a id="project-torps"></a>
785)     <h3>TorPS</a> (<a href="https://github.com/torps/torps">code</a>)</h3>
786) 
787)     <p>
788)     The Tor Path Simulator (TorPS) is a tool for efficiently simulating
789)     path selection in Tor. It chooses circuits and assigns user streams to
790)     those circuits in the same way that Tor does. TorPS is fast enough to
791)     perform thousands of simulations over periods of months.
792)     </p>
793) 

794)     <a id="project-torflow"></a>

795)     <h3><a href="https://trac.torproject.org/projects/tor/wiki/org/roadmaps/TorFlow">TorFlow</a> (<a

796)     href="https://gitweb.torproject.org/torflow.git">code</a>, <a
797)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=Torflow&order=priority">bug
798)     tracker</a>)</h3>

799) 

800)     <p>
801)     Library and collection of services for actively monitoring the Tor network.
802)     These include the Bandwidth Scanners (measuring throughput of relays) and
803)     SoaT (scans for malicious or misconfigured exit nodes). SoaT was last
804)     actively developed in the Summer of 2010, and the Bandwidth Scanners a few
805)     months later. Both have been under active use since then, but development
806)     has stopped.
807)     </p>

808) 

809)     <a id="project-torbel"></a>
810)     <h3><a

811)     href="https://blog.torproject.org/blog/torbel-tor-bulk-exit-list-tools">TorBEL</a> (<a
812)     href="https://gitweb.torproject.org/torbel.git">code</a>, <a

813)     href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_review&status=new&status=reopened&component=TorDNSEL/TorBEL&order=priority">bug
814)     tracker</a>)</h3>

815) 

816)     <p>
817)     The Tor Bulk Exitlist provides a method of identifying if IPs belong to
818)     exit nodes or not. This is a replacement for TorDNSEL which is a stable
819)     (though unmaintained) Haskell application for this purpose. The initial
820)     version of TorBEL was started in GSOC 2010 but since then the project has
821)     been inactive.
822)     </p>

823) 

824)     <p>
825)     <b>Project Ideas:</b><br />
826)     <i><a href="#stemUsability">Stem Usability and Porting (this includes an idea for finishing off TorBEL)</a></i>
827)     </p>
828) 

829)     <a id="project-tor2web"></a>
830)     <h3><a
831)     href="http://wiki.tor2web.org/index.php/Main_Page">Tor2web</a> (<a
832)     href="https://github.com/globaleaks/tor2web-3.0/wiki">code</a>)</h3>
833) 
834)     <p>
835)     Tor2web allows Internet users to browse websites running in <a
836)     href="<page docs/hidden-services>">Tor hidden services</a>. It trades
837)     user anonymity for usability by allowing anonymous content to be
838)     distributed to non-anonymous users.
839)     </p>
840) 

841)     <a id="project-anonbib"></a>
842)     <h3><a
843)     href="http://freehaven.net/anonbib/">Anonymity Bibliography</a> (<a
844)     href="https://gitweb.torproject.org/anonbib.git">code</a>)</h3>
845) 
846)     <p>

847)     Anonbib is a list of important papers in the field of anonymity. It's
848)     also a set of scripts to generate the website from Latex (bibtex). If
849)     we're missing any important papers, please let us know!

850)     </p>
851) 

852)     <a id="Coding"></a>
853)     <a id="Summer"></a>

854)     <h2><a class="anchor" href="#Coding">Project Ideas</a></h2>

855) 

856)     <p>

857)     You may find some of these projects to be good ideas for <a href="<page
858)     about/gsoc>">Google Summer of Code</a> and the <a
859)     href="https://live.gnome.org/OutreachProgramForWomen">Outreach Program for

860)     Women</a>. We have labelled each idea with how much work we expect it would
861)     be (effort level), how much clue you should start with (skill level),
862)     and which of our <a href="<page about/corepeople>">core developers</a>
863)     would be good mentors. If one or more of these ideas looks promising to
864)     you, please <a href="<page about/contact>">contact us</a> to discuss your
865)     plans rather than sending blind applications. You may also want to propose
866)     your own project idea &mdash; which often results in the best applications.

867)     </p>

868) 

869)     <ol>

870) 

871)     <a id="txtorcon-stemIntegration"></a>
872)     <li>
873)     <b>Txtorcon/Stem Integration</b>
874)     <br>
875)     Effort Level: <i>Medium</i>
876)     <br>
877)     Skill Level: <i>Medium</i>
878)     <br>
879)     Likely Mentors: <i>meejah, Damian (atagar)</i>
880)     <p>Txtorcon is a Twisted-based Python controller library, and Stem is a
881)     synchronous (threaded) one, also in Python. There is no need to have
882)     two implementations of (at least) the protocol parsing code. This
883)     project would entail eliminating duplication by leveraging Stem's
884)     parsing in txtorcon while keeping txtorcon's API the same (or at least
885)     close).</p>

886)     <p>Besides this you should identify some additional tasks to improve our
887)     controller space across these two libraries. Some ideas are...</p>
888)     <ul>
889)       <li>Write a tutorial for <a
890)       href="https://stem.torproject.org/tutorials.html">stem's tutorial
891)       page</a> demonstrating cross txtorcon/stem usage.</li>
892)       <li>Expand the txtorcon API to include functionality of <a
893)       href="https://gitweb.torproject.org/stem.git/blob/HEAD:/stem/control.py">stem's
894)       controller</a> that would be of interest to twisted users. All additions
895)       should include tests!</li>
896)       <li>Come up with some ideas of your own! We'd love to discuss them with
897)       you.</li>
898)     </ul>

899)     <p>This would very likely involve changes to both libraries, although
900)     most would be expected to be in txtorcon. meejah is available to
901)     mentor txtorcon changes, and Damian (atagar) can help with Stem.</p>
902)     <p>It would help if you're already familiar with event-based programming,
903)     bonus points if it's Twisted.</p>
904)     </li>
905) 

906)     <a id="httpsImpersonation"></a>

907)     <li>
908)     <b>HTTPS Server Impersonation</b>
909)     <br>
910)     Effort Level: <i>Medium to High</i>
911)     <br>
912)     Skill Level: <i>Medium to High</i>
913)     <br>
914)     Likely Mentors: <i>Nick (nickm)</i>

915)     <p>

916)     We have an open proposal for a way to make Tor bridges avoid censorship by
917)     impersonating an HTTPS server.  Specifically, we need to hack some popular
918)     SSL "reverse proxy" (your choice) so that it relays regular web connections
919)     to an HTTP server, but certain connections to a local Tor process.  <a
920)     href="https://gitweb.torproject.org/torspec.git/blob_plain/HEAD:/proposals/203-https-frontend.txt">Proposal
921)     203</a> has a general design sketch.

922)     </p>

923) 
924)     <p>
925)     <b>This project is likely trickier than it looks. You should avoid applying
926)     for this if you're uncertain about being able to complete it.</b>
927)     </p>
928)     </li>

929)     </li>

930) 

931)     <a id="chutneyExpansion"></a>
932)     <li>
933)     <b>Make Chutney Do More, More Reliably</b>
934)     <br>
935)     Effort Level: <i>Medium to High, depending on scope of project</i>
936)     <br>
937)     Skill Level: <i>Medium</i>
938)     <br>

939)     Likely Mentors: <i>Nick (nickm)</i>
940)     <p>

941)     We have a little Python tool called <a
942)     href="https://gitweb.torproject.org/nickm/chutney.git">Chutney</a> for
943)     making small local test networks.  It's small, not widely used, and not as
944)     automated as it could be.

945)     </p>

946) 

947)     <p>

948)     It would be great to see chutney extended and a set of supporting tests
949)     built to the point where we could use Chutney to exercise various Tor
950)     features as an automated integration test.

951)     </p>

952) 
953)     <p>
954)     <b>As part of your application for this project please submit a patch that
955)     expands Chutney.</b>
956)     </p>
957) 

958)     </li>

959) 

960)     <a id="limitCapabilities"></a>

961)     <li>

962)     <b>Run With Limited Capabilities</b>

963)     <br>
964)     Effort Level: <i>Medium to High</i>
965)     <br>

966)     Skill Level: <i>High</i>

967)     <br>
968)     Likely Mentors: <i>Nick (nickm)</i>
969)     <p>

970)     Many modern operating systems give a running program the ability to drop
971)     capabilities that it no longer needs, and other ways for a program to run
972)     pieces of itself in a sandbox with diminished privileges.

973)     </p>

974) 

975)     <p>

976)     We'd like to do this with Tor, to improve its resistance to attacks.  The
977)     easiest areas to address would be on systems like <a
978)     href="https://lwn.net/Articles/475361/">recent Linux kernels</a> that make
979)     it easy to drop or restrict the set of syscalls that a program can invoke.
980)     That's a great project, but probably not big enough for an internship just
981)     on its own.  For that, we'd want to make progress on at least multiple
982)     platforms, or look into refactoring Tor into pieces that need more
983)     privileges and pieces that don't with an eye towards sandboxing them
984)     differently.

985)     </p>

986) 

987)     <p>

988)     See tickets <a href="https://trac.torproject.org/7005">#7005</a> and <a
989)     href="https://trac.torproject.org/5219">#5219</a>, and their descendants,
990)     for more information.

991)     </p>
992)     </li>

993) 

994)     <a id="metricsSearch"></a>

995)     <li>

996)     <b>Searchable Tor descriptor and Metrics data archive</b>

997)     <br>
998)     Effort Level: <i>Medium</i>
999)     <br>
1000)     Skill Level: <i>Medium</i>
1001)     <br>

1002)     Likely Mentors: <i>Karsten</i>
1003)     <p>The <a href="https://metrics.torproject.org/data.html">Metrics data
1004)     archive</a> of Tor relay descriptors and other Tor-related network data has
1005)     grown to over 100G in size, bz2-compressed.  We have developed two search
1006)     interfaces: the <a
1007)     href="https://metrics.torproject.org/relay-search.html">relay search</a>
1008)     finds relays by nickname, fingerprint, or IP address in a given month; <a
1009)     href="https://metrics.torproject.org/exonerator.html">ExoneraTor</a> finds
1010)     whether a given IP address was a relay on a given day.</p>

1011) 

1012)     <p>We'd like to have a more general search application for Tor descriptors
1013)     and metrics data.  There are more <a
1014)     href="https://metrics.torproject.org/formats.html">descriptor types</a>
1015)     that we'd like to include in the search.  The search application should
1016)     handle most of them and understand some semantics like what's a timestamp,
1017)     what's an IP address, and what's a link to another descriptor.  Users
1018)     should then be able to search for arbitrary strings or limit their search
1019)     to given time periods or IP address ranges.  Descriptors that reference
1020)     other descriptors should contain links, and descriptors should be able to
1021)     say from where they are linked.  The goal is to make the archive easily
1022)     browsable.</p>

1023) 

1024)     <p>The search application shall be separate from the metrics website and
1025)     shouldn't rely on the metrics website codebase.  The search application
1026)     will contain hourly updated descriptor data from the metrics website via
1027)     rsync.  Programming language and database system are not specified yet,
1028)     though there's a slight preference for Python/Django and Postgres for
1029)     maintenance reasons.  If there are good reasons to pick something else,
1030)     e.g, some NoSQL variant or some search application framework, that's fine,
1031)     too.  Further requirements are that lookups should be really fast and that
1032)     changes to the search application can be implemented in reasonable
1033)     time.</p>

1034) 

1035)     <p>Applications for this project should come with a design of the proposed
1036)     search application, ideally with a proof-of-concept based on a subset of
1037)     the available data to show that it will be able to handle the 100G+ of
1038)     data.</p>

1039)     </li>

1040) 

1041)     <a id="stemUsability"></a>

1042)     <li>

1043)     <b>Stem Usability and Porting</b>

1044)     <br>
1045)     Effort Level: <i>Medium</i>
1046)     <br>
1047)     Skill Level: <i>Medium</i>
1048)     <br>

1049)     Likely Mentors: <i>Damian (atagar), Sebastian</i>

1050)     <p>

1051)     <a href="https://stem.torproject.org/">Stem</a> is a

1052)     python controller library for tor. Like it's predecessor, <a

1053)     href="https://gitweb.torproject.org/pytorctl.git">TorCtl</a>, it uses tor's <a

1054)     href="https://gitweb.torproject.org/torspec.git/blob/HEAD:/control-spec.txt">control
1055)     protocol</a> to help developers program against the tor process, enabling
1056)     them to build things similar to <a href="#project-vidalia">Vidalia</a> and

1057)     <a href="https://www.atagar.com/arm/">arm</a>.

1058)     </p>

1059) 

1060)     <p>
1061)     While TorCtl provided a fine first draft for this sort of functionality,
1062)     it has not proved to be extensible nor maintainable. Stem is a rewrite of
1063)     TorCtl with a heavy focus on testing, documentation, and providing a
1064)     developer friendly API.
1065)     </p>

1066) 

1067)     <p>

1068)     Stem has largely met these goals but there's still plenty of low hanging
1069)     fruit in terms of usability improvements. Also, we have clients still using

1070)     TorCtl that need to be ported over. This project would include several
1071)     subtasks. Some ideas for instance are...

1072)     </p>

1073) 

1074)     <ol>
1075)       <li>Come up with a better, more developer friendly "Module Overview" for our documentation (<a href="https://stem.torproject.org/api/control.html">example page</a>). For instance, it would be nice to provide interlinking between the overview and the classes/methods that it lists. This will probably involve asking for help from the <a href="http://sphinx-doc.org/">Sphinx user list</a>. (<a href="https://trac.torproject.org/7632">ticket</a>)</li>

1076)       <li>After getting some exposure to stem it would be time to give using it a try. Tor has a couple clients (<a href="https://trac.torproject.org/8263">TorBEL</a> and <a href="https://trac.torproject.org/8264">Tor Weather</a>) that are ready to be moved to stem. Hopefully porting these will also provide us with some lessons on how we can further improve stem's API. <b>Note that this would also involve polishing off <a href="#project-torbel">TorBEL</a>, including the <a href="https://trac.torproject.org/projects/tor/query?status=accepted&status=assigned&status=needs_information&status=needs_review&status=needs_revision&status=new&status=reopened&group=component&component=TorDNSEL%2FTorBEL&order=priority">issues that prevent us from deploying it</a></b>. This later portion would be primarily mentored by Sebastian.</li>

1077)       <li><b>... other ideas?</b> The above are just some ideas I've come up with to improve usability and likely not enough to fill the summer. Feel free to suggest some of your own! For instance, one option would be to expand <a href="https://stem.torproject.org/tutorials.html">stem's tutorials</a> with more examples, maybe <a href="https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev/">contacting tor-dev@</a> to brainstorm ideas. This last bit is pretty open so I look forward to seeing what you come up with!</li>

1078)     </ol>

1079) 

1080)     <p>

1081)     <b>As part of your application for this project please write a script that does something interesting with stem.</b> Bonus points if this is something that we can <a href="https://stem.torproject.org/tutorials.html">make a tutorial</a> around!

1082)     </p>

1083) 

1084)     <a id="stemTestingForTor"></a>
1085)     <li>
1086)     <b>Stem Tests for Tor</b>
1087)     <br>
1088)     Effort Level: <i>Medium</i>
1089)     <br>
1090)     Skill Level: <i>Medium</i>
1091)     <br>
1092)     Likely Mentors: <i>Damian (atagar)</i>
1093)     <p>
1094)     Stem is a library for interacting with Tor (see '<a href="#stemUsability">Stem Usability and Porting</a>' above for a summary). The library has both <a href="https://gitweb.torproject.org/stem.git/tree/HEAD:/test/unit">unit</a> and <a href="https://gitweb.torproject.org/stem.git/tree/HEAD:/test/integ">integration</a> tests. The unit tests provide a quick, direct test of stem's codebase while the integration test exercises its functionality against a live instance of Tor.
1095)     </p>
1096) 
1097)     <p>
1098)     Stem's integration tests have thus far been (unsurprisingly) designed to test stem but there's no need for them to be limited to that. Stem is a complete implementation of Tor's <a href="https://gitweb.torproject.org/torspec.git/blob/HEAD:/control-spec.txt">control-spec</a> and <a href="https://gitweb.torproject.org/torspec.git/blob/HEAD:/dir-spec.txt">dir-spec</a>. As such, stem's tests could be easily expanded to more dedicatedly test behavior involved in those portions of Tor's codebase, as well as provide a smoke test for its general functionality.
1099)     </p>
1100) 
1101)     <p>
1102)     This project would involve several components:
1103)     </p>
1104) 
1105)     <ol>
1106)       <li>Determine what kind of tests we need. <b>This should be done during the application phase</b> by <a href="https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev/">contacting tor-dev@</a>. Hopefully this will give us an idea of what would be the most useful kind of tests of this nature for Tor development.</li>

1107)       <li>Our <a href="https://jenkins.torproject.org/job/stem-tor-ci/">automated testing environment</a> presently sends the test output when they fail. We should think about having our tests optionally provide html formatted results (maybe this is something a testing framework can already provide?).</li>

1108)       <li>Implement the new suite of integration tests for Tor. This will likely include expanding Tor to support better testability. One useful candidate, for instance, would be a controller method to fetch our own descriptor. This would let us easily test various configurations to see if they provide valid descriptor content.</li>
1109)     </ol>
1110) 
1111)     <p>

1112)     <b>As part of your application for this project please write some code to expand stem's tests.</b> Bonus points if it implements one of your suggestions for better testing Tor!

1113)     </p>
1114) 

1115)     <a id="torCleanup"></a>

1116)     <li>

1117)     <b>Tor Codebase Cleanup</b>

1118)     <br>

1119)     Effort Level: <i>Low to High, depending on subproject chosen</i>

1120)     <br>

1121)     Skill Level: <i>Medium to High</i>

1122)     <br>

1123)     Likely Mentors: <i>Nick (nickm)</i>

1124)     <p>

1125)     The Tor code is almost 10 years old in places, and we haven't always had
1126)     enough time or wisdom to write things as well as we could have.  Our unit
1127)     test coverage is shamefully low, and the dependency graph of our modules is
1128)     shamefully convoluted . We could use refactoring and unit tests!  Please
1129)     look through the Tor source code and look for ugly or tricky code or
1130)     dependencies -- the uglier and trickier the better -- and think about how
1131)     you could make the code look better, read better, and (subject to testing)
1132)     work better.

1133)     </p>

1134) 

1135)     <p>

1136)     If this is for a fun side-project, it would be great for you to work on
1137)     anything that can be made better and more tested.  For an internship-level
1138)     position, we'd hope that you could find a number of particularly tricky or
1139)     knotty piece of the code to clean up, and aim for resolving the ugliest
1140)     problems, not necessarily the easiest.

1141)     </p>

1142) 

1143)     <p>

1144)     For a big project here, it would be great to pick one of the major
1145)     "submodules" of Tor -- path selection, node discovery, directory authority
1146)     operations, directory service -- and refactor its interface completely, to
1147)     minify and codify its points of contact with the rest of Tor.

1148)     </p>

1149) 
1150)     <p>
1151)     <b>As part of your application for this project please identify one of the
1152)     thorniest Tor functions and submit a patch refactoring it to be better. If
1153)     you find this to be difficult then this likely isn't the project for
1154)     you.</b>
1155)     </p>

1156)     </li>

1157) 

1158)     <a id="ooniprobeSimulator"></a>
1159)     <li>
1160)     <b>Create an Internet Censorship Virtual Machine Based Simulator</b>
1161)     <br>
1162)     Effort Level: <i>Medium</i>
1163)     <br>
1164)     Skill Level: <i>Medium</i>
1165)     <br>
1166)     Likely Mentors: <i>hellais</i>
1167)     <p>
1168)     The purpose of this is to create a virtual machine based environment for
1169)     recreating censorship. The task of the student will be to document and
1170)     implement a system that allows you to recreated a censored network with the
1171)     purpose of testing the proper functioning of ooniprobe tests.
1172)     </p>
1173) 
1174)     <p>
1175)     Some ideas of things that would be useful to have be emulated by the test
1176)     lab:
1177)     </p>
1178) 
1179)     <ul>
1180)       <li>A transparent HTTP proxy (based on squid)</li>
1181)       <li>NAT traversal</li>
1182)       <li>HTTP proxy blocking certain sites</li>
1183)       <li>DNS based censorship</li>
1184)     </ul>
1185) 
1186)     <p>
1187)     The process of setting up the virtual machines and simulating censorship
1188)     should be fully automated (<a
1189)     href="https://trac.torproject.org/projects/tor/ticket/7233">related
1190)     ticket</a>).
1191)     </p>
1192)     </li>
1193) 

1194)     <a id="steganographyBrowserAddon"></a>
1195)     <li>
1196)     <b>Steganography Browser Addon</b>
1197)     <br>
1198)     Effort Level: <i>Medium</i>
1199)     <br>
1200)     Skill Level: <i>Medium</i>
1201)     <br>
1202)     Likely Mentors: <i>sukhbir, Moritz (gamambel)</i>
1203)     <p>
1204)     To facilitate the sharing of bridge addresses and other secrets, we want
1205)     a browser addon that detects steganographically and  asymmetrically
1206)     encrypted content embedded in website content. It would ship with a set
1207)     of preconfigured keys, as well as allow users to modify that set.
1208)     Additionally, it should be able to embed secrets. It must be written in
1209)     an extensible way, so that other steganography libraries and supported
1210)     media types can be added to the code easily.
1211)     </p>
1212) 
1213)     <p>
1214)     As part of your application for this project assess the current state of
1215)     Javascript steganography libraries, tell us which one you would pick
1216)     primarily, and why. Ideally, your application comes with some mockups of
1217)     how parts of the user interface of your addon would look like.
1218)     </p>

1219) 
1220)     <p>
1221)     For more information see the <a
1222)     href="http://www.cs.kau.se/philwint/censorbib/#Invernizzi2012">Message In A
1223)     Bottle: Sailing Past Censorship</a> research paper.
1224)     </p>

1225)     </li>
1226) 

1227)     <a id="betterPluggableTransports"></a>
1228)     <li>
1229)     <b>Build Better Pluggable Transports</b>
1230)     <br>
1231)     Effort Level: <i>Medium to High</i>
1232)     <br>
1233)     Skill Level: <i>Medium</i>
1234)     <br>
1235)     Likely Mentors: <i>Steven (sjmurdoch)</i>
1236)     <p>
1237)     For Tor users in censored countries, we currently offer <a
1238)     href="https://www.torproject.org/projects/obfsproxy.html.en">obfsproxy</a>
1239)     bridges, which disguise Tor traffic by making it look random. This works
1240)     for many users, but it has disadvantages: firstly it does not disguise
1241)     packet size and secondly it looks like no real protocol. These weaknesses
1242)     may result in obfsproxy being blocked.
1243)     </p>
1244) 
1245)     <p>
1246)     The goal for this project will be to implement new pluggable transports,
1247)     which resolve these weaknesses and so can be deployed if/when obfsproxy is
1248)     blocked. Ideas for doing so include:
1249)       <ul>
1250)         <li>Impersonate a voice-over-IP protocol</li>
1251)         <li>Impersonate HTTP sufficiently well that traffic will go through a HTTP-only proxy</li>
1252)         <li>Implement <a href="http://cacr.uwaterloo.ca/techreports/2011/cacr2011-21.pdf">scanning resistance</a></a>
1253)       </ul>
1254)     </p>
1255) 
1256)     <a id="profileUDPTransport"></a>
1257)     <li>
1258)     <b>Profile UDP transport protocols</b>
1259)     <br>
1260)     Effort Level: <i>Medium to High</i>
1261)     <br>
1262)     Skill Level: <i>High</i>
1263)     <br>
1264)     Likely Mentors: <i>Steven (sjmurdoch)</i>
1265)     <p>
1266)     There are <a
1267)     href="https://research.torproject.org/techreports/datagram-comparison-2011-11-07.pdf">lots
1268)     of options</a> as to how Tor could send its data over UDP rather than TCP,
1269)     and some will likely perform significantly better than others. This project
1270)     will evaluate these options, so as to decide which should be used in future
1271)     versions of Tor. A first step will be to benchmark the various transport
1272)     protocols being considered, in terms of performance and also code quality,
1273)     including userspace TCP, <a
1274)     href="https://github.com/bittorrent/libutp">&mu;TP</a>, <a
1275)     href="http://en.wikipedia.org/wiki/Stream_Control_Transmission_Protocol">SCTP</a>
1276)     and <a href="http://curvecp.org/">CurveCP</a>. Initially these transport
1277)     protocols will be examined in isolation, but if the project progresses well
1278)     one or more could be integrated in Tor.
1279)     </p>
1280)     </li>
1281) 

1282)     <a id="reportingBuggyRulesets"></a>
1283)     <li>
1284)     <b>Automated Reporting of Buggy Rulesets</b>
1285)     <br>
1286)     Effort Level: <i>Medium</i>
1287)     <br>
1288)     Skill Level: <i>Medium</i>
1289)     <br>

1290)     Likely Mentors: <i>Peter Eckersley (pde), Micah Lee</i>

1291)     <p>
1292) When users manually disable an HTTPS Everywhere ruleset via the toolbar menu,
1293) that's a strong hint that that ruleset might be buggy.  If we could obtain
1294) statistics about which rulesets are manually disabled by the users of which
1295) HTTPS E versions, we could get a statistical picture of which rulesets need
1296) the most urgent debugging and/or disablement.  This would enormously improve
1297) the quality of the HTTPS Everywhere user experience.
1298)     </p>
1299) 
1300)     <p>
1301) HTTPS Everywhere already includes a pipeline for anonymised user submissions
1302) (via Tor where available) that is used for the Decentralized SSL Observatory.
1303) We should do a popup that asks the users to submit anonymous reports of
1304) disabled rules, when they manually disable one for the first time.
1305)     </p>
1306) 
1307)     <p>
1308) Perhaps this feature could optionally let users submit the URL of the page
1309) they were looking at when the bug occurred, although we would need to take
1310) care in handling those, and perhaps implement some countermeasures against
1311) sending passwords or auth tokens when URLs contain those.
1312)     </p>
1313)     </li>
1314) 
1315)     <a id="httpsEverywhereForFirefoxModile"></a>
1316)     <li>
1317)     <b>Port HTTPS Everywhere to Firefox Mobile</b>
1318)     <br>
1319)     Effort Level: <i>Medium</i>
1320)     <br>
1321)     Skill Level: <i>Medium</i>
1322)     <br>

1323)     Likely Mentors: <i>Peter Eckersley (pde), Micah Lee</i>

1324)     <p>
1325) In the past a Firefox Mobile port of HTTPS Everywhere was made impractically
1326) complicated by the Electrolysis threading architecture used in that variant of
1327) Firefox (<a href="https://trac.torproject.org/projects/tor/ticket/2471">ticket</a>).  However with
1328) the implementation of the simple NSIHTTPChannel.redirectTo() API in Firefox
1329) 20+ (<a href="https://bugzilla.mozilla.org/show_bug.cgi?id=765934">ticket</a>) we are probably very
1330) close to having a trivial port of HTTPS Everywhere to Firefox on Android.
1331)     </p>
1332) 
1333)     <p>
1334) This would make a great GSOC project for someone who'd like to learn some
1335) introductory skills with hacking on the internals of real web browsers!
1336)     </p>
1337)     </li>
1338) 
1339)     <a id="httpsEverywhereMixedContentHandling"></a>
1340)     <li>
1341)     <b>HTTPS Everywhere mixed content detection and handling</b>
1342)     <br>
1343)     Effort Level: <i>Medium</i>
1344)     <br>
1345)     Skill Level: <i>Medium</i>
1346)     <br>

1347)     Likely Mentors: <i>Peter Eckersley (pde), Micah Lee</i>

1348)     <p>
1349) Since version 20, Chrome has automatically blocked the loading of insecure
1350) HTTP scripts and CSS in HTTPS pages.  Firefox version 23 will do the same.
1351) This is good security practice, but it causes havoc with many sites where
1352) HTTPS Everywhere can secure some, but not all, of the site's content.
1353)     </p>
1354) 
1355)     <p>
1356) Before Firefox 23 launches, we will need a more coherent plan for detecting
1357) sites where we are causing these mixed content situations, and either
1358) disabling or working around the limitation.  Failure to do so will mean that
1359) HTTPS Everywhere user experience worsens dramatically when Firefox 23 is
1360) released.  Success will mean a dramatic improvement in user experience with
1361) HTTPS Everywhere for Chrome.
1362)     </p>
1363) 
1364)     <b>Critical-path tickets:</b>
1365) 
1366)     <ul>
1367)       <li><a href="https://trac.torproject.org/projects/tor/ticket/6975">6975</a></li>
1368)       <li><a href="https://trac.torproject.org/projects/tor/ticket/8664">8664</a></li>
1369)       <li><a href="https://trac.torproject.org/projects/tor/ticket/8776">8776</a></li>
1370)     </ul>
1371) 
1372)     <b>Related tickets:</b>
1373) 
1374)     <ul>
1375)       <li><a href="https://trac.torproject.org/projects/tor/ticket/3777">3777</a></li>
1376)       <li><a href="https://trac.torproject.org/projects/tor/ticket/6977">6977</a></li>
1377)     </ul>
1378)     </li>
1379) 
1380)     <a id="httpsEverywhereRulesetTesting"></a>
1381)     <li>
1382)     <b>Incorporate Ruleset Testing into the HTTPS Everywhere release process</b>
1383)     <br>
1384)     Effort Level: <i>Medium</i>
1385)     <br>
1386)     Skill Level: <i>Medium</i>
1387)     <br>

1388)     Likely Mentors: <i>Peter Eckersley (pde), Micah Lee</i>

1389)     <p>
1390) Ondrej Mikle has implemented a codebase for testing HTTPS Everywhere rulesets
1391) by crawling pages that are affected by the ruleset (<a href="https://github.com/hiviah/https-everywhere-checker">repository</a>).
1392)     </p>
1393) 
1394)     <p>
1395) This codebase still has some rough edges that need to be smoothed over, but
1396) once those are done it should be incorporated into the HTTPS Everywhere build
1397) process, in order to improve the quality of our releases.
1398)     </p>
1399)     </li>
1400) 

1401)     <a id="censorshipAnalyzer"></a>
1402)     <li>
1403)     <b>Develop a Censorship Analyzer</b>
1404)     <br>
1405)     Effort Level: <i>Medium</i>
1406)     <br>
1407)     Skill Level: <i>Medium to High (depends on the implemented tests)</i>
1408)     <br>
1409)     Likely Mentors: <i>Philipp (phw)</i>
1410)     <p>
1411) Tor is documented to be blocked in <a
1412) href="https://censorshipwiki.torproject.org">several countries</a>. Analyzing
1413) these censorship incidents can be a tedious task; especially without access to
1414) machines inside the censoring networks. To make analysis easier, it would be
1415) great to have a lightweight analysis tool which can be run by censored users.
1416) This tool would conduct a number of networking tests and figure out if and how
1417) Tor could be blocked. The tool's final report should then somehow make it back
1418) to the Tor project.
1419)     </p>
1420) 
1421)     <p>
1422) The theory behind this tool is already <a
1423) href="https://www.usenix.org/system/files/conference/foci13/foci13-winter.pdf">documented
1424) in a research paper</a>. What we now need is code! Implementing it would first
1425) mean getting familiar with <a href="https://ooni.torproject.org">OONI</a> and
1426) <a href="http://twistedmatrix.com/trac/">Twisted</a>. After that, the tool
1427) should be implemented as a number of OONI-specific networking tests.
1428)     </p>
1429)     </li>
1430) 

1431)     <li>
1432)     <b>Bring up new ideas!</b>

1433)     <br>

1434)     Don't like any of these? Look at the <a

1435)     href="/press/presskit/2008-12-19-roadmap-full.pdf">Tor development

1436)     roadmap</a> for more ideas, or just try out Tor, Vidalia, and Torbutton,
1437)     and find out what you think needs fixing.

1438)     Some of the <a href="<spectree>proposals">current proposals</a>

1439)     might also be short on developers.
1440)     </li>

1441) 

1442)     </ol>

1443) 

1444)     <a id="OtherCoding"></a>
1445)     <h2><a class="anchor" href="#OtherCoding">Other Coding and Design related ideas</a></h2>
1446)     <ol>
1447)     <li>Tor relays don't work well on Windows XP. On
1448)     Windows, Tor uses the standard <tt>select()</tt> system
1449)     call, which uses space in the non-page pool. This means
1450)     that a medium sized Tor relay will empty the non-page pool, <a

1451)     href="<wiki>doc/WindowsBufferProblems">causing

1452)     havoc and system crashes</a>. We should probably be using overlapped IO
1453)     instead. One solution would be to teach <a
1454)     href="http://www.monkey.org/~provos/libevent/">libevent</a> how to use
1455)     overlapped IO rather than select() on Windows, and then adapt Tor to
1456)     the new libevent interface. Christian King made a
1457)     <a href="https://svn.torproject.org/svn/libevent-urz/trunk/">good
1458)     start</a> on this in the summer of 2007.</li>

1459) 

1460)     <li>We need to actually start building our <a href="<page
1461)     docs/documentation>#DesignDoc">blocking-resistance design</a>. This involves
1462)     fleshing out the design, modifying many different pieces of Tor, adapting
1463)     <a href="<page projects/vidalia>">Vidalia</a> so it supports the
1464)     new features, and planning for deployment.</li>

1465) 

1466)     <li>We need a flexible simulator framework for studying end-to-end
1467)     traffic confirmation attacks. Many researchers have whipped up ad hoc
1468)     simulators to support their intuition either that the attacks work
1469)     really well or that some defense works great. Can we build a simulator
1470)     that's clearly documented and open enough that everybody knows it's
1471)     giving a reasonable answer? This will spur a lot of new research.
1472)     See the entry <a href="#Research">below</a> on confirmation attacks for
1473)     details on the research side of this task &mdash; who knows, when it's
1474)     done maybe you can help write a paper or three also.</li>

1475) 

1476)     <li>Tor 0.1.1.x and later include support for hardware crypto
1477)     accelerators via OpenSSL. It has been lightly tested and is
1478)     possibly very buggy.  We're looking for more rigorous testing,

1479)     performance analysis, and optimally, code fixes to OpenSSL and

1480)     Tor if needed.</li>

1481) 

1482)     <li>Write a <a
1483)     href="https://secure.wikimedia.org/wikipedia/en/wiki/Fuzz_testing">fuzzer</a>
1484)     for Tor to discover security vulnerabilities. Determine if there
1485)     are good fuzzing frameworks out there for what we want. Win fame by

1486)     getting credit when we put out a new release because of you!</li>

1487) 

1488)     <li>Tor uses TCP for transport and TLS for link
1489)     encryption. This is nice and simple, but it means all cells
1490)     on a link are delayed when a single packet gets dropped, and
1491)     it means we can only reasonably support TCP streams. We have a <a

1492)     href="<page docs/faq>#TransportIPnotTCP">list

1493)     of reasons why we haven't shifted to UDP transport</a>, but it would
1494)     be great to see that list get shorter. We also have a proposed <a

1495)     href="<specblob>proposals/100-tor-spec-udp.txt">specification

1496)     for Tor and
1497)     UDP</a> &mdash; please let us know what's wrong with it.</li>

1498) 

1499)     <li>We're not that far from having IPv6 support for destination addresses
1500)     (at exit nodes). If you care strongly about IPv6, that's probably the
1501)     first place to start.</li>

1502) 

1503)     <li>We need a way to generate the website diagrams (for example, the "How
1504)     Tor Works" pictures on the <a href="<page about/overview>">overview page</a>
1505)     from source, so we can translate them as UTF-8 text rather than edit
1506)     them by hand with Gimp. We might want to
1507)     integrate this as an wml file so translations are easy and images are
1508)     generated in multiple languages whenever we build the website.</li>

1509) 

1510)     <li>How can we make the various LiveCD/USB systems easier
1511)     to maintain, improve, and document?  One example is <a

1512)     href="https://tails.boum.org/">The Amnesic Incognito Live

1513)     System</a>.
1514)     </li>

1515) 

1516)     <li>
1517)     Another anti-censorship project is to try to make Tor
1518)     more scanning-resistant.  Right now, an adversary can identify <a

1519)     href="<specblob>proposals/125-bridges.txt">Tor bridges</a>

1520)     just by trying to connect to them, following the Tor protocol,
1521)     and seeing if they respond.  To solve this, bridges could <a
1522)     href="<svnprojects>design-paper/blocking.html#tth_sEc9.3">act like
1523)     webservers</a> (HTTP or HTTPS) when contacted by port-scanning tools,
1524)     and not act like bridges until the user provides a bridge-specific key.
1525)     To start, check out Shane Pope's <a
1526)     href="http://dl.dropbox.com/u/37735/index.html">thesis and prototype</a>.
1527)     </li>

1528) 

1529)     </ol>

1530) 

1531)     <a id="Research"></a>
1532)     <h2><a class="anchor" href="#Research">Research</a></h2>
1533)     <ol>
1534)     <li>The "end-to-end traffic confirmation attack":
1535)     by watching traffic at Alice and at Bob, we can <a
1536)     href="http://freehaven.net/anonbib/#danezis:pet2004">compare
1537)     traffic signatures and become convinced that we're watching the same
1538)     stream</a>. So far Tor accepts this as a fact of life and assumes this
1539)     attack is trivial in all cases. First of all, is that actually true? How
1540)     much traffic of what sort of distribution is needed before the adversary
1541)     is confident he has won? Are there scenarios (e.g. not transmitting much)
1542)     that slow down the attack? Do some traffic padding or traffic shaping
1543)     schemes work better than others?</li>
1544)     <li>A related question is: Does running a relay/bridge provide additional
1545)     protection against these timing attacks? Can an external adversary that can't
1546)     see inside TLS links still recognize individual streams reliably?
1547)     Does the amount of traffic carried degrade this ability any? What if the
1548)     client-relay deliberately delayed upstream relayed traffic to create a queue
1549)     that could be used to mimic timings of client downstream traffic to make it
1550)     look like it was also relayed? This same queue could also be used for masking
1551)     timings in client upstream traffic with the techniques from <a
1552)     href="http://www.freehaven.net/anonbib/#ShWa-Timing06">adaptive padding</a>,
1553)     but without the need for additional traffic. Would such an interleaving of
1554)     client upstream traffic obscure timings for external adversaries? Would the
1555)     strategies need to be adjusted for asymmetric links? For example, on
1556)     asymmetric links, is it actually possible to differentiate client traffic from
1557)     natural bursts due to their asymmetric capacity? Or is it easier than
1558)     symmetric links for some other reason?</li>
1559)     <li>Repeat Murdoch and Danezis's <a
1560)     href="http://www.cl.cam.ac.uk/~sjm217/projects/anon/#torta">attack from
1561)     Oakland 05</a> on the current Tor network. See if you can learn why it
1562)     works well on some nodes and not well on others. (My theory is that the
1563)     fast nodes with spare capacity resist the attack better.) If that's true,
1564)     then experiment with the RelayBandwidthRate and RelayBandwidthBurst
1565)     options to run a relay that is used as a client while relaying the
1566)     attacker's traffic: as we crank down the RelayBandwidthRate, does the
1567)     attack get harder? What's the right ratio of RelayBandwidthRate to
1568)     actually capacity? Or is it a ratio at all? While we're at it, does a
1569)     much larger set of candidate relays increase the false positive rate
1570)     or other complexity for the attack? (The Tor network is now almost two
1571)     orders of magnitude larger than it was when they wrote their paper.) Be
1572)     sure to read <a href="http://freehaven.net/anonbib/#clog-the-queue">Don't
1573)     Clog the Queue</a> too.</li>
1574)     <li>The "routing zones attack": most of the literature thinks of
1575)     the network path between Alice and her entry node (and between the
1576)     exit node and Bob) as a single link on some graph. In practice,
1577)     though, the path traverses many autonomous systems (ASes), and <a
1578)     href="http://freehaven.net/anonbib/#feamster:wpes2004">it's not uncommon
1579)     that the same AS appears on both the entry path and the exit path</a>.
1580)     Unfortunately, to accurately predict whether a given Alice, entry,
1581)     exit, Bob quad will be dangerous, we need to download an entire Internet
1582)     routing zone and perform expensive operations on it. Are there practical
1583)     approximations, such as avoiding IP addresses in the same /8 network?</li>
1584)     <li>Other research questions regarding geographic diversity consider
1585)     the tradeoff between choosing an efficient circuit and choosing a random
1586)     circuit. Look at Stephen Rollyson's <a
1587)     href="http://swiki.cc.gatech.edu:8080/ugResearch/uploads/7/ImprovingTor.pdf">position
1588)     paper</a> on how to discard particularly slow choices without hurting
1589)     anonymity "too much". This line of reasoning needs more work and more
1590)     thinking, but it looks very promising.</li>
1591)     <li>Tor doesn't work very well when relays have asymmetric bandwidth
1592)     (e.g. cable or DSL). Because Tor has separate TCP connections between
1593)     each hop, if the incoming bytes are arriving just fine and the outgoing
1594)     bytes are all getting dropped on the floor, the TCP push-back mechanisms
1595)     don't really transmit this information back to the incoming streams.
1596)     Perhaps Tor should detect when it's dropping a lot of outgoing packets,
1597)     and rate-limit incoming streams to regulate this itself? I can imagine
1598)     a build-up and drop-off scheme where we pick a conservative rate-limit,
1599)     slowly increase it until we get lost packets, back off, repeat. We
1600)     need somebody who's good with networks to simulate this and help design
1601)     solutions; and/or we need to understand the extent of the performance
1602)     degradation, and use this as motivation to reconsider UDP transport.</li>
1603)     <li>A related topic is congestion control. Is our
1604)     current design sufficient once we have heavy use? Maybe
1605)     we should experiment with variable-sized windows rather
1606)     than fixed-size windows? That seemed to go well in an <a

1607)     href="http://www.psc.edu/index.php/hpn-ssh/638">ssh

1608)     throughput experiment</a>. We'll need to measure and tweak, and maybe
1609)     overhaul if the results are good.</li>
1610)     <li>Our censorship-resistance goals include preventing
1611)     an attacker who's looking at Tor traffic on the wire from <a
1612)     href="<svnprojects>design-paper/blocking.html#sec:network-fingerprint">distinguishing
1613)     it from normal SSL traffic</a>. Obviously we can't achieve perfect
1614)     steganography and still remain usable, but for a first step we'd like to
1615)     block any attacks that can win by observing only a few packets. One of
1616)     the remaining attacks we haven't examined much is that Tor cells are 512
1617)     bytes, so the traffic on the wire may well be a multiple of 512 bytes.
1618)     How much does the batching and overhead in TLS records blur this on the
1619)     wire? Do different buffer flushing strategies in Tor affect this? Could
1620)     a bit of padding help a lot, or is this an attack we must accept?</li>
1621)     <li>Tor circuits are built one hop at a time, so in theory we have the
1622)     ability to make some streams exit from the second hop, some from the
1623)     third, and so on. This seems nice because it breaks up the set of exiting
1624)     streams that a given relay can see. But if we want each stream to be safe,
1625)     the "shortest" path should be at least 3 hops long by our current logic, so
1626)     the rest will be even longer. We need to examine this performance / security
1627)     tradeoff.</li>
1628)     <li>It's not that hard to DoS Tor relays or directory authorities. Are client
1629)     puzzles the right answer? What other practical approaches are there? Bonus
1630)     if they're backward-compatible with the current Tor protocol.</li>
1631)     <li>Programs like <a

1632)     href="<page torbutton/index>">Torbutton</a> aim to hide

1633)     your browser's UserAgent string by replacing it with a uniform answer for
1634)     every Tor user. That way the attacker can't splinter Tor's anonymity set
1635)     by looking at that header. It tries to pick a string that is commonly used
1636)     by non-Tor users too, so it doesn't stand out. Question one: how badly
1637)     do we hurt ourselves by periodically updating the version of Firefox
1638)     that Torbutton claims to be? If we update it too often, we splinter the
1639)     anonymity sets ourselves. If we don't update it often enough, then all the
1640)     Tor users stand out because they claim to be running a quite old version
1641)     of Firefox. The answer here probably depends on the Firefox versions seen
1642)     in the wild. Question two: periodically people ask us to cycle through N
1643)     UserAgent strings rather than stick with one. Does this approach help,
1644)     hurt, or not matter? Consider: cookies and recognizing Torbutton users
1645)     by their rotating UserAgents; malicious websites who only attack certain
1646)     browsers; and whether the answers to question one impact this answer.
1647)     </li>
1648)     <li>How many bridge relays do you need to know to maintain
1649)     reachability? We should measure the churn in our bridges. If there is
1650)     lots of churn, are there ways to keep bridge users more likely to stay
1651)     connected?
1652)     </li>
1653)     </ol>

1654) 

1655)     <p>
1656)     <a href="<page about/contact>">Let us know</a> if you've made progress on any
1657)     of these!
1658)     </p>
1659)   </div>
1660)   <!-- END MAINCOL -->
1661)   <div id = "sidecol">
1662) #include "side.wmi"
1663) #include "info.wmi"
1664)   </div>
1665)   <!-- END SIDECOL -->
1666) </div>
1667) <!-- END CONTENT -->