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5) #include "head.wmi" TITLE="Tor Project: FAQ" 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 docs/documentation>">Documentation &raquo; </a>
10)     <a href="<page docs/faq>">FAQ</a>
11)   </div>
12)   <div id="maincol">
13)     <!-- PUT CONTENT AFTER THIS TAG -->
14)     <h1>Tor FAQ</h1>

15)     <hr>

16) 

17)     <p>General questions:</p>
18)     <ul>
19)     <li><a href="#WhatIsTor">What is Tor?</a></li>

20)     <li><a href="#Torisdifferent">How is Tor different from other
21) proxies?</a></li>

22)     <li><a href="#CompatibleApplications">What programs can I use with
23)     Tor?</a></li>
24)     <li><a href="#WhyCalledTor">Why is it called Tor?</a></li>
25)     <li><a href="#Backdoor">Is there a backdoor in Tor?</a></li>

26)     <li><a href="#DistributingTor">Can I distribute Tor?</a></li>

27)     <li><a href="#SupportMail">How can I get support?</a></li>

28)     <li><a href="#Forum">Is there a Tor forum?</a></li>

29)     <li><a href="#WhySlow">Why is Tor so slow?</a></li>

30)     <li><a href="#FileSharing">How can I share files anonymously through Tor?
31)     </a></li>
32)     <li><a href="#OutboundPorts">Do I have to open all these outbound ports 
33)     on my firewall?</a></li>

34)     <li><a href="#Funding">What would The Tor Project do with more
35)     funding?</a></li>

36)     <li><a href="#IsItWorking">How can I tell if Tor is working, and that my 
37)     connections really are anonymized?</a></li>

38)     <li><a href="#FTP">How do I use my browser for ftp with Tor?</a></li>

39)     <li><a href="#Metrics">How many people use Tor? How many relays or
40)     exit nodes are there?</a></li>

41)     <li><a href="#SSLcertfingerprint">What are your SSL certificate

42)     fingerprints?</a></li>

43)     </ul>

44) 

45)     <p>Compilation and Installation:</p>
46)     <ul>
47)     <li><a href="#HowUninstallTor">How do I uninstall Tor?</a></li>
48)     <li><a href="#PGPSigs">What are these "sig" files on the download
49)     page?</a></li>

50)     <li><a href="#GetTor">Your website is blocked in my country. How
51)     do I download Tor?</a></li>

52)     <li><a href="#CompileTorWindows">How do I compile Tor under
53) Windows?</a></li>
54)     <li><a href="#VirusFalsePositives">Why does my Tor executable appear
55) to

56)     have a virus or spyware?</a></li>

57)     <li><a href="#LiveCD">Is there a LiveCD or other bundle that
58) includes Tor?</a></li>

59)     </ul>

60) 

61)     <p>Tor Browser Bundle:</p>
62)     <ul>

63) 

64)     <li><a href="#TBBFlash">Why can't I view videos on YouTube and other
65)     Flash-based sites?</a></li>

66)     <li><a href="#Ubuntu">I'm using Ubuntu and I can't start Tor Browser
67)     </a></li>

68)     <li><a href="#TBBSocksPort">I want to

69)     run another application through the Tor launched by Tor Browser

70)     Bundle.</a></li>

71)     <li><a href="#TBBPolipo">I need an HTTP proxy. Where did Polipo
72)     go?</a></li>

73)     <li><a href="#TBBOtherExtensions">Can I install other Firefox

74)     extensions? Which extensions should I avoid using?</a></li>

75)     <li><a href="#TBBJavaScriptEnabled">Why is NoScript configured to
76) allow JavaScript by default in the Tor Browser Bundle?  Isn't that
77) unsafe?</a></li>

78)     <li><a href="#TBBOtherBrowser">I want to use Chrome/IE/Opera/etc
79)     with Tor.</a></li>

80)     <li><a href="#TorbuttonOtherBrowser">Will Torbutton be available 
81)     for other browsers?</a></li>
82)     <li><a href="#NoDataScrubbing">Does Tor remove personal information 
83)     from the data my application sends?</a></li>

84)     <li><a href="#TBBCloseBrowser">I want to leave Tor Browser Bundle
85)     running but close the browser.</a></li>
86) 

87)     <li><a href="#GoogleCAPTCHA">Google makes me solve a CAPTCHA or

88) tells

89)     me I have spyware installed.</a></li>

90)     <li><a href="#ForeignLanguages">Why does Google show up in foreign 
91)     languages?</li></a>

92)     <li><a href="#GmailWarning">Gmail warns me that my account may have
93)     been compromised.</a></li>
94)     </ul>
95) 
96)     <p>Advanced Tor usage:</p>

97)     <ul>
98)     <li><a href="#torrc">I'm supposed to "edit my torrc". What does
99)     that mean?</a></li>

100)     <li><a href="#Logs">How do I set up logging, or see Tor's

101)     logs?</a></li>

102)     <li><a href="#LogLevel">What log level should I use?</a></li>

103)     <li><a href="#DoesntWork">Tor is running, but it's not working
104)     correctly.</a></li>

105)     <li><a href="#TorCrash">My Tor keeps crashing.</a></li>

106)     <li><a href="#VidaliaPassword">Tor/Vidalia prompts for a password at
107)     start.</a></li>

108)     <li><a href="#ChooseEntryExit">Can I control which nodes (or
109) country)

110)     are used for entry/exit?</a></li>

111)     <li><a href="#FirewallPorts">My firewall only allows a few outgoing
112)     ports.</a></li>

113)     <li><a href="#ExitPorts">Is there a list of default exit ports?</a></li>

114)     <li><a href="#SocksAndDNS">How do I check if my application that uses 
115)     SOCKS is leaking DNS requests?</a></li>
116)     <li><a href="#DifferentComputer">I want to run my Tor client on a 
117)     different computer than my applications.</a></li>
118)     <li><a href="#ServerClient">Can I install Tor on a central server, and 
119)     have my clients connect to it?</a></li>
120)     <li><a href="#JoinTheNetwork">So I can just configure a nickname and 
121)     ORPort and join the network?</a></li>

122)     </ul>

123) 

124)     <p>Running a Tor relay:</p>
125)     <ul>

126)     

127)     <li><a href="#RelayFlexible">How stable does my relay need to
128) be?</a></li>
129)     <li><a href="#ExitPolicies">I'd run a relay, but I don't want to
130) deal

131)     with abuse issues.</a></li>
132)     <li><a href="#RelayOrBridge">Should I be a normal relay or bridge
133)     relay?</a></li>

134)     <li><a href="#UpgradeOrMove">I want to upgrade/move my relay. How do I 
135)     keep the same key?</a></li>

136)     <li><a href="#MultipleRelays">I want to run more than one
137) relay.</a></li>

138)     <li><a href="#NTService">How do I run my Tor relay as an NT service?
139)     </a></li>
140)     <li><a href="#VirtualServer">Can I run a Tor relay from my virtual server 
141)     account?</a></li>

142)     <li><a href="#WrongIP">My relay is picking the wrong IP address.</a></li>
143)     <li><a href="#BehindANAT">I'm behind a NAT/Firewall</a></li>

144)     <li><a href="#RelayMemory">Why is my Tor relay using so much memory?
145)     </a></li>
146)     <li><a href="#BetterAnonymity">Do I get better anonymity if I run a relay?
147)     </a></li>

148)     <li><a href="#RelayDonations">Can I donate for a relay rather than
149)     run my own?</a></li>

150)     </ul>

151) 

152)     <p>Tor hidden services:</p>
153)     <ul>
154)     <li><a href="#AccessHiddenServices">How do I access hidden services?</a></li>
155)     <li><a href="#ProvideAHiddenService">How do I provide a hidden service</a></li>
156)     </ul>

157) 

158)     <p>Anonymity and Security:</p>
159)     <ul>

160)     <li><a href="#WhatProtectionsDoesTorProvide">What protections does Tor 
161)     provide?</a></li>
162)     <li><a href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop on 
163)     communications? Isn't that bad? </a></li>
164)     <li><a href="#ExitEnclaving">What is Exit Enclaving?</a></li>

165)     <li><a href="#KeyManagement">Tell me about all the keys Tor
166) uses.</a></li>

167)     <li><a href="#EntryGuards">What are Entry Guards?</a></li>

168)     <li><a href="#ChangePaths">How often does Tor change its paths?</a></li>

169)     <li><a href="#CellSize">Tor uses hundreds of bytes for every IRC line. I 
170)     can't afford that!</a></li>
171)     <li><a href="#OutboundConnections">Why does netstat show these outbound 
172)     connections?</a></li>
173)     <li><a href="#PowerfulBlockers">What about powerful blocking mechanisms
174)     </a></li>
175)     <li><a href="#RemotePhysicalDeviceFingerprinting">Does Tor resist 
176)     "remote physical device fingerprinting"?</a></li>
177)     <li><a href="#AttacksOnOnionRouting">What attacks remain against onion 
178)     routing?</a></li>

179)     </ul>

180) 

181)     <p>Alternate designs that we don't do (yet):</p>
182)     <ul>
183)     <li><a href="#EverybodyARelay">You should make every Tor user be a
184)     relay.</a></li>

185)     <li><a href="#TransportIPnotTCP">You should transport all IP
186) packets,

187)     not just TCP packets.</a></li>

188)     <li><a href="#HideExits">You should hide the list of Tor relays,
189)     so people can't block the exits.</a></li>

190)     <li><a href="#ChoosePathLength">You should let people choose their path 
191)     length.</a></li>
192)     <li><a href="#SplitEachConnection">You should split each connection over 
193)     many paths.</a></li>
194)     <li><a href="#UnallocatedNetBlocks">Your default exit policy should block 
195)     unallocated net blocks too.</a></li>
196)     <li><a href="#BlockWebsites">Exit policies should be able to block 
197)     websites, not just IP addresses.</a></li>
198)     <li><a href="#BlockContent">You should change Tor to prevent users from 
199)     posting certain content.</a></li>

200)     <li><a href="#IPv6">Tor should support IPv6.</a></li>

201)     </ul>

202) 

203)     <p>Abuse:</p>

204)     <ul>

205)     <li><a href="#Criminals">Doesn't Tor enable criminals to do bad
206) things?</a></li>

207)     <li><a href="#RespondISP">How do I respond to my ISP about my exit
208)     relay?</a></li>
209)     </ul>

210) 

211)     <p>For other questions not yet on this version of the FAQ, see the
212) <a

213)     href="<wikifaq>">wiki FAQ</a> for now.</p>

214) 

215)     <hr>

216) 

217)     <a id="General"></a>

218) 

219)     <a id="WhatIsTor"></a>
220)     <h3><a class="anchor" href="#WhatIsTor">What is Tor?</a></h3>

221) 

222)     <p>
223)     The name "Tor" can refer to several different components.
224)     </p>

225) 

226)     <p>

227)     The Tor software is a program you can run on your computer that
228) helps keep
229)     you safe on the Internet. Tor protects you by bouncing your
230) communications

231)     around a distributed network of relays run by volunteers all around

232)     the world: it prevents somebody watching your Internet connection
233) from

234)     learning what sites you visit, and it prevents the sites you visit

235)     from learning your physical location. This set of volunteer relays
236) is
237)     called the Tor network. You can read more about how Tor works on the
238) <a

239)     href="<page about/overview>">overview page</a>.
240)     </p>

241) 

242)     <p>

243)     The Tor Project is a non-profit (charity) organization that
244) maintains

245)     and develops the Tor software.
246)     </p>

247) 

248)     <hr>

249) 

250)     <a id="Torisdifferent"></a>

251)     <h3><a class="anchor" href="#Torisdifferent">How is Tor different
252) from other proxies?</a></h3>
253)     <p>
254)     A typical proxy provider sets up a server somewhere on the Internet
255) and
256) allows you to use it to relay your traffic.  This creates a simple, easy
257) to
258) maintain architecture.  The users all enter and leave through the same
259) server.
260) The provider may charge for use of the proxy, or fund their costs
261) through
262) advertisements on the server.  In the simplest configuration, you don't
263) have to
264) install anything.  You just have to point your browser at their proxy
265) server.
266) Simple proxy providers are fine solutions if you do not want protections
267) for
268) your privacy and anonymity online and you trust the provider from doing
269) bad
270) things.  Some simple proxy providers use SSL to secure your connection
271) to them.
272) This may protect you against local eavesdroppers, such as those at a
273) cafe with

274) free wifi Internet.
275)     </p>
276)     <p>

277)     Simple proxy providers also create a single point of failure.  The
278) provider
279) knows who you are and where you browse on the Internet.  They can see
280) your
281) traffic as it passes through their server.  In some cases, they can even
282) see

283) inside your

284) encrypted traffic as they relay it to your banking site or to ecommerce
285) stores.

286) You have to trust the provider isn't doing any number of things, such as

287) watching your traffic, injecting their own advertisements into your
288) traffic

289) stream, and recording your personal details.

290)     </p>
291)     <p>

292)     Tor passes your traffic through at least 3 different servers before
293) sending
294) it on to the destination. Because there's a separate layer of encryption
295) for
296) each of the three relays, Tor does not modify, or even know, what you
297) are
298) sending into it.  It merely relays your traffic, completely encrypted
299) through
300) the Tor network and has it pop out somewhere else in the world,
301) completely
302) intact.  The Tor client is required because we assume you trust your
303) local
304) computer.  The Tor client manages the encryption and the path chosen
305) through
306) the network.  The relays located all over the world merely pass
307) encrypted

308) packets between themselves.</p>

309)     <p>
310)     <dl>

311)     <dt>Doesn't the first server see who I am?</dt><dd>Possibly. A bad
312) first of
313) three servers can see encrypted Tor traffic coming from your computer.
314) It
315) still doesn't know who you are and what you are doing over Tor.  It
316) merely sees
317) "This IP address is using Tor".  Tor is not illegal anywhere in the
318) world, so
319) using Tor by itself is fine.  You are still protected from this node
320) figuring

321) out who you are and where you are going on the Internet.</dd>

322)     <dt>Can't the third server see my traffic?</dt><dd>Possibly.  A bad
323) third
324) of three servers can see the traffic you sent into Tor.  It won't know
325) who sent

326) this traffic.  If you're using encryption, such as visiting a bank or

327) e-commerce website, or encrypted mail connections, etc, it will only
328) know the
329) destination.  It won't be able to see the data inside the traffic
330) stream.  You

331) are still protected from this node figuring out who you are and if using
332) encryption, what data you're sending to the destination.</dd>

333)     </dl>
334)     </p>

335) 

336)     <hr>

337) 

338)     <a id="CompatibleApplications"></a>

339)     <h3><a class="anchor" href="#CompatibleApplications">What programs
340) can I use with Tor?</a></h3>

341) 

342)     <p>

343)     If you want to use Tor with a web browser, we provide the Tor Browser 
344)     Bundle, which includes everything you need to browse the web safely using 
345)     Tor. If you want to use another web browser with Tor, see <a 
346)     href="#TBBOtherBrowser">Other web browsers</a>. 

347)     </p>
348)     <p>
349)     There are plenty of other programs you can use with Tor,
350)     but we haven't researched the application-level anonymity

351)     issues on all of them well enough to be able to recommend a safe

352)     configuration. Our wiki has a list of instructions for <a

353)     href="<wiki>doc/TorifyHOWTO">Torifying

354)     specific applications</a>.

355)     Please add to these lists and help us keep them accurate!
356)     </p>

357) 

358)     <hr>

359) 

360)     <a id="WhyCalledTor"></a>

361)     <h3><a class="anchor" href="#WhyCalledTor">Why is it called
362) Tor?</a></h3>

363) 

364)     <p>
365)     Because Tor is the onion routing network. When we were starting the
366)     new next-generation design and implementation of onion routing in
367)     2001-2002, we would tell people we were working on onion routing,
368)     and they would say "Neat. Which one?" Even if onion routing has
369)     become a standard household term, Tor was born out of the actual <a
370)     href="http://www.onion-router.net/">onion routing project</a> run by
371)     the Naval Research Lab.
372)     </p>

373) 

374)     <p>
375)     (It's also got a fine translation from German and Turkish.)
376)     </p>

377) 

378)     <p>

379)     Note: even though it originally came from an acronym, Tor is not
380) spelled

381)     "TOR". Only the first letter is capitalized. In fact, we can usually

382)     spot people who haven't read any of our website (and have instead
383) learned
384)     everything they know about Tor from news articles) by the fact that
385) they

386)     spell it wrong.
387)     </p>

388) 

389)     <hr>

390) 

391)     <a id="Backdoor"></a>

392)     <h3><a class="anchor" href="#Backdoor">Is there a backdoor in
393) Tor?</a></h3>

394) 

395)     <p>

396)     There is absolutely no backdoor in Tor. Nobody has asked us to put
397) one
398)     in, and we know some smart lawyers who say that it's unlikely that
399) anybody

400)     will try to make us add one in our jurisdiction (U.S.). If they do
401)     ask us, we will fight them, and (the lawyers say) probably win.
402)     </p>

403) 

404)     <p>
405)     We think that putting a backdoor in Tor would be tremendously

406)     irresponsible to our users, and a bad precedent for security
407) software

408)     in general. If we ever put a deliberate backdoor in our security
409)     software, it would ruin our professional reputations. Nobody would
410)     trust our software ever again — for excellent reason!
411)     </p>

412) 

413)     <p>
414)     But that said, there are still plenty of subtle attacks
415)     people might try. Somebody might impersonate us, or break into our

416)     computers, or something like that. Tor is open source, and you
417) should
418)     always check the source (or at least the diffs since the last
419) release)

420)     for suspicious things. If we (or the distributors) don't give you
421)     source, that's a sure sign something funny might be going on. You
422)     should also check the <a href="<page docs/verifying-signatures>">PGP
423)     signatures</a> on the releases, to make sure nobody messed with the
424)     distribution sites.
425)     </p>

426) 

427)     <p>
428)     Also, there might be accidental bugs in Tor that could affect your

429)     anonymity. We periodically find and fix anonymity-related bugs, so
430) make

431)     sure you keep your Tor versions up-to-date.
432)     </p>

433) 

434)     <hr>

435) 

436)     <a id="DistributingTor"></a>

437)     <h3><a class="anchor" href="#DistributingTor">Can I distribute
438) Tor?</a></h3>

439) 

440)     <p>
441)     Yes.
442)     </p>

443) 

444)     <p>

445)     The Tor software is <a href="https://www.fsf.org/">free
446) software</a>. This
447)     means we give you the rights to redistribute the Tor software,
448) either
449)     modified or unmodified, either for a fee or gratis. You don't have
450) to

451)     ask us for specific permission.
452)     </p>

453) 

454)     <p>

455)     However, if you want to redistribute the Tor software you must
456) follow our

457)     <a href="<gitblob>LICENSE">LICENSE</a>.

458)     Essentially this means that you need to include our LICENSE file
459) along

460)     with whatever part of the Tor software you're distributing.
461)     </p>

462) 

463)     <p>

464)     Most people who ask us this question don't want to distribute just
465) the

466)     Tor software, though. They want to distribute the <a

467)     href="<page projects/torbrowser>">Tor Browser</a>. This includes <a

468)     href="https://www.mozilla.org/en-US/firefox/all-aurora.html">Mozilla
469)     Aurora</a> and <a href="<page projects/vidalia>">Vidalia</a>.

470)     You will need to follow the licenses for those programs
471)     as well. Both of them are distributed under the <a
472)     href="https://www.fsf.org/licensing/licenses/gpl.html">GNU General

473)     Public License</a>. The simplest way to obey their licenses is
474)     to include the source code for these programs everywhere you
475)     include the bundles themselves. Look for "source" packages on
476)     the <a href="<page projects/vidalia>">Vidalia page</a> and <a
477)     href="https://www.mozilla.org/en-US/firefox/all-aurora.html">Mozilla
478)     Aurora</a> pages.

479)     </p>

480) 

481)     <p>

482)     Also, you should make sure not to confuse your readers about what
483) Tor is,
484)     who makes it, and what properties it provides (and doesn't provide).
485) See
486)     our <a href="<page docs/trademark-faq>">trademark FAQ</a> for
487) details.

488)     </p>

489) 

490)     <p>
491)     Lastly, you should realize that we release new versions of the
492)     Tor software frequently, and sometimes we make backward incompatible

493)     changes. So if you distribute a particular version of the Tor
494) software, it
495)     may not be supported — or even work — six months later.
496) This

497)     is a fact of life for all security software under heavy development.
498)     </p>

499) 

500)     <hr>

501) 

502)     <a id="SupportMail"></a>

503)     <h3><a class="anchor" href="#SupportMail">How can I get
504) support?</a></h3>

505) 

506)     <p>Your best bet is to first try the following:</p>

507)     <ol>
508)     <li>Read through this <a href="<page docs/faq>">FAQ</a>.</li>

509)     <li>Read through the <a href="<page
510) docs/documentation>">documentation</a>.</li>

511)     <li>Read through the <a

512) 
513) href="https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk">
514) tor-talk

515)     archives</a> and see if your question is already answered.</li>

516)     <li>Join our <a href="ircs://irc.torproject.org#tor">irc channel</a>
517) and

518)     state the issue and wait for help.</li>

519)     <li>Send an email to <a

520) 
521) href="mailto:help@rt.torproject.org">help@rt.torproject.org</a>.</li>
522)     <li>If all else fails, try <a href="<page about/contact>">contacting
523) us</a> directly.</li>

524)     </ol>

525) 

526)     <p>If you find your answer, please stick around on the IRC channel
527) or the

528)     mailing list to help others who were once in your position.</p>

529) 

530)     <hr>

531) 

532)     <a id="Forum"></a>
533)     <h3><a class="anchor" href="#Forum">Is there a Tor forum?</a></h3>
534) 
535)     <p>Not yet, but we're working on it. Most forum software is
536)     a disaster to maintain and keep secure, and at the same time
537)     too many of the Tor developers are spread too thin to be able

538)     to contribute enough to a forum.

539)     </p>
540) 
541)     <hr>
542) 

543)     <a id="WhySlow"></a>
544)     <h3><a class="anchor" href="#WhySlow">Why is Tor so slow?</a></h3>

545) 

546)     <p>
547)     There are many reasons why the Tor network is currently slow.
548)     </p>

549) 

550)     <p>

551)     Before we answer, though, you should realize that Tor is never going
552) to
553)     be blazing fast. Your traffic is bouncing through volunteers'
554) computers
555)     in various parts of the world, and some bottlenecks and network
556) latency

557)     will always be present. You shouldn't expect to see university-style
558)     bandwidth through Tor.
559)     </p>

560) 

561)     <p>

562)     But that doesn't mean that it can't be improved. The current Tor
563) network
564)     is quite small compared to the number of people trying to use it,
565) and
566)     many of these users don't understand or care that Tor can't
567) currently

568)     handle file-sharing traffic load.
569)     </p>

570) 

571)     <p>
572)     For the much more in-depth answer, see <a

573)     href="<blog>why-tor-is-slow">Roger's blog

574)     post on the topic</a>, which includes both a detailed PDF and a
575) video

576)     to go with it.
577)     </p>

578) 

579)     <p>
580)     What can you do to help?
581)     </p>

582) 

583)     <ul>

584) 

585)     <li>

586)     <a href="<page docs/tor-doc-relay>">Configure your Tor to relay
587) traffic
588)     for others</a>. Help make the Tor network large enough that we can
589) handle

590)     all the users who want privacy and security on the Internet.
591)     </li>

592) 

593)     <li>

594)     <a href="<page projects/vidalia>">Help us make Tor more usable</a>.
595) We

596)     especially need people to help make it easier to configure your Tor
597)     as a relay. Also, we need help with clear simple documentation to
598)     walk people through setting it up.
599)     </li>

600) 

601)     <li>

602)     There are some bottlenecks in the current Tor network. Help us
603) design
604)     experiments to track down and demonstrate where the problems are,
605) and

606)     then we can focus better on fixing them.
607)     </li>

608) 

609)     <li>
610)     Tor needs some architectural changes too. One important change is to

611)     start providing <a href="#EverybodyARelay">better service to people
612) who
613)     relay traffic</a>. We're working on this, and we'll finish faster if
614) we

615)     get to spend more time on it.
616)     </li>

617) 

618)     <li>

619)     Help do other things so we can do the hard stuff. Please take a
620) moment
621)     to figure out what your skills and interests are, and then <a
622) href="<page

623)     getinvolved/volunteer>">look at our volunteer page</a>.
624)     </li>

625) 

626)     <li>

627)     Help find sponsors for Tor. Do you work at a company or government
628) agency

629)     that uses Tor or has a use for Internet privacy, e.g. to browse the

630)     competition's websites discreetly, or to connect back to the home
631) servers
632)     when on the road without revealing affiliations? If your
633) organization has
634)     an interest in keeping the Tor network working, please contact them
635) about
636)     supporting Tor. Without sponsors, Tor is going to become even
637) slower.

638)     </li>

639) 

640)     <li>
641)     If you can't help out with any of the above, you can still help out

642)     individually by <a href="<page donate/donate>">donating a bit of
643) money to the

644)     cause</a>. It adds up!
645)     </li>

646) 

647)     </ul>

648) 

649)     <hr>

650) 

651)     <a id="FileSharing"></a>

652)     <h3><a class="anchor" href="#FileSharing">How can I share files 
653)     anonymously through Tor?</a></h3>

654) 
655)     <p>

656)     File sharing (peer-to-peer/P2P) is widely unwanted in the Tor network, 
657)     and exit nodes are configured to block file sharing traffic by default. 
658)     Tor is not really designed for it, and file sharing through Tor slows 
659)     down everyone's browsing. Also, Bittorrent over Tor <a 
660)     href="https://blog.torproject.org/blog/bittorrent-over-tor-isnt-good-idea">
661)     is not anonymous</a>!

662)     </p>
663) 
664)     <hr>
665) 

666)     <a id="Funding"></a>

667)     <h3><a class="anchor" href="#Funding">What would The Tor Project do
668) with more funding?</a></h3>

669) 

670)     <p>

671)     The Tor network's <a

672) 
673) href="https://metrics.torproject.org/network.html#networksize">several

674)     thousand</a> relays push <a
675)     href="https://metrics.torproject.org/network.html#bandwidth">over
676)     1GB per second on average</a>. We have <a

677) 
678) href="https://metrics.torproject.org/users.html#direct-users">several

679)     hundred thousand daily users</a>. But the Tor network is not yet
680)     self-sustaining.

681)     </p>

682) 

683)     <p>

684)     There are six main development/maintenance pushes that need
685) attention:

686)     </p>

687) 

688)     <ul>

689) 

690)     <li>
691)     Scalability: We need to keep scaling and decentralizing the Tor
692)     architecture so it can handle thousands of relays and millions of

693)     users. The upcoming stable release is a major improvement, but
694) there's

695)     lots more to be done next in terms of keeping Tor fast and stable.
696)     </li>

697) 

698)     <li>

699)     User support: With this many users, a lot of people are asking
700) questions
701)     all the time, offering to help out with things, and so on. We need
702) good
703)     clean docs, and we need to spend some effort coordinating
704) volunteers.

705)     </li>

706) 

707)     <li>

708)     Relay support: the Tor network is run by volunteers, but they still
709) need

710)     attention with prompt bug fixes, explanations when things go wrong,

711)     reminders to upgrade, and so on. The network itself is a commons,
712) and
713)     somebody needs to spend some energy making sure the relay operators
714) stay
715)     happy. We also need to work on stability on some platforms —
716) e.g.,

717)     Tor relays have problems on Win XP currently.

718)     </li>

719) 

720)     <li>

721)     Usability: Beyond documentation, we also need to work on usability
722) of the
723)     software itself. This includes installers, clean GUIs, easy
724) configuration
725)     to interface with other applications, and generally automating all
726) of
727)     the difficult and confusing steps inside Tor. We've got a start on
728) this
729)     with the <a href="<page projects/vidalia>">Vidalia GUI</a>, but much
730) more work

731)     remains — usability for privacy software has never been easy.
732)     </li>

733) 

734)     <li>
735)     Incentives: We need to work on ways to encourage people to configure
736)     their Tors as relays and exit nodes rather than just clients.

737)     <a href="#EverybodyARelay">We need to make it easy to become a
738) relay,

739)     and we need to give people incentives to do it.</a>
740)     </li>

741) 

742)     <li>
743)     Research: The anonymous communications field is full
744)     of surprises and gotchas. In our copious free time, we
745)     also help run top anonymity and privacy conferences like <a
746)     href="http://petsymposium.org/">PETS</a>. We've identified a set of

747)     critical <a href="<page getinvolved/volunteer>#Research">Tor
748) research questions</a>
749)     that will help us figure out how to make Tor secure against the
750) variety of
751)     attacks out there. Of course, there are more research questions
752) waiting

753)     behind these.
754)     </li>

755) 

756)     </ul>

757) 

758)     <p>
759)     We're continuing to move forward on all of these, but at this rate

760)     <a href="#WhySlow">the Tor network is growing faster than the
761) developers

762)     can keep up</a>.

763)     Now would be an excellent time to add a few more developers to the
764) effort

765)     so we can continue to grow the network.
766)     </p>

767) 

768)     <p>
769)     We are also excited about tackling related problems, such as
770)     censorship-resistance.
771)     </p>

772) 

773)     <p>

774)     We are proud to have <a href="<page about/sponsors>">sponsorship and
775) support</a>
776)     from the Omidyar Network, the International Broadcasting Bureau,
777) Bell
778)     Security Solutions, the Electronic Frontier Foundation, several
779) government

780)     agencies and research groups, and hundreds of private contributors.
781)     </p>

782) 

783)     <p>

784)     However, this support is not enough to keep Tor abreast of changes
785) in the
786)     Internet privacy landscape. Please <a href="<page
787) donate/donate>">donate</a>
788)     to the project, or <a href="<page about/contact>">contact</a> our
789) executive

790)     director for information on making grants or major donations.
791)     </p>

792) 

793)     <hr>
794) 

795)      <a id="OutboundPorts"></a>

796)     <h3><a class="anchor" href="#OutboundPorts">Do I have to open all these 
797)     outbound ports on my firewall?</a></h3>

798) 
799)     <p>

800)     Tor may attempt to connect to any port that is advertised in the 
801)     directory as an ORPort (for making Tor connections) or a DirPort (for 
802)     fetching updates to the directory). There are a variety of these ports, 
803)     but many of them are running on 80, 443, 9001, and 9030.

804)     </p>
805)     <p>

806)     So as a client, you could probably get away with opening only those four 
807)     ports. Since Tor does all its connections in the background, it will retry 
808)     ones that fail, and hopefully you'll never have to know that it failed, as 
809)     long as it finds a working one often enough. However, to get the most 
810)     diversity in your entry nodes -- and thus the most security -- as well as 
811)     the most robustness in your connectivity, you'll want to let it connect 
812)     to all of them.

813)     </p>
814)     <p>

815)     If you really need to connect to only a small set of ports, see the FAQ 
816)     entry on firewalled ports.

817)     </p>
818)     <p>

819)     Note that if you're running Tor as a relay, you must allow outgoing 
820)     connections to every other relay and to anywhere your exit policy 
821)     advertises that you allow. The cleanest way to do that is simply to allow 
822)     all outgoing connections at your firewall. If you don't, clients will try 
823)     to use these connections and things won't work. 

824)     </p>
825)     
826)     <hr>
827)     
828)     <a id="IsItWorking"></a>

829)     <h3><a class="anchor" href="#IsItWorking">How can I tell if Tor is 
830)     working, and that my connections really are anonymized?</a></h3>

831) 
832)     <p>

833)     There are sites you can visit that will tell you if you appear to be 
834)     coming through the Tor network. Try the <a href="https://check.torproject.org">
835)     Tor Check</a> site and see whether it thinks you are using Tor or not.

836)     </p>
837)     <p>

838)     If that site is down, you can still test, but it will involve more effort. 
839)     Sites like <a href="http://ipid.shat.net">http://ipid.shat.net</a> and 
840)     <a href="http://www.showmyip.com/">http://www.showmyip.com/</a> will tell 
841)     you what your IP address appears to be, but you'll need to know your 
842)     current IP address so you can compare and decide whether you're using Tor 
843)     correctly.

844)     </p>
845)     <p>

846)     To learn your IP address on OS X, Linux, BSD, etc, run "ifconfig". On 
847)     Windows, go to the Start menu, click Run and enter "cmd". At the command 
848)     prompt, enter "ipconfig /a".

849)     </p>
850)     <p>

851)     If you are behind a NAT or firewall, though, your IP address will be 
852)     within the range of 10.XXX.XXX.XXX, 192.168.XXX.XXX, or 172.16.XXX.XXX - 
853)     172.31.XXX.XXX, which is not your public IP address. In this case, you 
854)     should check your IP address with one of the sites above without using 
855)     Tor, and then check again using Tor to see whether your IP address has 
856)     changed. 

857)     </p>
858)     
859)     <hr>
860)     
861)     <a id="FTP"></a>
862)     <h3><a class="anchor" href="#FTP">How do I use my browser for ftp with Tor?
863)     </a></h3>
864) 

865)     <p>
866)     Use the Tor Browser Bundle. If you want a separate application for an 
867)     ftp client, we've heard good things about  FileZilla for Windows. You can 
868)     configure it to point to Tor as a "socks4a" proxy on "localhost" port 
869)     "9050". 
870)     </p>

871)     <hr>
872)     

873)     <a id="Metrics"></a>

874)     <h3><a class="anchor" href="#Metrics">How many people use Tor? How

875)     many relays or exit nodes are there?</a></h3>

876) 

877)     <p>
878)     All this and more about measuring Tor can be found at the <a

879)     href="https://metrics.torproject.org/">Tor Metrics Portal</a>.</p>

880)     <hr>

881) 

882)     <a id="SSLcertfingerprint"></a>

883)     <h3><a class="anchor" href="#SSLcertfingerprint">What are the SSL 
884)     certificate fingerprints for Tor's various websites?</a></h3>

885)     <p>

886)     <pre>

887)     *.torproject.org SSL certificate from Digicert:

888)     The serial number is:

889) 06:DE:97:E5:1D:C3:9D:C2:64:8D:AC:72:DD:41:01:FC
890)     The SHA-1 fingerprint is: 1f9d306e8bfccfcb03981a71a27a9f5d1e0876ce

891)     The SHA-256 fingerprint is:

892) 3613d2b22a750094760c41ad19db52a4f05bdea80172e2578761ad967f7ed9aa

893) 

894)     blog.torproject.org SSL certificate from RapidSSL:

895)     The serial number is: 00:EF:A3
896)     The SHA-1 fingerprint is: 50af43db8438e67f305a3257d8ef198e8c42f13f

897)     </pre>

898)     </p>
899)     <hr>
900) 

901)     <a id="HowUninstallTor"></a>

902)     <h3><a class="anchor" href="#HowUninstallTor">How do I uninstall
903) Tor?</a></h3>
904) 
905)     <p>
906)     Tor Browser does not install itself in the classic sense of
907) applications. You just simply delete the folder or directory named "Tor
908) Browser" and it is removed from your system.
909)     </p>

910) 

911)     <p>

912)     If this is not related to Tor Browser, uninstallation depends
913) entirely on how you installed it and which operating system you
914)     have. If you installed a package, then hopefully your package has a
915) way to

916)     uninstall itself. The Windows packages include uninstallers. 

917)     </p>

918) 

919)     <p>
920)     For Mac OS X, follow the <a
921)     href="<page docs/tor-doc-osx>#uninstall">uninstall directions</a>.
922)     </p>

923) 

924)     <p>

925)     If you installed by source, I'm afraid there is no easy uninstall
926) method. But
927)     on the bright side, by default it only installs into /usr/local/ and
928) it should

929)     be pretty easy to notice things there.
930)     </p>

931) 

932)     <hr>

933) 

934)     <a id="PGPSigs"></a>

935)     <h3><a class="anchor" href="#PGPSigs">What are these "sig" files on
936) the download page?</a></h3>

937) 

938)     <p>

939)     These are PGP signatures, so you can verify that the file you've
940) downloaded is

941)     exactly the one that we intended you to get.
942)     </p>

943) 

944)     <p>
945)     Please read the <a

946)     href="<page docs/verifying-signatures>">verifying signatures</a>
947) page for details.

948)     </p>

949) 

950) <hr>
951) 
952) <a id="GetTor"></a>
953) <h3><a class="anchor" href="#GetTor">Your website is blocked in my
954) country. How do I download Tor?</a></h3>
955) 
956) <p>
957) Some government or corporate firewalls censor connections to Tor's
958) website. In those cases, you have three options. First, get it from

959) a friend &mdash; the <a href="<page projects/torbrowser>">Tor Browser

960) Bundle</a> fits nicely on a USB key. Second, find the <a

961) href="https://encrypted.google.com/search?q=tor+mirrors">google
962) cache</a>

963) for the <a href="<page getinvolved/mirrors>">Tor mirrors</a> page
964) and see if any of those copies of our website work for you. Third,
965) you can download Tor via email: log in to your Gmail account and mail

966) '<tt>gettor@gettor.torproject.org</tt>'. If you include the word 'help'

967) in the body of the email, it will reply with instructions. Note that
968) only a few webmail providers are supported, since they need to be able
969) to receive very large attachments.
970) </p>
971) 
972) <p>

973) Be sure to <a href="<page docs/verifying-signatures>">verify the
974) signature</a>

975) of any package you download, especially when you get it from somewhere
976) other than our official HTTPS website.

977) </p>
978) 
979) <hr>

980) 

981)     <a id="CompileTorWindows"></a>

982)     <h3><a class="anchor" href="#CompileTorWindows">How do I compile Tor
983) under Windows?</a></h3>

984) 

985)     <p>

986)     Try following the steps at <a
987) href="<gitblob>doc/tor-win32-mingw-creation.txt">

988)     tor-win32-mingw-creation.txt</a>.
989)     </p>

990) 

991)     <p>
992)     (Note that you don't need to compile Tor yourself in order to use

993)     it. Most people just use the packages available on the <a
994) href="<page

995)     download/download>">download page</a>.)
996)     </p>

997) 

998)     <hr>

999) 

1000)     <a id="VirusFalsePositives"></a>

1001)     <h3><a class="anchor" href="#VirusFalsePositives">Why does my Tor
1002) executable appear to have a virus or spyware?</a></h3>

1003) 

1004)     <p>

1005)     Sometimes, overzealous Windows virus and spyware detectors trigger
1006) on some
1007)     parts of the Tor Windows binary. Our best guess is that these are
1008) false
1009)     positives — after all, the anti-virus and anti-spyware
1010) business is just a
1011)     guessing game anyway. You should contact your vendor and explain
1012) that you have
1013)     a program that seems to be triggering false positives. Or pick a
1014) better vendor.

1015)     </p>

1016) 

1017)     <p>
1018)     In the meantime, we encourage you to not just take our word for

1019)     it. Our job is to provide the source; if you're concerned, please do
1020) <a

1021)     href="#CompileTorWindows">recompile it yourself</a>.
1022)     </p>

1023) 

1024)     <hr>

1025) 

1026)     <a id="LiveCD"></a>

1027)     <h3><a class="anchor" href="#LiveCD">Is there a LiveCD or other
1028) bundle that includes Tor?</a></h3>

1029) 

1030)     <p>

1031)     Yes.  Use <a href="https://tails.boum.org/">The Amnesic Incognito

1032)     Live System</a> or <a href="<page projects/torbrowser>">the Tor
1033) Browser

1034)     Bundle</a>.

1035)     </p>

1036) 
1037) <hr>
1038) 

1039) <a id="TBBFlash"></a>

1040) <h3><a class="anchor" href="#TBBFlash">Why can't I view videos on
1041) YouTube

1042) and other Flash-based sites?</a></h3>

1043) 
1044) <p>

1045) YouTube and similar sites require third party browser plugins such as Flash.
1046) Plugins operate independently from Firefox and can perform
1047) activity on your computer that ruins your anonymity. This includes
1048) but is not limited to: <a href="http://decloak.net">completely disregarding
1049) proxy settings</a>, querying your <a

1050) href="http://forums.sun.com/thread.jspa?threadID=5162138&messageID=9618376">
1051) local IP address</a>, and <a

1052) href="http://epic.org/privacy/cookies/flash.html">storing their own
1053) cookies</a>. It is possible to use a LiveCD solution such as

1054) or <a href="https://tails.boum.org/">The Amnesic Incognito Live System</a> 
1055) that creates a secure, transparent proxy to protect you from proxy bypass, 
1056) however issues with local IP address discovery and Flash cookies still remain. 
1057) </p>

1058) 
1059) <p>

1060) <a href="https://www.youtube.com/html5">YouTube offers experimental HTML5 video
1061) support</a> for many of their videos. You can use their Advanced Search to

1062) find HTML5 videos.
1063) </p>
1064) 

1065) <hr>
1066) 

1067) <a id="Ubuntu"></a>
1068) <h3><a class="anchor" href="#Ubuntu">
1069) I'm using Ubuntu and I can't start Tor Browser</a></h3>
1070) <p>

1071) Ubuntu prevents its users from executing shell scripts by clicking them, 
1072) even when the file permissions are set correctly. For now you need to 
1073) start the Tor Browser from the command line by running </p>

1074) <pre>
1075) ./start-tor-browser
1076) </pre>
1077) <p>
1078) from inside the Tor Browser directory.
1079) </p>
1080) 
1081) <hr>
1082) 

1083) <a id="TBBSocksPort"></a>

1084) <h3><a class="anchor" href="#TBBSocksPort">

1085) I want to run another application through the Tor launched by Tor

1086) Browser Bundle.</a></h3>

1087) 
1088) <p>

1089) Typically Tor listens for Socks connections on port 9050. TBB listens

1090) on port 9150.

1091) The goal is to avoid conflicting with a "system" Tor install,

1092) so you can run a system Tor and TBB at the same time. We're <a
1093) href="https://trac.torproject.org/projects/tor/ticket/3948">working on
1094) a feature</a> where Tor will try the usual ports first and then back

1095) off to a random choice if they're already in use.

1096) </p>
1097) 
1098) <hr>
1099) 
1100) <a id="TBBPolipo"></a>
1101) <h3><a class="anchor" href="#TBBPolipo">I need an HTTP proxy. Where did
1102) Polipo go?</a></h3>
1103) 
1104) <p>
1105) In the past, Tor bundles included an HTTP proxy like Privoxy or Polipo,
1106) solely to work around a bug in Firefox that was finally fixed in Firefox
1107) 6. Now you don't need a separate HTTP proxy to use Tor, and in fact
1108) leaving it out makes you safer because Torbutton has better control over
1109) Firefox's interaction with websites.
1110) </p>
1111) 
1112) <p>
1113) If you are trying to use some external application with Tor, step zero

1114) should be to <a href="<page download/download>#warning">reread the set

1115) of warnings</a> for ways you can screw up. Step one should be to try

1116) to use a Socks proxy rather than an http proxy — Tor runs a Socks

1117) proxy on port 9050 on Windows, or <a href="#TBBSocksPort">see above</a>
1118) for OSX and Linux.
1119) </p>
1120) 
1121) <p>

1122) If that fails, feel free to install <a

1123) href="http://www.privoxy.org/">privoxy</a>.
1124) However, please realize that this approach is not recommended for novice
1125) users. Privoxy has an <a
1126) href="http://www.privoxy.org/faq/misc.html#TOR">example
1127) configuration</a> of Tor and Privoxy.

1128) </p>
1129) 
1130) <hr>
1131) 

1132) <a id="TBBOtherExtensions"></a>
1133) <h3><a class="anchor" href="#TBBOtherExtensions">Can I install other
1134) Firefox extensions?</a></h3>
1135) 
1136) <p>

1137) The Tor Browser is free software, so there is nothing preventing you from 
1138) modifying it any way you like. However, we do not recommend installing any 
1139) additional Firefox add-ons with the Tor Browser Bundle. Add-ons can break 
1140) your anonymity in a number of ways, including browser fingerprinting and 
1141) bypassing proxy settings.

1142) </p>

1143) <p>

1144) Some people have suggested we include ad-blocking software or 
1145) anti-tracking software with the Tor Browser Bundle. Right now, we do not 
1146) think that's such a good idea. The Tor Browser Bundle aims to provide 
1147) sufficient privacy that additional add-ons to stop ads and trackers are 
1148) not necessary. Using add-ons like these may cause some sites to break, which 
1149) <a href="https://www.torproject.org/projects/torbrowser/design/#philosophy">
1150) we don't want to do</a>. Additionally, maintaining a list of "bad" sites that 
1151) should be black-listed provides another opportunity to uniquely fingerprint 
1152) users. 

1153) </p>

1154) 

1155) <hr>
1156) 

1157) <a id="TBBJavaScriptEnabled"></a>

1158) <a id="TBBCanIBlockJS"></a>

1159) <h3><a class="anchor" href="#TBBJavaScriptEnabled">Why is NoScript
1160) configured to allow JavaScript by default in the Tor Browser Bundle?
1161) Isn't that unsafe?</a></h3>

1162) 
1163) <p>
1164) We configure NoScript to allow JavaScript by default in the Tor
1165) Browser Bundle because many websites will not work with JavaScript
1166) disabled.  Most users would give up on Tor entirely if a website
1167) they want to use requires JavaScript, because they would not know
1168) how to allow a website to use JavaScript (or that enabling
1169) JavaScript might make a website work).
1170) </p>
1171) 

1172) <p>
1173) There's a tradeoff here. On the one hand, we should leave
1174) JavaScript enabled by default so websites work the way
1175) users expect. On the other hand, we should disable JavaScript
1176) by default to better protect against browser vulnerabilities (<a

1177) href="https://blog.torproject.org/blog/tor-security-advisory-old-tor-browser-bundles-vulnerable">
1178) not just a theoretical concern!</a>). But there's a third issue: websites

1179) can easily determine whether you have allowed JavaScript for them,
1180) and if you disable JavaScript by default but then allow a few websites
1181) to run scripts (the way most people use NoScript), then your choice of
1182) whitelisted websites acts as a sort of cookie that makes you recognizable
1183) (and distinguishable), thus harming your anonymity.
1184) </p>

1185) 
1186) <p>

1187) Ultimately, we want the default Tor bundles to use
1188) a combination of firewalls (like the iptables rules
1189) in <a href="https://tails.boum.org/">Tails</a>) and <a
1190) href="https://trac.torproject.org/projects/tor/ticket/7680">sandboxes</a>
1191) to make JavaScript not so scary. In
1192) the shorter term, TBB 3.0 will hopefully <a
1193) href="https://trac.torproject.org/projects/tor/ticket/9387">allow users
1194) to choose their JavaScript settings more easily</a> &mdash; but the
1195) partitioning concern will remain.

1196) </p>
1197) 
1198) <p>

1199) Until we get there, feel free to leave JavaScript on or off depending
1200) on your security, anonymity, and usability priorities.

1201) </p>
1202) 
1203) <hr>
1204) 

1205) <a id="TBBOtherBrowser"></a>
1206) <h3><a class="anchor" href="#TBBOtherBrowser">I want to use
1207) Chrome/IE/Opera/etc with Tor.</a></h3>
1208) 
1209) <p>
1210) Unfortunately, Torbutton only works with Firefox right now, and without
1211) <a href="https://www.torproject.org/torbutton/en/design/">Torbutton's
1212) extensive privacy fixes</a> there are many ways for websites or other

1213) attackers to recognize you, track you back to your IP address, and so
1214) on.

1215) In short, using any browser besides Tor Browser Bundle with Tor is a
1216) really bad idea.
1217) </p>
1218) 
1219) <p>
1220) We're working with the Chrome team to <a

1221) href="https://blog.torproject.org/blog/google-chrome-incognito-mode-tor-
1222) and-fingerprinting">fix
1223) some bugs and missing APIs in Chrome</a> so it will be possible to write
1224) a
1225) Torbutton for Chrome. No support for any other browser is on the
1226) horizon.

1227) </p>
1228) 
1229) <hr>
1230) 

1231) <a id="TorbuttonOtherBrowser"></a>
1232) <h3><a class="anchor" href="#TorbuttonOtherBrowser">
1233) Will Torbutton be available for other browsers?</a></h3>
1234) 
1235) <p>
1236)  We don't support IE, Opera or Safari and never plan to. There are too many 
1237)  ways that your privacy can go wrong with those browsers, and because of 
1238)  their closed design it is really hard for us to do anything to change these 
1239)  privacy problems.
1240) </p>
1241) <p>
1242) We are working with the Chrome people to modify Chrome's internals so that 
1243) we can eventually support it. But for now, Firefox is the only safe choice. 
1244) </p>
1245) 
1246) <hr>
1247) 
1248) <a id="NoDataScrubbing"></a>
1249) <h3><a class="anchor" href="#NoDataScrubbing">
1250) Does Tor remove personal information from the data my application sends?
1251) </a></h3>
1252) <p>
1253) No, it doesn't. You need to use a separate program that understands your 
1254) application and protocol and knows how to clean or "scrub" the data it 
1255) sends. Privoxy is an example of this for web browsing. But note that even 
1256) Privoxy won't protect you completely: you may still fall victim to viruses, 
1257) Java Script attacks, etc; and Privoxy can't do anything about text that you 
1258) type into forms. Be careful and be smart. 
1259) </p>
1260) 
1261) </hr>
1262) 

1263) <a id="TBBCloseBrowser"></a>

1264) <h3><a class="anchor" href="#TBBCloseBrowser">I want to leave Tor
1265) Browser

1266) Bundle running but close the browser.</a></h3>
1267) 
1268) <p>
1269) We're working on a way to make this possible on all platforms. Please
1270) be patient.
1271) </p>
1272) 
1273) <hr>
1274) 

1275) <a id="GoogleCAPTCHA"></a>
1276) <h3><a class="anchor" href="#GoogleCAPTCHA">Google makes me solve a
1277) CAPTCHA or tells me I have spyware installed.</a></h3>

1278) 
1279) <p>
1280) This is a known and intermittent problem; it does not mean that Google
1281) considers Tor to be spyware.
1282) </p>
1283) 
1284) <p>

1285) When you use Tor, you are sending queries through exit relays that are
1286) also

1287) shared by thousands of other users. Tor users typically see this message

1288) when many Tor users are querying Google in a short period of time.
1289) Google

1290) interprets the high volume of traffic from a single IP address (the exit
1291) relay you happened to pick) as somebody trying to "crawl" their website,
1292) so it slows down traffic from that IP address for a short time.
1293) </p>
1294) <p>
1295) An alternate explanation is that Google tries to detect certain
1296) kinds of spyware or viruses that send distinctive queries to Google
1297) Search. It notes the IP addresses from which those queries are received
1298) (not realizing that they are Tor exit relays), and tries to warn any
1299) connections coming from those IP addresses that recent queries indicate
1300) an infection.
1301) </p>
1302) 
1303) <p>

1304) To our knowledge, Google is not doing anything intentionally
1305) specifically

1306) to deter or block Tor use. The error message about an infected machine
1307) should clear up again after a short time.
1308) </p>
1309) 
1310) <p>
1311) Torbutton 1.2.5 (released in mid 2010) detects Google captchas and can
1312) automatically redirect you to a more Tor-friendly search engine such as

1313) DuckDuckGo, ixquick, or Bing.

1314) </p>
1315) 
1316) <hr />
1317) 

1318) <a id="ForeignLanguages"></a>
1319) <h3><a class="anchor" href="#ForeignLanguages">
1320) Why does Google show up in foreign languages?</a></h3>
1321) 
1322) <p>

1323)  Google uses "geolocation" to determine where in the world you are, so it 
1324)  can give you a personalized experience. This includes using the language 
1325)  it thinks you prefer, and it also includes giving you different results 
1326)  on your queries.

1327) </p>
1328) <p>

1329) If you really want to see Google in English you can click the link that 
1330) provides that. But we consider this a feature with Tor, not a bug --- the 
1331) Internet is not flat, and it in fact does look different depending on 
1332) where you are. This feature reminds people of this fact. The easy way to 
1333) avoid this "feature" is to use 
1334) <a href="https://google.com/ncr">https://google.com/ncr</a>.

1335) </p>
1336) <p>

1337) Note that Google search URLs take name/value pairs as arguments and one 
1338) of those names is "hl". If you set "hl" to "en" then Google will return 
1339) search results in English regardless of what Google server you have been 
1340) sent to. On a query this looks like: 
1341) </p>
1342) <pre>https://encrypted.google.com/search?q=online%20anonymity&hl=en

1343) </pre>

1344) <p>

1345) Another method is to simply use your country code for accessing Google. 
1346) This can be google.be, google.de, google.us and so on. 

1347) </p>
1348) <hr />

1349) <a id="GmailWarning"></a>

1350) <h3><a class="anchor" href="#GmailWarning">Gmail warns me that my

1351) account may have been compromised.</a></h3>

1352) 
1353) <p>
1354) Sometimes, after you've used Gmail over Tor, Google presents a
1355) pop-up notification that your account may have been compromised.
1356) The notification window lists a series of IP addresses and locations
1357) throughout the world recently used to access your account.
1358) </p>
1359) 
1360) <p>
1361) In general this is a false alarm: Google saw a bunch of logins from

1362) different places, as a result of running the service via Tor, and
1363) decided

1364) it was a good idea to confirm the account was being accessed by it's
1365) rightful owner.
1366) </p>
1367) 
1368) <p>
1369) Even though this may be a biproduct of using the service via tor,
1370) that doesn't mean you can entirely ignore the warning. It is
1371) <i>probably</i> a false positive, but it might not be since it is
1372) possible for someone to hijack your Google cookie.
1373) </p>
1374) 
1375) <p>
1376) Cookie hijacking is possible by either physical access to your computer
1377) or by watching your network traffic.  In theory only physical access
1378) should compromise your system because Gmail and similar services
1379) should only send the cookie over an SSL link. In practice, alas, it's <a

1380) href="http://fscked.org/blog/fully-automated-active-https-cookie-
1381) hijacking">

1382) way more complex than that</a>.
1383) </p>
1384) 
1385) <p>
1386) And if somebody <i>did</i> steal your google cookie, they might end
1387) up logging in from unusual places (though of course they also might
1388) not). So the summary is that since you're using Tor, this security
1389) measure that Google uses isn't so useful for you, because it's full of
1390) false positives. You'll have to use other approaches, like seeing if
1391) anything looks weird on the account, or looking at the timestamps for
1392) recent logins and wondering if you actually logged in at those times.
1393) </p>
1394) 
1395) <hr>
1396) 

1397) <a id="torrc"></a>

1398) <h3><a class="anchor" href="#torrc">I'm supposed to "edit my torrc".
1399) What does that mean?</a></h3>

1400) 
1401) <p>
1402) Tor installs a text file called torrc that contains configuration
1403) instructions for how your Tor program should behave. The default
1404) configuration should work fine for most Tor users. Users of Vidalia can
1405) make common changes through the Vidalia interface &mdash; only advanced
1406) users should need to modify their torrc file directly.
1407) </p>

1408) <p>

1409) Tor Browser Bundle users should edit your torrc through Vidalia. Open
1410) the
1411) Vidalia Control Panel. Choose Settings. Choose Advanced. Click the
1412) button

1413) labelled "Edit current torrc". Remember to make sure the checkbox for
1414) "Save Settings." is checked. Hit the Ok button and you are done.
1415) </p>

1416) <p>

1417) Otherwise, you will need to edit the file manually.

1418) The location of your torrc file depends on the way you installed Tor:
1419) </p>
1420) <ul>

1421) <li>If you installed Tor Browser Bundle, look for
1422) <code>Data/Tor/torrc</code> inside your Tor Browser Bundle directory.
1423) </li>

1424) <li>On Windows, if you installed a Tor bundle with Vidalia, you can
1425) find your torrc file in the Start menu under Programs -&gt; Vidalia
1426) Bundle -&gt; Tor, or you can find it by hand in <code>\Documents and
1427) Settings\<i>username</i>\Application Data\Vidalia\torrc</code>. If you
1428) installed Tor without Vidalia, you can find your torrc in the Start
1429) menu under Programs -&gt; Tor, or manually in either <code>\Documents
1430) and Settings\Application Data\tor\torrc</code> or <code>\Documents and
1431) Settings\<i>username</i>\Application Data\tor\torrc</code>.
1432) </li>
1433) <li>On OS X, if you use Vidalia, edit
1434) <code>~/.vidalia/torrc</code>. Otherwise, open your favorite text editor
1435) and load <code>/Library/Tor/torrc</code>.
1436) </li>
1437) <li>On Unix, if you installed a pre-built package, look for
1438) <code>/etc/tor/torrc</code> or <code>/etc/torrc</code> or consult your
1439) package's documentation.
1440) </li>
1441) <li>Finally, if you installed from source, you may not have a torrc
1442) installed yet: look in <code>/usr/local/etc/</code> and note that you

1443) may need to manually copy <code>torrc.sample</code> to
1444) <code>torrc</code>.

1445) </li>
1446) </ul>
1447) 
1448) <p>
1449) If you use Vidalia, be sure to exit both Tor and Vidalia before you edit

1450) your torrc file manually. Otherwise Vidalia might overwrite your
1451) changes.

1452) </p>
1453) 
1454) <p>
1455) Once you've changed your torrc, you will need to restart Tor for the
1456) changes to take effect. (For advanced users on OS X and Unix, note that

1457) you actually only need to send Tor a HUP signal, not actually restart
1458) it.)

1459) </p>
1460) 
1461) <p>
1462) For other configuration options you can use, look at the <a href="<page
1463) docs/tor-manual>">Tor manual page</a>. Remember, all lines beginning
1464) with # in torrc are treated as comments and have no effect on Tor's
1465) configuration.
1466) </p>
1467) 
1468) <hr>
1469) 

1470) <a id="Logs"></a>

1471) <h3><a class="anchor" href="#Logs">How do I set up logging, or see Tor's
1472) logs?</a></h3>

1473) 
1474) <p>

1475) If you installed a Tor bundle that includes Vidalia, then Vidalia has a

1476) window called "Message Log" that will show you Tor's log messages. Click
1477) on "Advanced" to see more details. You can click on "Settings" to change
1478) your log verbosity or save the messages to a file. You're all set.

1479) </p>
1480) 
1481) <p>
1482) If you're not using Vidalia, you'll have to go find the log files by

1483) hand. Here are some likely places for your logs to be:

1484) </p>
1485) 
1486) <ul>
1487) <li>On OS X, Debian, Red Hat, etc, the logs are in /var/log/tor/
1488) </li>

1489) <li>On Windows, there are no default log files currently. If you enable
1490) logs in your torrc file, they default to <code>\username\Application
1491) Data\tor\log\</code> or <code>\Application Data\tor\log\</code>
1492) </li>
1493) <li>If you compiled Tor from source, by default your Tor logs to <a
1494) href="http://en.wikipedia.org/wiki/Standard_streams">"stdout"</a>
1495) at log-level notice. If you enable logs in your torrc file, they
1496) default to <code>/usr/local/var/log/tor/</code>.

1497) </li>
1498) </ul>
1499) 
1500) <p>

1501) To change your logging setup by hand, <a href="#torrc">edit your
1502) torrc</a>

1503) and find the section (near the top of the file) which contains the
1504) following line:

1505) </p>
1506) 
1507) <pre>

1508) \## Logs go to stdout at level "notice" unless redirected by something
1509) \## else, like one of the below lines.

1510) </pre>

1511) 
1512) <p>

1513) For example, if you want Tor to send complete debug, info, notice, warn,

1514) and err level messages to a file, append the following line to the end
1515) of the section:
1516) </p>
1517) 
1518) <pre>
1519) Log debug file c:/program files/tor/debug.log
1520) </pre>
1521) 
1522) <p>

1523) Replace <code>c:/program files/tor/debug.log</code> with a directory
1524) and filename for your Tor log.

1525) </p>
1526) 
1527) <hr>
1528) 

1529) 
1530) <a id="LogLevel"></a>
1531) <h3><a class="anchor" href="#LogLevel">What log level should I use?</a></h3>
1532) 
1533) <p>

1534) There are five log levels (also called "log severities") you might see in 
1535) Tor's logs:

1536) </p>
1537) 
1538) <ul>

1539)     <li>"err": something bad just happened, and we can't recover. Tor will 
1540)     exit.</li>
1541)     <li>"warn": something bad happened, but we're still running. The bad 
1542)     thing might be a bug in the code, some other Tor process doing something 
1543)     unexpected, etc. The operator should examine the message and try to 
1544)     correct the problem.</li>

1545)     <li>"notice": something the operator will want to know about.</li>

1546)     <li>"info": something happened (maybe bad, maybe ok), but there's 
1547)     nothing you need to (or can) do about it.</li>

1548)     <li>"debug": for everything louder than info. It is quite loud indeed.</li> 
1549) </ul>
1550) 
1551) <p>

1552) Alas, some of the warn messages are hard for ordinary users to correct -- the 
1553) developers are slowly making progress at making Tor automatically react 
1554) correctly for each situation.

1555) </p>
1556) 
1557) <p>

1558) We recommend running at the default, which is "notice". You will hear about 
1559) important things, and you won't hear about unimportant things.

1560) </p>
1561) 
1562) <p>

1563) Tor relays in particular should avoid logging at info or debug in normal 
1564) operation, since they might end up recording sensitive information in 
1565) their logs. 

1566) </p>
1567) 

1568) <hr>
1569) 

1570) <a id="DoesntWork"></a>

1571) <h3><a class="anchor" href="#DoesntWork">I installed Tor but it's not
1572) working.</a></h3>

1573) 
1574) <p>

1575) Once you've got the Tor bundle up and running, the first question to
1576) ask is whether your Tor client is able to establish a circuit.

1577) </p>
1578) 
1579) <p>If Tor can establish a circuit, the onion icon in

1580) Vidalia will turn green (and if you're running Tor Browser Bundle, it
1581) will
1582) automatically launch a browser for you). You can also check in the
1583) Vidalia

1584) Control Panel to make sure it says "Connected to the Tor
1585) network!" under Status. For those not using Vidalia, check your <a

1586) href="#Logs">Tor logs</a> for

1587) a line saying that Tor "has successfully opened a circuit. Looks like
1588) client functionality is working."
1589) </p>
1590) 
1591) <p>
1592) If Tor can't establish a circuit, here are some hints:
1593) </p>
1594) 
1595) <ol>
1596) <li>Are you sure Tor is running? If you're using Vidalia, you may have
1597) to click on the onion and select "Start" to launch Tor.</li>
1598) <li>Check your system clock. If it's more than a few hours off, Tor will

1599) refuse to build circuits. For Microsoft Windows users, synchronize your
1600) clock under the clock -> Internet time tab. In addition, correct the

1601) day and date under the 'Date & Time' Tab. Also make sure your time
1602) zone is correct.</li>

1603) <li>Is your Internet connection <a href="#FirewallPorts">firewalled
1604) by port</a>, or do you normally need to use a <a

1605) href="<wikifaq>#MyInternetconnectionrequiresanHTTPorSOCKSproxy.">proxy</a>?

1606) </li>

1607) <li>Are you running programs like Norton Internet Security or SELinux
1608) that

1609) block certain connections, even though you don't realize they do? They
1610) could be preventing Tor from making network connections.</li>
1611) <li>Are you in China, or behind a restrictive corporate network firewall
1612) that blocks the public Tor relays? If so, you should learn about <a

1613) href="<page docs/bridges>">Tor bridges</a>.</li>

1614) <li>Check your <a href="#Logs">Tor logs</a>. Do they give you any hints
1615) about what's going wrong?</li>

1616) </ol>
1617) 
1618) <hr />
1619) 

1620) <a id="TorCrash"></a>
1621) <h3><a class="anchor" href="#TorCrash">My Tor keeps crashing.</a></h3>
1622) <p>
1623)  We want to hear from you! There are supposed to be zero crash bugs in Tor. 
1624)  This FAQ entry describes the best way for you to be helpful to us. But even 
1625)  if you can't work out all the details, we still want to hear about it, so 
1626)  we can help you track it down. 
1627) </p>
1628) <p>
1629) First, make sure you're using the latest version of Tor (either the latest 
1630) stable or the latest development version). 
1631) </p>
1632) <p>
1633) Second, make sure your version of libevent is new enough. We recommend at 
1634) least libevent 1.3a. 
1635) </p>
1636) <p>
1637) Third, see if there's already an entry for your bug in the <a 
1638) href="https://bugs.torproject.org/">Tor bugtracker</a>. If so, 
1639) check if there are any new details that you can add. 
1640) </p>
1641) <p>
1642) Fourth, is the crash repeatable? Can you cause the crash? Can 
1643) you isolate some of the circumstances or config options that 
1644) make it happen? How quickly or often does the bug show up? 
1645) Can you check if it happens with other versions of Tor, for 
1646) example the latest stable release? 
1647) </p>
1648) <p>
1649) Fifth, what sort of crash do you get? 
1650) </p>
1651) <ul>
1652) <li>
1653) Does your Tor log include an "assert failure"? If so, please 
1654) tell us that line, since it helps us figure out what's going on. 
1655) Tell us the previous couple of log messages as well, especially 
1656) if they seem important. 
1657) </li>
1658) <li>
1659) If it says "Segmentation fault - core dumped" then you need to 
1660) do a bit more to track it down. Look for a file like "core" or 
1661) "tor.core" or "core.12345" in your current directory, or in your 
1662) Data Directory. If it's there, run "gdb tor core" and then "bt", 
1663) and include the output. If you can't find a core, run "ulimit -c 
1664) unlimited", restart Tor, and try to make it crash again. (This core 
1665) thing will only work on Unix -- alas, tracking down bugs on Windows 
1666) is harder. If you're on Windows, can you get somebody to duplicate 
1667) your bug on Unix?)
1668) </li>
1669) <li>
1670) If Tor simply vanishes mysteriously, it probably is a segmentation 
1671) fault but you're running Tor in the background (as a daemon) so you 
1672) won't notice. Go look at the end of your log file, and look for a 
1673) core file as above. If you don't find any good hints, you should 
1674) consider running Tor in the foreground (from a shell) so you can 
1675) see how it dies. Warning: if you switch to running Tor in the foreground, 
1676) you might start using a different torrc file, with a different default 
1677) Data Directory; see the <a href="#UpgradeOrMove">relay-upgrade FAQ entry</a> 
1678) for details. 
1679) </li>
1680) <li>
1681) If it's still vanishing mysteriously, perhaps something else is killing it? 
1682) Do you have resource limits (ulimits) configured that kill off processes 
1683) sometimes? (This is especially common on OpenBSD.) On Linux, try running 
1684) "dmesg" to see if the out-of-memory killer removed your process. (Tor will 
1685) exit cleanly if it notices that it's run out of memory, but in some cases 
1686) it might not have time to notice.) In very rare circumstances, hardware 
1687) problems could also be the culprit. 
1688) </li>
1689) </ul>
1690) <p>
1691) Sixth, if the above ideas don't point out the bug, consider increasing your 
1692) log level to "loglevel debug". You can look at the log-configuration FAQ 
1693) entry for instructions on what to put in your torrc file. If it usually 
1694) takes a long time for the crash to show up, you will want to reserve a whole 
1695) lot of disk space for the debug log. Alternatively, you could just send 
1696) debug-level logs to the screen (it's called "stdout" in the torrc), and then 
1697) when it crashes you'll see the last couple of log lines it had printed. 
1698) (Note that running with verbose logging like this will slow Tor down 
1699) considerably, and note also that it's generally not a good idea security-wise 
1700) to keep logs like this sitting around.) 
1701) </p>
1702) 
1703) <hr />
1704) 

1705) <a id="VidaliaPassword"></a>

1706) <h3><a class="anchor" href="#VidaliaPassword">Tor/Vidalia prompts for a
1707) password at start.</a></h3>

1708) 
1709) <p>
1710) Vidalia interacts with the Tor software via Tor's "control port". The
1711) control port lets Vidalia receive status updates from Tor, request a new
1712) identity, configure Tor's settings, etc. Each time Vidalia starts Tor,
1713) Vidalia sets a random password for Tor's control port to prevent other
1714) applications from also connecting to the control port and potentially
1715) compromising your anonymity.
1716) </p>
1717) 
1718) <p>
1719) Usually this process of generating and setting a random control password
1720) happens in the background. There are three common situations, though,
1721) where Vidalia may prompt you for a password:
1722) </p>
1723) 
1724) <ol>
1725) <li>You're already running Vidalia and Tor. For example, this situation
1726) can happen if you installed the Vidalia bundle and now you're trying to
1727) run the Tor Browser Bundle. In that case, you'll need to close the old
1728) Vidalia and Tor before you can run this one.
1729) </li>
1730) <li>Vidalia crashed, but left Tor running with the last known random
1731) password. After you restart Vidalia, it generates a new random password,

1732) but Vidalia can't talk to Tor, because the random passwords are
1733) different.

1734) <br />

1735) If the dialog that prompts you for a control password has a Reset
1736) button,

1737) you can click the button and Vidalia will restart Tor with a new random
1738) control password.
1739) <br />
1740) If you do not see a Reset button, or if Vidalia is unable to restart
1741) Tor for you, you can still fix the problem manually. Simply go into your
1742) process or task manager, and terminate the Tor process. Then use Vidalia
1743) to restart Tor and all will work again.
1744) </li>
1745) <li>You had previously set Tor to run as a Windows NT service. When Tor
1746) is set to
1747) run as a service, it starts up when the system boots. If you configured
1748) Tor to start as a service through Vidalia, a random password was set
1749) and saved in Tor. When you reboot, Tor starts up and uses the random
1750) password it saved. You login and start up Vidalia. Vidalia attempts to
1751) talk to the already running Tor. Vidalia generates a random password,
1752) but it is different than the saved password in the Tor service.
1753) <br />
1754) You need to reconfigure Tor to not be a service. See the FAQ entry on

1755) <a href="#NTservice">running Tor as a

1756) Windows NT service</a>

1757) for more information on how to remove the Tor service.
1758) </li>
1759) </ol>
1760) 

1761)     <hr>

1762) 

1763)     <a id="ChooseEntryExit"></a>

1764)     <h3><a class="anchor" href="#ChooseEntryExit">Can I control which
1765) nodes (or country) are used for entry/exit?</a></h3>

1766) 

1767)     <p>

1768)     Yes. You can set preferred entry and exit nodes as well as
1769)     inform Tor which nodes you do not want to use.

1770)     The following options can be added to your config file <a
1771)     href="#torrc">"torrc"</a> or specified on the command line:

1772)     </p>
1773)     <dl>
1774)       <dt><tt>EntryNodes $fingerprint,$fingerprint,...</tt></dt>

1775)         <dd>A list of preferred nodes to use for the first hop in the
1776) circuit, if possible.

1777)         </dd>
1778)       <dt><tt>ExitNodes $fingerprint,$fingerprint,...</tt></dt>

1779)         <dd>A list of preferred nodes to use for the last hop in the
1780) circuit, if possible.

1781)         </dd>
1782)       <dt><tt>ExcludeNodes $fingerprint,$fingerprint,...</tt></dt>

1783)         <dd>A list of nodes to never use when building a circuit.

1784)         </dd>
1785)       <dt><tt>ExcludeExitNodes $fingerprint,$fingerprint,...</tt></dt>

1786)         <dd>A list of nodes to never use when picking an exit.

1787)             Nodes listed in <tt>ExcludeNodes</tt> are automatically in
1788) this list.

1789)         </dd>
1790)     </dl>
1791)     <p>

1792)     <em>We recommend you do not use these</em>

1793)     — they are intended for testing and may disappear in future
1794) versions.

1795)     You get the best security that Tor can provide when you leave the
1796)     route selection to Tor; overriding the entry / exit nodes can mess
1797)     up your anonymity in ways we don't understand.

1798)     </p>
1799)     <p>

1800)     Note also that not every circuit is used to deliver traffic outside of 
1801)     the Tor network. It is normal to see non-exit circuits (such as those 
1802)     used to connect to hidden services, those that do directory fetches, 
1803)     those used for relay reachability self-tests, and so on) that end at 
1804)     a non-exit node. To keep a node from being used entirely, see 
1805)     <tt>ExcludeNodes</tt> and <tt>StrictNodes</tt> in the 
1806)     <a href="<page docs/tor-manual>">manual</a>.

1807)     </p>
1808)     <p>

1809)     Instead of <tt>$fingerprint</tt> you can also specify a <a

1810) 
1811) href="https://secure.wikimedia.org/wikipedia/en/wiki/ISO_3166-1_alpha-2"
1812) >2

1813)     letter ISO3166 country code</a> in curly braces (for example <tt>{de}</tt>),

1814)     or an ip address pattern (for example 255.254.0.0/8), or a node
1815)     nickname. Make sure there are no spaces between the commas and the
1816)     list items.

1817)     </p>
1818)     <p>

1819)     If you want to access a service directly through Tor's Socks
1820) interface

1821)     (eg. using ssh via connect.c), another option is to set up an

1822)     internal mapping in your configuration file using
1823) <tt>MapAddress</tt>.

1824)     See the manual page for details.
1825)     </p>

1826) 

1827)     <hr>

1828) 

1829) <a id="FirewallPorts"></a>

1830) <h3><a class="anchor" href="#FirewallPorts">My firewall only allows a
1831) few outgoing ports.</a></h3>

1832) 
1833) <p>
1834) If your firewall works by blocking ports, then you can tell Tor to only

1835) use the ports that your firewall permits by adding "FascistFirewall 1"
1836) to

1837) your <a href="<page docs/faq>#torrc">torrc

1838) configuration file</a>, or by clicking "My firewall only lets me connect
1839) to certain ports" in Vidalia's Network Settings window.
1840) </p>
1841) 
1842) <p>
1843) By default, when you set this Tor assumes that your firewall allows only
1844) port 80 and port 443 (HTTP and HTTPS respectively). You can select a
1845) different set of ports with the FirewallPorts torrc option.
1846) </p>
1847) 
1848) <p>
1849) If you want to be more fine-grained with your controls, you can also
1850) use the ReachableAddresses config options, e.g.:
1851) </p>
1852) 
1853) <pre>
1854)   ReachableDirAddresses *:80
1855)   ReachableORAddresses *:443
1856) </pre>
1857) 
1858) <hr>

1859) 

1860)     <a id="ExitPorts"></a>

1861)     <h3><a class="anchor" href="#ExitPorts">Is there a list of default exit 
1862)     ports?</a></h3>

1863)     <p>

1864) The default open ports are listed below but keep in mind that, any port or 
1865) ports can be opened by the relay operator by configuring it in torrc or 
1866) modifying the source code. But the default according to src/or/policies.c 
1867) from the source code release tor-0.2.4.16-rc is: 

1868)     </p>
1869)     <pre>
1870)   reject 0.0.0.0/8
1871)   reject 169.254.0.0/16
1872)   reject 127.0.0.0/8
1873)   reject 192.168.0.0/16
1874)   reject 10.0.0.0/8
1875)   reject 172.16.0.0/12
1876)   reject *:25
1877)   reject *:119
1878)   reject *:135-139
1879)   reject *:445
1880)   reject *:563
1881)   reject *:1214
1882)   reject *:4661-4666
1883)   reject *:6346-6429
1884)   reject *:6699
1885)   reject *:6881-6999
1886)   accept *:*
1887)     </pre>
1888)     <p>

1889)     A relay will block access to its own IP address, as well local network 
1890)     IP addresses. A relay always blocks itself by default. This prevents 
1891)     Tor users from accidentally accessing any of the exit operator's local 
1892)     services. 
1893)     </p>
1894) 
1895)     <hr>
1896) 
1897)     <a id="SocksAndDNS"></a>
1898)     <h3><a class="anchor" href="#SocksAndDNS">How do I check if my application that uses 
1899)     SOCKS is leaking DNS requests?</a></h3>
1900) 
1901)     <p>
1902)     These are two steps you need to take here. The first is to make sure 
1903)     that it's using the correct variant of the SOCKS protocol, and the 
1904)     second is to make sure that there aren't other leaks. 
1905)     </p>
1906) 
1907)     <p>
1908)     Step one: add "TestSocks 1" to your torrc file, and then watch your 
1909)     logs as you use your application. Tor will then log, for each SOCKS 
1910)     connection, whether it was using a 'good' variant or a 'bad' one. 
1911)     (If you want to automatically disable all 'bad' variants, set 
1912)     "SafeSocks 1" in your <a href="#torrc">torrc</a> file.) 
1913)     </p>
1914) 
1915)     <p>
1916)     Step two: even if your application is using the correct variant of 
1917)     the SOCKS protocol, there is still a risk that it could be leaking 
1918)     DNS queries. This problem happens in Firefox extensions that resolve 
1919)     the destination hostname themselves, for example to show you its IP 
1920)     address, what country it's in, etc. These applications may use a safe 
1921)     SOCKS variant when actually making connections, but they still do DNS 
1922)     resolves locally. If you suspect your application might behave like 
1923)     this, you should use a network sniffer like <a 
1924)     href="https://www.wireshark.org/">Wireshark</a> and look for 
1925)     suspicious outbound DNS requests. I'm afraid the details of how to look 
1926)     for these problems are beyond the scope of a FAQ entry though -- find 
1927)     a friend to help if you have problems. 

1928)     </p>
1929) 
1930)     <hr>
1931) 

1932)     <a id="RelayFlexible"></a>

1933)     <h3><a class="anchor" href="#RelayFlexible">How stable does my relay
1934) need to be?</a></h3>

1935) 

1936)     <p>
1937)     We aim to make setting up a Tor relay easy and convenient:
1938)     </p>

1939) 

1940)     <ul>
1941)     <li>Tor has built-in support for <a

1942)     href="<wikifaq>#WhatbandwidthshapingoptionsareavailabletoTorrelays">

1943)     rate limiting</a>. Further, if you have a fast
1944)     link but want to limit the number of bytes per
1945)     day (or week or month) that you donate, check out the <a

1946) 
1947) href="<wikifaq>#HowcanIlimitthetotalamountofbandwidthusedbymyTorrelay">
1948) hibernation

1949)     feature</a>.
1950)     </li>

1951)     <li>Each Tor relay has an <a href="#ExitPolicies">exit policy</a>
1952) that
1953)     specifies what sort of outbound connections are allowed or refused
1954) from
1955)     that relay. If you are uncomfortable allowing people to exit from
1956) your
1957)     relay, you can set it up to only allow connections to other Tor
1958) relays.

1959)     </li>
1960)     <li>It's fine if the relay goes offline sometimes. The directories
1961)     notice this quickly and stop advertising the relay. Just try to make
1962)     sure it's not too often, since connections using the relay when it
1963)     disconnects will break.
1964)     </li>
1965)     <li>We can handle relays with dynamic IPs just fine &mdash; simply
1966)     leave the Address config option blank, and Tor will try to guess.
1967)     </li>
1968)     <li>If your relay is behind a NAT and it doesn't know its public
1969)     IP (e.g. it has an IP of 192.168.x.y), you'll need to set up port

1970)     forwarding. Forwarding TCP connections is system dependent but

1971)     <a href="<wikifaq>#ImbehindaNATFirewall">this FAQ entry</a>

1972)     offers some examples on how to do this.
1973)     </li>
1974)     <li>Your relay will passively estimate and advertise its recent

1975)     bandwidth capacity, so high-bandwidth relays will attract more users
1976) than
1977)     low-bandwidth ones. Therefore having low-bandwidth relays is useful
1978) too.

1979)     </li>
1980)     </ul>

1981) 

1982)     <hr>

1983) 

1984)     <a id="ExitPolicies"></a>

1985)     <h3><a class="anchor" href="#ExitPolicies">I'd run a relay, but I
1986) don't want to deal with abuse issues.</a></h3>

1987) 

1988)     <p>
1989)     Great. That's exactly why we implemented exit policies.
1990)     </p>

1991) 

1992)     <p>
1993)     Each Tor relay has an exit policy that specifies what sort of

1994)     outbound connections are allowed or refused from that relay. The
1995) exit

1996)     policies are propagated to Tor clients via the directory, so clients
1997)     will automatically avoid picking exit relays that would refuse to
1998)     exit to their intended destination. This way each relay can decide
1999)     the services, hosts, and networks he wants to allow connections to,

2000)     based on abuse potential and his own situation. Read the FAQ entry
2001) on
2002)     <a href="<page docs/faq-abuse>#TypicalAbuses">issues you might
2003) encounter</a>

2004)     if you use the default exit policy, and then read Mike Perry's

2005)     <a href="<blog>tips-running-exit-node-minimal-harassment">tips

2006)     for running an exit node with minimal harassment</a>.
2007)     </p>

2008) 

2009)     <p>

2010)     The default exit policy allows access to many popular services

2011)     (e.g. web browsing), but <a
2012) href="<wikifaq>#Istherealistofdefaultexitports">restricts</a>

2013)     some due to abuse potential (e.g. mail) and some since
2014)     the Tor network can't handle the load (e.g. default
2015)     file-sharing ports). You can change your exit policy

2016)     using Vidalia's "Sharing" tab, or by manually editing your

2017)     <a href="<page docs/faq>#torrc">torrc</a>

2018)     file. If you want to avoid most if not all abuse potential, set it
2019) to
2020)     "reject *:*" (or un-check all the boxes in Vidalia). This setting
2021) means
2022)     that your relay will be used for relaying traffic inside the Tor
2023) network,

2024)     but not for connections to external websites or other services.
2025)     </p>

2026) 

2027)     <p>

2028)     If you do allow any exit connections, make sure name resolution
2029) works

2030)     (that is, your computer can resolve Internet addresses correctly).

2031)     If there are any resources that your computer can't reach (for
2032) example,

2033)     you are behind a restrictive firewall or content filter), please

2034)     explicitly reject them in your exit policy — otherwise Tor
2035) users

2036)     will be impacted too.
2037)     </p>

2038) 

2039)     <hr>

2040) 

2041)     <a id="DifferentComputer"></a>

2042)     <h3><a class="anchor" href="#DifferentComputer">I want to run my 
2043)     Tor client on a different computer than my applications.</a></h3>

2044)     <p>

2045)     By default, your Tor client only listens for applications that 
2046)     connect from localhost. Connections from other computers are 
2047)     refused. If you want to torify applications on different computers 
2048)     than the Tor client, you should edit your torrc to define 
2049)     SocksListenAddress 0.0.0.0 g and then restart (or hup) Tor. If you 
2050)     want to get more advanced, you can configure your Tor client on a 
2051)     firewall to bind to your internal IP but not your external IP.  

2052)     </p>
2053) 
2054)     <hr>
2055) 
2056)     <a id="ServerClient"></a>

2057)     <h3><a class="anchor" href="#ServerClient">Can I install Tor on a 
2058)     central server, and have my clients connect to it?</a></h3>
2059)     <p>
2060)      Yes. Tor can be configured as a client or a relay on another 
2061)      machine, and allow other machines to be able to connect to it 
2062)      for anonymity. This is most useful in an environment where many 
2063)      computers want a gateway of anonymity to the rest of the world. 
2064)      However, be forwarned that with this configuration, anyone within 
2065)      your private network (existing between you and the Tor 
2066)      client/relay) can see what traffic you are sending in clear text. 
2067)      The anonymity doesn't start until you get to the Tor relay. 
2068)      Because of this, if you are the controller of your domain and you 
2069)      know everything's locked down, you will be OK, but this configuration 
2070)      may not be suitable for large private networks where security is 
2071)      key all around.
2072)     </p>
2073)     <p>
2074) Configuration is simple, editing your torrc file's SocksListenAddress 
2075) according to the following examples:

2076)     </p>
2077)     <pre>

2078) 
2079)   #This provides local interface access only, 
2080)   #needs SocksPort to be greater than 0
2081)   SocksListenAddress 127.0.0.1 
2082) 
2083)   #This provides access to Tor on a specified interface
2084)   SocksListenAddress 192.168.x.x:9100 
2085) 
2086)   #Accept from all interfaces
2087)   SocksListenAddress 0.0.0.0:9100
2088)    </pre>

2089)     <p>

2090) You can state multiple listen addresses, in the case that you are 
2091) part of several networks or subnets.

2092)     </p>
2093)     <pre>
2094)   SocksListenAddress 192.168.x.x:9100 #eth0
2095)   SocksListenAddress 10.x.x.x:9100 #eth1
2096)     </pre>
2097)     <p>

2098) After this, your clients on their respective networks/subnets would specify 
2099) a socks proxy with the address and port you specified SocksListenAddress 
2100) to be. 

2101)     </p>
2102)     <p>

2103) Please note that the SocksPort configuration option gives the port ONLY for 
2104) localhost (127.0.0.1). When setting up your SocksListenAddress(es), you need 
2105) to give the port with the address, as shown above.

2106)     <p>

2107) If you are interested in forcing all outgoing data through the central Tor 
2108) client/relay, instead of the server only being an optional proxy, you may find 
2109) the program iptables (for *nix) useful. 

2110)     </p>
2111) 
2112)     <hr>
2113) 

2114)     <a id="JoinTheNetwork"></a>

2115)     <h3><a class="anchor" href="#JoinTheNetwork">So I can just configure a 
2116)     nickname and ORPort and join the network?</a></h3>

2117) 
2118)     <p>

2119)      Yes. You can join the network and be a useful relay just by configuring 
2120)      your Tor to be a relay and making sure it's reachable from the outside.

2121)     </p>
2122)     <p>
2123) 30 Seconds to a Tor Relay:
2124)     </p>
2125)     <ul><li>
2126)     Configure a Nickname: 
2127)     </li></ul>
2128)     <pre>
2129) Nickname ididnteditheconfig
2130)     </pre>

2131)     <ul><li>

2132)     Configure ORPort: 

2133)     </li></ul>

2134)     <pre>
2135) ORPort 9001
2136)     </pre>

2137)     <ul><li>

2138)     Configure Contact Info: 

2139)     </li></ul>

2140) 
2141)     <pre>
2142) ContactInfo human@…

2143)     </pre>
2144)     <ul><li>

2145)     Start Tor. Watch the log file for a log entry that states: "Self-testing 
2146)     indicates your ORPort is reachable from the outside. Excellent. Publishing 
2147)     server descriptor."

2148)     </li></ul>

2149) 
2150)     <hr />

2151) 

2152)     <a id="RelayOrBridge"></a>

2153)     <h3><a class="anchor" href="#RelayOrBridge">Should I be a normal
2154) relay or bridge relay?</a></h3>

2155) 

2156)     <p><a href="<page docs/bridges>">Bridge relays</a> (or "bridges" for
2157) short)
2158)     are <a href="<page docs/tor-doc-relay>">Tor relays</a> that aren't

2159)     listed in the public Tor directory.

2160)     That means that ISPs or governments trying to block access to the

2161)     Tor network can't simply block all bridges.

2162)     </p>

2163) 

2164)     <p>Being a normal relay vs being a bridge relay is almost the same
2165)     configuration: it's just a matter of whether your relay is listed

2166)     publicly or not.

2167)     </p>

2168) 

2169)     <p>

2170)     So bridges are useful a) for Tor users in oppressive regimes,

2171)     and b) for people who want an extra layer of security

2172)     because they're worried somebody will recognize that it's a public
2173)     Tor relay IP address they're contacting.

2174)     </p>

2175) 

2176)     <p>
2177)     Several countries, including China and Iran, have found ways to

2178)     detect and block connections to Tor bridges.

2179)     <a href="<page projects/obfsproxy>">Obfsproxy</a> bridges address

2180)     this by adding another layer of obfuscation.

2181)     </p>
2182) 

2183)     <p>So should you run a normal relay or bridge relay? If you have
2184) lots

2185)     of bandwidth, you should definitely run a normal relay.
2186)     If you're willing

2187)     to <a href="#ExitPolicies">be an exit</a>, you should definitely
2188)     run a normal relay, since we need more exits. If you can't be an
2189)     exit and only have a little bit of bandwidth, be a bridge. Thanks
2190)     for volunteering!

2191)     </p>

2192) 

2193)     <hr>

2194) 

2195) <a id="UpgradeOrMove"></a>

2196) <h3><a class="anchor" href="#UpgradeOrMove">I want to upgrade/move my relay. 
2197) How do I keep the same key?</a></h3>

2198) 
2199) <p>

2200)  When upgrading your Tor relay, or running it on a different computer, 
2201)  the important part is to keep the same nickname (defined in your torrc 
2202)  file) and the same identity key (stored in "keys/secret_id_key" in 
2203)  your DataDirectory).

2204) </p>
2205) <p>

2206) This means that if you're upgrading your Tor relay and you keep the same 
2207) torrc and the same DataDirectory, then the upgrade should just work and 
2208) your relay will keep using the same key. If you need to pick a new 
2209) DataDirectory, be sure to copy your old keys/secret_id_key over. 

2210) </p>
2211) 
2212)     <hr>
2213) 
2214) <a id="NTService"></a>

2215) <h3><a class="anchor" href="#NTService">How do I run my Tor relay as an NT 
2216) service?</a></h3>

2217) 
2218) <p>

2219)  You can run Tor as a service on all versions of Windows except Windows 
2220)  95/98/ME. This way you can run a Tor relay without needing to always have 
2221)  Vidalia running.

2222) </p>
2223) <p>

2224) If you've already configured your Tor to be a relay, please note that when 
2225) you enable Tor as a service, it will use a different DatagDirectory, and 
2226) thus will generate a different key. If you want to keep using the old key, 
2227) see the Upgrading your Tor relay FAQ entry for how to restore the old 
2228) identity key.

2229) </p>
2230) <p>
2231) To install Tor as a service, you can simply run:
2232) </p>
2233) <pre>
2234) tor --service install
2235) </pre>
2236) <p>

2237) A service called Tor Win32 Service will be installed and started. This 
2238) service will also automatically start every time Windows boots, unless 
2239) you change the Start-up type. An easy way to check the status of Tor, 
2240) start or stop the service, and change the start-up type is by running 
2241) services.msc and finding the Tor service in the list of currently 
2242) installed services.

2243) </p>
2244) <p>

2245) Optionally, you can specify additional options for the Tor service using 
2246) the -options argument. For example, if you want Tor to use C:\tor\torrc, 
2247) instead of the default torrc, and open a control port on port 9151, you 
2248) would run:

2249) </p>
2250) <pre>
2251) tor --service install -options -f C:\tor\torrc ControlPort 9151
2252) </pre>
2253) <p>
2254) You can also start or stop the Tor service from the command line by typing:
2255) </p>
2256) <pre>
2257)  tor --service start
2258) </pre>
2259) <p>
2260) or
2261) </p>
2262) <pre>
2263)  tor --service stop
2264) </pre>
2265) <p>
2266) To remove the Tor service, you can run the following command:
2267) </p>
2268) <pre>
2269) tor --service remove
2270) </pre>
2271) <p>

2272) If you are running Tor as a service and you want to uninstall Tor entirely, 
2273) be sure to run the service removal command (shown above) first before 
2274) running the uninstaller from "Add/Remove Programs". The uninstaller is 
2275) currently not capable of removing the active service.

2276) </p>
2277) 
2278) <hr>
2279) 
2280) <a id="VirtualServer"></a>

2281) <h3><a class="anchor" href="#VirtualServer">Can I run a Tor relay from my 
2282) virtual server account?</a></h3>

2283) 
2284) <p>

2285) Some ISPs are selling "vserver" accounts that provide what they call a 
2286) virtual server -- you can't actually interact with the hardware, and 
2287) they can artificially limit certain resources such as the number of file 
2288) descriptors you can open at once. Competent vserver admins are able to 
2289) configure your server to not hit these limits. For example, in SWSoft's 
2290) Virtuozzo, investigate /proc/user_beancounters. Look for "failcnt" in 
2291) tcpsndbuf, tcprecvbuf, numothersock, and othersockbuf. Ask for these to 
2292) be increased accordingly. Some users have seen settings work well as follows: 

2293) <p>

2294) <table border="1">

2295) <tr>
2296) <td>
2297) <i>resource</i>
2298) </td>
2299) <td>
2300) <i>held</i>
2301) </td>
2302) <td>
2303) <i>maxheld</i>
2304) </td>
2305) <td>
2306) <i>barrier</i>
2307) </td>
2308) <td>
2309) <i>limit</i>
2310) </td>
2311) <td>
2312) <i>failcnt</i>
2313) </td>
2314) </tr>
2315) <tr>
2316) <td>
2317) tcpsndbuf
2318) </td>
2319) <td>
2320) 46620
2321) </td>
2322) <td>
2323) 48840
2324) </td>
2325) <td>
2326) 3440640
2327) </td>
2328) <td>
2329) 5406720
2330) </td>
2331) <td>
2332) 0
2333) </td>
2334) </tr>
2335) <tr>
2336) <td>
2337) tcprcvbuf
2338) </td>
2339) <td>
2340) 0
2341) </td>
2342) <td>
2343) 2220
2344) </td>
2345) <td>
2346) 3440640
2347) </td>
2348) <td>
2349) 5406720
2350) </td>
2351) <td>
2352) 0
2353) </td>
2354) </tr>
2355) <tr>
2356) <td>
2357) othersockbuf
2358) </td>
2359) <td>
2360) 243516
2361) </td>
2362) <td>
2363) 260072
2364) </td>
2365) <td>
2366) 2252160
2367) </td>
2368) <td>
2369) 4194304
2370) </td>
2371) <td>
2372) 0
2373) </td>
2374) </tr>
2375) <tr>
2376) <td>
2377) numothersock
2378) </td>
2379) <td>
2380) 151
2381) </td>
2382) <td>
2383) 153
2384) </td>
2385) <td>
2386) 720
2387) </td>
2388) <td>
2389) 720
2390) </td>
2391) <td>
2392) 0
2393) </td>
2394) </tr>
2395) </table>
2396) <p>
2397)  Xen, Virtual Box and VMware virtual servers have no such limits normally.
2398) </p>
2399) <p>

2400) If the vserver admin will not increase system limits another option is 
2401) to reduce the memory allocated to the send and receive buffers on TCP 
2402) connections Tor uses. An experimental feature to constrain socket buffers 
2403) has recently been added. If your version of Tor supports it, set 
2404) "ConstrainedSockets 1" in your configuration. See the tor man page for 
2405) additional details about this option.

2406) </p>
2407) <p>

2408) Unfortunately, since Tor currently requires you to be able to connect to 
2409) all the other Tor relays, we need you to be able to use at least 1024 file 
2410) descriptors. This means we can't make use of Tor relays that are crippled 
2411) in this way.

2412) </p>
2413) <p>

2414) We hope to fix this in the future, once we know how to build a Tor network 
2415) with restricted topologies -- that is, where each node connects to only a 
2416) few other nodes. But this is still a long way off.

2417) </p>
2418) 

2419) <hr>
2420) 

2421) <a id="MultipleRelays"></a>

2422) <h3><a class="anchor" href="#MultipleRelays">I want to run more than one
2423) relay.</a></h3>

2424) 
2425) <p>
2426) Great. If you want to run several relays to donate more to the network,
2427) we're happy with that. But please don't run more than a few dozen on
2428) the same network, since part of the goal of the Tor network is dispersal
2429) and diversity.
2430) </p>
2431) 
2432) <p>
2433) If you do decide to run more than one relay, please set the "MyFamily"

2434) config option in the <a href="#torrc">torrc</a> of each relay, listing
2435) all the relays (comma-separated) that are under your control:

2436) </p>
2437) 
2438) <pre>
2439)     MyFamily $fingerprint1,$fingerprint2,$fingerprint3
2440) </pre>
2441) 
2442) <p>
2443) where each fingerprint is the 40 character identity fingerprint (without

2444) spaces). You can also list them by nickname, but fingerprint is safer.
2445) Be

2446) sure to prefix the digest strings with a dollar sign ('$') so that the
2447) digest is not confused with a nickname in the config file.
2448) </p>
2449) 
2450) <p>
2451) That way clients will know to avoid using more than one of your relays
2452) in a single circuit. You should set MyFamily if you have administrative
2453) control of the computers or of their network, even if they're not all in
2454) the same geographic location.
2455) </p>
2456) 
2457)     <hr>
2458) 

2459)     <a id="WrongIP"></a>

2460)     <h3><a class="anchor" href="#WrongIP">My relay is picking the wrong 
2461)     IP address.</a></h3>

2462)     <p>

2463)  Tor guesses its IP address by asking the computer for its hostname, and 
2464)  then resolving that hostname. Often people have old entries in their 
2465)  /etc/hosts file that point to old IP addresses.

2466)     </p>
2467)     <p>

2468) If that doesn't fix it, you should use the "Address" config option to 
2469) specify the IP you want it to pick. If your computer is behind a NAT and 
2470) it only has an internal IP address, see the following FAQ entry on <a 
2471) href="https://www.torproject.org/docs/faq.html.en#RelayFlexible">dynamic 
2472) IP addresses</a>.

2473)     </p>
2474)     <p>

2475) Also, if you have many addresses, you might also want to set 
2476) "OutboundBindAddress" so external connections come from the IP you intend 
2477) to present to the world. 

2478)     </p>
2479) 
2480)     <hr>
2481) 
2482)     <a id="BehindANAT"></a>
2483)     <h3><a class="anchor" href="#BehindANAT">I'm behind a NAT/Firewall.</a></h3>
2484) 
2485)     <p>

2486) See <a>​http://portforward.com/</a> for directions on how to port forward with 
2487) your NAT/router device.

2488) </p>
2489) <p>

2490) If your relay is running on a internal net you need to setup port forwarding. 
2491) Forwarding TCP connections is system dependent but the firewalled-clients FAQ 
2492) entry offers some examples on how to do this.

2493) </p>
2494) <p>

2495) Also, here's an example of how you would do this on GNU/Linux if you're using 
2496) iptables:

2497) </p>
2498) <pre>
2499) /sbin/iptables -A INPUT -i eth0 -p tcp --destination-port 9001 -j ACCEPT
2500) </pre>
2501) <p>

2502) You may have to change "eth0" if you have a different external interface 
2503) (the one connected to the Internet). Chances are you have only one (except 
2504) the loopback) so it shouldn't be too hard to figure out. 

2505)     </p>
2506)     <hr>
2507) 

2508)     <a id="RelayMemory"></a>

2509)     <h3><a class="anchor" href="#RelayMemory">Why is my Tor relay using
2510) so much memory?</a></h3>

2511) 

2512)     <p>If your Tor relay is using more memory than you'd like, here are
2513) some

2514)     tips for reducing its footprint:
2515)     </p>

2516) 

2517)     <ol>
2518)     <li>If you're on Linux, you may be encountering memory fragmentation

2519)     bugs in glibc's malloc implementation. That is, when Tor releases
2520) memory
2521)     back to the system, the pieces of memory are fragmented so they're
2522) hard
2523)     to reuse. The Tor tarball ships with OpenBSD's malloc
2524) implementation,
2525)     which doesn't have as many fragmentation bugs (but the tradeoff is
2526) higher
2527)     CPU load). You can tell Tor to use this malloc implementation
2528) instead:

2529)     <tt>./configure --enable-openbsd-malloc</tt></li>

2530) 

2531)     <li>If you're running a fast relay, meaning you have many TLS
2532) connections

2533)     open, you are probably losing a lot of memory to OpenSSL's internal
2534)     buffers (38KB+ per socket). We've patched OpenSSL to <a

2535) 
2536) href="https://lists.torproject.org/pipermail/tor-dev/2008-June/001519.
2537) html">release

2538)     unused buffer memory more aggressively</a>. If you update to OpenSSL

2539)     1.0.0 or newer, Tor's build process will automatically recognize and
2540) use

2541)     this feature.</li>

2542) 

2543)     <li>If you're running on Solaris, OpenBSD, NetBSD, or
2544)     old FreeBSD, Tor is probably forking separate processes
2545)     rather than using threads. Consider switching to a <a
2546)     href="<wikifaq>#WhydoesntmyWindowsorotherOSTorrelayrunwell">better
2547)     operating system</a>.</li>

2548) 

2549)     <li>If you still can't handle the memory load, consider reducing the

2550)     amount of bandwidth your relay advertises. Advertising less
2551) bandwidth

2552)     means you will attract fewer users, so your relay shouldn't grow
2553)     as large. See the <tt>MaxAdvertisedBandwidth</tt> option in the man
2554)     page.</li>

2555) 

2556)     </ol>

2557) 

2558)     <p>

2559)     All of this said, fast Tor relays do use a lot of ram. It is not
2560) unusual

2561)     for a fast exit relay to use 500-1000 MB of memory.
2562)     </p>

2563) 

2564)     <hr>

2565) 

2566)     <a id="BetterAnonymity"></a>

2567)     <h3><a class="anchor" href="#BetterAnonymity">Do I get better anonymity 
2568)     if I run a relay?</a></h3>

2569) 

2570)     <p>

2571) Yes, you do get better anonymity against some attacks.
2572)     </p>
2573)     <p>

2574) The simplest example is an attacker who owns a small number of Tor relays. 
2575) He will see a connection from you, but he won't be able to know whether 
2576) the connection originated at your computer or was relayed from somebody else.

2577)     </p>
2578)     <p>

2579) There are some cases where it doesn't seem to help: if an attacker can 
2580) watch all of your incoming and outgoing traffic, then it's easy for him 
2581) to learn which connections were relayed and which started at you. (In 
2582) this case he still doesn't know your destinations unless he is watching 
2583) them too, but you're no better off than if you were an ordinary client.)

2584)     </p>
2585)     <p>

2586) There are also some downsides to running a Tor relay. First, while we 
2587) only have a few hundred relays, the fact that you're running one might 
2588) signal to an attacker that you place a high value on your anonymity. 
2589) Second, there are some more esoteric attacks that are not as 
2590) well-understood or well-tested that involve making use of the knowledge 
2591) that you're running a relay -- for example, an attacker may be able to 
2592) "observe" whether you're sending traffic even if he can't actually watch 
2593) your network, by relaying traffic through your Tor relay and noticing 
2594) changes in traffic timing.

2595)     </p>
2596)     <p>

2597) It is an open research question whether the benefits outweigh the risks. 
2598) A lot of that depends on the attacks you are most worried about. For 
2599) most users, we think it's a smart move. 

2600)     </p>

2601) 

2602)     <hr>

2603) 

2604)     <a id="RelayDonations"></a>

2605)     <h3><a class="anchor" href="#RelayDonations">Can I donate for a
2606)     relay rather than run my own?</a></h3>

2607) 
2608)     <p>

2609)     Sure! We recommend these non-profit charities that are happy to turn

2610)     your donations into better speed and anonymity for the Tor network:
2611)     </p>
2612)     <ul>
2613)     <li><a href="https://www.torservers.net/">torservers.net</a>
2614)     is a German charitable non-profit that runs a wide variety of

2615)     exit relays worldwide. They also like donations of bandwidth from
2616)     ISPs.</li>

2617)     <li><a

2618) href="https://www.noisebridge.net/wiki/Noisebridge_Tor">Noisebridge</a>

2619)     is a US-based 501(c)(3) non-profit that collects donations and turns

2620)     them into more US-based exit relay capacity.</li>
2621)     <li><a href="https://nos-oignons.net/">Nos Oignons</a> is a French
2622)     charitable non-profit that runs fast exit relays in France.</li>

2623)     </ul>
2624) 
2625)     <p>
2626)     These organizations are not the same as <a href="<page
2627)     donate/donate>">The Tor Project, Inc</a>, but we consider that a

2628)     good thing. They're both run by nice people who are part of the
2629)     Tor community.

2630)     </p>
2631) 
2632)     <p>
2633)     Note that there can be a tradeoff here between anonymity and

2634)     performance. The Tor network's anonymity comes in part from
2635) diversity,

2636)     so if you are in a position to run your own relay, you will be

2637)     improving Tor's anonymity more than by donating. At the same time
2638)     though, economies

2639)     of scale for bandwidth mean that combining many small donations into

2640)     several larger relays is more efficient at improving network

2641)     performance. Improving anonymity and improving performance are both
2642)     worthwhile goals, so however you can help is great!
2643)     </p>
2644) 
2645)     <hr>
2646) 

2647)     <a id="AccessHiddenServices"></a>
2648)     <h3><a class="anchor" href="#AccessHiddenServices">How do I access 
2649)     hidden services?</a></h3>
2650)     
2651)     <p>
2652)     Tor hidden services are named with a special top-level domain (TLD) 
2653)     name in DNS: .onion. Since the .onion TLD is not recognized by the 
2654)     official root DNS servers on the Internet, your application will not 
2655)     get the response it needs to locate the service. Currently, the Tor 
2656)     directory server provides this look-up service; and thus the look-up 
2657)     request must get to the Tor network. 
2658)     </p>
2659) 
2660) <p>
2661)  Therefore, your application <b>needs</b> to pass the .onion hostname to 
2662)  Tor directly. You can't try to resolve it to an IP address, since there 
2663)  <i>is</i> no corresponding IP address: the server is hidden, after all! 
2664) </p>
2665)     
2666)     <p>
2667)     So, how do you make your application pass the hostname directly to Tor? 
2668)     You can't use SOCKS 4, since SOCKS 4 proxies require an IP from the 
2669)     client (a web browser is an example of a SOCKS client). Even though 
2670)     SOCKS 5 can accept either an IP or a hostname, most applications 
2671)     supporting SOCKS 5 try to resolve the name before passing it to the 
2672)     SOCKS proxy. SOCKS 4a, however, always accepts a hostname: You'll need 
2673)     to use SOCKS 4a. 
2674)     </p>
2675)     
2676)     <p>
2677)     Some applications, such as the browsers Mozilla Firefox and Apple's 
2678)     Safari, support sending DNS queries to Tor's SOCKS 5 proxy. Most web 
2679)     browsers don't support SOCKS 4a very well, though. The workaround is 
2680)     to point your web browser at an HTTP proxy, and tell the HTTP proxy 
2681)     to speak to Tor with SOCKS 4a. We recommend Polipo as your HTTP proxy.
2682)     </p>
2683)     
2684)     <p>
2685)     For applications that do not support HTTP proxy, and so cannot use 
2686)     Polipo, <a href="http://www.freecap.ru/eng/">FreeCap</a> is an 
2687)     alternative. When using FreeCap set proxy protocol  to SOCKS 5 and under 
2688)     settings set DNS name resolving to remote. This 
2689)     will allow you to use almost any program with Tor without leaking DNS 
2690)     lookups and allow those same programs to access hidden services. 
2691)     </p>
2692)     
2693)     <p>
2694)     See also the <a href="#SocksAndDNS">question on DNS</a>. 
2695)     </p>    
2696)     
2697)     <hr>
2698) 
2699)     <a id="ProvideAHiddenService"></a>
2700)     <h3><a class="anchor" href="#ProvideAHiddenService">How do I provide a 
2701)     hidden service?</a></h3>
2702)     
2703)     <p>

2704)     See the <a href="https://www.torproject.org/docs/tor-hidden-service.html.en">

2705)     official hidden service configuration instructions</a>.
2706)     </p>
2707) 
2708)     <hr>
2709)     

2710)     <a id="WhatProtectionsDoesTorProvide"></a>
2711)     <h3><a class="anchor" href="#WhatProtectionsDoesTorProvide">What 
2712)     protections does Tor provide?</a></h3>
2713)     
2714)     <p>
2715)      Internet communication is based on a store-and-forward model that 
2716)      can be understood in analogy to postal mail: Data is transmitted in 
2717)      blocks called IP datagrams or packets. Every packet includes a source 
2718)      IP address (of the sender) and a destination IP address (of the 
2719)      receiver), just as ordinary letters contain postal addresses of sender 
2720)      and receiver. The way from sender to receiver involves multiple hops of 
2721)      routers, where each router inspects the destination IP address and 
2722)      forwards the packet closer to its destination. Thus, every router 
2723)      between sender and receiver learns that the sender is communicating 
2724)      with the receiver. In particular, your local ISP is in the position to 
2725)      build a complete profile of your Internet usage. In addition, every 
2726)      server in the Internet that can see any of the packets can profile your 
2727)      behaviour. 
2728)     </p>
2729)     
2730)     <p>
2731)     The aim of Tor is to improve your privacy by sending your traffic through 
2732)     a series of proxies. Your communication is encrypted in multiple layers 
2733)     and routed via multiple hops through the Tor network to the final 
2734)     receiver. More details on this process can be found in the <a 
2735)     href="https://www.torproject.org/about/overview">Tor overview</a>. 
2736)     Note that all your local ISP can observe now is that you are 
2737)     communicating with Tor nodes. Similarly, servers in the Internet just 
2738)     see that they are being contacted by Tor nodes.
2739)     </p>
2740)     
2741)     <p>
2742)     Generally speaking, Tor aims to solve three privacy problems: 
2743)     </p>
2744)     
2745)     <p>
2746)     First, Tor prevents websites and other services from learning 
2747)     your location, which they can use to build databases about your 
2748)     habits and interests. With Tor, your Internet connections don't 
2749)     give you away by default -- now you can have the ability to choose, 
2750)     for each connection, how much information to reveal. 
2751)     </p>
2752)     
2753)     <p>
2754)     Second, Tor prevents people watching your traffic locally (such as 
2755)     your ISP) from learning what information you're fetching and where 
2756)     you're fetching it from. It also stops them from deciding what you're 
2757)     allowed to learn and publish -- if you can get to any part of the Tor 
2758)     network, you can reach any site on the Internet.     
2759)     </p>
2760) 
2761)     <p>
2762)     Third, Tor routes your connection through more than one Tor relay 
2763)     so no single relay can learn what you're up to. Because these relays 
2764)     are run by different individuals or organizations, distributing trust 
2765)     provides more security than the old <a href="#Torisdifferent">one hop proxy
2766)     </a> approach. 
2767)     </p>
2768)     
2769)     <p>
2770)     Note, however, that there are situations where Tor fails to solve these 
2771)     privacy problems entirely: see the entry below on <a 
2772)     href="#AttacksOnOnionRouting">remaining attacks</a>.    
2773)     </p>
2774)     
2775)     <hr>
2776)     
2777)     <a id="CanExitNodesEavesdrop"></a>
2778)     <h3><a class="anchor" href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop 
2779)     on communications? Isn't that bad?</a></h3>
2780)     
2781)     <p>
2782)     Yes, the guy running the exit node can read the bytes that come in and 
2783)     out there. Tor anonymizes the origin of your traffic, and it makes sure 
2784)     to encrypt everything inside the Tor network, but it does not magically 
2785)     encrypt all traffic throughout the Internet. 
2786)     </p>
2787)     
2788)     <p>
2789)     This is why you should always use end-to-end encryption such as SSL for 
2790)     sensitive Internet connections. (The corollary to this answer is that if 
2791)     you are worried about somebody intercepting your traffic and you're 
2792)     *not* using end-to-end encryption at the application layer, then something 
2793)     has already gone wrong and you shouldn't be thinking that Tor is the problem.) 
2794)     </p>
2795)     
2796)     <p>
2797)     Tor does provide a partial solution in a very specific situation, though. 
2798)     When you make a connection to a destination that also runs a Tor relay, 
2799)     Tor will automatically extend your circuit so you exit from that circuit. 
2800)     So for example if Indymedia ran a Tor relay on the same IP address as 
2801)     their website, people using Tor to get to the Indymedia website would 
2802)     automatically exit from their Tor relay, thus getting *better* encryption 
2803)     and authentication properties than just browsing there the normal way. 
2804)     </p>
2805) 
2806)     <p>
2807)     We'd like to make it still work even if the service is nearby the Tor 
2808)     relay but not on the same IP address. But there are a variety of 
2809)     technical problems we need to overcome first (the main one being "how 
2810)     does the Tor client learn which relays are associated with which 
2811)     websites in a decentralized yet non-gamable way?"). 
2812)     </p>
2813)             
2814)     <hr>
2815)     
2816)     <a id="ExitEnclaving"></a>
2817)     <h3><a class="anchor" href="#ExitEnclaving">What is Exit Enclaving?</a></h3>
2818) 
2819)     <p>
2820)     When a machine that runs a Tor relay also runs a public service, such as 
2821)     a webserver, you can configure Tor to offer Exit Enclaving to that 
2822)     service. Running an Exit Enclave for all of your services you wish to 
2823)     be accessible via Tor provides your users the assurance that they will 
2824)     exit through your server, rather than exiting from a randomly selected 
2825)     exit node that could be watched. Normally, a tor circuit would end at 
2826)     an exit node and then that node would make a connection to your service. 
2827)     Anyone watching that exit node could see the connection to your service, 
2828)     and be able to snoop on the contents if it were an unencrypted 
2829)     connection. If you run an Exit Enclave for your service, then the exit 
2830)     from the Tor network happens on the machine that runs your service, 
2831)     rather than on an untrusted random node. This works when Tor clients 
2832)     wishing to connect to this public service extend their their circuit 
2833)     to exit from the Tor relay running on that same host. For example, if 
2834)     the server at 1.2.3.4 runs a web server on port 80 and also acts as a 
2835)     Tor relay configured for Exit Enclaving, then Tor clients wishing to 
2836)     connect to the webserver will extend their circuit a fourth hop to exit 
2837)     to port 80 on the Tor relay running on 1.2.3.4. 
2838)     </p>
2839)     <p>
2840)     Exit Enclaving is disabled by default to prevent attackers from 
2841)     exploiting trust relationships with locally bound services. For 
2842)     example, often 127.0.0.1 will run services that are not designed to 
2843)     be shared with the entire world. Sometimes these services will also 
2844)     be bound to the public IP address, but will only allow connections if 
2845)     the source address is something trusted, such as 127.0.0.1. 
2846)     </p>
2847)     <p>
2848)     As a result of possible trust issues, relay operators must configure 
2849)     their exit policy to allow connections to themselves, but they should 
2850)     do so only when they are certain that this is a feature that they would 
2851)     like. Once certain, turning off the ExitPolicyRejectPrivate option will 
2852)     enable Exit Enclaving. An example configuration would be as follows: 
2853)     </p>
2854)     <pre>
2855)     ExitPolicy accept 1.2.3.4:80
2856)     ExitPolicy reject 127.0.0.1/8
2857)     ExitPolicyRejectPrivate 0
2858)     </pre>
2859)     <p>
2860)     This option should be used with care as it may expose internal network 
2861)     blocks that are not meant to be accessible from the outside world or 
2862)     the Tor network. Please tailor your ExitPolicy to reflect all netblocks 
2863)     that you want to prohibit access. 
2864)     </p>
2865)     <p>
2866)     This option should be used with care as it may expose internal network 
2867)     blocks that are not meant to be accessible from the outside world or 
2868)     the Tor network. Please tailor your ExitPolicy to reflect all netblocks 
2869)     that you want to prohibit access. 
2870)     </p>
2871)     <p>
2872)     While useful, this behavior may go away in the future because it is 
2873)     imperfect. A great idea but not such a great implementation. 
2874)     </p>
2875) 
2876)     <hr>
2877)     

2878)     <a id="KeyManagement"></a>

2879)     <h3><a class="anchor" href="#KeyManagement">Tell me about all the
2880) keys Tor uses.</a></h3>

2881) 

2882)     <p>
2883)     Tor uses a variety of different keys, with three goals in mind: 1)
2884)     encryption to ensure privacy of data within the Tor network, 2)
2885)     authentication so clients know they're

2886)     talking to the relays they meant to talk to, and 3) signatures to
2887) make

2888)     sure all clients know the same set of relays.
2889)     </p>

2890) 

2891)     <p>

2892)     <b>Encryption</b>: first, all connections in Tor use TLS link
2893) encryption,

2894)     so observers can't look inside to see which circuit a given cell is

2895)     intended for. Further, the Tor client establishes an ephemeral
2896) encryption

2897)     key with each relay in the circuit; these extra layers of encryption
2898)     mean that only the exit relay can read

2899)     the cells. Both sides discard the circuit key when the circuit ends,

2900)     so logging traffic and then breaking into the relay to discover the

2901)     key won't work.

2902)     </p>

2903) 

2904)     <p>
2905)     <b>Authentication</b>:
2906)     Every Tor relay has a public decryption key called the "onion key".

2907)     Each relay rotates its onion key once a week.

2908)     When the Tor client establishes circuits, at each step it <a

2909) 
2910) href="<svnprojects>design-paper/tor-design.html#subsec:circuits">demands

2911)     that the Tor relay prove knowledge of its onion key</a>. That way
2912)     the first node in the path can't just spoof the rest of the path.

2913)     Because the Tor client chooses the path, it can make sure to get
2914)     Tor's "distributed trust" property: no single relay in the path can
2915)     know about both the client and what the client is doing.

2916)     </p>

2917) 

2918)     <p>
2919)     <b>Coordination</b>:

2920)     How do clients know what the relays are, and how do they know that
2921) they
2922)     have the right keys for them? Each relay has a long-term public
2923) signing
2924)     key called the "identity key". Each directory authority additionally
2925) has a

2926)     "directory signing key". The directory authorities <a

2927)     href="<specblob>dir-spec.txt">provide a signed list</a>

2928)     of all the known relays, and in that list are a set of certificates
2929) from
2930)     each relay (self-signed by their identity key) specifying their
2931) keys,
2932)     locations, exit policies, and so on. So unless the adversary can
2933) control

2934)     a majority of the directory authorities (as of 2012 there are 8

2935)     directory authorities), he can't trick the Tor client into using
2936)     other Tor relays.

2937)     </p>