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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 for other browsers?</a></li>

81)     <li><a href="#TBBCloseBrowser">I want to leave Tor Browser Bundle
82)     running but close the browser.</a></li>
83) 

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

85) tells

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

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

89)     <li><a href="#GmailWarning">Gmail warns me that my account may have
90)     been compromised.</a></li>

91)     <li><a href="#NeedToUseAProxy">My internet connection requires an HTTP 
92)     or SOCKS Proxy</a></li>

93)     <li><a href="#CantSetProxy">What should I do if I can't set a proxy 
94)     with my application?</a></li>
95)     <li><a href="#WarningsAboutSOCKSandDNSInformationLeaks">I keep seeing 
96)     these warnings about SOCKS and DNS information leaks. Should I 
97)     worry?</a></li>

98)     </ul>
99) 
100)     <p>Advanced Tor usage:</p>

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

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

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

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

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

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

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

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

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

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

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

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

126)     </ul>

127) 

128)     <p>Running a Tor relay:</p>
129)     <ul>

130) 
131)     <li><a href="#HowDoIDecide">How do I decide if I should run a relay?
132)     </a></li>

133)     <li><a href="#WhyIsntMyRelayBeingUsedMore">Why isn't my relay being 
134)     used more?</a></li>
135)     <li><a href="#HighCapacityConnection">How can I get Tor to fully 
136)     make use of my high capacity connection?</a></li>

137)     <li><a href="#RelayFlexible">How stable does my relay need to
138) be?</a></li>
139)     <li><a href="#ExitPolicies">I'd run a relay, but I don't want to
140) deal

141)     with abuse issues.</a></li>
142)     <li><a href="#RelayOrBridge">Should I be a normal relay or bridge
143)     relay?</a></li>

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

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

148)     <li><a href="#NTService">How do I run my Tor relay as an NT service?
149)     </a></li>
150)     <li><a href="#VirtualServer">Can I run a Tor relay from my virtual server 
151)     account?</a></li>

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

154)     <li><a href="#RelayMemory">Why is my Tor relay using so much memory?
155)     </a></li>
156)     <li><a href="#BetterAnonymity">Do I get better anonymity if I run a relay?
157)     </a></li>

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

160)     </ul>

161) 

162)     <p>Tor hidden services:</p>
163)     <ul>
164)     <li><a href="#AccessHiddenServices">How do I access hidden services?</a></li>
165)     <li><a href="#ProvideAHiddenService">How do I provide a hidden service</a></li>
166)     </ul>

167) 

168)     <p>Development</p>
169)     <ul>
170)     <li><a href="#WhoIsResponsible">Who is responsible for Tor?</a></li>
171)     <li><a href="#VersionNumbers">What do these weird version numbers 
172)     mean?</a></li>
173)     <li><a href="#PrivateTorNetwork">How do I set up my own private
174)     Tor network?</a></li>
175)     <li><a href="#UseTorWithJava">How can I make my Java program use the 
176)     Tor network?</a></li>
177)     <li><a href="#WhatIsLibevent">What is Libevent?</a></li>
178)     <li><a href="#MyNewFeature">What do I need to do to get a new feature 
179)     into Tor?</a></li>
180)     </ul>
181) 

182)     <p>Anonymity and Security:</p>
183)     <ul>

184)     <li><a href="#WhatProtectionsDoesTorProvide">What protections does Tor 
185)     provide?</a></li>
186)     <li><a href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop on 
187)     communications? Isn't that bad? </a></li>

188)     <li><a href="#AmITotallyAnonymous">So I'm totally anonymous if I use 
189)     Tor?</a></li>

190)     <li><a href="#ExitEnclaving">What is Exit Enclaving?</a></li>

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

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

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

195)     <li><a href="#CellSize">Tor uses hundreds of bytes for every IRC line. I 
196)     can't afford that!</a></li>
197)     <li><a href="#OutboundConnections">Why does netstat show these outbound 
198)     connections?</a></li>
199)     <li><a href="#PowerfulBlockers">What about powerful blocking mechanisms
200)     </a></li>
201)     <li><a href="#RemotePhysicalDeviceFingerprinting">Does Tor resist 
202)     "remote physical device fingerprinting"?</a></li>

203)     <li><a href="#VPN">What's safer, Tor or a VPN?</a></li>
204)     <li><a href="#Proxychains">Aren't 10 proxies (proxychains) better than 
205)     Tor with only 3 hops?</a></li>

206)     <li><a href="#AttacksOnOnionRouting">What attacks remain against onion 
207)     routing?</a></li>

208)     </ul>

209) 

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

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

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

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

219)     <li><a href="#ChoosePathLength">You should let people choose their path 
220)     length.</a></li>
221)     <li><a href="#SplitEachConnection">You should split each connection over 
222)     many paths.</a></li>
223)     <li><a href="#UnallocatedNetBlocks">Your default exit policy should block 
224)     unallocated net blocks too.</a></li>
225)     <li><a href="#BlockWebsites">Exit policies should be able to block 
226)     websites, not just IP addresses.</a></li>
227)     <li><a href="#BlockContent">You should change Tor to prevent users from 
228)     posting certain content.</a></li>

229)     <li><a href="#SendPadding">You should send padding so it's more secure.
230)     </a></li>
231)     <li><a href="#Steganography">You should use steganography to hide Tor 
232)     traffic.</a></li>

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

234)     </ul>

235) 

236)     <p>Abuse:</p>

237)     <ul>

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

240)     <li><a href="#RespondISP">How do I respond to my ISP about my exit
241)     relay?</a></li>

242)     <li><a href="#HelpPoliceOrLawyers">I have questions about
243)    a Tor IP address for a legal case.</a></li>

244)     </ul>

245) 

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

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

249) 

250)     <hr>

251) 

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

253) 

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

256) 

257)     <p>
258)     The name "Tor" can refer to several different components.
259)     </p>

260) 

261)     <p>

262)     The Tor software is a program you can run on your computer that
263) helps keep
264)     you safe on the Internet. Tor protects you by bouncing your
265) communications

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

267)     the world: it prevents somebody watching your Internet connection
268) from

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

270)     from learning your physical location. This set of volunteer relays
271) is
272)     called the Tor network. You can read more about how Tor works on the
273) <a

274)     href="<page about/overview>">overview page</a>.
275)     </p>

276) 

277)     <p>

278)     The Tor Project is a non-profit (charity) organization that
279) maintains

280)     and develops the Tor software.
281)     </p>

282) 

283)     <hr>

284) 

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

286)     <h3><a class="anchor" href="#Torisdifferent">How is Tor different
287) from other proxies?</a></h3>
288)     <p>
289)     A typical proxy provider sets up a server somewhere on the Internet
290) and
291) allows you to use it to relay your traffic.  This creates a simple, easy
292) to
293) maintain architecture.  The users all enter and leave through the same
294) server.
295) The provider may charge for use of the proxy, or fund their costs
296) through
297) advertisements on the server.  In the simplest configuration, you don't
298) have to
299) install anything.  You just have to point your browser at their proxy
300) server.
301) Simple proxy providers are fine solutions if you do not want protections
302) for
303) your privacy and anonymity online and you trust the provider from doing
304) bad
305) things.  Some simple proxy providers use SSL to secure your connection
306) to them.
307) This may protect you against local eavesdroppers, such as those at a
308) cafe with

309) free wifi Internet.
310)     </p>
311)     <p>

312)     Simple proxy providers also create a single point of failure.  The
313) provider
314) knows who you are and where you browse on the Internet.  They can see
315) your
316) traffic as it passes through their server.  In some cases, they can even
317) see

318) inside your

319) encrypted traffic as they relay it to your banking site or to ecommerce
320) stores.

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

322) watching your traffic, injecting their own advertisements into your
323) traffic

324) stream, and recording your personal details.

325)     </p>
326)     <p>

327)     Tor passes your traffic through at least 3 different servers before
328) sending
329) it on to the destination. Because there's a separate layer of encryption
330) for
331) each of the three relays, Tor does not modify, or even know, what you
332) are
333) sending into it.  It merely relays your traffic, completely encrypted
334) through
335) the Tor network and has it pop out somewhere else in the world,
336) completely
337) intact.  The Tor client is required because we assume you trust your
338) local
339) computer.  The Tor client manages the encryption and the path chosen
340) through
341) the network.  The relays located all over the world merely pass
342) encrypted

343) packets between themselves.</p>

344)     <p>
345)     <dl>

346)     <dt>Doesn't the first server see who I am?</dt><dd>Possibly. A bad
347) first of
348) three servers can see encrypted Tor traffic coming from your computer.
349) It
350) still doesn't know who you are and what you are doing over Tor.  It
351) merely sees
352) "This IP address is using Tor".  Tor is not illegal anywhere in the
353) world, so
354) using Tor by itself is fine.  You are still protected from this node
355) figuring

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

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

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

362) e-commerce website, or encrypted mail connections, etc, it will only
363) know the
364) destination.  It won't be able to see the data inside the traffic
365) stream.  You

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

368)     </dl>
369)     </p>

370) 

371)     <hr>

372) 

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

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

376) 

377)     <p>

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

382)     </p>
383)     <p>
384)     There are plenty of other programs you can use with Tor,
385)     but we haven't researched the application-level anonymity

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

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

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

389)     specific applications</a>.

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

392) 

393)     <hr>

394) 

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

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

398) 

399)     <p>
400)     Because Tor is the onion routing network. When we were starting the
401)     new next-generation design and implementation of onion routing in
402)     2001-2002, we would tell people we were working on onion routing,
403)     and they would say "Neat. Which one?" Even if onion routing has
404)     become a standard household term, Tor was born out of the actual <a
405)     href="http://www.onion-router.net/">onion routing project</a> run by
406)     the Naval Research Lab.
407)     </p>

408) 

409)     <p>
410)     (It's also got a fine translation from German and Turkish.)
411)     </p>

412) 

413)     <p>

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

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

417)     spot people who haven't read any of our website (and have instead
418) learned
419)     everything they know about Tor from news articles) by the fact that
420) they

421)     spell it wrong.
422)     </p>

423) 

424)     <hr>

425) 

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

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

429) 

430)     <p>

431)     There is absolutely no backdoor in Tor. Nobody has asked us to put
432) one
433)     in, and we know some smart lawyers who say that it's unlikely that
434) anybody

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

438) 

439)     <p>
440)     We think that putting a backdoor in Tor would be tremendously

441)     irresponsible to our users, and a bad precedent for security
442) software

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

447) 

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

451)     computers, or something like that. Tor is open source, and you
452) should
453)     always check the source (or at least the diffs since the last
454) release)

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

461) 

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

464)     anonymity. We periodically find and fix anonymity-related bugs, so
465) make

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

468) 

469)     <hr>

470) 

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

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

474) 

475)     <p>
476)     Yes.
477)     </p>

478) 

479)     <p>

480)     The Tor software is <a href="https://www.fsf.org/">free
481) software</a>. This
482)     means we give you the rights to redistribute the Tor software,
483) either
484)     modified or unmodified, either for a fee or gratis. You don't have
485) to

486)     ask us for specific permission.
487)     </p>

488) 

489)     <p>

490)     However, if you want to redistribute the Tor software you must
491) follow our

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

493)     Essentially this means that you need to include our LICENSE file
494) along

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

497) 

498)     <p>

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

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

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

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

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

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

514)     </p>

515) 

516)     <p>

517)     Also, you should make sure not to confuse your readers about what
518) Tor is,
519)     who makes it, and what properties it provides (and doesn't provide).
520) See
521)     our <a href="<page docs/trademark-faq>">trademark FAQ</a> for
522) details.

523)     </p>

524) 

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

528)     changes. So if you distribute a particular version of the Tor
529) software, it
530)     may not be supported — or even work — six months later.
531) This

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

534) 

535)     <hr>

536) 

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

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

540) 

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

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

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

546)     <li>Read through the <a

547) 
548) href="https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk">
549) tor-talk

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

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

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

554)     <li>Send an email to <a

555) 
556) href="mailto:help@rt.torproject.org">help@rt.torproject.org</a>.</li>
557)     <li>If all else fails, try <a href="<page about/contact>">contacting
558) us</a> directly.</li>

559)     </ol>

560) 

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

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

564) 

565)     <hr>

566) 

567)     <a id="Forum"></a>
568)     <h3><a class="anchor" href="#Forum">Is there a Tor forum?</a></h3>
569) 

570)     <p>We have a <a href="https://tor.stackexchange.com/">StackExchange 

571)     page</a> that is currently in public beta.

572)     </p>
573) 
574)     <hr>
575) 

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

578) 

579)     <p>
580)     There are many reasons why the Tor network is currently slow.
581)     </p>

582) 

583)     <p>

584)     Before we answer, though, you should realize that Tor is never going
585) to
586)     be blazing fast. Your traffic is bouncing through volunteers'
587) computers
588)     in various parts of the world, and some bottlenecks and network
589) latency

590)     will always be present. You shouldn't expect to see university-style
591)     bandwidth through Tor.
592)     </p>

593) 

594)     <p>

595)     But that doesn't mean that it can't be improved. The current Tor
596) network
597)     is quite small compared to the number of people trying to use it,
598) and
599)     many of these users don't understand or care that Tor can't
600) currently

601)     handle file-sharing traffic load.
602)     </p>

603) 

604)     <p>
605)     For the much more in-depth answer, see <a

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

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

609)     to go with it.
610)     </p>

611) 

612)     <p>
613)     What can you do to help?
614)     </p>

615) 

616)     <ul>

617) 

618)     <li>

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

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

625) 

626)     <li>

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

629)     especially need people to help make it easier to configure your Tor
630)     as a relay. Also, we need help with clear simple documentation to
631)     walk people through setting it up.
632)     </li>

633) 

634)     <li>

635)     There are some bottlenecks in the current Tor network. Help us
636) design
637)     experiments to track down and demonstrate where the problems are,
638) and

639)     then we can focus better on fixing them.
640)     </li>

641) 

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

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

648)     get to spend more time on it.
649)     </li>

650) 

651)     <li>

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

656)     getinvolved/volunteer>">look at our volunteer page</a>.
657)     </li>

658) 

659)     <li>

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

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

663)     competition's websites discreetly, or to connect back to the home
664) servers
665)     when on the road without revealing affiliations? If your
666) organization has
667)     an interest in keeping the Tor network working, please contact them
668) about
669)     supporting Tor. Without sponsors, Tor is going to become even
670) slower.

671)     </li>

672) 

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

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

677)     cause</a>. It adds up!
678)     </li>

679) 

680)     </ul>

681) 

682)     <hr>

683) 

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

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

687) 
688)     <p>

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

695)     </p>
696) 
697)     <hr>
698) 

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

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

702) 

703)     <p>

704)     The Tor network's <a

705) 
706) href="https://metrics.torproject.org/network.html#networksize">several

707)     thousand</a> relays push <a
708)     href="https://metrics.torproject.org/network.html#bandwidth">over
709)     1GB per second on average</a>. We have <a

710) 
711) href="https://metrics.torproject.org/users.html#direct-users">several

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

714)     </p>

715) 

716)     <p>

717)     There are six main development/maintenance pushes that need
718) attention:

719)     </p>

720) 

721)     <ul>

722) 

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

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

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

730) 

731)     <li>

732)     User support: With this many users, a lot of people are asking
733) questions
734)     all the time, offering to help out with things, and so on. We need
735) good
736)     clean docs, and we need to spend some effort coordinating
737) volunteers.

738)     </li>

739) 

740)     <li>

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

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

744)     reminders to upgrade, and so on. The network itself is a commons,
745) and
746)     somebody needs to spend some energy making sure the relay operators
747) stay
748)     happy. We also need to work on stability on some platforms —
749) e.g.,

750)     Tor relays have problems on Win XP currently.

751)     </li>

752) 

753)     <li>

754)     Usability: Beyond documentation, we also need to work on usability
755) of the
756)     software itself. This includes installers, clean GUIs, easy
757) configuration
758)     to interface with other applications, and generally automating all
759) of
760)     the difficult and confusing steps inside Tor. We've got a start on
761) this
762)     with the <a href="<page projects/vidalia>">Vidalia GUI</a>, but much
763) more work

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

766) 

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

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

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

774) 

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

780)     critical <a href="<page getinvolved/volunteer>#Research">Tor
781) research questions</a>
782)     that will help us figure out how to make Tor secure against the
783) variety of
784)     attacks out there. Of course, there are more research questions
785) waiting

786)     behind these.
787)     </li>

788) 

789)     </ul>

790) 

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

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

795)     can keep up</a>.

796)     Now would be an excellent time to add a few more developers to the
797) effort

798)     so we can continue to grow the network.
799)     </p>

800) 

801)     <p>
802)     We are also excited about tackling related problems, such as
803)     censorship-resistance.
804)     </p>

805) 

806)     <p>

807)     We are proud to have <a href="<page about/sponsors>">sponsorship and
808) support</a>
809)     from the Omidyar Network, the International Broadcasting Bureau,
810) Bell
811)     Security Solutions, the Electronic Frontier Foundation, several
812) government

813)     agencies and research groups, and hundreds of private contributors.
814)     </p>

815) 

816)     <p>

817)     However, this support is not enough to keep Tor abreast of changes
818) in the
819)     Internet privacy landscape. Please <a href="<page
820) donate/donate>">donate</a>
821)     to the project, or <a href="<page about/contact>">contact</a> our
822) executive

823)     director for information on making grants or major donations.
824)     </p>

825) 

826)     <hr>
827) 

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

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

831) 
832)     <p>

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

837)     </p>
838)     <p>

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

846)     </p>
847)     <p>

848)     If you really need to connect to only a small set of ports, see the FAQ 

849)     entry on <a href="#FirewallPorts">firewalled ports</a>.

850)     </p>
851)     <p>

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

857)     </p>
858)     
859)     <hr>
860)     
861)     <a id="IsItWorking"></a>

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

864) 
865)     <p>

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

869)     </p>
870)     <p>

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

877)     </p>
878)     <p>

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

882)     </p>
883)     <p>

884)     If you are behind a NAT or firewall, though, your IP address will be 
885)     within the range of 10.XXX.XXX.XXX, 192.168.XXX.XXX, or 172.16.XXX.XXX - 
886)     172.31.XXX.XXX, which is not your public IP address. In this case, you 
887)     should check your IP address with one of the sites above without using 
888)     Tor, and then check again using Tor to see whether your IP address has 
889)     changed. 

890)     </p>
891)     
892)     <hr>
893)     
894)     <a id="FTP"></a>
895)     <h3><a class="anchor" href="#FTP">How do I use my browser for ftp with Tor?
896)     </a></h3>
897) 

898)     <p>
899)     Use the Tor Browser Bundle. If you want a separate application for an 
900)     ftp client, we've heard good things about  FileZilla for Windows. You can 
901)     configure it to point to Tor as a "socks4a" proxy on "localhost" port 
902)     "9050". 
903)     </p>

904)     <hr>
905)     

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

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

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

909) 

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

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

913)     <hr>

914) 

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

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

918)     <p>

919)     <pre>

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

921)     The serial number is:

922) 06:DE:97:E5:1D:C3:9D:C2:64:8D:AC:72:DD:41:01:FC
923)     The SHA-1 fingerprint is: 1f9d306e8bfccfcb03981a71a27a9f5d1e0876ce

924)     The SHA-256 fingerprint is:

925) 3613d2b22a750094760c41ad19db52a4f05bdea80172e2578761ad967f7ed9aa

926) 

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

928)     The serial number is: 00:EF:A3
929)     The SHA-1 fingerprint is: 50af43db8438e67f305a3257d8ef198e8c42f13f

930)     </pre>

931)     </p>
932)     <hr>
933) 

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

935)     <h3><a class="anchor" href="#HowUninstallTor">How do I uninstall
936) Tor?</a></h3>
937) 
938)     <p>
939)     Tor Browser does not install itself in the classic sense of
940) applications. You just simply delete the folder or directory named "Tor
941) Browser" and it is removed from your system.
942)     </p>

943) 

944)     <p>

945)     If this is not related to Tor Browser, uninstallation depends
946) entirely on how you installed it and which operating system you
947)     have. If you installed a package, then hopefully your package has a
948) way to

949)     uninstall itself. The Windows packages include uninstallers. 

950)     </p>

951) 

952)     <p>
953)     For Mac OS X, follow the <a
954)     href="<page docs/tor-doc-osx>#uninstall">uninstall directions</a>.
955)     </p>

956) 

957)     <p>

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

962)     be pretty easy to notice things there.
963)     </p>

964) 

965)     <hr>

966) 

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

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

970) 

971)     <p>

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

974)     exactly the one that we intended you to get.
975)     </p>

976) 

977)     <p>
978)     Please read the <a

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

981)     </p>

982) 

983) <hr>
984) 
985) <a id="GetTor"></a>
986) <h3><a class="anchor" href="#GetTor">Your website is blocked in my
987) country. How do I download Tor?</a></h3>
988) 
989) <p>
990) Some government or corporate firewalls censor connections to Tor's
991) website. In those cases, you have three options. First, get it from

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

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

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

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

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

1000) in the body of the email, it will reply with instructions. Note that
1001) only a few webmail providers are supported, since they need to be able
1002) to receive very large attachments.
1003) </p>
1004) 
1005) <p>

1006) Be sure to <a href="<page docs/verifying-signatures>">verify the
1007) signature</a>

1008) of any package you download, especially when you get it from somewhere
1009) other than our official HTTPS website.

1010) </p>
1011) 
1012) <hr>

1013) 

1014)     <a id="CompileTorWindows"></a>

1015)     <h3><a class="anchor" href="#CompileTorWindows">How do I compile Tor
1016) under Windows?</a></h3>

1017) 

1018)     <p>

1019)     Try following the steps at <a
1020) href="<gitblob>doc/tor-win32-mingw-creation.txt">

1021)     tor-win32-mingw-creation.txt</a>.
1022)     </p>

1023) 

1024)     <p>
1025)     (Note that you don't need to compile Tor yourself in order to use

1026)     it. Most people just use the packages available on the <a
1027) href="<page

1028)     download/download>">download page</a>.)
1029)     </p>

1030) 

1031)     <hr>

1032) 

1033)     <a id="VirusFalsePositives"></a>

1034)     <h3><a class="anchor" href="#VirusFalsePositives">Why does my Tor
1035) executable appear to have a virus or spyware?</a></h3>

1036) 

1037)     <p>

1038)     Sometimes, overzealous Windows virus and spyware detectors trigger
1039) on some
1040)     parts of the Tor Windows binary. Our best guess is that these are
1041) false
1042)     positives — after all, the anti-virus and anti-spyware
1043) business is just a
1044)     guessing game anyway. You should contact your vendor and explain
1045) that you have
1046)     a program that seems to be triggering false positives. Or pick a
1047) better vendor.

1048)     </p>

1049) 

1050)     <p>
1051)     In the meantime, we encourage you to not just take our word for

1052)     it. Our job is to provide the source; if you're concerned, please do
1053) <a

1054)     href="#CompileTorWindows">recompile it yourself</a>.
1055)     </p>

1056) 

1057)     <hr>

1058) 

1059)     <a id="LiveCD"></a>

1060)     <h3><a class="anchor" href="#LiveCD">Is there a LiveCD or other
1061) bundle that includes Tor?</a></h3>

1062) 

1063)     <p>

1064)     Yes.  Use <a href="https://tails.boum.org/">The Amnesic Incognito

1065)     Live System</a> or <a href="<page projects/torbrowser>">the Tor
1066) Browser

1067)     Bundle</a>.

1068)     </p>

1069) 
1070) <hr>
1071) 

1072) <a id="TBBFlash"></a>

1073) <h3><a class="anchor" href="#TBBFlash">Why can't I view videos on
1074) YouTube

1075) and other Flash-based sites?</a></h3>

1076) 
1077) <p>

1078) YouTube and similar sites require third party browser plugins such as Flash.
1079) Plugins operate independently from Firefox and can perform
1080) activity on your computer that ruins your anonymity. This includes
1081) but is not limited to: <a href="http://decloak.net">completely disregarding
1082) proxy settings</a>, querying your <a

1083) href="http://forums.sun.com/thread.jspa?threadID=5162138&messageID=9618376">
1084) local IP address</a>, and <a

1085) href="http://epic.org/privacy/cookies/flash.html">storing their own
1086) cookies</a>. It is possible to use a LiveCD solution such as

1087) or <a href="https://tails.boum.org/">The Amnesic Incognito Live System</a> 
1088) that creates a secure, transparent proxy to protect you from proxy bypass, 
1089) however issues with local IP address discovery and Flash cookies still remain. 
1090) </p>

1091) 
1092) <p>

1093) <a href="https://www.youtube.com/html5">YouTube offers experimental HTML5 video
1094) support</a> for many of their videos. You can use their Advanced Search to

1095) find HTML5 videos.
1096) </p>
1097) 

1098) <hr>
1099) 

1100) <a id="Ubuntu"></a>
1101) <h3><a class="anchor" href="#Ubuntu">
1102) I'm using Ubuntu and I can't start Tor Browser</a></h3>
1103) <p>

1104) Ubuntu prevents its users from executing shell scripts by clicking them, 
1105) even when the file permissions are set correctly. For now you need to 
1106) start the Tor Browser from the command line by running </p>

1107) <pre>
1108) ./start-tor-browser
1109) </pre>
1110) <p>
1111) from inside the Tor Browser directory.
1112) </p>
1113) 
1114) <hr>
1115) 

1116) <a id="TBBSocksPort"></a>

1117) <h3><a class="anchor" href="#TBBSocksPort">

1118) I want to run another application through the Tor launched by Tor

1119) Browser Bundle.</a></h3>

1120) 
1121) <p>

1122) Typically Tor listens for Socks connections on port 9050. TBB listens

1123) on port 9150.

1124) The goal is to avoid conflicting with a "system" Tor install,

1125) so you can run a system Tor and TBB at the same time. We're <a
1126) href="https://trac.torproject.org/projects/tor/ticket/3948">working on
1127) a feature</a> where Tor will try the usual ports first and then back

1128) off to a random choice if they're already in use.

1129) </p>
1130) 
1131) <hr>
1132) 
1133) <a id="TBBPolipo"></a>
1134) <h3><a class="anchor" href="#TBBPolipo">I need an HTTP proxy. Where did
1135) Polipo go?</a></h3>
1136) 
1137) <p>
1138) In the past, Tor bundles included an HTTP proxy like Privoxy or Polipo,
1139) solely to work around a bug in Firefox that was finally fixed in Firefox
1140) 6. Now you don't need a separate HTTP proxy to use Tor, and in fact
1141) leaving it out makes you safer because Torbutton has better control over
1142) Firefox's interaction with websites.
1143) </p>
1144) 
1145) <p>
1146) If you are trying to use some external application with Tor, step zero

1147) should be to <a href="<page download/download>#warning">reread the set

1148) of warnings</a> for ways you can screw up. Step one should be to try

1149) to use a Socks proxy rather than an http proxy — Tor runs a Socks

1150) proxy on port 9050 on Windows, or <a href="#TBBSocksPort">see above</a>
1151) for OSX and Linux.
1152) </p>
1153) 
1154) <p>

1155) If that fails, feel free to install <a

1156) href="http://www.privoxy.org/">privoxy</a>.
1157) However, please realize that this approach is not recommended for novice
1158) users. Privoxy has an <a
1159) href="http://www.privoxy.org/faq/misc.html#TOR">example
1160) configuration</a> of Tor and Privoxy.

1161) </p>
1162) 
1163) <hr>
1164) 

1165) <a id="TBBOtherExtensions"></a>
1166) <h3><a class="anchor" href="#TBBOtherExtensions">Can I install other
1167) Firefox extensions?</a></h3>
1168) 
1169) <p>

1170) The Tor Browser is free software, so there is nothing preventing you from 
1171) modifying it any way you like. However, we do not recommend installing any 
1172) additional Firefox add-ons with the Tor Browser Bundle. Add-ons can break 
1173) your anonymity in a number of ways, including browser fingerprinting and 
1174) bypassing proxy settings.

1175) </p>

1176) <p>

1177) Some people have suggested we include ad-blocking software or 
1178) anti-tracking software with the Tor Browser Bundle. Right now, we do not 
1179) think that's such a good idea. The Tor Browser Bundle aims to provide 
1180) sufficient privacy that additional add-ons to stop ads and trackers are 
1181) not necessary. Using add-ons like these may cause some sites to break, which 
1182) <a href="https://www.torproject.org/projects/torbrowser/design/#philosophy">
1183) we don't want to do</a>. Additionally, maintaining a list of "bad" sites that 
1184) should be black-listed provides another opportunity to uniquely fingerprint 
1185) users. 

1186) </p>

1187) 

1188) <hr>
1189) 

1190) <a id="TBBJavaScriptEnabled"></a>

1191) <a id="TBBCanIBlockJS"></a>

1192) <h3><a class="anchor" href="#TBBJavaScriptEnabled">Why is NoScript
1193) configured to allow JavaScript by default in the Tor Browser Bundle?
1194) Isn't that unsafe?</a></h3>

1195) 
1196) <p>
1197) We configure NoScript to allow JavaScript by default in the Tor
1198) Browser Bundle because many websites will not work with JavaScript
1199) disabled.  Most users would give up on Tor entirely if a website
1200) they want to use requires JavaScript, because they would not know
1201) how to allow a website to use JavaScript (or that enabling
1202) JavaScript might make a website work).
1203) </p>
1204) 

1205) <p>
1206) There's a tradeoff here. On the one hand, we should leave
1207) JavaScript enabled by default so websites work the way
1208) users expect. On the other hand, we should disable JavaScript
1209) by default to better protect against browser vulnerabilities (<a

1210) href="https://blog.torproject.org/blog/tor-security-advisory-old-tor-browser-bundles-vulnerable">
1211) not just a theoretical concern!</a>). But there's a third issue: websites

1212) can easily determine whether you have allowed JavaScript for them,
1213) and if you disable JavaScript by default but then allow a few websites
1214) to run scripts (the way most people use NoScript), then your choice of
1215) whitelisted websites acts as a sort of cookie that makes you recognizable
1216) (and distinguishable), thus harming your anonymity.
1217) </p>

1218) 
1219) <p>

1220) Ultimately, we want the default Tor bundles to use
1221) a combination of firewalls (like the iptables rules
1222) in <a href="https://tails.boum.org/">Tails</a>) and <a
1223) href="https://trac.torproject.org/projects/tor/ticket/7680">sandboxes</a>
1224) to make JavaScript not so scary. In
1225) the shorter term, TBB 3.0 will hopefully <a
1226) href="https://trac.torproject.org/projects/tor/ticket/9387">allow users
1227) to choose their JavaScript settings more easily</a> &mdash; but the
1228) partitioning concern will remain.

1229) </p>
1230) 
1231) <p>

1232) Until we get there, feel free to leave JavaScript on or off depending
1233) on your security, anonymity, and usability priorities.

1234) </p>
1235) 
1236) <hr>
1237) 

1238) <a id="TBBOtherBrowser"></a>
1239) <h3><a class="anchor" href="#TBBOtherBrowser">I want to use
1240) Chrome/IE/Opera/etc with Tor.</a></h3>
1241) 
1242) <p>
1243) Unfortunately, Torbutton only works with Firefox right now, and without
1244) <a href="https://www.torproject.org/torbutton/en/design/">Torbutton's
1245) extensive privacy fixes</a> there are many ways for websites or other

1246) attackers to recognize you, track you back to your IP address, and so
1247) on.

1248) In short, using any browser besides Tor Browser Bundle with Tor is a
1249) really bad idea.
1250) </p>
1251) 
1252) <p>
1253) We're working with the Chrome team to <a

1254) href="https://blog.torproject.org/blog/google-chrome-incognito-mode-tor-
1255) and-fingerprinting">fix
1256) some bugs and missing APIs in Chrome</a> so it will be possible to write
1257) a
1258) Torbutton for Chrome. No support for any other browser is on the
1259) horizon.

1260) </p>
1261) 
1262) <hr>
1263) 

1264) <a id="TorbuttonOtherBrowser"></a>

1265) <h3><a class="anchor" href="TorbuttonOtherBrowser">
1266) Will ​Torbutton be available for other browsers?</a></h3>

1267) 
1268) <p>

1269)  We don't support IE, Opera or Safari and never plan to. There are too many ways that your privacy can go wrong with those browsers, and because of their closed design it is really hard for us to do anything to change these privacy problems.

1270) </p>
1271) <p>

1272) We are working with the Chrome people to modify Chrome's internals so that we can eventually support it. But for now, Firefox is the only safe choice. 

1273) </p>
1274) 

1275) <hr>

1276) 

1277) <a id="TBBCloseBrowser"></a>

1278) <h3><a class="anchor" href="#TBBCloseBrowser">I want to leave Tor
1279) Browser

1280) Bundle running but close the browser.</a></h3>
1281) 
1282) <p>
1283) We're working on a way to make this possible on all platforms. Please
1284) be patient.
1285) </p>
1286) 
1287) <hr>
1288) 

1289) <a id="GoogleCAPTCHA"></a>
1290) <h3><a class="anchor" href="#GoogleCAPTCHA">Google makes me solve a
1291) CAPTCHA or tells me I have spyware installed.</a></h3>

1292) 
1293) <p>
1294) This is a known and intermittent problem; it does not mean that Google
1295) considers Tor to be spyware.
1296) </p>
1297) 
1298) <p>

1299) When you use Tor, you are sending queries through exit relays that are
1300) also

1301) shared by thousands of other users. Tor users typically see this message

1302) when many Tor users are querying Google in a short period of time.
1303) Google

1304) interprets the high volume of traffic from a single IP address (the exit
1305) relay you happened to pick) as somebody trying to "crawl" their website,
1306) so it slows down traffic from that IP address for a short time.
1307) </p>
1308) <p>
1309) An alternate explanation is that Google tries to detect certain
1310) kinds of spyware or viruses that send distinctive queries to Google
1311) Search. It notes the IP addresses from which those queries are received
1312) (not realizing that they are Tor exit relays), and tries to warn any
1313) connections coming from those IP addresses that recent queries indicate
1314) an infection.
1315) </p>
1316) 
1317) <p>

1318) To our knowledge, Google is not doing anything intentionally
1319) specifically

1320) to deter or block Tor use. The error message about an infected machine
1321) should clear up again after a short time.
1322) </p>
1323) 
1324) <p>
1325) Torbutton 1.2.5 (released in mid 2010) detects Google captchas and can
1326) automatically redirect you to a more Tor-friendly search engine such as

1327) DuckDuckGo, ixquick, or Bing.

1328) </p>
1329) 
1330) <hr />
1331) 

1332) <a id="ForeignLanguages"></a>
1333) <h3><a class="anchor" href="#ForeignLanguages">
1334) Why does Google show up in foreign languages?</a></h3>
1335) 
1336) <p>

1337)  Google uses "geolocation" to determine where in the world you are, so it 
1338)  can give you a personalized experience. This includes using the language 
1339)  it thinks you prefer, and it also includes giving you different results 
1340)  on your queries.

1341) </p>
1342) <p>

1343) If you really want to see Google in English you can click the link that 
1344) provides that. But we consider this a feature with Tor, not a bug --- the 
1345) Internet is not flat, and it in fact does look different depending on 
1346) where you are. This feature reminds people of this fact. The easy way to 
1347) avoid this "feature" is to use 
1348) <a href="https://google.com/ncr">https://google.com/ncr</a>.

1349) </p>
1350) <p>

1351) Note that Google search URLs take name/value pairs as arguments and one 
1352) of those names is "hl". If you set "hl" to "en" then Google will return 
1353) search results in English regardless of what Google server you have been 
1354) sent to. On a query this looks like: 
1355) </p>
1356) <pre>https://encrypted.google.com/search?q=online%20anonymity&hl=en

1357) </pre>

1358) <p>

1359) Another method is to simply use your country code for accessing Google. 
1360) This can be google.be, google.de, google.us and so on. 

1361) </p>
1362) <hr />

1363) <a id="GmailWarning"></a>

1364) <h3><a class="anchor" href="#GmailWarning">Gmail warns me that my

1365) account may have been compromised.</a></h3>

1366) 
1367) <p>
1368) Sometimes, after you've used Gmail over Tor, Google presents a
1369) pop-up notification that your account may have been compromised.
1370) The notification window lists a series of IP addresses and locations
1371) throughout the world recently used to access your account.
1372) </p>
1373) 
1374) <p>
1375) In general this is a false alarm: Google saw a bunch of logins from

1376) different places, as a result of running the service via Tor, and
1377) decided

1378) it was a good idea to confirm the account was being accessed by it's
1379) rightful owner.
1380) </p>
1381) 
1382) <p>
1383) Even though this may be a biproduct of using the service via tor,
1384) that doesn't mean you can entirely ignore the warning. It is
1385) <i>probably</i> a false positive, but it might not be since it is
1386) possible for someone to hijack your Google cookie.
1387) </p>
1388) 
1389) <p>
1390) Cookie hijacking is possible by either physical access to your computer
1391) or by watching your network traffic.  In theory only physical access
1392) should compromise your system because Gmail and similar services
1393) should only send the cookie over an SSL link. In practice, alas, it's <a

1394) href="http://fscked.org/blog/fully-automated-active-https-cookie-
1395) hijacking">

1396) way more complex than that</a>.
1397) </p>
1398) 
1399) <p>
1400) And if somebody <i>did</i> steal your google cookie, they might end
1401) up logging in from unusual places (though of course they also might
1402) not). So the summary is that since you're using Tor, this security
1403) measure that Google uses isn't so useful for you, because it's full of
1404) false positives. You'll have to use other approaches, like seeing if
1405) anything looks weird on the account, or looking at the timestamps for
1406) recent logins and wondering if you actually logged in at those times.
1407) </p>
1408) 
1409) <hr>
1410) 

1411) <a id="NeedToUseAProxy"></a>

1412) <h3><a class="anchor" href="#NeedToUseAProxy">My internet connection 
1413) requires an HTTP or SOCKS Proxy</a></h3>

1414) 
1415) <p>
1416) You can set Proxy IP address, port, and authentication information in 
1417) Tor Browser's Network Settings. If you're using Tor another way, check 
1418) out the HTTPProxy and HTTPSProxy config options in the <a 
1419) href="https://www.torproject.org/docs/tor-manual.html.en">man page</a>, 
1420) and modify your torrc file accordingly. You will need an HTTP proxy for 
1421) doing GET requests to fetch the Tor directory, and you will need an 
1422) HTTPS proxy for doing CONNECT requests to get to Tor relays. (It's fine 
1423) if they're the same proxy.) Tor also recognizes the torrc options 
1424) Socks4Proxy and Socks5Proxy. 
1425) </p>
1426) <p>

1427) Also read up on the HTTPProxyAuthenticator and HTTPSProxyAuthenticator 
1428) options if your proxy requires auth. We only support basic auth currently, 
1429) but if you need NTLM authentication, you may find <a 

1430) href="http://archives.seul.org/or/talk/Jun-2005/msg00223.html">this post 
1431) in the archives</a> useful. 
1432) </p>
1433) <p>
1434) If your proxies only allow you to connect to certain ports, look at the 
1435) entry on <a href="#FirewallPorts">Firewalled clients</a> for how 
1436) to restrict what ports your Tor will try to access. 
1437) </p>
1438) 
1439) <hr>
1440) 

1441) <a id="CantSetProxy"></a>
1442) <h3><a class="anchor" href="#CantSetProxy">What should I do if I can't 
1443) set a proxy with my application?</a></h3>
1444) 
1445) <p>
1446) On Unix, we recommend you give <a 
1447) href="https://github.com/dgoulet/torsocks/">torsocks</a> a try. 
1448) Alternative proxifying tools like <a 
1449) href="http://www.dest-unreach.org/socat/">socat</a> and <a 
1450) href="http://proxychains.sourceforge.net/">proxychains</a> are also 
1451) available.</p>
1452) <p> 
1453) The Windows way to force applications through Tor is less clear. <a 
1454) href="http://freecap.ru/eng/">Some</a> <a 
1455) href="http://www.freehaven.net/~aphex/torcap/">tools</a> have been <a 
1456) href="http://www.crowdstrike.com/community-tools/index.html#tool-79">proposed
1457) </a>, but we'd also like to see further testing done here. 
1458) </p>
1459) 
1460) <hr>
1461) 
1462) <a id="WarningsAboutSOCKSandDNSInformationLeaks"></a>
1463) <h3><a class="anchor" href="#WarningsAboutSOCKSandDNSInformationLeaks">I 
1464) keep seeing these warnings about SOCKS and DNS information leaks. 
1465) Should I worry?</a></h3>
1466) <p>
1467) The warning is: 
1468) </p>
1469) <p>
1470) Your application (using socks5 on port %d) is giving Tor only an IP address. Applications that do DNS resolves themselves may leak information. Consider using Socks4A (e.g. via Polipo or socat) instead. 
1471) </p>
1472) <p>
1473) If you are running Tor to get anonymity, and you are worried about an attacker who is even slightly clever, then yes, you should worry. Here's why. 
1474) </p>
1475) <p>
1476) <b>The Problem.</b> When your applications connect to servers on the Internet, they need to resolve hostnames that you can read (like www.torproject.org) into IP addresses that the Internet can use (like 209.237.230.66). To do this, your application sends a request to a DNS server, telling it the hostname it wants to resolve. The DNS server replies by telling your application the IP address. 
1477) </p>
1478) <p>
1479) Clearly, this is a bad idea if you plan to connect to the remote host anonymously: when your application sends the request to the DNS server, the DNS server (and anybody else who might be watching) can see what hostname you are asking for. Even if your application then uses Tor to connect to the IP anonymously, it will be pretty obvious that the user making the anonymous connection is probably the same person who made the DNS request. 
1480) </p>
1481) <p>
1482) <b>Where SOCKS comes in.</b> Your application uses the SOCKS protocol to connect to your local Tor client. There are 3 versions of SOCKS you are likely to run into: SOCKS 4 (which only uses IP addresses), SOCKS 5 (which usually uses IP addresses in practice), and SOCKS 4a (which uses hostnames). 
1483) </p>
1484) <p>
1485) When your application uses SOCKS 4 or SOCKS 5 to give Tor an IP address, Tor guesses that it 'probably' got the IP address non-anonymously from a DNS server. That's why it gives you a warning message: you probably aren't as anonymous as you think. 
1486) </p>
1487) <p>
1488) <b>So what can I do?</b> We describe a few solutions below. 
1489) </p>
1490) <ul>
1491) <li>If your application speaks SOCKS 4a, use it. </li>
1492) <li>If you only need one or two hosts, or you are good at programming, you may be able to get a socks-based port-forwarder like socat to work for you; see <a href="https://trac.torproject.org/projects/tor/wiki/doc/TorifyHOWTO">the Torify HOWTO</a> for examples. </li>
1493) <li>Tor ships with a program called tor-resolve that can use the Tor network to look up hostnames remotely; if you resolve hostnames to IPs with tor-resolve, then pass the IPs to your applications, you'll be fine. (Tor will still give the warning, but now you know what it means.) </li>
1494) <!-- I'm not sure if this project is still maintained or not
1495) 
1496) <li>You can use TorDNS as a local DNS server to rectify the DNS leakage. See the Torify HOWTO for info on how to run particular applications anonymously. </li>
1497) !-->
1498) </ul>
1499) <p>
1500)  If you think that you applied one of the solutions properly but still experience DNS leaks please verify there is no third-party application using DNS independently of Tor. Please see <a href="#AmITotallyAnonymous">the FAQ entry on whether you're really absolutely anonymous using Tor</a> for some examples. 
1501) </p>
1502) 
1503) <hr>
1504) 

1505) <a id="torrc"></a>

1506) <h3><a class="anchor" href="#torrc">I'm supposed to "edit my torrc".
1507) What does that mean?</a></h3>

1508) 
1509) <p>
1510) Tor installs a text file called torrc that contains configuration
1511) instructions for how your Tor program should behave. The default

1512) configuration should work fine for most Tor users. 

1513) </p>

1514) <p>

1515) If you installed Tor Browser Bundle, look for

1516) <code>Data/Tor/torrc</code> inside your Tor Browser Bundle directory. 
1517) </p>
1518) <p>
1519) Core tor puts the torrc file in <code>/usr/local/etc/tor/torrc</code> if you compiled tor from source, and <code>/etc/tor/torrc</code> or <code>/etc/torrc</code> if you installed a pre-built package.</p>

1520) 
1521) <p>

1522) Once you've changed your torrc, you will need to restart tor for the
1523) changes to take effect. (For advanced users, note that

1524) you actually only need to send Tor a HUP signal, not actually restart
1525) it.)

1526) </p>
1527) 
1528) <p>
1529) For other configuration options you can use, look at the <a href="<page
1530) docs/tor-manual>">Tor manual page</a>. Remember, all lines beginning
1531) with # in torrc are treated as comments and have no effect on Tor's
1532) configuration.
1533) </p>
1534) 
1535) <hr>
1536) 

1537) <a id="Logs"></a>

1538) <h3><a class="anchor" href="#Logs">How do I set up logging, or see Tor's
1539) logs?</a></h3>

1540) 
1541) <p>

1542) If you installed a Tor bundle that includes Vidalia, then Vidalia has a

1543) window called "Message Log" that will show you Tor's log messages. Click
1544) on "Advanced" to see more details. You can click on "Settings" to change
1545) your log verbosity or save the messages to a file. You're all set.

1546) </p>
1547) 
1548) <p>
1549) If you're not using Vidalia, you'll have to go find the log files by

1550) hand. Here are some likely places for your logs to be:

1551) </p>
1552) 
1553) <ul>
1554) <li>On OS X, Debian, Red Hat, etc, the logs are in /var/log/tor/
1555) </li>

1556) <li>On Windows, there are no default log files currently. If you enable
1557) logs in your torrc file, they default to <code>\username\Application
1558) Data\tor\log\</code> or <code>\Application Data\tor\log\</code>
1559) </li>
1560) <li>If you compiled Tor from source, by default your Tor logs to <a
1561) href="http://en.wikipedia.org/wiki/Standard_streams">"stdout"</a>
1562) at log-level notice. If you enable logs in your torrc file, they
1563) default to <code>/usr/local/var/log/tor/</code>.

1564) </li>
1565) </ul>
1566) 
1567) <p>

1568) To change your logging setup by hand, <a href="#torrc">edit your
1569) torrc</a>

1570) and find the section (near the top of the file) which contains the
1571) following line:

1572) </p>
1573) 
1574) <pre>

1575) \## Logs go to stdout at level "notice" unless redirected by something
1576) \## else, like one of the below lines.

1577) </pre>

1578) 
1579) <p>

1580) For example, if you want Tor to send complete debug, info, notice, warn,

1581) and err level messages to a file, append the following line to the end
1582) of the section:
1583) </p>
1584) 
1585) <pre>
1586) Log debug file c:/program files/tor/debug.log
1587) </pre>
1588) 
1589) <p>

1590) Replace <code>c:/program files/tor/debug.log</code> with a directory
1591) and filename for your Tor log.

1592) </p>
1593) 
1594) <hr>
1595) 

1596) 
1597) <a id="LogLevel"></a>
1598) <h3><a class="anchor" href="#LogLevel">What log level should I use?</a></h3>
1599) 
1600) <p>

1601) There are five log levels (also called "log severities") you might see in 
1602) Tor's logs:

1603) </p>
1604) 
1605) <ul>

1606)     <li>"err": something bad just happened, and we can't recover. Tor will 
1607)     exit.</li>
1608)     <li>"warn": something bad happened, but we're still running. The bad 
1609)     thing might be a bug in the code, some other Tor process doing something 
1610)     unexpected, etc. The operator should examine the message and try to 
1611)     correct the problem.</li>

1612)     <li>"notice": something the operator will want to know about.</li>

1613)     <li>"info": something happened (maybe bad, maybe ok), but there's 
1614)     nothing you need to (or can) do about it.</li>

1615)     <li>"debug": for everything louder than info. It is quite loud indeed.</li> 
1616) </ul>
1617) 
1618) <p>

1619) Alas, some of the warn messages are hard for ordinary users to correct -- the 
1620) developers are slowly making progress at making Tor automatically react 
1621) correctly for each situation.

1622) </p>
1623) 
1624) <p>

1625) We recommend running at the default, which is "notice". You will hear about 
1626) important things, and you won't hear about unimportant things.

1627) </p>
1628) 
1629) <p>

1630) Tor relays in particular should avoid logging at info or debug in normal 
1631) operation, since they might end up recording sensitive information in 
1632) their logs. 

1633) </p>
1634) 

1635) <hr>
1636) 

1637) <a id="DoesntWork"></a>

1638) <h3><a class="anchor" href="#DoesntWork">I installed Tor but it's not
1639) working.</a></h3>

1640) 
1641) <p>

1642) Once you've got the Tor bundle up and running, the first question to
1643) ask is whether your Tor client is able to establish a circuit.

1644) </p>
1645) 
1646) <p>If Tor can establish a circuit, the onion icon in

1647) Vidalia will turn green (and if you're running Tor Browser Bundle, it
1648) will
1649) automatically launch a browser for you). You can also check in the
1650) Vidalia

1651) Control Panel to make sure it says "Connected to the Tor
1652) network!" under Status. For those not using Vidalia, check your <a

1653) href="#Logs">Tor logs</a> for

1654) a line saying that Tor "has successfully opened a circuit. Looks like
1655) client functionality is working."
1656) </p>
1657) 
1658) <p>
1659) If Tor can't establish a circuit, here are some hints:
1660) </p>
1661) 
1662) <ol>
1663) <li>Are you sure Tor is running? If you're using Vidalia, you may have
1664) to click on the onion and select "Start" to launch Tor.</li>
1665) <li>Check your system clock. If it's more than a few hours off, Tor will

1666) refuse to build circuits. For Microsoft Windows users, synchronize your
1667) clock under the clock -> Internet time tab. In addition, correct the

1668) day and date under the 'Date & Time' Tab. Also make sure your time
1669) zone is correct.</li>

1670) <li>Is your Internet connection <a href="#FirewallPorts">firewalled
1671) by port</a>, or do you normally need to use a <a

1672) href="<#NeedToUseAProxy">proxy</a>?

1673) </li>

1674) <li>Are you running programs like Norton Internet Security or SELinux
1675) that

1676) block certain connections, even though you don't realize they do? They
1677) could be preventing Tor from making network connections.</li>
1678) <li>Are you in China, or behind a restrictive corporate network firewall
1679) that blocks the public Tor relays? If so, you should learn about <a

1680) href="<page docs/bridges>">Tor bridges</a>.</li>

1681) <li>Check your <a href="#Logs">Tor logs</a>. Do they give you any hints
1682) about what's going wrong?</li>

1683) </ol>
1684) 
1685) <hr />
1686) 

1687) <a id="TorCrash"></a>
1688) <h3><a class="anchor" href="#TorCrash">My Tor keeps crashing.</a></h3>
1689) <p>
1690)  We want to hear from you! There are supposed to be zero crash bugs in Tor. 
1691)  This FAQ entry describes the best way for you to be helpful to us. But even 
1692)  if you can't work out all the details, we still want to hear about it, so 
1693)  we can help you track it down. 
1694) </p>
1695) <p>
1696) First, make sure you're using the latest version of Tor (either the latest 
1697) stable or the latest development version). 
1698) </p>
1699) <p>
1700) Second, make sure your version of libevent is new enough. We recommend at 
1701) least libevent 1.3a. 
1702) </p>
1703) <p>
1704) Third, see if there's already an entry for your bug in the <a 
1705) href="https://bugs.torproject.org/">Tor bugtracker</a>. If so, 
1706) check if there are any new details that you can add. 
1707) </p>
1708) <p>
1709) Fourth, is the crash repeatable? Can you cause the crash? Can 
1710) you isolate some of the circumstances or config options that 
1711) make it happen? How quickly or often does the bug show up? 
1712) Can you check if it happens with other versions of Tor, for 
1713) example the latest stable release? 
1714) </p>
1715) <p>
1716) Fifth, what sort of crash do you get? 
1717) </p>
1718) <ul>
1719) <li>
1720) Does your Tor log include an "assert failure"? If so, please 
1721) tell us that line, since it helps us figure out what's going on. 
1722) Tell us the previous couple of log messages as well, especially 
1723) if they seem important. 
1724) </li>
1725) <li>
1726) If it says "Segmentation fault - core dumped" then you need to 
1727) do a bit more to track it down. Look for a file like "core" or 
1728) "tor.core" or "core.12345" in your current directory, or in your 
1729) Data Directory. If it's there, run "gdb tor core" and then "bt", 
1730) and include the output. If you can't find a core, run "ulimit -c 
1731) unlimited", restart Tor, and try to make it crash again. (This core 
1732) thing will only work on Unix -- alas, tracking down bugs on Windows 
1733) is harder. If you're on Windows, can you get somebody to duplicate 
1734) your bug on Unix?)
1735) </li>
1736) <li>
1737) If Tor simply vanishes mysteriously, it probably is a segmentation 
1738) fault but you're running Tor in the background (as a daemon) so you 
1739) won't notice. Go look at the end of your log file, and look for a 
1740) core file as above. If you don't find any good hints, you should 
1741) consider running Tor in the foreground (from a shell) so you can 
1742) see how it dies. Warning: if you switch to running Tor in the foreground, 
1743) you might start using a different torrc file, with a different default 
1744) Data Directory; see the <a href="#UpgradeOrMove">relay-upgrade FAQ entry</a> 
1745) for details. 
1746) </li>
1747) <li>
1748) If it's still vanishing mysteriously, perhaps something else is killing it? 
1749) Do you have resource limits (ulimits) configured that kill off processes 
1750) sometimes? (This is especially common on OpenBSD.) On Linux, try running 
1751) "dmesg" to see if the out-of-memory killer removed your process. (Tor will 
1752) exit cleanly if it notices that it's run out of memory, but in some cases 
1753) it might not have time to notice.) In very rare circumstances, hardware 
1754) problems could also be the culprit. 
1755) </li>
1756) </ul>
1757) <p>
1758) Sixth, if the above ideas don't point out the bug, consider increasing your 
1759) log level to "loglevel debug". You can look at the log-configuration FAQ 
1760) entry for instructions on what to put in your torrc file. If it usually 
1761) takes a long time for the crash to show up, you will want to reserve a whole 
1762) lot of disk space for the debug log. Alternatively, you could just send 
1763) debug-level logs to the screen (it's called "stdout" in the torrc), and then 
1764) when it crashes you'll see the last couple of log lines it had printed. 
1765) (Note that running with verbose logging like this will slow Tor down 
1766) considerably, and note also that it's generally not a good idea security-wise 
1767) to keep logs like this sitting around.) 
1768) </p>
1769) 
1770) <hr />
1771) 

1772) <a id="VidaliaPassword"></a>

1773) <h3><a class="anchor" href="#VidaliaPassword">Tor/Vidalia prompts for a
1774) password at start.</a></h3>

1775) 
1776) <p>
1777) Vidalia interacts with the Tor software via Tor's "control port". The
1778) control port lets Vidalia receive status updates from Tor, request a new
1779) identity, configure Tor's settings, etc. Each time Vidalia starts Tor,
1780) Vidalia sets a random password for Tor's control port to prevent other
1781) applications from also connecting to the control port and potentially
1782) compromising your anonymity.
1783) </p>
1784) 
1785) <p>
1786) Usually this process of generating and setting a random control password
1787) happens in the background. There are three common situations, though,
1788) where Vidalia may prompt you for a password:
1789) </p>
1790) 
1791) <ol>
1792) <li>You're already running Vidalia and Tor. For example, this situation
1793) can happen if you installed the Vidalia bundle and now you're trying to
1794) run the Tor Browser Bundle. In that case, you'll need to close the old
1795) Vidalia and Tor before you can run this one.
1796) </li>
1797) <li>Vidalia crashed, but left Tor running with the last known random
1798) password. After you restart Vidalia, it generates a new random password,

1799) but Vidalia can't talk to Tor, because the random passwords are
1800) different.

1801) <br />

1802) If the dialog that prompts you for a control password has a Reset
1803) button,

1804) you can click the button and Vidalia will restart Tor with a new random
1805) control password.
1806) <br />
1807) If you do not see a Reset button, or if Vidalia is unable to restart
1808) Tor for you, you can still fix the problem manually. Simply go into your
1809) process or task manager, and terminate the Tor process. Then use Vidalia
1810) to restart Tor and all will work again.
1811) </li>
1812) <li>You had previously set Tor to run as a Windows NT service. When Tor
1813) is set to
1814) run as a service, it starts up when the system boots. If you configured
1815) Tor to start as a service through Vidalia, a random password was set
1816) and saved in Tor. When you reboot, Tor starts up and uses the random
1817) password it saved. You login and start up Vidalia. Vidalia attempts to
1818) talk to the already running Tor. Vidalia generates a random password,
1819) but it is different than the saved password in the Tor service.
1820) <br />
1821) You need to reconfigure Tor to not be a service. See the FAQ entry on

1822) <a href="#NTservice">running Tor as a

1823) Windows NT service</a>

1824) for more information on how to remove the Tor service.
1825) </li>
1826) </ol>
1827) 

1828)     <hr>

1829) 

1830)     <a id="ChooseEntryExit"></a>

1831)     <h3><a class="anchor" href="#ChooseEntryExit">Can I control which
1832) nodes (or country) are used for entry/exit?</a></h3>

1833) 

1834)     <p>

1835)     Yes. You can set preferred entry and exit nodes as well as
1836)     inform Tor which nodes you do not want to use.

1837)     The following options can be added to your config file <a
1838)     href="#torrc">"torrc"</a> or specified on the command line:

1839)     </p>
1840)     <dl>
1841)       <dt><tt>EntryNodes $fingerprint,$fingerprint,...</tt></dt>

1842)         <dd>A list of preferred nodes to use for the first hop in the
1843) circuit, if possible.

1844)         </dd>
1845)       <dt><tt>ExitNodes $fingerprint,$fingerprint,...</tt></dt>

1846)         <dd>A list of preferred nodes to use for the last hop in the
1847) circuit, if possible.

1848)         </dd>
1849)       <dt><tt>ExcludeNodes $fingerprint,$fingerprint,...</tt></dt>

1850)         <dd>A list of nodes to never use when building a circuit.

1851)         </dd>
1852)       <dt><tt>ExcludeExitNodes $fingerprint,$fingerprint,...</tt></dt>

1853)         <dd>A list of nodes to never use when picking an exit.

1854)             Nodes listed in <tt>ExcludeNodes</tt> are automatically in
1855) this list.

1856)         </dd>
1857)     </dl>
1858)     <p>

1859)     <em>We recommend you do not use these</em>

1860)     — they are intended for testing and may disappear in future
1861) versions.

1862)     You get the best security that Tor can provide when you leave the
1863)     route selection to Tor; overriding the entry / exit nodes can mess
1864)     up your anonymity in ways we don't understand.

1865)     </p>
1866)     <p>

1867)     Note also that not every circuit is used to deliver traffic outside of 
1868)     the Tor network. It is normal to see non-exit circuits (such as those 
1869)     used to connect to hidden services, those that do directory fetches, 
1870)     those used for relay reachability self-tests, and so on) that end at 
1871)     a non-exit node. To keep a node from being used entirely, see 
1872)     <tt>ExcludeNodes</tt> and <tt>StrictNodes</tt> in the 
1873)     <a href="<page docs/tor-manual>">manual</a>.

1874)     </p>
1875)     <p>

1876)     Instead of <tt>$fingerprint</tt> you can also specify a <a

1877) 
1878) href="https://secure.wikimedia.org/wikipedia/en/wiki/ISO_3166-1_alpha-2"
1879) >2

1880)     letter ISO3166 country code</a> in curly braces (for example <tt>{de}</tt>),

1881)     or an ip address pattern (for example 255.254.0.0/8), or a node
1882)     nickname. Make sure there are no spaces between the commas and the
1883)     list items.

1884)     </p>
1885)     <p>

1886)     If you want to access a service directly through Tor's Socks
1887) interface

1888)     (eg. using ssh via connect.c), another option is to set up an

1889)     internal mapping in your configuration file using
1890) <tt>MapAddress</tt>.

1891)     See the manual page for details.
1892)     </p>

1893) 

1894)     <hr>

1895) 

1896) <a id="FirewallPorts"></a>

1897) <h3><a class="anchor" href="#FirewallPorts">My firewall only allows a
1898) few outgoing ports.</a></h3>

1899) 
1900) <p>
1901) If your firewall works by blocking ports, then you can tell Tor to only

1902) use the ports that your firewall permits by adding "FascistFirewall 1"
1903) to

1904) your <a href="<page docs/faq>#torrc">torrc

1905) configuration file</a>, or by clicking "My firewall only lets me connect
1906) to certain ports" in Vidalia's Network Settings window.
1907) </p>
1908) 
1909) <p>
1910) By default, when you set this Tor assumes that your firewall allows only
1911) port 80 and port 443 (HTTP and HTTPS respectively). You can select a
1912) different set of ports with the FirewallPorts torrc option.
1913) </p>
1914) 
1915) <p>
1916) If you want to be more fine-grained with your controls, you can also
1917) use the ReachableAddresses config options, e.g.:
1918) </p>
1919) 
1920) <pre>
1921)   ReachableDirAddresses *:80
1922)   ReachableORAddresses *:443
1923) </pre>
1924) 
1925) <hr>

1926) 

1927)     <a id="DefaultExitPorts"></a>
1928)     <h3><a class="anchor" href="#DefaultExitPorts">Is there a list of default exit 

1929)     ports?</a></h3>

1930)     <p>

1931) The default open ports are listed below but keep in mind that, any port or 
1932) ports can be opened by the relay operator by configuring it in torrc or 
1933) modifying the source code. But the default according to src/or/policies.c 
1934) from the source code release tor-0.2.4.16-rc is: 

1935)     </p>
1936)     <pre>
1937)   reject 0.0.0.0/8
1938)   reject 169.254.0.0/16
1939)   reject 127.0.0.0/8
1940)   reject 192.168.0.0/16
1941)   reject 10.0.0.0/8
1942)   reject 172.16.0.0/12
1943)   reject *:25
1944)   reject *:119
1945)   reject *:135-139
1946)   reject *:445
1947)   reject *:563
1948)   reject *:1214
1949)   reject *:4661-4666
1950)   reject *:6346-6429
1951)   reject *:6699
1952)   reject *:6881-6999
1953)   accept *:*
1954)     </pre>
1955)     <p>

1956)     A relay will block access to its own IP address, as well local network 
1957)     IP addresses. A relay always blocks itself by default. This prevents 
1958)     Tor users from accidentally accessing any of the exit operator's local 
1959)     services. 
1960)     </p>
1961) 
1962)     <hr>
1963) 
1964)     <a id="SocksAndDNS"></a>
1965)     <h3><a class="anchor" href="#SocksAndDNS">How do I check if my application that uses 
1966)     SOCKS is leaking DNS requests?</a></h3>
1967) 
1968)     <p>
1969)     These are two steps you need to take here. The first is to make sure 
1970)     that it's using the correct variant of the SOCKS protocol, and the 
1971)     second is to make sure that there aren't other leaks. 
1972)     </p>
1973) 
1974)     <p>
1975)     Step one: add "TestSocks 1" to your torrc file, and then watch your 
1976)     logs as you use your application. Tor will then log, for each SOCKS 
1977)     connection, whether it was using a 'good' variant or a 'bad' one. 
1978)     (If you want to automatically disable all 'bad' variants, set 
1979)     "SafeSocks 1" in your <a href="#torrc">torrc</a> file.) 
1980)     </p>
1981) 
1982)     <p>
1983)     Step two: even if your application is using the correct variant of 
1984)     the SOCKS protocol, there is still a risk that it could be leaking 
1985)     DNS queries. This problem happens in Firefox extensions that resolve 
1986)     the destination hostname themselves, for example to show you its IP 
1987)     address, what country it's in, etc. These applications may use a safe 
1988)     SOCKS variant when actually making connections, but they still do DNS 
1989)     resolves locally. If you suspect your application might behave like 
1990)     this, you should use a network sniffer like <a 
1991)     href="https://www.wireshark.org/">Wireshark</a> and look for 
1992)     suspicious outbound DNS requests. I'm afraid the details of how to look 
1993)     for these problems are beyond the scope of a FAQ entry though -- find 
1994)     a friend to help if you have problems. 

1995)     </p>
1996) 
1997)     <hr>
1998) 

1999)     <a id="HowDoIDecide"></a>
2000)     <h3><a class="anchor" href="#HowDoIDecide">How do I decide if I should 
2001)     run a relay?</a></h3>
2002)     <p>
2003)     We're looking for people with reasonably reliable Internet connections, 
2004)     that have at least 20 kilobytes/second each way. If that's you, please 
2005)     consider <a href="https://www.torproject.org/docs/tor-relay-debian">helping 
2006)     out</a>. 
2007)     </p>
2008)     
2009)     <hr>
2010)     
2011)     <a id="WhyIsntMyRelayBeingUsedMore"></a>
2012)     <h3><a class="anchor" href="#WhyIsntMyRelayBeingUsedMore">Why isn't my 
2013)     relay being used more?</a></h3>
2014)     <p>
2015)     If your relay is relatively new then give it time. Tor decides which 
2016)     relays it uses heuristically based on reports from Bandwidth 
2017)     Authorities. These authorities take measurements of your relay's 
2018)     capacity and, over time, directs more traffic there until it reaches 
2019)     an optimal load. The lifecycle of a new relay is explained in more 
2020)     depth in <a href="https://blog.torproject.org/blog/lifecycle-of-a-new-relay">
2021)     this blog post</a>.
2022)     </p>
2023)     <p>
2024)     If you've been running a relay for a while and still having issues 
2025)     then try asking on the <a href=
2026)     "https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays/">
2027)     tor-relays list</a>. 
2028)     </p>
2029)     
2030)     <hr>
2031) 

2032)     <a id="HighCapacityConnection"></a>    
2033)     <h3><a class="anchor" href="#HighCapacityConnection">How can I get Tor to fully 
2034)     make use of my high capacity connection?</a></h3>
2035)     
2036)     <p>
2037)     See <a href="http://archives.seul.org/or/relays/Aug-2010/msg00034.html">this 
2038)     tor-relays thread</a>.
2039)     </p>
2040)     
2041)     <hr>    
2042)     

2043)     <a id="RelayFlexible"></a>

2044)     <h3><a class="anchor" href="#RelayFlexible">How stable does my relay
2045) need to be?</a></h3>

2046) 

2047)     <p>
2048)     We aim to make setting up a Tor relay easy and convenient:
2049)     </p>

2050) 

2051)     <ul>
2052)     <li>Tor has built-in support for <a

2053)     href="<wikifaq>#WhatbandwidthshapingoptionsareavailabletoTorrelays">

2054)     rate limiting</a>. Further, if you have a fast
2055)     link but want to limit the number of bytes per
2056)     day (or week or month) that you donate, check out the <a

2057) 
2058) href="<wikifaq>#HowcanIlimitthetotalamountofbandwidthusedbymyTorrelay">
2059) hibernation

2060)     feature</a>.
2061)     </li>

2062)     <li>Each Tor relay has an <a href="#ExitPolicies">exit policy</a>
2063) that
2064)     specifies what sort of outbound connections are allowed or refused
2065) from
2066)     that relay. If you are uncomfortable allowing people to exit from
2067) your
2068)     relay, you can set it up to only allow connections to other Tor
2069) relays.

2070)     </li>
2071)     <li>It's fine if the relay goes offline sometimes. The directories
2072)     notice this quickly and stop advertising the relay. Just try to make
2073)     sure it's not too often, since connections using the relay when it
2074)     disconnects will break.
2075)     </li>
2076)     <li>We can handle relays with dynamic IPs just fine &mdash; simply
2077)     leave the Address config option blank, and Tor will try to guess.
2078)     </li>
2079)     <li>If your relay is behind a NAT and it doesn't know its public
2080)     IP (e.g. it has an IP of 192.168.x.y), you'll need to set up port

2081)     forwarding. Forwarding TCP connections is system dependent but

2082)     <a href="#BehindANAT">this FAQ entry</a>

2083)     offers some examples on how to do this.
2084)     </li>
2085)     <li>Your relay will passively estimate and advertise its recent

2086)     bandwidth capacity, so high-bandwidth relays will attract more users
2087) than
2088)     low-bandwidth ones. Therefore having low-bandwidth relays is useful
2089) too.

2090)     </li>
2091)     </ul>

2092) 

2093)     <hr>

2094) 

2095)     <a id="ExitPolicies"></a>

2096)     <h3><a class="anchor" href="#ExitPolicies">I'd run a relay, but I
2097) don't want to deal with abuse issues.</a></h3>

2098) 

2099)     <p>
2100)     Great. That's exactly why we implemented exit policies.
2101)     </p>

2102) 

2103)     <p>
2104)     Each Tor relay has an exit policy that specifies what sort of

2105)     outbound connections are allowed or refused from that relay. The
2106) exit

2107)     policies are propagated to Tor clients via the directory, so clients
2108)     will automatically avoid picking exit relays that would refuse to
2109)     exit to their intended destination. This way each relay can decide
2110)     the services, hosts, and networks he wants to allow connections to,

2111)     based on abuse potential and his own situation. Read the FAQ entry
2112) on
2113)     <a href="<page docs/faq-abuse>#TypicalAbuses">issues you might
2114) encounter</a>

2115)     if you use the default exit policy, and then read Mike Perry's

2116)     <a href="<blog>tips-running-exit-node-minimal-harassment">tips

2117)     for running an exit node with minimal harassment</a>.
2118)     </p>

2119) 

2120)     <p>

2121)     The default exit policy allows access to many popular services

2122)     (e.g. web browsing), but <a

2123) href="#DefaultExitPorts">restricts</a>

2124)     some due to abuse potential (e.g. mail) and some since
2125)     the Tor network can't handle the load (e.g. default
2126)     file-sharing ports). You can change your exit policy

2127)     using Vidalia's "Sharing" tab, or by manually editing your

2128)     <a href="<page docs/faq>#torrc">torrc</a>

2129)     file. If you want to avoid most if not all abuse potential, set it
2130) to
2131)     "reject *:*" (or un-check all the boxes in Vidalia). This setting
2132) means
2133)     that your relay will be used for relaying traffic inside the Tor
2134) network,

2135)     but not for connections to external websites or other services.
2136)     </p>

2137) 

2138)     <p>

2139)     If you do allow any exit connections, make sure name resolution
2140) works

2141)     (that is, your computer can resolve Internet addresses correctly).

2142)     If there are any resources that your computer can't reach (for
2143) example,

2144)     you are behind a restrictive firewall or content filter), please

2145)     explicitly reject them in your exit policy — otherwise Tor
2146) users

2147)     will be impacted too.
2148)     </p>

2149) 

2150)     <hr>

2151) 

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

2153)     <h3><a class="anchor" href="#DifferentComputer">I want to run my 
2154)     Tor client on a different computer than my applications.</a></h3>

2155)     <p>

2156)     By default, your Tor client only listens for applications that 
2157)     connect from localhost. Connections from other computers are 
2158)     refused. If you want to torify applications on different computers 
2159)     than the Tor client, you should edit your torrc to define 
2160)     SocksListenAddress 0.0.0.0 g and then restart (or hup) Tor. If you 
2161)     want to get more advanced, you can configure your Tor client on a 
2162)     firewall to bind to your internal IP but not your external IP.  

2163)     </p>
2164) 
2165)     <hr>
2166) 
2167)     <a id="ServerClient"></a>

2168)     <h3><a class="anchor" href="#ServerClient">Can I install Tor on a 
2169)     central server, and have my clients connect to it?</a></h3>
2170)     <p>
2171)      Yes. Tor can be configured as a client or a relay on another 
2172)      machine, and allow other machines to be able to connect to it 
2173)      for anonymity. This is most useful in an environment where many 
2174)      computers want a gateway of anonymity to the rest of the world. 
2175)      However, be forwarned that with this configuration, anyone within 
2176)      your private network (existing between you and the Tor 
2177)      client/relay) can see what traffic you are sending in clear text. 
2178)      The anonymity doesn't start until you get to the Tor relay. 
2179)      Because of this, if you are the controller of your domain and you 
2180)      know everything's locked down, you will be OK, but this configuration 
2181)      may not be suitable for large private networks where security is 
2182)      key all around.
2183)     </p>
2184)     <p>
2185) Configuration is simple, editing your torrc file's SocksListenAddress 
2186) according to the following examples:

2187)     </p>
2188)     <pre>

2189) 
2190)   #This provides local interface access only, 
2191)   #needs SocksPort to be greater than 0
2192)   SocksListenAddress 127.0.0.1 
2193) 
2194)   #This provides access to Tor on a specified interface
2195)   SocksListenAddress 192.168.x.x:9100 
2196) 
2197)   #Accept from all interfaces
2198)   SocksListenAddress 0.0.0.0:9100
2199)    </pre>

2200)     <p>

2201) You can state multiple listen addresses, in the case that you are 
2202) part of several networks or subnets.

2203)     </p>
2204)     <pre>
2205)   SocksListenAddress 192.168.x.x:9100 #eth0
2206)   SocksListenAddress 10.x.x.x:9100 #eth1
2207)     </pre>
2208)     <p>

2209) After this, your clients on their respective networks/subnets would specify 
2210) a socks proxy with the address and port you specified SocksListenAddress 
2211) to be. 

2212)     </p>
2213)     <p>

2214) Please note that the SocksPort configuration option gives the port ONLY for 
2215) localhost (127.0.0.1). When setting up your SocksListenAddress(es), you need 
2216) to give the port with the address, as shown above.

2217)     <p>

2218) If you are interested in forcing all outgoing data through the central Tor 
2219) client/relay, instead of the server only being an optional proxy, you may find 
2220) the program iptables (for *nix) useful. 

2221)     </p>
2222) 
2223)     <hr>
2224) 

2225)     <a id="JoinTheNetwork"></a>

2226)     <h3><a class="anchor" href="#JoinTheNetwork">So I can just configure a 
2227)     nickname and ORPort and join the network?</a></h3>

2228) 
2229)     <p>

2230)      Yes. You can join the network and be a useful relay just by configuring 
2231)      your Tor to be a relay and making sure it's reachable from the outside.

2232)     </p>
2233)     <p>
2234) 30 Seconds to a Tor Relay:
2235)     </p>
2236)     <ul><li>
2237)     Configure a Nickname: 
2238)     </li></ul>
2239)     <pre>
2240) Nickname ididnteditheconfig
2241)     </pre>

2242)     <ul><li>

2243)     Configure ORPort: 

2244)     </li></ul>

2245)     <pre>
2246) ORPort 9001
2247)     </pre>

2248)     <ul><li>

2249)     Configure Contact Info: 

2250)     </li></ul>

2251) 
2252)     <pre>
2253) ContactInfo human@…

2254)     </pre>
2255)     <ul><li>

2256)     Start Tor. Watch the log file for a log entry that states: "Self-testing 
2257)     indicates your ORPort is reachable from the outside. Excellent. Publishing 
2258)     server descriptor."

2259)     </li></ul>

2260) 
2261)     <hr />

2262) 

2263)     <a id="RelayOrBridge"></a>

2264)     <h3><a class="anchor" href="#RelayOrBridge">Should I be a normal
2265) relay or bridge relay?</a></h3>

2266) 

2267)     <p><a href="<page docs/bridges>">Bridge relays</a> (or "bridges" for
2268) short)
2269)     are <a href="<page docs/tor-doc-relay>">Tor relays</a> that aren't

2270)     listed in the public Tor directory.

2271)     That means that ISPs or governments trying to block access to the

2272)     Tor network can't simply block all bridges.

2273)     </p>

2274) 

2275)     <p>Being a normal relay vs being a bridge relay is almost the same
2276)     configuration: it's just a matter of whether your relay is listed

2277)     publicly or not.

2278)     </p>

2279) 

2280)     <p>

2281)     So bridges are useful a) for Tor users in oppressive regimes,

2282)     and b) for people who want an extra layer of security

2283)     because they're worried somebody will recognize that it's a public
2284)     Tor relay IP address they're contacting.

2285)     </p>

2286) 

2287)     <p>
2288)     Several countries, including China and Iran, have found ways to

2289)     detect and block connections to Tor bridges.

2290)     <a href="<page projects/obfsproxy>">Obfsproxy</a> bridges address

2291)     this by adding another layer of obfuscation.

2292)     </p>
2293) 

2294)     <p>So should you run a normal relay or bridge relay? If you have
2295) lots

2296)     of bandwidth, you should definitely run a normal relay.
2297)     If you're willing

2298)     to <a href="#ExitPolicies">be an exit</a>, you should definitely
2299)     run a normal relay, since we need more exits. If you can't be an
2300)     exit and only have a little bit of bandwidth, be a bridge. Thanks
2301)     for volunteering!

2302)     </p>

2303) 

2304)     <hr>

2305) 

2306) <a id="UpgradeOrMove"></a>

2307) <h3><a class="anchor" href="#UpgradeOrMove">I want to upgrade/move my relay. 
2308) How do I keep the same key?</a></h3>

2309) 
2310) <p>

2311)  When upgrading your Tor relay, or running it on a different computer, 
2312)  the important part is to keep the same nickname (defined in your torrc 
2313)  file) and the same identity key (stored in "keys/secret_id_key" in 
2314)  your DataDirectory).

2315) </p>
2316) <p>

2317) This means that if you're upgrading your Tor relay and you keep the same 
2318) torrc and the same DataDirectory, then the upgrade should just work and 
2319) your relay will keep using the same key. If you need to pick a new 
2320) DataDirectory, be sure to copy your old keys/secret_id_key over. 

2321) </p>
2322) 
2323)     <hr>
2324) 
2325) <a id="NTService"></a>

2326) <h3><a class="anchor" href="#NTService">How do I run my Tor relay as an NT 
2327) service?</a></h3>

2328) 
2329) <p>

2330)  You can run Tor as a service on all versions of Windows except Windows 
2331)  95/98/ME. This way you can run a Tor relay without needing to always have 
2332)  Vidalia running.

2333) </p>
2334) <p>

2335) If you've already configured your Tor to be a relay, please note that when 
2336) you enable Tor as a service, it will use a different DatagDirectory, and 
2337) thus will generate a different key. If you want to keep using the old key, 
2338) see the Upgrading your Tor relay FAQ entry for how to restore the old 
2339) identity key.

2340) </p>
2341) <p>
2342) To install Tor as a service, you can simply run:
2343) </p>
2344) <pre>
2345) tor --service install
2346) </pre>
2347) <p>

2348) A service called Tor Win32 Service will be installed and started. This 
2349) service will also automatically start every time Windows boots, unless 
2350) you change the Start-up type. An easy way to check the status of Tor, 
2351) start or stop the service, and change the start-up type is by running 
2352) services.msc and finding the Tor service in the list of currently 
2353) installed services.

2354) </p>
2355) <p>

2356) Optionally, you can specify additional options for the Tor service using 
2357) the -options argument. For example, if you want Tor to use C:\tor\torrc, 
2358) instead of the default torrc, and open a control port on port 9151, you 
2359) would run:

2360) </p>
2361) <pre>
2362) tor --service install -options -f C:\tor\torrc ControlPort 9151
2363) </pre>
2364) <p>
2365) You can also start or stop the Tor service from the command line by typing:
2366) </p>
2367) <pre>
2368)  tor --service start
2369) </pre>
2370) <p>
2371) or
2372) </p>
2373) <pre>
2374)  tor --service stop
2375) </pre>
2376) <p>
2377) To remove the Tor service, you can run the following command:
2378) </p>
2379) <pre>
2380) tor --service remove
2381) </pre>
2382) <p>

2383) If you are running Tor as a service and you want to uninstall Tor entirely, 
2384) be sure to run the service removal command (shown above) first before 
2385) running the uninstaller from "Add/Remove Programs". The uninstaller is 
2386) currently not capable of removing the active service.

2387) </p>
2388) 
2389) <hr>
2390) 
2391) <a id="VirtualServer"></a>

2392) <h3><a class="anchor" href="#VirtualServer">Can I run a Tor relay from my 
2393) virtual server account?</a></h3>

2394) 
2395) <p>

2396) Some ISPs are selling "vserver" accounts that provide what they call a 
2397) virtual server -- you can't actually interact with the hardware, and 
2398) they can artificially limit certain resources such as the number of file 
2399) descriptors you can open at once. Competent vserver admins are able to 
2400) configure your server to not hit these limits. For example, in SWSoft's 
2401) Virtuozzo, investigate /proc/user_beancounters. Look for "failcnt" in 
2402) tcpsndbuf, tcprecvbuf, numothersock, and othersockbuf. Ask for these to 
2403) be increased accordingly. Some users have seen settings work well as follows: 

2404) <p>

2405) <table border="1">

2406) <tr>
2407) <td>
2408) <i>resource</i>
2409) </td>
2410) <td>
2411) <i>held</i>
2412) </td>
2413) <td>
2414) <i>maxheld</i>
2415) </td>
2416) <td>
2417) <i>barrier</i>
2418) </td>
2419) <td>
2420) <i>limit</i>
2421) </td>
2422) <td>
2423) <i>failcnt</i>
2424) </td>
2425) </tr>
2426) <tr>
2427) <td>
2428) tcpsndbuf
2429) </td>
2430) <td>
2431) 46620
2432) </td>
2433) <td>
2434) 48840
2435) </td>
2436) <td>
2437) 3440640
2438) </td>
2439) <td>
2440) 5406720
2441) </td>
2442) <td>
2443) 0
2444) </td>
2445) </tr>
2446) <tr>
2447) <td>
2448) tcprcvbuf
2449) </td>
2450) <td>
2451) 0
2452) </td>
2453) <td>
2454) 2220
2455) </td>
2456) <td>
2457) 3440640
2458) </td>
2459) <td>
2460) 5406720
2461) </td>
2462) <td>
2463) 0
2464) </td>
2465) </tr>
2466) <tr>
2467) <td>
2468) othersockbuf
2469) </td>
2470) <td>
2471) 243516
2472) </td>
2473) <td>
2474) 260072
2475) </td>
2476) <td>
2477) 2252160
2478) </td>
2479) <td>
2480) 4194304
2481) </td>
2482) <td>
2483) 0
2484) </td>
2485) </tr>
2486) <tr>
2487) <td>
2488) numothersock
2489) </td>
2490) <td>
2491) 151
2492) </td>
2493) <td>
2494) 153
2495) </td>
2496) <td>
2497) 720
2498) </td>
2499) <td>
2500) 720
2501) </td>
2502) <td>
2503) 0
2504) </td>
2505) </tr>
2506) </table>
2507) <p>
2508)  Xen, Virtual Box and VMware virtual servers have no such limits normally.
2509) </p>
2510) <p>

2511) If the vserver admin will not increase system limits another option is 
2512) to reduce the memory allocated to the send and receive buffers on TCP 
2513) connections Tor uses. An experimental feature to constrain socket buffers 
2514) has recently been added. If your version of Tor supports it, set 
2515) "ConstrainedSockets 1" in your configuration. See the tor man page for 
2516) additional details about this option.

2517) </p>
2518) <p>

2519) Unfortunately, since Tor currently requires you to be able to connect to 
2520) all the other Tor relays, we need you to be able to use at least 1024 file 
2521) descriptors. This means we can't make use of Tor relays that are crippled 
2522) in this way.

2523) </p>
2524) <p>

2525) We hope to fix this in the future, once we know how to build a Tor network 
2526) with restricted topologies -- that is, where each node connects to only a 
2527) few other nodes. But this is still a long way off.

2528) </p>
2529) 

2530) <hr>
2531) 

2532) <a id="MultipleRelays"></a>

2533) <h3><a class="anchor" href="#MultipleRelays">I want to run more than one
2534) relay.</a></h3>

2535) 
2536) <p>
2537) Great. If you want to run several relays to donate more to the network,
2538) we're happy with that. But please don't run more than a few dozen on
2539) the same network, since part of the goal of the Tor network is dispersal
2540) and diversity.
2541) </p>
2542) 
2543) <p>
2544) If you do decide to run more than one relay, please set the "MyFamily"

2545) config option in the <a href="#torrc">torrc</a> of each relay, listing
2546) all the relays (comma-separated) that are under your control:

2547) </p>
2548) 
2549) <pre>
2550)     MyFamily $fingerprint1,$fingerprint2,$fingerprint3
2551) </pre>
2552) 
2553) <p>
2554) where each fingerprint is the 40 character identity fingerprint (without

2555) spaces). You can also list them by nickname, but fingerprint is safer.
2556) Be

2557) sure to prefix the digest strings with a dollar sign ('$') so that the
2558) digest is not confused with a nickname in the config file.
2559) </p>
2560) 
2561) <p>
2562) That way clients will know to avoid using more than one of your relays
2563) in a single circuit. You should set MyFamily if you have administrative
2564) control of the computers or of their network, even if they're not all in
2565) the same geographic location.
2566) </p>
2567) 
2568)     <hr>
2569) 

2570)     <a id="WrongIP"></a>

2571)     <h3><a class="anchor" href="#WrongIP">My relay is picking the wrong 
2572)     IP address.</a></h3>

2573)     <p>

2574)  Tor guesses its IP address by asking the computer for its hostname, and 
2575)  then resolving that hostname. Often people have old entries in their 
2576)  /etc/hosts file that point to old IP addresses.

2577)     </p>
2578)     <p>

2579) If that doesn't fix it, you should use the "Address" config option to 
2580) specify the IP you want it to pick. If your computer is behind a NAT and 
2581) it only has an internal IP address, see the following FAQ entry on <a 
2582) href="https://www.torproject.org/docs/faq.html.en#RelayFlexible">dynamic 
2583) IP addresses</a>.

2584)     </p>
2585)     <p>

2586) Also, if you have many addresses, you might also want to set 
2587) "OutboundBindAddress" so external connections come from the IP you intend 
2588) to present to the world. 

2589)     </p>
2590) 
2591)     <hr>
2592) 
2593)     <a id="BehindANAT"></a>
2594)     <h3><a class="anchor" href="#BehindANAT">I'm behind a NAT/Firewall.</a></h3>
2595) 
2596)     <p>

2597) See <a>​http://portforward.com/</a> for directions on how to port forward with 
2598) your NAT/router device.

2599) </p>
2600) <p>

2601) If your relay is running on a internal net you need to setup port forwarding. 
2602) Forwarding TCP connections is system dependent but the firewalled-clients FAQ 
2603) entry offers some examples on how to do this.

2604) </p>
2605) <p>

2606) Also, here's an example of how you would do this on GNU/Linux if you're using 
2607) iptables:

2608) </p>
2609) <pre>
2610) /sbin/iptables -A INPUT -i eth0 -p tcp --destination-port 9001 -j ACCEPT
2611) </pre>
2612) <p>

2613) You may have to change "eth0" if you have a different external interface 
2614) (the one connected to the Internet). Chances are you have only one (except 
2615) the loopback) so it shouldn't be too hard to figure out. 

2616)     </p>
2617)     <hr>
2618) 

2619)     <a id="RelayMemory"></a>

2620)     <h3><a class="anchor" href="#RelayMemory">Why is my Tor relay using
2621) so much memory?</a></h3>

2622) 

2623)     <p>If your Tor relay is using more memory than you'd like, here are
2624) some

2625)     tips for reducing its footprint:
2626)     </p>

2627) 

2628)     <ol>
2629)     <li>If you're on Linux, you may be encountering memory fragmentation

2630)     bugs in glibc's malloc implementation. That is, when Tor releases
2631) memory
2632)     back to the system, the pieces of memory are fragmented so they're
2633) hard
2634)     to reuse. The Tor tarball ships with OpenBSD's malloc
2635) implementation,
2636)     which doesn't have as many fragmentation bugs (but the tradeoff is
2637) higher
2638)     CPU load). You can tell Tor to use this malloc implementation
2639) instead:

2640)     <tt>./configure --enable-openbsd-malloc</tt></li>

2641) 

2642)     <li>If you're running a fast relay, meaning you have many TLS
2643) connections

2644)     open, you are probably losing a lot of memory to OpenSSL's internal
2645)     buffers (38KB+ per socket). We've patched OpenSSL to <a

2646) 
2647) href="https://lists.torproject.org/pipermail/tor-dev/2008-June/001519.
2648) html">release

2649)     unused buffer memory more aggressively</a>. If you update to OpenSSL

2650)     1.0.0 or newer, Tor's build process will automatically recognize and
2651) use

2652)     this feature.</li>

2653) 

2654) <!-- Nickm says he's not sure this is still accurate
2655) 

2656)     <li>If you're running on Solaris, OpenBSD, NetBSD, or
2657)     old FreeBSD, Tor is probably forking separate processes
2658)     rather than using threads. Consider switching to a <a
2659)     href="<wikifaq>#WhydoesntmyWindowsorotherOSTorrelayrunwell">better
2660)     operating system</a>.</li>

2661) -->

2662)     <li>If you still can't handle the memory load, consider reducing the

2663)     amount of bandwidth your relay advertises. Advertising less
2664) bandwidth

2665)     means you will attract fewer users, so your relay shouldn't grow
2666)     as large. See the <tt>MaxAdvertisedBandwidth</tt> option in the man
2667)     page.</li>

2668) 

2669)     </ol>

2670) 

2671)     <p>

2672)     All of this said, fast Tor relays do use a lot of ram. It is not
2673) unusual

2674)     for a fast exit relay to use 500-1000 MB of memory.
2675)     </p>

2676) 

2677)     <hr>

2678) 

2679)     <a id="BetterAnonymity"></a>

2680)     <h3><a class="anchor" href="#BetterAnonymity">Do I get better anonymity 
2681)     if I run a relay?</a></h3>

2682) 

2683)     <p>

2684) Yes, you do get better anonymity against some attacks.
2685)     </p>
2686)     <p>

2687) The simplest example is an attacker who owns a small number of Tor relays. 
2688) He will see a connection from you, but he won't be able to know whether 
2689) the connection originated at your computer or was relayed from somebody else.

2690)     </p>
2691)     <p>

2692) There are some cases where it doesn't seem to help: if an attacker can 
2693) watch all of your incoming and outgoing traffic, then it's easy for him 
2694) to learn which connections were relayed and which started at you. (In 
2695) this case he still doesn't know your destinations unless he is watching 
2696) them too, but you're no better off than if you were an ordinary client.)

2697)     </p>
2698)     <p>

2699) There are also some downsides to running a Tor relay. First, while we 
2700) only have a few hundred relays, the fact that you're running one might 
2701) signal to an attacker that you place a high value on your anonymity. 
2702) Second, there are some more esoteric attacks that are not as 
2703) well-understood or well-tested that involve making use of the knowledge 
2704) that you're running a relay -- for example, an attacker may be able to 
2705) "observe" whether you're sending traffic even if he can't actually watch 
2706) your network, by relaying traffic through your Tor relay and noticing 
2707) changes in traffic timing.

2708)     </p>
2709)     <p>

2710) It is an open research question whether the benefits outweigh the risks. 
2711) A lot of that depends on the attacks you are most worried about. For 
2712) most users, we think it's a smart move. 

2713)     </p>

2714) 

2715)     <hr>

2716) 

2717)     <a id="RelayDonations"></a>

2718)     <h3><a class="anchor" href="#RelayDonations">Can I donate for a
2719)     relay rather than run my own?</a></h3>

2720) 
2721)     <p>

2722)     Sure! We recommend these non-profit charities that are happy to turn

2723)     your donations into better speed and anonymity for the Tor network:
2724)     </p>
2725)     <ul>
2726)     <li><a href="https://www.torservers.net/">torservers.net</a>
2727)     is a German charitable non-profit that runs a wide variety of

2728)     exit relays worldwide. They also like donations of bandwidth from
2729)     ISPs.</li>

2730)     <li><a

2731) href="https://www.noisebridge.net/wiki/Noisebridge_Tor">Noisebridge</a>

2732)     is a US-based 501(c)(3) non-profit that collects donations and turns

2733)     them into more US-based exit relay capacity.</li>
2734)     <li><a href="https://nos-oignons.net/">Nos Oignons</a> is a French
2735)     charitable non-profit that runs fast exit relays in France.</li>

2736)     </ul>
2737) 
2738)     <p>
2739)     These organizations are not the same as <a href="<page
2740)     donate/donate>">The Tor Project, Inc</a>, but we consider that a

2741)     good thing. They're both run by nice people who are part of the
2742)     Tor community.

2743)     </p>
2744) 
2745)     <p>
2746)     Note that there can be a tradeoff here between anonymity and

2747)     performance. The Tor network's anonymity comes in part from
2748) diversity,

2749)     so if you are in a position to run your own relay, you will be

2750)     improving Tor's anonymity more than by donating. At the same time
2751)     though, economies

2752)     of scale for bandwidth mean that combining many small donations into

2753)     several larger relays is more efficient at improving network

2754)     performance. Improving anonymity and improving performance are both
2755)     worthwhile goals, so however you can help is great!
2756)     </p>
2757) 
2758)     <hr>
2759) 

2760)     <a id="AccessHiddenServices"></a>
2761)     <h3><a class="anchor" href="#AccessHiddenServices">How do I access 
2762)     hidden services?</a></h3>
2763)     
2764)     <p>
2765)     Tor hidden services are named with a special top-level domain (TLD) 
2766)     name in DNS: .onion. Since the .onion TLD is not recognized by the 
2767)     official root DNS servers on the Internet, your application will not 
2768)     get the response it needs to locate the service. Currently, the Tor 
2769)     directory server provides this look-up service; and thus the look-up 
2770)     request must get to the Tor network. 
2771)     </p>
2772) 
2773) <p>
2774)  Therefore, your application <b>needs</b> to pass the .onion hostname to 
2775)  Tor directly. You can't try to resolve it to an IP address, since there 
2776)  <i>is</i> no corresponding IP address: the server is hidden, after all! 
2777) </p>
2778)     
2779)     <p>
2780)     So, how do you make your application pass the hostname directly to Tor? 
2781)     You can't use SOCKS 4, since SOCKS 4 proxies require an IP from the 
2782)     client (a web browser is an example of a SOCKS client). Even though 
2783)     SOCKS 5 can accept either an IP or a hostname, most applications 
2784)     supporting SOCKS 5 try to resolve the name before passing it to the 
2785)     SOCKS proxy. SOCKS 4a, however, always accepts a hostname: You'll need 
2786)     to use SOCKS 4a. 
2787)     </p>
2788)     
2789)     <p>
2790)     Some applications, such as the browsers Mozilla Firefox and Apple's 
2791)     Safari, support sending DNS queries to Tor's SOCKS 5 proxy. Most web 
2792)     browsers don't support SOCKS 4a very well, though. The workaround is 
2793)     to point your web browser at an HTTP proxy, and tell the HTTP proxy 
2794)     to speak to Tor with SOCKS 4a. We recommend Polipo as your HTTP proxy.
2795)     </p>
2796)     
2797)     <p>
2798)     For applications that do not support HTTP proxy, and so cannot use 
2799)     Polipo, <a href="http://www.freecap.ru/eng/">FreeCap</a> is an 
2800)     alternative. When using FreeCap set proxy protocol  to SOCKS 5 and under 
2801)     settings set DNS name resolving to remote. This 
2802)     will allow you to use almost any program with Tor without leaking DNS 
2803)     lookups and allow those same programs to access hidden services. 
2804)     </p>
2805)     
2806)     <p>
2807)     See also the <a href="#SocksAndDNS">question on DNS</a>. 
2808)     </p>    
2809)     
2810)     <hr>
2811) 
2812)     <a id="ProvideAHiddenService"></a>
2813)     <h3><a class="anchor" href="#ProvideAHiddenService">How do I provide a 
2814)     hidden service?</a></h3>
2815)     
2816)     <p>

2817)     See the <a href="https://www.torproject.org/docs/tor-hidden-service.html.en">

2818)     official hidden service configuration instructions</a>.
2819)     </p>
2820) 
2821)     <hr>
2822)     

2823)     <a id="WhoIsResponsible"></a>
2824)     <h3><a class="anchor" href="#WhoIsResponsible">Who is responsible 
2825)     for Tor?</a></h3>
2826) 
2827)     <p>
2828)     <a href="http://www.freehaven.net/~arma/cv.html">Roger Dingledine</a> and 
2829)     <a href="http://www.wangafu.net/~nickm/">Nick Mathewson</a> are the main 
2830)     developers of Tor. You can read more at 
2831)     <a href="https://www.torproject.org/about/corepeople">Tor's People 
2832)     page</a>. 
2833)     </p>
2834) 
2835)     <hr>
2836) 
2837)     <a id="VersionNumbers"></a>
2838)     <h3><a class="anchor" href="#VersionNumbers">What do these weird 
2839)     version numbers mean?</a></h3>
2840) 
2841)     <p>
2842)     Versions of Tor before 0.1.0 used a strange and hard-to-explain version scheme. Let's forget about those.
2843)     </p>
2844)     <p>
2845)     Starting with 0.1.0, versions all look like this: 
2846)     MAJOR.MINOR.MICRO(.PATCHLEVEL)(-TAG). The stuff in parenthesis is 
2847)     optional. MAJOR, MINOR, MICRO, and PATCHLEVEL are all numbers. Only one 
2848)     release is ever made with any given set of these version numbers. The 
2849)     TAG lets you know how stable we think the release is: "alpha" is pretty 
2850)     unstable; "rc" is a release candidate; and no tag at all means that we 
2851)     have a final release. If the tag ends with "-cvs", you're looking at 
2852)     a development snapshot that came after a given release. 
2853)     </p>
2854)     <p>
2855)     So for example, we might start a development branch with (say) 
2856)     0.1.1.1-alpha. The patchlevel increments consistently as the status 
2857)     tag changes, for example, as in: 0.1.1.2-alpha, 0.1.1.3-alpha, 
2858)     0.1.1.4-rc, 0.1.1.5-rc, etc. Eventually, we would release 0.1.1.6. 
2859)     The next stable release would be 0.1.1.7.
2860)     </p>
2861)     <p>
2862)     Why do we do it like this? Because every release has a unique 
2863)     version number, it is easy for tools like package manager to tell 
2864)     which release is newer than another. The tag makes it easy for users 
2865)     to tell how stable the release is likely to be. 
2866)     </p>
2867) 
2868)     <hr>
2869) 
2870)     <a id="PrivateTorNetwork"></a>
2871)     <h3><a class="anchor" href="#PrivateTorNetwork">How do I set up my 
2872)     own private Tor network?</a></h3>
2873)     
2874)     <p>
2875)     If you want to experiment locally with your own network, or you're 
2876)     cut off from the Internet and want to be able to mess with Tor still, 
2877)     then you may want to set up your own separate Tor network. 
2878)     </p>
2879)     <p>
2880)     To set up your own Tor network, you need to run your own authoritative 
2881)     directory servers, and your clients and relays must be configured so 
2882)     they know about your directory servers rather than the default public 
2883)     ones. 
2884)     </p>
2885)     <p>
2886)     Apart from the somewhat tedious method of manually configuring a couple 
2887)     of directory authorities, relays and clients there are two separate 
2888)     tools that could help. One is Chutney, the other is Shadow. 
2889)     </p>
2890)     <p>
2891)     <a href="https://gitweb.torproject.org/chutney.git">Chutney</a> is a 
2892)     tool for configuring, controlling and running tests on a 
2893)     testing Tor network. It requires that you have Tor and Python (2.5 or 
2894)     later) installed on your system. You can use Chutney to create a testing
2895)     network by generating Tor configuration files (torrc) and necssary keys 
2896)     (for the directory authorities). Then you can let Chutney start your Tor
2897)     authorities, relays and clients and wait for the network to bootstrap.
2898)     Finally, you can have Chutney run tests on your network to see which 
2899)     things work and which do not. Chutney is typically used for running a 
2900)     testing network with about 10 instances of Tor. Every instance of Tor 
2901)     binds to one or two ports on localhost (127.0.0.1) and all Tor 
2902)     communication is done over the loopback interface. The <a 
2903)     href="https://gitweb.torproject.org/chutney.git/blob/HEAD:/README">Chutney 
2904)     README</a> is a good starting point for getting it up and running. 
2905)     </p>
2906)     <p>
2907)     <a href="https://github.com/shadow/shadow">Shadow</a> is a network 
2908)     simulator that can run Tor through its Scallion plug-in. Although 
2909)     it's typically used for running load and performance tests on 
2910)     substantially larger Tor test networks than what's feasible with 
2911)     Chutney, it also makes for an excellent debugging tool since you can 
2912)     run completely deterministic experiments. A large Shadow network is on 
2913)     the size of thousands of instances of Tor, and you can run experiments 
2914)     out of the box using one of Shadow's several included scallion experiment 
2915)     configurations. Shadow can be run on any linux machine without root, 
2916)     and can also run on EC2 using a pre-configured image. Also, Shadow 
2917)     controls the time of the simulation with the effect that 
2918)     time-consuming tests can be done more efficiently than in an 
2919)     ordinary testing network. The <a 
2920)     href="https://github.com/shadow/shadow/wiki">Shadow wiki</a> and 
2921)     <a href="http://shadow.github.io/">Shadow website</a> are 
2922)     good places to get started. 
2923)     </p>
2924) 
2925)     <hr>
2926) 

2927)     <a id="UseTorWithJava"></a>
2928)     <h3><a class="anchor" href="#UseTorWithJava">How can I make my Java 

2929)     program use the Tor Network?</a></h3>
2930) 
2931)     <p>
2932)     The newest versions of Java now have SOCKS4/5 support built in. 
2933)     Unfortunately, the SOCKS interface is not very well documented and 
2934)     may still leak your DNS lookups. The safest way to use Tor is to 
2935)     interface the SOCKS protocol directly or go through an application-level 
2936)     proxy that speaks SOCKS4a. For an example and libraries that implement 
2937)     the SOCKS4a connection, go to Joe Foley's TorLib in the <a 
2938)     href="http://web.mit.edu/foley/www/TinFoil/">TinFoil Project</a>. 
2939)     </p>
2940) 
2941)     <p>
2942)     A fully Java implementation of the Tor client is now available as <a 
2943)     href="http://www.subgraph.com/orchid.html">Orchid</a>. We still consider 
2944)     Orchid to be experimental, so use with care. 
2945)     </p>
2946) 
2947)     <hr>
2948) 
2949) 
2950)     <a id="WhatIsLibevent"></a>
2951)     <h3><a class="anchor" href="#WhatIsLibevent">What is Libevent?</a></h3>
2952)     
2953)     <p>
2954)     When you want to deal with a bunch of net connections at once, you 
2955)     have a few options: 
2956)     </p>
2957)     <p>
2958)     One is multithreading: you have a separate micro-program inside the 
2959)     main program for each net connection that reads and writes to the 
2960)     connection as needed.This, performance-wise, sucks. 
2961)     </p>
2962)     <p>
2963)     Another is asynchronous network programming: you have a single main 
2964)     program that finds out when various net connections are ready to 
2965)     read/write, and acts accordingly.
2966)     </p>
2967)     <p>
2968)     The problem is that the oldest ways to find out when net connections 
2969)     are ready to read/write, suck. And the newest ways are finally fast, 
2970)     but are not available on all platforms. 
2971)     </p>
2972)     <p>
2973)     This is where Libevent comes in and wraps all these ways to find 
2974)     out whether net connections are ready to read/write, so that Tor 
2975)     (and other programs) can use the fastest one that your platform 
2976)     supports, but can still work on older platforms (these methods are 
2977)     all different depending on the platorm) So Libevent presents a 
2978)     consistent and fast interface to select, poll, kqueue, epoll, 
2979)     /dev/poll, and windows select. 
2980)     </p>
2981)     <p>
2982)     However, On the the Win32 platform (by Microsoft) the only good 
2983)     way to do fast IO on windows with hundreds of sockets is using 
2984)     overlapped IO, which is grossly unlike every other BSD sockets 
2985)     interface. 
2986)     </p>
2987)     <p>Libevent has <a href="http://www.monkey.org/~provos/libevent/">its 
2988)     own website</a>.
2989)     </p>
2990)     <hr>
2991) 
2992)     <a id="MyNewFeature"></a>
2993)     <h3><a class="anchor" href="#MyNewFeature">What do I need to do to get 
2994)     a new feature into Tor?</a></h3>
2995)     
2996)     <p>
2997)     For a new feature to go into Tor, it needs to be designed (explain what 
2998)     you think Tor should do), argued to be secure (explain why it's better 
2999)     or at least as good as what Tor does now), specified (explained at the 
3000)     byte level at approximately the level of detail in tor-spec.txt), and 
3001)     implemented (done in software). 
3002)     </p>
3003) 
3004)     <p>
3005)     You probably shouldn't count on other people doing all of these steps 
3006)     for you: people who are skilled enough to do this stuff generally 
3007)     have their own favorite feature requests.
3008)     </p>
3009) 
3010)     <hr>
3011) 

3012)     <a id="WhatProtectionsDoesTorProvide"></a>
3013)     <h3><a class="anchor" href="#WhatProtectionsDoesTorProvide">What 
3014)     protections does Tor provide?</a></h3>
3015)     
3016)     <p>

3017)     Internet communication is based on a store-and-forward model that 
3018)     can be understood in analogy to postal mail: Data is transmitted in 
3019)     blocks called IP datagrams or packets. Every packet includes a source 
3020)     IP address (of the sender) and a destination IP address (of the 
3021)     receiver), just as ordinary letters contain postal addresses of sender 
3022)     and receiver. The way from sender to receiver involves multiple hops of 
3023)     routers, where each router inspects the destination IP address and 
3024)     forwards the packet closer to its destination. Thus, every router 
3025)     between sender and receiver learns that the sender is communicating 
3026)     with the receiver. In particular, your local ISP is in the position to 
3027)     build a complete profile of your Internet usage. In addition, every 
3028)     server in the Internet that can see any of the packets can profile your 
3029)     behaviour. 

3030)     </p>
3031)     
3032)     <p>
3033)     The aim of Tor is to improve your privacy by sending your traffic through 
3034)     a series of proxies. Your communication is encrypted in multiple layers 
3035)     and routed via multiple hops through the Tor network to the final 
3036)     receiver. More details on this process can be found in the <a 
3037)     href="https://www.torproject.org/about/overview">Tor overview</a>. 
3038)     Note that all your local ISP can observe now is that you are 
3039)     communicating with Tor nodes. Similarly, servers in the Internet just 
3040)     see that they are being contacted by Tor nodes.
3041)     </p>
3042)     
3043)     <p>
3044)     Generally speaking, Tor aims to solve three privacy problems: 
3045)     </p>
3046)     
3047)     <p>
3048)     First, Tor prevents websites and other services from learning 
3049)     your location, which they can use to build databases about your 
3050)     habits and interests. With Tor, your Internet connections don't 
3051)     give you away by default -- now you can have the ability to choose, 
3052)     for each connection, how much information to reveal. 
3053)     </p>
3054)     
3055)     <p>
3056)     Second, Tor prevents people watching your traffic locally (such as 
3057)     your ISP) from learning what information you're fetching and where 
3058)     you're fetching it from. It also stops them from deciding what you're 
3059)     allowed to learn and publish -- if you can get to any part of the Tor 
3060)     network, you can reach any site on the Internet.     
3061)     </p>
3062) 
3063)     <p>
3064)     Third, Tor routes your connection through more than one Tor relay 
3065)     so no single relay can learn what you're up to. Because these relays 
3066)     are run by different individuals or organizations, distributing trust 
3067)     provides more security than the old <a href="#Torisdifferent">one hop proxy
3068)     </a> approach. 
3069)     </p>
3070)     
3071)     <p>
3072)     Note, however, that there are situations where Tor fails to solve these 
3073)     privacy problems entirely: see the entry below on <a 
3074)     href="#AttacksOnOnionRouting">remaining attacks</a>.    
3075)     </p>
3076)     
3077)     <hr>
3078)     
3079)     <a id="CanExitNodesEavesdrop"></a>
3080)     <h3><a class="anchor" href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop 
3081)     on communications? Isn't that bad?</a></h3>
3082)     
3083)     <p>
3084)     Yes, the guy running the exit node can read the bytes that come in and 
3085)     out there. Tor anonymizes the origin of your traffic, and it makes sure 
3086)     to encrypt everything inside the Tor network, but it does not magically 
3087)     encrypt all traffic throughout the Internet. 
3088)     </p>
3089)     
3090)     <p>
3091)     This is why you should always use end-to-end encryption such as SSL for 
3092)     sensitive Internet connections. (The corollary to this answer is that if 
3093)     you are worried about somebody intercepting your traffic and you're 
3094)     *not* using end-to-end encryption at the application layer, then something 
3095)     has already gone wrong and you shouldn't be thinking that Tor is the problem.) 
3096)     </p>
3097)     
3098)     <p>
3099)     Tor does provide a partial solution in a very specific situation, though. 
3100)     When you make a connection to a destination that also runs a Tor relay, 
3101)     Tor will automatically extend your circuit so you exit from that circuit. 
3102)     So for example if Indymedia ran a Tor relay on the same IP address as 
3103)     their website, people using Tor to get to the Indymedia website would 
3104)     automatically exit from their Tor relay, thus getting *better* encryption 
3105)     and authentication properties than just browsing there the normal way. 
3106)     </p>
3107) 
3108)     <p>
3109)     We'd like to make it still work even if the service is nearby the Tor 
3110)     relay but not on the same IP address. But there are a variety of 
3111)     technical problems we need to overcome first (the main one being "how 
3112)     does the Tor client learn which relays are associated with which 
3113)     websites in a decentralized yet non-gamable way?"). 
3114)     </p>
3115)             
3116)     <hr>
3117)     

3118)     <a id="AmITotallyAnonymous"></a>
3119)     <h3><a class="anchor" href="#AmITotallyAnonymous">So I'm totally anonymous 
3120)     if I use Tor?</a></h3>
3121) 
3122)     <p>
3123)     <b>No.</b>
3124)     </p>
3125)     <p>
3126)     First, Tor protects the network communications. It separates where you 
3127)     are from where you are going on the Internet. What content and data you 
3128)     transmit over Tor is controlled by you. If you login to Google or 
3129)     Facebook via Tor, the local ISP or network provider doesn't know you 
3130)     are visiting Google or Facebook. Google and Facebook don't know where 
3131)     you are in the world. However, since you have logged into their sites, 
3132)     they know who you are. If you don't want to share information, you are 
3133)     in control. 
3134)     </p>
3135) 
3136)     <p>
3137)     Second, active content, such as Java, Javascript, Adobe Flash, Adobe 
3138)     Shockwave, QuickTime, RealAudio, ActiveX controls, and VBScript, are 
3139)     binary applications. These binary applications run as your user account 
3140)     with your permissions in your operating system. This means these 
3141)     applications can access anything that your user account can access. Some 
3142)     of these technologies, such as Java and Adobe Flash for instance, run in 
3143)     what is known as a virtual machine. This virtual machine may have the 
3144)     ability to ignore your configured proxy settings, and therefore bypass 
3145)     Tor and share information directly to other sites on the Internet. The 
3146)     virtual machine may be able to store data, such as cookies, completely 
3147)     separate from your browser or operating system data stores. Therefore, 
3148)     these technologies must be disabled in your browser to use Tor safely.
3149)     </p>
3150)     <p>
3151)     That's where the <a 
3152)     href="https://torproject.org/projects/torbrowser.html.en">Tor Browser 
3153)     Bundle</a> comes in. We produce a web browser that is preconfigured to 
3154)     help you control the risks to your privacy and anonymity while browsing 
3155)     the Internet. Not only are the above technologies disabled to prevent 
3156)     identity leaks, the Tor Browser also includes browser extensions like 
3157)     NoScript and Torbutton, as well as patches to the Firefox source
3158)     code. The full design of the Tor Browser can be read <a 
3159)     href="https://www.torproject.org/projects/torbrowser/design/">here</a>. 
3160)     In designing a safe, secure solution for browsing the web with Tor,