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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)     </ul>
94) 
95)     <p>Advanced Tor usage:</p>

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

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

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

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

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

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

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

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

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

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

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

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

121)     </ul>

122) 

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

125) 
126)     <li><a href="#HowDoIDecide">How do I decide if I should run a relay?
127)     </a></li>

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

132)     <li><a href="#RelayFlexible">How stable does my relay need to
133) be?</a></li>
134)     <li><a href="#ExitPolicies">I'd run a relay, but I don't want to
135) deal

136)     with abuse issues.</a></li>
137)     <li><a href="#RelayOrBridge">Should I be a normal relay or bridge
138)     relay?</a></li>

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

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

143)     <li><a href="#NTService">How do I run my Tor relay as an NT service?
144)     </a></li>
145)     <li><a href="#VirtualServer">Can I run a Tor relay from my virtual server 
146)     account?</a></li>

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

149)     <li><a href="#RelayMemory">Why is my Tor relay using so much memory?
150)     </a></li>
151)     <li><a href="#BetterAnonymity">Do I get better anonymity if I run a relay?
152)     </a></li>

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

155)     </ul>

156) 

157)     <p>Tor hidden services:</p>
158)     <ul>
159)     <li><a href="#AccessHiddenServices">How do I access hidden services?</a></li>
160)     <li><a href="#ProvideAHiddenService">How do I provide a hidden service</a></li>
161)     </ul>

162) 

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

177)     <p>Anonymity and Security:</p>
178)     <ul>

179)     <li><a href="#WhatProtectionsDoesTorProvide">What protections does Tor 
180)     provide?</a></li>
181)     <li><a href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop on 
182)     communications? Isn't that bad? </a></li>
183)     <li><a href="#ExitEnclaving">What is Exit Enclaving?</a></li>

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

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

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

188)     <li><a href="#CellSize">Tor uses hundreds of bytes for every IRC line. I 
189)     can't afford that!</a></li>
190)     <li><a href="#OutboundConnections">Why does netstat show these outbound 
191)     connections?</a></li>
192)     <li><a href="#PowerfulBlockers">What about powerful blocking mechanisms
193)     </a></li>
194)     <li><a href="#RemotePhysicalDeviceFingerprinting">Does Tor resist 
195)     "remote physical device fingerprinting"?</a></li>

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

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

201)     </ul>

202) 

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

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

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

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

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

222)     <li><a href="#SendPadding">You should send padding so it's more secure.
223)     </a></li>
224)     <li><a href="#Steganography">You should use steganography to hide Tor 
225)     traffic.</a></li>

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

227)     </ul>

228) 

229)     <p>Abuse:</p>

230)     <ul>

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

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

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

237)     </ul>

238) 

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

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

242) 

243)     <hr>

244) 

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

246) 

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

249) 

250)     <p>
251)     The name "Tor" can refer to several different components.
252)     </p>

253) 

254)     <p>

255)     The Tor software is a program you can run on your computer that
256) helps keep
257)     you safe on the Internet. Tor protects you by bouncing your
258) communications

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

260)     the world: it prevents somebody watching your Internet connection
261) from

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

263)     from learning your physical location. This set of volunteer relays
264) is
265)     called the Tor network. You can read more about how Tor works on the
266) <a

267)     href="<page about/overview>">overview page</a>.
268)     </p>

269) 

270)     <p>

271)     The Tor Project is a non-profit (charity) organization that
272) maintains

273)     and develops the Tor software.
274)     </p>

275) 

276)     <hr>

277) 

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

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

302) free wifi Internet.
303)     </p>
304)     <p>

305)     Simple proxy providers also create a single point of failure.  The
306) provider
307) knows who you are and where you browse on the Internet.  They can see
308) your
309) traffic as it passes through their server.  In some cases, they can even
310) see

311) inside your

312) encrypted traffic as they relay it to your banking site or to ecommerce
313) stores.

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

315) watching your traffic, injecting their own advertisements into your
316) traffic

317) stream, and recording your personal details.

318)     </p>
319)     <p>

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

336) packets between themselves.</p>

337)     <p>
338)     <dl>

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

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

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

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

355) e-commerce website, or encrypted mail connections, etc, it will only
356) know the
357) destination.  It won't be able to see the data inside the traffic
358) stream.  You

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

361)     </dl>
362)     </p>

363) 

364)     <hr>

365) 

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

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

369) 

370)     <p>

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

375)     </p>
376)     <p>
377)     There are plenty of other programs you can use with Tor,
378)     but we haven't researched the application-level anonymity

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

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

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

382)     specific applications</a>.

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

385) 

386)     <hr>

387) 

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

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

391) 

392)     <p>
393)     Because Tor is the onion routing network. When we were starting the
394)     new next-generation design and implementation of onion routing in
395)     2001-2002, we would tell people we were working on onion routing,
396)     and they would say "Neat. Which one?" Even if onion routing has
397)     become a standard household term, Tor was born out of the actual <a
398)     href="http://www.onion-router.net/">onion routing project</a> run by
399)     the Naval Research Lab.
400)     </p>

401) 

402)     <p>
403)     (It's also got a fine translation from German and Turkish.)
404)     </p>

405) 

406)     <p>

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

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

410)     spot people who haven't read any of our website (and have instead
411) learned
412)     everything they know about Tor from news articles) by the fact that
413) they

414)     spell it wrong.
415)     </p>

416) 

417)     <hr>

418) 

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

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

422) 

423)     <p>

424)     There is absolutely no backdoor in Tor. Nobody has asked us to put
425) one
426)     in, and we know some smart lawyers who say that it's unlikely that
427) anybody

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

431) 

432)     <p>
433)     We think that putting a backdoor in Tor would be tremendously

434)     irresponsible to our users, and a bad precedent for security
435) software

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

440) 

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

444)     computers, or something like that. Tor is open source, and you
445) should
446)     always check the source (or at least the diffs since the last
447) release)

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

454) 

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

457)     anonymity. We periodically find and fix anonymity-related bugs, so
458) make

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

461) 

462)     <hr>

463) 

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

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

467) 

468)     <p>
469)     Yes.
470)     </p>

471) 

472)     <p>

473)     The Tor software is <a href="https://www.fsf.org/">free
474) software</a>. This
475)     means we give you the rights to redistribute the Tor software,
476) either
477)     modified or unmodified, either for a fee or gratis. You don't have
478) to

479)     ask us for specific permission.
480)     </p>

481) 

482)     <p>

483)     However, if you want to redistribute the Tor software you must
484) follow our

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

486)     Essentially this means that you need to include our LICENSE file
487) along

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

490) 

491)     <p>

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

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

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

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

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

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

507)     </p>

508) 

509)     <p>

510)     Also, you should make sure not to confuse your readers about what
511) Tor is,
512)     who makes it, and what properties it provides (and doesn't provide).
513) See
514)     our <a href="<page docs/trademark-faq>">trademark FAQ</a> for
515) details.

516)     </p>

517) 

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

521)     changes. So if you distribute a particular version of the Tor
522) software, it
523)     may not be supported — or even work — six months later.
524) This

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

527) 

528)     <hr>

529) 

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

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

533) 

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

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

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

539)     <li>Read through the <a

540) 
541) href="https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk">
542) tor-talk

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

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

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

547)     <li>Send an email to <a

548) 
549) href="mailto:help@rt.torproject.org">help@rt.torproject.org</a>.</li>
550)     <li>If all else fails, try <a href="<page about/contact>">contacting
551) us</a> directly.</li>

552)     </ol>

553) 

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

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

557) 

558)     <hr>

559) 

560)     <a id="Forum"></a>
561)     <h3><a class="anchor" href="#Forum">Is there a Tor forum?</a></h3>
562) 

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

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

565)     </p>
566) 
567)     <hr>
568) 

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

571) 

572)     <p>
573)     There are many reasons why the Tor network is currently slow.
574)     </p>

575) 

576)     <p>

577)     Before we answer, though, you should realize that Tor is never going
578) to
579)     be blazing fast. Your traffic is bouncing through volunteers'
580) computers
581)     in various parts of the world, and some bottlenecks and network
582) latency

583)     will always be present. You shouldn't expect to see university-style
584)     bandwidth through Tor.
585)     </p>

586) 

587)     <p>

588)     But that doesn't mean that it can't be improved. The current Tor
589) network
590)     is quite small compared to the number of people trying to use it,
591) and
592)     many of these users don't understand or care that Tor can't
593) currently

594)     handle file-sharing traffic load.
595)     </p>

596) 

597)     <p>
598)     For the much more in-depth answer, see <a

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

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

602)     to go with it.
603)     </p>

604) 

605)     <p>
606)     What can you do to help?
607)     </p>

608) 

609)     <ul>

610) 

611)     <li>

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

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

618) 

619)     <li>

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

622)     especially need people to help make it easier to configure your Tor
623)     as a relay. Also, we need help with clear simple documentation to
624)     walk people through setting it up.
625)     </li>

626) 

627)     <li>

628)     There are some bottlenecks in the current Tor network. Help us
629) design
630)     experiments to track down and demonstrate where the problems are,
631) and

632)     then we can focus better on fixing them.
633)     </li>

634) 

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

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

641)     get to spend more time on it.
642)     </li>

643) 

644)     <li>

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

649)     getinvolved/volunteer>">look at our volunteer page</a>.
650)     </li>

651) 

652)     <li>

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

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

656)     competition's websites discreetly, or to connect back to the home
657) servers
658)     when on the road without revealing affiliations? If your
659) organization has
660)     an interest in keeping the Tor network working, please contact them
661) about
662)     supporting Tor. Without sponsors, Tor is going to become even
663) slower.

664)     </li>

665) 

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

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

670)     cause</a>. It adds up!
671)     </li>

672) 

673)     </ul>

674) 

675)     <hr>

676) 

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

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

680) 
681)     <p>

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

688)     </p>
689) 
690)     <hr>
691) 

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

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

695) 

696)     <p>

697)     The Tor network's <a

698) 
699) href="https://metrics.torproject.org/network.html#networksize">several

700)     thousand</a> relays push <a
701)     href="https://metrics.torproject.org/network.html#bandwidth">over
702)     1GB per second on average</a>. We have <a

703) 
704) href="https://metrics.torproject.org/users.html#direct-users">several

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

707)     </p>

708) 

709)     <p>

710)     There are six main development/maintenance pushes that need
711) attention:

712)     </p>

713) 

714)     <ul>

715) 

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

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

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

723) 

724)     <li>

725)     User support: With this many users, a lot of people are asking
726) questions
727)     all the time, offering to help out with things, and so on. We need
728) good
729)     clean docs, and we need to spend some effort coordinating
730) volunteers.

731)     </li>

732) 

733)     <li>

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

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

737)     reminders to upgrade, and so on. The network itself is a commons,
738) and
739)     somebody needs to spend some energy making sure the relay operators
740) stay
741)     happy. We also need to work on stability on some platforms —
742) e.g.,

743)     Tor relays have problems on Win XP currently.

744)     </li>

745) 

746)     <li>

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

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

759) 

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

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

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

767) 

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

773)     critical <a href="<page getinvolved/volunteer>#Research">Tor
774) research questions</a>
775)     that will help us figure out how to make Tor secure against the
776) variety of
777)     attacks out there. Of course, there are more research questions
778) waiting

779)     behind these.
780)     </li>

781) 

782)     </ul>

783) 

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

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

788)     can keep up</a>.

789)     Now would be an excellent time to add a few more developers to the
790) effort

791)     so we can continue to grow the network.
792)     </p>

793) 

794)     <p>
795)     We are also excited about tackling related problems, such as
796)     censorship-resistance.
797)     </p>

798) 

799)     <p>

800)     We are proud to have <a href="<page about/sponsors>">sponsorship and
801) support</a>
802)     from the Omidyar Network, the International Broadcasting Bureau,
803) Bell
804)     Security Solutions, the Electronic Frontier Foundation, several
805) government

806)     agencies and research groups, and hundreds of private contributors.
807)     </p>

808) 

809)     <p>

810)     However, this support is not enough to keep Tor abreast of changes
811) in the
812)     Internet privacy landscape. Please <a href="<page
813) donate/donate>">donate</a>
814)     to the project, or <a href="<page about/contact>">contact</a> our
815) executive

816)     director for information on making grants or major donations.
817)     </p>

818) 

819)     <hr>
820) 

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

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

824) 
825)     <p>

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

830)     </p>
831)     <p>

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

839)     </p>
840)     <p>

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

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

843)     </p>
844)     <p>

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

850)     </p>
851)     
852)     <hr>
853)     
854)     <a id="IsItWorking"></a>

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

857) 
858)     <p>

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

862)     </p>
863)     <p>

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

870)     </p>
871)     <p>

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

875)     </p>
876)     <p>

877)     If you are behind a NAT or firewall, though, your IP address will be 
878)     within the range of 10.XXX.XXX.XXX, 192.168.XXX.XXX, or 172.16.XXX.XXX - 
879)     172.31.XXX.XXX, which is not your public IP address. In this case, you 
880)     should check your IP address with one of the sites above without using 
881)     Tor, and then check again using Tor to see whether your IP address has 
882)     changed. 

883)     </p>
884)     
885)     <hr>
886)     
887)     <a id="FTP"></a>
888)     <h3><a class="anchor" href="#FTP">How do I use my browser for ftp with Tor?
889)     </a></h3>
890) 

891)     <p>
892)     Use the Tor Browser Bundle. If you want a separate application for an 
893)     ftp client, we've heard good things about  FileZilla for Windows. You can 
894)     configure it to point to Tor as a "socks4a" proxy on "localhost" port 
895)     "9050". 
896)     </p>

897)     <hr>
898)     

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

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

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

902) 

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

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

906)     <hr>

907) 

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

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

911)     <p>

912)     <pre>

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

914)     The serial number is:

915) 06:DE:97:E5:1D:C3:9D:C2:64:8D:AC:72:DD:41:01:FC
916)     The SHA-1 fingerprint is: 1f9d306e8bfccfcb03981a71a27a9f5d1e0876ce

917)     The SHA-256 fingerprint is:

918) 3613d2b22a750094760c41ad19db52a4f05bdea80172e2578761ad967f7ed9aa

919) 

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

921)     The serial number is: 00:EF:A3
922)     The SHA-1 fingerprint is: 50af43db8438e67f305a3257d8ef198e8c42f13f

923)     </pre>

924)     </p>
925)     <hr>
926) 

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

928)     <h3><a class="anchor" href="#HowUninstallTor">How do I uninstall
929) Tor?</a></h3>
930) 
931)     <p>
932)     Tor Browser does not install itself in the classic sense of
933) applications. You just simply delete the folder or directory named "Tor
934) Browser" and it is removed from your system.
935)     </p>

936) 

937)     <p>

938)     If this is not related to Tor Browser, uninstallation depends
939) entirely on how you installed it and which operating system you
940)     have. If you installed a package, then hopefully your package has a
941) way to

942)     uninstall itself. The Windows packages include uninstallers. 

943)     </p>

944) 

945)     <p>
946)     For Mac OS X, follow the <a
947)     href="<page docs/tor-doc-osx>#uninstall">uninstall directions</a>.
948)     </p>

949) 

950)     <p>

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

955)     be pretty easy to notice things there.
956)     </p>

957) 

958)     <hr>

959) 

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

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

963) 

964)     <p>

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

967)     exactly the one that we intended you to get.
968)     </p>

969) 

970)     <p>
971)     Please read the <a

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

974)     </p>

975) 

976) <hr>
977) 
978) <a id="GetTor"></a>
979) <h3><a class="anchor" href="#GetTor">Your website is blocked in my
980) country. How do I download Tor?</a></h3>
981) 
982) <p>
983) Some government or corporate firewalls censor connections to Tor's
984) website. In those cases, you have three options. First, get it from

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

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

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

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

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

993) in the body of the email, it will reply with instructions. Note that
994) only a few webmail providers are supported, since they need to be able
995) to receive very large attachments.
996) </p>
997) 
998) <p>

999) Be sure to <a href="<page docs/verifying-signatures>">verify the
1000) signature</a>

1001) of any package you download, especially when you get it from somewhere
1002) other than our official HTTPS website.

1003) </p>
1004) 
1005) <hr>

1006) 

1007)     <a id="CompileTorWindows"></a>

1008)     <h3><a class="anchor" href="#CompileTorWindows">How do I compile Tor
1009) under Windows?</a></h3>

1010) 

1011)     <p>

1012)     Try following the steps at <a
1013) href="<gitblob>doc/tor-win32-mingw-creation.txt">

1014)     tor-win32-mingw-creation.txt</a>.
1015)     </p>

1016) 

1017)     <p>
1018)     (Note that you don't need to compile Tor yourself in order to use

1019)     it. Most people just use the packages available on the <a
1020) href="<page

1021)     download/download>">download page</a>.)
1022)     </p>

1023) 

1024)     <hr>

1025) 

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

1027)     <h3><a class="anchor" href="#VirusFalsePositives">Why does my Tor
1028) executable appear to have a virus or spyware?</a></h3>

1029) 

1030)     <p>

1031)     Sometimes, overzealous Windows virus and spyware detectors trigger
1032) on some
1033)     parts of the Tor Windows binary. Our best guess is that these are
1034) false
1035)     positives — after all, the anti-virus and anti-spyware
1036) business is just a
1037)     guessing game anyway. You should contact your vendor and explain
1038) that you have
1039)     a program that seems to be triggering false positives. Or pick a
1040) better vendor.

1041)     </p>

1042) 

1043)     <p>
1044)     In the meantime, we encourage you to not just take our word for

1045)     it. Our job is to provide the source; if you're concerned, please do
1046) <a

1047)     href="#CompileTorWindows">recompile it yourself</a>.
1048)     </p>

1049) 

1050)     <hr>

1051) 

1052)     <a id="LiveCD"></a>

1053)     <h3><a class="anchor" href="#LiveCD">Is there a LiveCD or other
1054) bundle that includes Tor?</a></h3>

1055) 

1056)     <p>

1057)     Yes.  Use <a href="https://tails.boum.org/">The Amnesic Incognito

1058)     Live System</a> or <a href="<page projects/torbrowser>">the Tor
1059) Browser

1060)     Bundle</a>.

1061)     </p>

1062) 
1063) <hr>
1064) 

1065) <a id="TBBFlash"></a>

1066) <h3><a class="anchor" href="#TBBFlash">Why can't I view videos on
1067) YouTube

1068) and other Flash-based sites?</a></h3>

1069) 
1070) <p>

1071) YouTube and similar sites require third party browser plugins such as Flash.
1072) Plugins operate independently from Firefox and can perform
1073) activity on your computer that ruins your anonymity. This includes
1074) but is not limited to: <a href="http://decloak.net">completely disregarding
1075) proxy settings</a>, querying your <a

1076) href="http://forums.sun.com/thread.jspa?threadID=5162138&messageID=9618376">
1077) local IP address</a>, and <a

1078) href="http://epic.org/privacy/cookies/flash.html">storing their own
1079) cookies</a>. It is possible to use a LiveCD solution such as

1080) or <a href="https://tails.boum.org/">The Amnesic Incognito Live System</a> 
1081) that creates a secure, transparent proxy to protect you from proxy bypass, 
1082) however issues with local IP address discovery and Flash cookies still remain. 
1083) </p>

1084) 
1085) <p>

1086) <a href="https://www.youtube.com/html5">YouTube offers experimental HTML5 video
1087) support</a> for many of their videos. You can use their Advanced Search to

1088) find HTML5 videos.
1089) </p>
1090) 

1091) <hr>
1092) 

1093) <a id="Ubuntu"></a>
1094) <h3><a class="anchor" href="#Ubuntu">
1095) I'm using Ubuntu and I can't start Tor Browser</a></h3>
1096) <p>

1097) Ubuntu prevents its users from executing shell scripts by clicking them, 
1098) even when the file permissions are set correctly. For now you need to 
1099) start the Tor Browser from the command line by running </p>

1100) <pre>
1101) ./start-tor-browser
1102) </pre>
1103) <p>
1104) from inside the Tor Browser directory.
1105) </p>
1106) 
1107) <hr>
1108) 

1109) <a id="TBBSocksPort"></a>

1110) <h3><a class="anchor" href="#TBBSocksPort">

1111) I want to run another application through the Tor launched by Tor

1112) Browser Bundle.</a></h3>

1113) 
1114) <p>

1115) Typically Tor listens for Socks connections on port 9050. TBB listens

1116) on port 9150.

1117) The goal is to avoid conflicting with a "system" Tor install,

1118) so you can run a system Tor and TBB at the same time. We're <a
1119) href="https://trac.torproject.org/projects/tor/ticket/3948">working on
1120) a feature</a> where Tor will try the usual ports first and then back

1121) off to a random choice if they're already in use.

1122) </p>
1123) 
1124) <hr>
1125) 
1126) <a id="TBBPolipo"></a>
1127) <h3><a class="anchor" href="#TBBPolipo">I need an HTTP proxy. Where did
1128) Polipo go?</a></h3>
1129) 
1130) <p>
1131) In the past, Tor bundles included an HTTP proxy like Privoxy or Polipo,
1132) solely to work around a bug in Firefox that was finally fixed in Firefox
1133) 6. Now you don't need a separate HTTP proxy to use Tor, and in fact
1134) leaving it out makes you safer because Torbutton has better control over
1135) Firefox's interaction with websites.
1136) </p>
1137) 
1138) <p>
1139) If you are trying to use some external application with Tor, step zero

1140) should be to <a href="<page download/download>#warning">reread the set

1141) of warnings</a> for ways you can screw up. Step one should be to try

1142) to use a Socks proxy rather than an http proxy — Tor runs a Socks

1143) proxy on port 9050 on Windows, or <a href="#TBBSocksPort">see above</a>
1144) for OSX and Linux.
1145) </p>
1146) 
1147) <p>

1148) If that fails, feel free to install <a

1149) href="http://www.privoxy.org/">privoxy</a>.
1150) However, please realize that this approach is not recommended for novice
1151) users. Privoxy has an <a
1152) href="http://www.privoxy.org/faq/misc.html#TOR">example
1153) configuration</a> of Tor and Privoxy.

1154) </p>
1155) 
1156) <hr>
1157) 

1158) <a id="TBBOtherExtensions"></a>
1159) <h3><a class="anchor" href="#TBBOtherExtensions">Can I install other
1160) Firefox extensions?</a></h3>
1161) 
1162) <p>

1163) The Tor Browser is free software, so there is nothing preventing you from 
1164) modifying it any way you like. However, we do not recommend installing any 
1165) additional Firefox add-ons with the Tor Browser Bundle. Add-ons can break 
1166) your anonymity in a number of ways, including browser fingerprinting and 
1167) bypassing proxy settings.

1168) </p>

1169) <p>

1170) Some people have suggested we include ad-blocking software or 
1171) anti-tracking software with the Tor Browser Bundle. Right now, we do not 
1172) think that's such a good idea. The Tor Browser Bundle aims to provide 
1173) sufficient privacy that additional add-ons to stop ads and trackers are 
1174) not necessary. Using add-ons like these may cause some sites to break, which 
1175) <a href="https://www.torproject.org/projects/torbrowser/design/#philosophy">
1176) we don't want to do</a>. Additionally, maintaining a list of "bad" sites that 
1177) should be black-listed provides another opportunity to uniquely fingerprint 
1178) users. 

1179) </p>

1180) 

1181) <hr>
1182) 

1183) <a id="TBBJavaScriptEnabled"></a>

1184) <a id="TBBCanIBlockJS"></a>

1185) <h3><a class="anchor" href="#TBBJavaScriptEnabled">Why is NoScript
1186) configured to allow JavaScript by default in the Tor Browser Bundle?
1187) Isn't that unsafe?</a></h3>

1188) 
1189) <p>
1190) We configure NoScript to allow JavaScript by default in the Tor
1191) Browser Bundle because many websites will not work with JavaScript
1192) disabled.  Most users would give up on Tor entirely if a website
1193) they want to use requires JavaScript, because they would not know
1194) how to allow a website to use JavaScript (or that enabling
1195) JavaScript might make a website work).
1196) </p>
1197) 

1198) <p>
1199) There's a tradeoff here. On the one hand, we should leave
1200) JavaScript enabled by default so websites work the way
1201) users expect. On the other hand, we should disable JavaScript
1202) by default to better protect against browser vulnerabilities (<a

1203) href="https://blog.torproject.org/blog/tor-security-advisory-old-tor-browser-bundles-vulnerable">
1204) not just a theoretical concern!</a>). But there's a third issue: websites

1205) can easily determine whether you have allowed JavaScript for them,
1206) and if you disable JavaScript by default but then allow a few websites
1207) to run scripts (the way most people use NoScript), then your choice of
1208) whitelisted websites acts as a sort of cookie that makes you recognizable
1209) (and distinguishable), thus harming your anonymity.
1210) </p>

1211) 
1212) <p>

1213) Ultimately, we want the default Tor bundles to use
1214) a combination of firewalls (like the iptables rules
1215) in <a href="https://tails.boum.org/">Tails</a>) and <a
1216) href="https://trac.torproject.org/projects/tor/ticket/7680">sandboxes</a>
1217) to make JavaScript not so scary. In
1218) the shorter term, TBB 3.0 will hopefully <a
1219) href="https://trac.torproject.org/projects/tor/ticket/9387">allow users
1220) to choose their JavaScript settings more easily</a> &mdash; but the
1221) partitioning concern will remain.

1222) </p>
1223) 
1224) <p>

1225) Until we get there, feel free to leave JavaScript on or off depending
1226) on your security, anonymity, and usability priorities.

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

1231) <a id="TBBOtherBrowser"></a>
1232) <h3><a class="anchor" href="#TBBOtherBrowser">I want to use
1233) Chrome/IE/Opera/etc with Tor.</a></h3>
1234) 
1235) <p>
1236) Unfortunately, Torbutton only works with Firefox right now, and without
1237) <a href="https://www.torproject.org/torbutton/en/design/">Torbutton's
1238) extensive privacy fixes</a> there are many ways for websites or other

1239) attackers to recognize you, track you back to your IP address, and so
1240) on.

1241) In short, using any browser besides Tor Browser Bundle with Tor is a
1242) really bad idea.
1243) </p>
1244) 
1245) <p>
1246) We're working with the Chrome team to <a

1247) href="https://blog.torproject.org/blog/google-chrome-incognito-mode-tor-
1248) and-fingerprinting">fix
1249) some bugs and missing APIs in Chrome</a> so it will be possible to write
1250) a
1251) Torbutton for Chrome. No support for any other browser is on the
1252) horizon.

1253) </p>
1254) 
1255) <hr>
1256) 

1257) <a id="TorbuttonOtherBrowser"></a>

1258) <h3><a class="anchor" href="TorbuttonOtherBrowser">
1259) Will ​Torbutton be available for other browsers?</a></h3>

1260) 
1261) <p>

1262)  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.

1263) </p>
1264) <p>

1265) 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. 

1266) </p>
1267) 

1268) <hr>

1269) 

1270) <a id="TBBCloseBrowser"></a>

1271) <h3><a class="anchor" href="#TBBCloseBrowser">I want to leave Tor
1272) Browser

1273) Bundle running but close the browser.</a></h3>
1274) 
1275) <p>
1276) We're working on a way to make this possible on all platforms. Please
1277) be patient.
1278) </p>
1279) 
1280) <hr>
1281) 

1282) <a id="GoogleCAPTCHA"></a>
1283) <h3><a class="anchor" href="#GoogleCAPTCHA">Google makes me solve a
1284) CAPTCHA or tells me I have spyware installed.</a></h3>

1285) 
1286) <p>
1287) This is a known and intermittent problem; it does not mean that Google
1288) considers Tor to be spyware.
1289) </p>
1290) 
1291) <p>

1292) When you use Tor, you are sending queries through exit relays that are
1293) also

1294) shared by thousands of other users. Tor users typically see this message

1295) when many Tor users are querying Google in a short period of time.
1296) Google

1297) interprets the high volume of traffic from a single IP address (the exit
1298) relay you happened to pick) as somebody trying to "crawl" their website,
1299) so it slows down traffic from that IP address for a short time.
1300) </p>
1301) <p>
1302) An alternate explanation is that Google tries to detect certain
1303) kinds of spyware or viruses that send distinctive queries to Google
1304) Search. It notes the IP addresses from which those queries are received
1305) (not realizing that they are Tor exit relays), and tries to warn any
1306) connections coming from those IP addresses that recent queries indicate
1307) an infection.
1308) </p>
1309) 
1310) <p>

1311) To our knowledge, Google is not doing anything intentionally
1312) specifically

1313) to deter or block Tor use. The error message about an infected machine
1314) should clear up again after a short time.
1315) </p>
1316) 
1317) <p>
1318) Torbutton 1.2.5 (released in mid 2010) detects Google captchas and can
1319) automatically redirect you to a more Tor-friendly search engine such as

1320) DuckDuckGo, ixquick, or Bing.

1321) </p>
1322) 
1323) <hr />
1324) 

1325) <a id="ForeignLanguages"></a>
1326) <h3><a class="anchor" href="#ForeignLanguages">
1327) Why does Google show up in foreign languages?</a></h3>
1328) 
1329) <p>

1330)  Google uses "geolocation" to determine where in the world you are, so it 
1331)  can give you a personalized experience. This includes using the language 
1332)  it thinks you prefer, and it also includes giving you different results 
1333)  on your queries.

1334) </p>
1335) <p>

1336) If you really want to see Google in English you can click the link that 
1337) provides that. But we consider this a feature with Tor, not a bug --- the 
1338) Internet is not flat, and it in fact does look different depending on 
1339) where you are. This feature reminds people of this fact. The easy way to 
1340) avoid this "feature" is to use 
1341) <a href="https://google.com/ncr">https://google.com/ncr</a>.

1342) </p>
1343) <p>

1344) Note that Google search URLs take name/value pairs as arguments and one 
1345) of those names is "hl". If you set "hl" to "en" then Google will return 
1346) search results in English regardless of what Google server you have been 
1347) sent to. On a query this looks like: 
1348) </p>
1349) <pre>https://encrypted.google.com/search?q=online%20anonymity&hl=en

1350) </pre>

1351) <p>

1352) Another method is to simply use your country code for accessing Google. 
1353) This can be google.be, google.de, google.us and so on. 

1354) </p>
1355) <hr />

1356) <a id="GmailWarning"></a>

1357) <h3><a class="anchor" href="#GmailWarning">Gmail warns me that my

1358) account may have been compromised.</a></h3>

1359) 
1360) <p>
1361) Sometimes, after you've used Gmail over Tor, Google presents a
1362) pop-up notification that your account may have been compromised.
1363) The notification window lists a series of IP addresses and locations
1364) throughout the world recently used to access your account.
1365) </p>
1366) 
1367) <p>
1368) In general this is a false alarm: Google saw a bunch of logins from

1369) different places, as a result of running the service via Tor, and
1370) decided

1371) it was a good idea to confirm the account was being accessed by it's
1372) rightful owner.
1373) </p>
1374) 
1375) <p>
1376) Even though this may be a biproduct of using the service via tor,
1377) that doesn't mean you can entirely ignore the warning. It is
1378) <i>probably</i> a false positive, but it might not be since it is
1379) possible for someone to hijack your Google cookie.
1380) </p>
1381) 
1382) <p>
1383) Cookie hijacking is possible by either physical access to your computer
1384) or by watching your network traffic.  In theory only physical access
1385) should compromise your system because Gmail and similar services
1386) should only send the cookie over an SSL link. In practice, alas, it's <a

1387) href="http://fscked.org/blog/fully-automated-active-https-cookie-
1388) hijacking">

1389) way more complex than that</a>.
1390) </p>
1391) 
1392) <p>
1393) And if somebody <i>did</i> steal your google cookie, they might end
1394) up logging in from unusual places (though of course they also might
1395) not). So the summary is that since you're using Tor, this security
1396) measure that Google uses isn't so useful for you, because it's full of
1397) false positives. You'll have to use other approaches, like seeing if
1398) anything looks weird on the account, or looking at the timestamps for
1399) recent logins and wondering if you actually logged in at those times.
1400) </p>
1401) 
1402) <hr>
1403) 

1404) <a id="NeedToUseAProxy"></a>
1405) <h3><a class="anchor" href="#NeedToUseAProxy">My internet connection requires an HTTP 
1406)     or SOCKS Proxy</a></h3>
1407) 
1408) <p>
1409) You can set Proxy IP address, port, and authentication information in 
1410) Tor Browser's Network Settings. If you're using Tor another way, check 
1411) out the HTTPProxy and HTTPSProxy config options in the <a 
1412) href="https://www.torproject.org/docs/tor-manual.html.en">man page</a>, 
1413) and modify your torrc file accordingly. You will need an HTTP proxy for 
1414) doing GET requests to fetch the Tor directory, and you will need an 
1415) HTTPS proxy for doing CONNECT requests to get to Tor relays. (It's fine 
1416) if they're the same proxy.) Tor also recognizes the torrc options 
1417) Socks4Proxy and Socks5Proxy. 
1418) </p>
1419) <p>
1420) Also check out HTTPProxyAuthenticator and HTTPSProxyAuthenticator if your 
1421) proxy requires auth. We only support basic auth currently, but if you need 
1422) NTLM authentication, you find <a 
1423) href="http://archives.seul.org/or/talk/Jun-2005/msg00223.html">this post 
1424) in the archives</a> useful. 
1425) </p>
1426) <p>
1427) If your proxies only allow you to connect to certain ports, look at the 
1428) entry on <a href="#FirewallPorts">Firewalled clients</a> for how 
1429) to restrict what ports your Tor will try to access. 
1430) </p>
1431) 
1432) <hr>
1433) 

1434) <a id="torrc"></a>

1435) <h3><a class="anchor" href="#torrc">I'm supposed to "edit my torrc".
1436) What does that mean?</a></h3>

1437) 
1438) <p>
1439) Tor installs a text file called torrc that contains configuration
1440) instructions for how your Tor program should behave. The default
1441) configuration should work fine for most Tor users. Users of Vidalia can
1442) make common changes through the Vidalia interface &mdash; only advanced
1443) users should need to modify their torrc file directly.
1444) </p>

1445) <p>

1446) Tor Browser Bundle users should edit your torrc through Vidalia. Open
1447) the
1448) Vidalia Control Panel. Choose Settings. Choose Advanced. Click the
1449) button

1450) labelled "Edit current torrc". Remember to make sure the checkbox for
1451) "Save Settings." is checked. Hit the Ok button and you are done.
1452) </p>

1453) <p>

1454) Otherwise, you will need to edit the file manually.

1455) The location of your torrc file depends on the way you installed Tor:
1456) </p>
1457) <ul>

1458) <li>If you installed Tor Browser Bundle, look for
1459) <code>Data/Tor/torrc</code> inside your Tor Browser Bundle directory.
1460) </li>

1461) <li>On Windows, if you installed a Tor bundle with Vidalia, you can
1462) find your torrc file in the Start menu under Programs -&gt; Vidalia
1463) Bundle -&gt; Tor, or you can find it by hand in <code>\Documents and
1464) Settings\<i>username</i>\Application Data\Vidalia\torrc</code>. If you
1465) installed Tor without Vidalia, you can find your torrc in the Start
1466) menu under Programs -&gt; Tor, or manually in either <code>\Documents
1467) and Settings\Application Data\tor\torrc</code> or <code>\Documents and
1468) Settings\<i>username</i>\Application Data\tor\torrc</code>.
1469) </li>
1470) <li>On OS X, if you use Vidalia, edit
1471) <code>~/.vidalia/torrc</code>. Otherwise, open your favorite text editor
1472) and load <code>/Library/Tor/torrc</code>.
1473) </li>
1474) <li>On Unix, if you installed a pre-built package, look for
1475) <code>/etc/tor/torrc</code> or <code>/etc/torrc</code> or consult your
1476) package's documentation.
1477) </li>
1478) <li>Finally, if you installed from source, you may not have a torrc
1479) installed yet: look in <code>/usr/local/etc/</code> and note that you

1480) may need to manually copy <code>torrc.sample</code> to
1481) <code>torrc</code>.

1482) </li>
1483) </ul>
1484) 
1485) <p>
1486) If you use Vidalia, be sure to exit both Tor and Vidalia before you edit

1487) your torrc file manually. Otherwise Vidalia might overwrite your
1488) changes.

1489) </p>
1490) 
1491) <p>
1492) Once you've changed your torrc, you will need to restart Tor for the
1493) changes to take effect. (For advanced users on OS X and Unix, note that

1494) you actually only need to send Tor a HUP signal, not actually restart
1495) it.)

1496) </p>
1497) 
1498) <p>
1499) For other configuration options you can use, look at the <a href="<page
1500) docs/tor-manual>">Tor manual page</a>. Remember, all lines beginning
1501) with # in torrc are treated as comments and have no effect on Tor's
1502) configuration.
1503) </p>
1504) 
1505) <hr>
1506) 

1507) <a id="Logs"></a>

1508) <h3><a class="anchor" href="#Logs">How do I set up logging, or see Tor's
1509) logs?</a></h3>

1510) 
1511) <p>

1512) If you installed a Tor bundle that includes Vidalia, then Vidalia has a

1513) window called "Message Log" that will show you Tor's log messages. Click
1514) on "Advanced" to see more details. You can click on "Settings" to change
1515) your log verbosity or save the messages to a file. You're all set.

1516) </p>
1517) 
1518) <p>
1519) If you're not using Vidalia, you'll have to go find the log files by

1520) hand. Here are some likely places for your logs to be:

1521) </p>
1522) 
1523) <ul>
1524) <li>On OS X, Debian, Red Hat, etc, the logs are in /var/log/tor/
1525) </li>

1526) <li>On Windows, there are no default log files currently. If you enable
1527) logs in your torrc file, they default to <code>\username\Application
1528) Data\tor\log\</code> or <code>\Application Data\tor\log\</code>
1529) </li>
1530) <li>If you compiled Tor from source, by default your Tor logs to <a
1531) href="http://en.wikipedia.org/wiki/Standard_streams">"stdout"</a>
1532) at log-level notice. If you enable logs in your torrc file, they
1533) default to <code>/usr/local/var/log/tor/</code>.

1534) </li>
1535) </ul>
1536) 
1537) <p>

1538) To change your logging setup by hand, <a href="#torrc">edit your
1539) torrc</a>

1540) and find the section (near the top of the file) which contains the
1541) following line:

1542) </p>
1543) 
1544) <pre>

1545) \## Logs go to stdout at level "notice" unless redirected by something
1546) \## else, like one of the below lines.

1547) </pre>

1548) 
1549) <p>

1550) For example, if you want Tor to send complete debug, info, notice, warn,

1551) and err level messages to a file, append the following line to the end
1552) of the section:
1553) </p>
1554) 
1555) <pre>
1556) Log debug file c:/program files/tor/debug.log
1557) </pre>
1558) 
1559) <p>

1560) Replace <code>c:/program files/tor/debug.log</code> with a directory
1561) and filename for your Tor log.

1562) </p>
1563) 
1564) <hr>
1565) 

1566) 
1567) <a id="LogLevel"></a>
1568) <h3><a class="anchor" href="#LogLevel">What log level should I use?</a></h3>
1569) 
1570) <p>

1571) There are five log levels (also called "log severities") you might see in 
1572) Tor's logs:

1573) </p>
1574) 
1575) <ul>

1576)     <li>"err": something bad just happened, and we can't recover. Tor will 
1577)     exit.</li>
1578)     <li>"warn": something bad happened, but we're still running. The bad 
1579)     thing might be a bug in the code, some other Tor process doing something 
1580)     unexpected, etc. The operator should examine the message and try to 
1581)     correct the problem.</li>

1582)     <li>"notice": something the operator will want to know about.</li>

1583)     <li>"info": something happened (maybe bad, maybe ok), but there's 
1584)     nothing you need to (or can) do about it.</li>

1585)     <li>"debug": for everything louder than info. It is quite loud indeed.</li> 
1586) </ul>
1587) 
1588) <p>

1589) Alas, some of the warn messages are hard for ordinary users to correct -- the 
1590) developers are slowly making progress at making Tor automatically react 
1591) correctly for each situation.

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

1595) We recommend running at the default, which is "notice". You will hear about 
1596) important things, and you won't hear about unimportant things.

1597) </p>
1598) 
1599) <p>

1600) Tor relays in particular should avoid logging at info or debug in normal 
1601) operation, since they might end up recording sensitive information in 
1602) their logs. 

1603) </p>
1604) 

1605) <hr>
1606) 

1607) <a id="DoesntWork"></a>

1608) <h3><a class="anchor" href="#DoesntWork">I installed Tor but it's not
1609) working.</a></h3>

1610) 
1611) <p>

1612) Once you've got the Tor bundle up and running, the first question to
1613) ask is whether your Tor client is able to establish a circuit.

1614) </p>
1615) 
1616) <p>If Tor can establish a circuit, the onion icon in

1617) Vidalia will turn green (and if you're running Tor Browser Bundle, it
1618) will
1619) automatically launch a browser for you). You can also check in the
1620) Vidalia

1621) Control Panel to make sure it says "Connected to the Tor
1622) network!" under Status. For those not using Vidalia, check your <a

1623) href="#Logs">Tor logs</a> for

1624) a line saying that Tor "has successfully opened a circuit. Looks like
1625) client functionality is working."
1626) </p>
1627) 
1628) <p>
1629) If Tor can't establish a circuit, here are some hints:
1630) </p>
1631) 
1632) <ol>
1633) <li>Are you sure Tor is running? If you're using Vidalia, you may have
1634) to click on the onion and select "Start" to launch Tor.</li>
1635) <li>Check your system clock. If it's more than a few hours off, Tor will

1636) refuse to build circuits. For Microsoft Windows users, synchronize your
1637) clock under the clock -> Internet time tab. In addition, correct the

1638) day and date under the 'Date & Time' Tab. Also make sure your time
1639) zone is correct.</li>

1640) <li>Is your Internet connection <a href="#FirewallPorts">firewalled
1641) by port</a>, or do you normally need to use a <a

1642) href="<#NeedToUseAProxy">proxy</a>?

1643) </li>

1644) <li>Are you running programs like Norton Internet Security or SELinux
1645) that

1646) block certain connections, even though you don't realize they do? They
1647) could be preventing Tor from making network connections.</li>
1648) <li>Are you in China, or behind a restrictive corporate network firewall
1649) that blocks the public Tor relays? If so, you should learn about <a

1650) href="<page docs/bridges>">Tor bridges</a>.</li>

1651) <li>Check your <a href="#Logs">Tor logs</a>. Do they give you any hints
1652) about what's going wrong?</li>

1653) </ol>
1654) 
1655) <hr />
1656) 

1657) <a id="TorCrash"></a>
1658) <h3><a class="anchor" href="#TorCrash">My Tor keeps crashing.</a></h3>
1659) <p>
1660)  We want to hear from you! There are supposed to be zero crash bugs in Tor. 
1661)  This FAQ entry describes the best way for you to be helpful to us. But even 
1662)  if you can't work out all the details, we still want to hear about it, so 
1663)  we can help you track it down. 
1664) </p>
1665) <p>
1666) First, make sure you're using the latest version of Tor (either the latest 
1667) stable or the latest development version). 
1668) </p>
1669) <p>
1670) Second, make sure your version of libevent is new enough. We recommend at 
1671) least libevent 1.3a. 
1672) </p>
1673) <p>
1674) Third, see if there's already an entry for your bug in the <a 
1675) href="https://bugs.torproject.org/">Tor bugtracker</a>. If so, 
1676) check if there are any new details that you can add. 
1677) </p>
1678) <p>
1679) Fourth, is the crash repeatable? Can you cause the crash? Can 
1680) you isolate some of the circumstances or config options that 
1681) make it happen? How quickly or often does the bug show up? 
1682) Can you check if it happens with other versions of Tor, for 
1683) example the latest stable release? 
1684) </p>
1685) <p>
1686) Fifth, what sort of crash do you get? 
1687) </p>
1688) <ul>
1689) <li>
1690) Does your Tor log include an "assert failure"? If so, please 
1691) tell us that line, since it helps us figure out what's going on. 
1692) Tell us the previous couple of log messages as well, especially 
1693) if they seem important. 
1694) </li>
1695) <li>
1696) If it says "Segmentation fault - core dumped" then you need to 
1697) do a bit more to track it down. Look for a file like "core" or 
1698) "tor.core" or "core.12345" in your current directory, or in your 
1699) Data Directory. If it's there, run "gdb tor core" and then "bt", 
1700) and include the output. If you can't find a core, run "ulimit -c 
1701) unlimited", restart Tor, and try to make it crash again. (This core 
1702) thing will only work on Unix -- alas, tracking down bugs on Windows 
1703) is harder. If you're on Windows, can you get somebody to duplicate 
1704) your bug on Unix?)
1705) </li>
1706) <li>
1707) If Tor simply vanishes mysteriously, it probably is a segmentation 
1708) fault but you're running Tor in the background (as a daemon) so you 
1709) won't notice. Go look at the end of your log file, and look for a 
1710) core file as above. If you don't find any good hints, you should 
1711) consider running Tor in the foreground (from a shell) so you can 
1712) see how it dies. Warning: if you switch to running Tor in the foreground, 
1713) you might start using a different torrc file, with a different default 
1714) Data Directory; see the <a href="#UpgradeOrMove">relay-upgrade FAQ entry</a> 
1715) for details. 
1716) </li>
1717) <li>
1718) If it's still vanishing mysteriously, perhaps something else is killing it? 
1719) Do you have resource limits (ulimits) configured that kill off processes 
1720) sometimes? (This is especially common on OpenBSD.) On Linux, try running 
1721) "dmesg" to see if the out-of-memory killer removed your process. (Tor will 
1722) exit cleanly if it notices that it's run out of memory, but in some cases 
1723) it might not have time to notice.) In very rare circumstances, hardware 
1724) problems could also be the culprit. 
1725) </li>
1726) </ul>
1727) <p>
1728) Sixth, if the above ideas don't point out the bug, consider increasing your 
1729) log level to "loglevel debug". You can look at the log-configuration FAQ 
1730) entry for instructions on what to put in your torrc file. If it usually 
1731) takes a long time for the crash to show up, you will want to reserve a whole 
1732) lot of disk space for the debug log. Alternatively, you could just send 
1733) debug-level logs to the screen (it's called "stdout" in the torrc), and then 
1734) when it crashes you'll see the last couple of log lines it had printed. 
1735) (Note that running with verbose logging like this will slow Tor down 
1736) considerably, and note also that it's generally not a good idea security-wise 
1737) to keep logs like this sitting around.) 
1738) </p>
1739) 
1740) <hr />
1741) 

1742) <a id="VidaliaPassword"></a>

1743) <h3><a class="anchor" href="#VidaliaPassword">Tor/Vidalia prompts for a
1744) password at start.</a></h3>

1745) 
1746) <p>
1747) Vidalia interacts with the Tor software via Tor's "control port". The
1748) control port lets Vidalia receive status updates from Tor, request a new
1749) identity, configure Tor's settings, etc. Each time Vidalia starts Tor,
1750) Vidalia sets a random password for Tor's control port to prevent other
1751) applications from also connecting to the control port and potentially
1752) compromising your anonymity.
1753) </p>
1754) 
1755) <p>
1756) Usually this process of generating and setting a random control password
1757) happens in the background. There are three common situations, though,
1758) where Vidalia may prompt you for a password:
1759) </p>
1760) 
1761) <ol>
1762) <li>You're already running Vidalia and Tor. For example, this situation
1763) can happen if you installed the Vidalia bundle and now you're trying to
1764) run the Tor Browser Bundle. In that case, you'll need to close the old
1765) Vidalia and Tor before you can run this one.
1766) </li>
1767) <li>Vidalia crashed, but left Tor running with the last known random
1768) password. After you restart Vidalia, it generates a new random password,

1769) but Vidalia can't talk to Tor, because the random passwords are
1770) different.

1771) <br />

1772) If the dialog that prompts you for a control password has a Reset
1773) button,

1774) you can click the button and Vidalia will restart Tor with a new random
1775) control password.
1776) <br />
1777) If you do not see a Reset button, or if Vidalia is unable to restart
1778) Tor for you, you can still fix the problem manually. Simply go into your
1779) process or task manager, and terminate the Tor process. Then use Vidalia
1780) to restart Tor and all will work again.
1781) </li>
1782) <li>You had previously set Tor to run as a Windows NT service. When Tor
1783) is set to
1784) run as a service, it starts up when the system boots. If you configured
1785) Tor to start as a service through Vidalia, a random password was set
1786) and saved in Tor. When you reboot, Tor starts up and uses the random
1787) password it saved. You login and start up Vidalia. Vidalia attempts to
1788) talk to the already running Tor. Vidalia generates a random password,
1789) but it is different than the saved password in the Tor service.
1790) <br />
1791) You need to reconfigure Tor to not be a service. See the FAQ entry on

1792) <a href="#NTservice">running Tor as a

1793) Windows NT service</a>

1794) for more information on how to remove the Tor service.
1795) </li>
1796) </ol>
1797) 

1798)     <hr>

1799) 

1800)     <a id="ChooseEntryExit"></a>

1801)     <h3><a class="anchor" href="#ChooseEntryExit">Can I control which
1802) nodes (or country) are used for entry/exit?</a></h3>

1803) 

1804)     <p>

1805)     Yes. You can set preferred entry and exit nodes as well as
1806)     inform Tor which nodes you do not want to use.

1807)     The following options can be added to your config file <a
1808)     href="#torrc">"torrc"</a> or specified on the command line:

1809)     </p>
1810)     <dl>
1811)       <dt><tt>EntryNodes $fingerprint,$fingerprint,...</tt></dt>

1812)         <dd>A list of preferred nodes to use for the first hop in the
1813) circuit, if possible.

1814)         </dd>
1815)       <dt><tt>ExitNodes $fingerprint,$fingerprint,...</tt></dt>

1816)         <dd>A list of preferred nodes to use for the last hop in the
1817) circuit, if possible.

1818)         </dd>
1819)       <dt><tt>ExcludeNodes $fingerprint,$fingerprint,...</tt></dt>

1820)         <dd>A list of nodes to never use when building a circuit.

1821)         </dd>
1822)       <dt><tt>ExcludeExitNodes $fingerprint,$fingerprint,...</tt></dt>

1823)         <dd>A list of nodes to never use when picking an exit.

1824)             Nodes listed in <tt>ExcludeNodes</tt> are automatically in
1825) this list.

1826)         </dd>
1827)     </dl>
1828)     <p>

1829)     <em>We recommend you do not use these</em>

1830)     — they are intended for testing and may disappear in future
1831) versions.

1832)     You get the best security that Tor can provide when you leave the
1833)     route selection to Tor; overriding the entry / exit nodes can mess
1834)     up your anonymity in ways we don't understand.

1835)     </p>
1836)     <p>

1837)     Note also that not every circuit is used to deliver traffic outside of 
1838)     the Tor network. It is normal to see non-exit circuits (such as those 
1839)     used to connect to hidden services, those that do directory fetches, 
1840)     those used for relay reachability self-tests, and so on) that end at 
1841)     a non-exit node. To keep a node from being used entirely, see 
1842)     <tt>ExcludeNodes</tt> and <tt>StrictNodes</tt> in the 
1843)     <a href="<page docs/tor-manual>">manual</a>.

1844)     </p>
1845)     <p>

1846)     Instead of <tt>$fingerprint</tt> you can also specify a <a

1847) 
1848) href="https://secure.wikimedia.org/wikipedia/en/wiki/ISO_3166-1_alpha-2"
1849) >2

1850)     letter ISO3166 country code</a> in curly braces (for example <tt>{de}</tt>),

1851)     or an ip address pattern (for example 255.254.0.0/8), or a node
1852)     nickname. Make sure there are no spaces between the commas and the
1853)     list items.

1854)     </p>
1855)     <p>

1856)     If you want to access a service directly through Tor's Socks
1857) interface

1858)     (eg. using ssh via connect.c), another option is to set up an

1859)     internal mapping in your configuration file using
1860) <tt>MapAddress</tt>.

1861)     See the manual page for details.
1862)     </p>

1863) 

1864)     <hr>

1865) 

1866) <a id="FirewallPorts"></a>

1867) <h3><a class="anchor" href="#FirewallPorts">My firewall only allows a
1868) few outgoing ports.</a></h3>

1869) 
1870) <p>
1871) If your firewall works by blocking ports, then you can tell Tor to only

1872) use the ports that your firewall permits by adding "FascistFirewall 1"
1873) to

1874) your <a href="<page docs/faq>#torrc">torrc

1875) configuration file</a>, or by clicking "My firewall only lets me connect
1876) to certain ports" in Vidalia's Network Settings window.
1877) </p>
1878) 
1879) <p>
1880) By default, when you set this Tor assumes that your firewall allows only
1881) port 80 and port 443 (HTTP and HTTPS respectively). You can select a
1882) different set of ports with the FirewallPorts torrc option.
1883) </p>
1884) 
1885) <p>
1886) If you want to be more fine-grained with your controls, you can also
1887) use the ReachableAddresses config options, e.g.:
1888) </p>
1889) 
1890) <pre>
1891)   ReachableDirAddresses *:80
1892)   ReachableORAddresses *:443
1893) </pre>
1894) 
1895) <hr>

1896) 

1897)     <a id="DefaultExitPorts"></a>
1898)     <h3><a class="anchor" href="#DefaultExitPorts">Is there a list of default exit 

1899)     ports?</a></h3>

1900)     <p>

1901) The default open ports are listed below but keep in mind that, any port or 
1902) ports can be opened by the relay operator by configuring it in torrc or 
1903) modifying the source code. But the default according to src/or/policies.c 
1904) from the source code release tor-0.2.4.16-rc is: 

1905)     </p>
1906)     <pre>
1907)   reject 0.0.0.0/8
1908)   reject 169.254.0.0/16
1909)   reject 127.0.0.0/8
1910)   reject 192.168.0.0/16
1911)   reject 10.0.0.0/8
1912)   reject 172.16.0.0/12
1913)   reject *:25
1914)   reject *:119
1915)   reject *:135-139
1916)   reject *:445
1917)   reject *:563
1918)   reject *:1214
1919)   reject *:4661-4666
1920)   reject *:6346-6429
1921)   reject *:6699
1922)   reject *:6881-6999
1923)   accept *:*
1924)     </pre>
1925)     <p>

1926)     A relay will block access to its own IP address, as well local network 
1927)     IP addresses. A relay always blocks itself by default. This prevents 
1928)     Tor users from accidentally accessing any of the exit operator's local 
1929)     services. 
1930)     </p>
1931) 
1932)     <hr>
1933) 
1934)     <a id="SocksAndDNS"></a>
1935)     <h3><a class="anchor" href="#SocksAndDNS">How do I check if my application that uses 
1936)     SOCKS is leaking DNS requests?</a></h3>
1937) 
1938)     <p>
1939)     These are two steps you need to take here. The first is to make sure 
1940)     that it's using the correct variant of the SOCKS protocol, and the 
1941)     second is to make sure that there aren't other leaks. 
1942)     </p>
1943) 
1944)     <p>
1945)     Step one: add "TestSocks 1" to your torrc file, and then watch your 
1946)     logs as you use your application. Tor will then log, for each SOCKS 
1947)     connection, whether it was using a 'good' variant or a 'bad' one. 
1948)     (If you want to automatically disable all 'bad' variants, set 
1949)     "SafeSocks 1" in your <a href="#torrc">torrc</a> file.) 
1950)     </p>
1951) 
1952)     <p>
1953)     Step two: even if your application is using the correct variant of 
1954)     the SOCKS protocol, there is still a risk that it could be leaking 
1955)     DNS queries. This problem happens in Firefox extensions that resolve 
1956)     the destination hostname themselves, for example to show you its IP 
1957)     address, what country it's in, etc. These applications may use a safe 
1958)     SOCKS variant when actually making connections, but they still do DNS 
1959)     resolves locally. If you suspect your application might behave like 
1960)     this, you should use a network sniffer like <a 
1961)     href="https://www.wireshark.org/">Wireshark</a> and look for 
1962)     suspicious outbound DNS requests. I'm afraid the details of how to look 
1963)     for these problems are beyond the scope of a FAQ entry though -- find 
1964)     a friend to help if you have problems. 

1965)     </p>
1966) 
1967)     <hr>
1968) 

1969)     <a id="HowDoIDecide"></a>
1970)     <h3><a class="anchor" href="#HowDoIDecide">How do I decide if I should 
1971)     run a relay?</a></h3>
1972)     <p>
1973)     We're looking for people with reasonably reliable Internet connections, 
1974)     that have at least 20 kilobytes/second each way. If that's you, please 
1975)     consider <a href="https://www.torproject.org/docs/tor-relay-debian">helping 
1976)     out</a>. 
1977)     </p>
1978)     
1979)     <hr>
1980)     
1981)     <a id="WhyIsntMyRelayBeingUsedMore"></a>
1982)     <h3><a class="anchor" href="#WhyIsntMyRelayBeingUsedMore">Why isn't my 
1983)     relay being used more?</a></h3>
1984)     <p>
1985)     If your relay is relatively new then give it time. Tor decides which 
1986)     relays it uses heuristically based on reports from Bandwidth 
1987)     Authorities. These authorities take measurements of your relay's 
1988)     capacity and, over time, directs more traffic there until it reaches 
1989)     an optimal load. The lifecycle of a new relay is explained in more 
1990)     depth in <a href="https://blog.torproject.org/blog/lifecycle-of-a-new-relay">
1991)     this blog post</a>.
1992)     </p>
1993)     <p>
1994)     If you've been running a relay for a while and still having issues 
1995)     then try asking on the <a href=
1996)     "https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays/">
1997)     tor-relays list</a>. 
1998)     </p>
1999)     
2000)     <hr>
2001) 

2002)     <a id="HighCapacityConnection"></a>    
2003)     <h3><a class="anchor" href="#HighCapacityConnection">How can I get Tor to fully 
2004)     make use of my high capacity connection?</a></h3>
2005)     
2006)     <p>
2007)     See <a href="http://archives.seul.org/or/relays/Aug-2010/msg00034.html">this 
2008)     tor-relays thread</a>.
2009)     </p>
2010)     
2011)     <hr>    
2012)     

2013)     <a id="RelayFlexible"></a>

2014)     <h3><a class="anchor" href="#RelayFlexible">How stable does my relay
2015) need to be?</a></h3>

2016) 

2017)     <p>
2018)     We aim to make setting up a Tor relay easy and convenient:
2019)     </p>

2020) 

2021)     <ul>
2022)     <li>Tor has built-in support for <a

2023)     href="<wikifaq>#WhatbandwidthshapingoptionsareavailabletoTorrelays">

2024)     rate limiting</a>. Further, if you have a fast
2025)     link but want to limit the number of bytes per
2026)     day (or week or month) that you donate, check out the <a

2027) 
2028) href="<wikifaq>#HowcanIlimitthetotalamountofbandwidthusedbymyTorrelay">
2029) hibernation

2030)     feature</a>.
2031)     </li>

2032)     <li>Each Tor relay has an <a href="#ExitPolicies">exit policy</a>
2033) that
2034)     specifies what sort of outbound connections are allowed or refused
2035) from
2036)     that relay. If you are uncomfortable allowing people to exit from
2037) your
2038)     relay, you can set it up to only allow connections to other Tor
2039) relays.

2040)     </li>
2041)     <li>It's fine if the relay goes offline sometimes. The directories
2042)     notice this quickly and stop advertising the relay. Just try to make
2043)     sure it's not too often, since connections using the relay when it
2044)     disconnects will break.
2045)     </li>
2046)     <li>We can handle relays with dynamic IPs just fine &mdash; simply
2047)     leave the Address config option blank, and Tor will try to guess.
2048)     </li>
2049)     <li>If your relay is behind a NAT and it doesn't know its public
2050)     IP (e.g. it has an IP of 192.168.x.y), you'll need to set up port

2051)     forwarding. Forwarding TCP connections is system dependent but

2052)     <a href="#BehindANAT">this FAQ entry</a>

2053)     offers some examples on how to do this.
2054)     </li>
2055)     <li>Your relay will passively estimate and advertise its recent

2056)     bandwidth capacity, so high-bandwidth relays will attract more users
2057) than
2058)     low-bandwidth ones. Therefore having low-bandwidth relays is useful
2059) too.

2060)     </li>
2061)     </ul>

2062) 

2063)     <hr>

2064) 

2065)     <a id="ExitPolicies"></a>

2066)     <h3><a class="anchor" href="#ExitPolicies">I'd run a relay, but I
2067) don't want to deal with abuse issues.</a></h3>

2068) 

2069)     <p>
2070)     Great. That's exactly why we implemented exit policies.
2071)     </p>

2072) 

2073)     <p>
2074)     Each Tor relay has an exit policy that specifies what sort of

2075)     outbound connections are allowed or refused from that relay. The
2076) exit

2077)     policies are propagated to Tor clients via the directory, so clients
2078)     will automatically avoid picking exit relays that would refuse to
2079)     exit to their intended destination. This way each relay can decide
2080)     the services, hosts, and networks he wants to allow connections to,

2081)     based on abuse potential and his own situation. Read the FAQ entry
2082) on
2083)     <a href="<page docs/faq-abuse>#TypicalAbuses">issues you might
2084) encounter</a>

2085)     if you use the default exit policy, and then read Mike Perry's

2086)     <a href="<blog>tips-running-exit-node-minimal-harassment">tips

2087)     for running an exit node with minimal harassment</a>.
2088)     </p>

2089) 

2090)     <p>

2091)     The default exit policy allows access to many popular services

2092)     (e.g. web browsing), but <a

2093) href="#DefaultExitPorts">restricts</a>

2094)     some due to abuse potential (e.g. mail) and some since
2095)     the Tor network can't handle the load (e.g. default
2096)     file-sharing ports). You can change your exit policy

2097)     using Vidalia's "Sharing" tab, or by manually editing your

2098)     <a href="<page docs/faq>#torrc">torrc</a>

2099)     file. If you want to avoid most if not all abuse potential, set it
2100) to
2101)     "reject *:*" (or un-check all the boxes in Vidalia). This setting
2102) means
2103)     that your relay will be used for relaying traffic inside the Tor
2104) network,

2105)     but not for connections to external websites or other services.
2106)     </p>

2107) 

2108)     <p>

2109)     If you do allow any exit connections, make sure name resolution
2110) works

2111)     (that is, your computer can resolve Internet addresses correctly).

2112)     If there are any resources that your computer can't reach (for
2113) example,

2114)     you are behind a restrictive firewall or content filter), please

2115)     explicitly reject them in your exit policy — otherwise Tor
2116) users

2117)     will be impacted too.
2118)     </p>

2119) 

2120)     <hr>

2121) 

2122)     <a id="DifferentComputer"></a>

2123)     <h3><a class="anchor" href="#DifferentComputer">I want to run my 
2124)     Tor client on a different computer than my applications.</a></h3>

2125)     <p>

2126)     By default, your Tor client only listens for applications that 
2127)     connect from localhost. Connections from other computers are 
2128)     refused. If you want to torify applications on different computers 
2129)     than the Tor client, you should edit your torrc to define 
2130)     SocksListenAddress 0.0.0.0 g and then restart (or hup) Tor. If you 
2131)     want to get more advanced, you can configure your Tor client on a 
2132)     firewall to bind to your internal IP but not your external IP.  

2133)     </p>
2134) 
2135)     <hr>
2136) 
2137)     <a id="ServerClient"></a>

2138)     <h3><a class="anchor" href="#ServerClient">Can I install Tor on a 
2139)     central server, and have my clients connect to it?</a></h3>
2140)     <p>
2141)      Yes. Tor can be configured as a client or a relay on another 
2142)      machine, and allow other machines to be able to connect to it 
2143)      for anonymity. This is most useful in an environment where many 
2144)      computers want a gateway of anonymity to the rest of the world. 
2145)      However, be forwarned that with this configuration, anyone within 
2146)      your private network (existing between you and the Tor 
2147)      client/relay) can see what traffic you are sending in clear text. 
2148)      The anonymity doesn't start until you get to the Tor relay. 
2149)      Because of this, if you are the controller of your domain and you 
2150)      know everything's locked down, you will be OK, but this configuration 
2151)      may not be suitable for large private networks where security is 
2152)      key all around.
2153)     </p>
2154)     <p>
2155) Configuration is simple, editing your torrc file's SocksListenAddress 
2156) according to the following examples:

2157)     </p>
2158)     <pre>

2159) 
2160)   #This provides local interface access only, 
2161)   #needs SocksPort to be greater than 0
2162)   SocksListenAddress 127.0.0.1 
2163) 
2164)   #This provides access to Tor on a specified interface
2165)   SocksListenAddress 192.168.x.x:9100 
2166) 
2167)   #Accept from all interfaces
2168)   SocksListenAddress 0.0.0.0:9100
2169)    </pre>

2170)     <p>

2171) You can state multiple listen addresses, in the case that you are 
2172) part of several networks or subnets.

2173)     </p>
2174)     <pre>
2175)   SocksListenAddress 192.168.x.x:9100 #eth0
2176)   SocksListenAddress 10.x.x.x:9100 #eth1
2177)     </pre>
2178)     <p>

2179) After this, your clients on their respective networks/subnets would specify 
2180) a socks proxy with the address and port you specified SocksListenAddress 
2181) to be. 

2182)     </p>
2183)     <p>

2184) Please note that the SocksPort configuration option gives the port ONLY for 
2185) localhost (127.0.0.1). When setting up your SocksListenAddress(es), you need 
2186) to give the port with the address, as shown above.

2187)     <p>

2188) If you are interested in forcing all outgoing data through the central Tor 
2189) client/relay, instead of the server only being an optional proxy, you may find 
2190) the program iptables (for *nix) useful. 

2191)     </p>
2192) 
2193)     <hr>
2194) 

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

2196)     <h3><a class="anchor" href="#JoinTheNetwork">So I can just configure a 
2197)     nickname and ORPort and join the network?</a></h3>

2198) 
2199)     <p>

2200)      Yes. You can join the network and be a useful relay just by configuring 
2201)      your Tor to be a relay and making sure it's reachable from the outside.

2202)     </p>
2203)     <p>
2204) 30 Seconds to a Tor Relay:
2205)     </p>
2206)     <ul><li>
2207)     Configure a Nickname: 
2208)     </li></ul>
2209)     <pre>
2210) Nickname ididnteditheconfig
2211)     </pre>

2212)     <ul><li>

2213)     Configure ORPort: 

2214)     </li></ul>

2215)     <pre>
2216) ORPort 9001
2217)     </pre>

2218)     <ul><li>

2219)     Configure Contact Info: 

2220)     </li></ul>

2221) 
2222)     <pre>
2223) ContactInfo human@…

2224)     </pre>
2225)     <ul><li>

2226)     Start Tor. Watch the log file for a log entry that states: "Self-testing 
2227)     indicates your ORPort is reachable from the outside. Excellent. Publishing 
2228)     server descriptor."

2229)     </li></ul>

2230) 
2231)     <hr />

2232) 

2233)     <a id="RelayOrBridge"></a>

2234)     <h3><a class="anchor" href="#RelayOrBridge">Should I be a normal
2235) relay or bridge relay?</a></h3>

2236) 

2237)     <p><a href="<page docs/bridges>">Bridge relays</a> (or "bridges" for
2238) short)
2239)     are <a href="<page docs/tor-doc-relay>">Tor relays</a> that aren't

2240)     listed in the public Tor directory.

2241)     That means that ISPs or governments trying to block access to the

2242)     Tor network can't simply block all bridges.

2243)     </p>

2244) 

2245)     <p>Being a normal relay vs being a bridge relay is almost the same
2246)     configuration: it's just a matter of whether your relay is listed

2247)     publicly or not.

2248)     </p>

2249) 

2250)     <p>

2251)     So bridges are useful a) for Tor users in oppressive regimes,

2252)     and b) for people who want an extra layer of security

2253)     because they're worried somebody will recognize that it's a public
2254)     Tor relay IP address they're contacting.

2255)     </p>

2256) 

2257)     <p>
2258)     Several countries, including China and Iran, have found ways to

2259)     detect and block connections to Tor bridges.

2260)     <a href="<page projects/obfsproxy>">Obfsproxy</a> bridges address

2261)     this by adding another layer of obfuscation.

2262)     </p>
2263) 

2264)     <p>So should you run a normal relay or bridge relay? If you have
2265) lots

2266)     of bandwidth, you should definitely run a normal relay.
2267)     If you're willing

2268)     to <a href="#ExitPolicies">be an exit</a>, you should definitely
2269)     run a normal relay, since we need more exits. If you can't be an
2270)     exit and only have a little bit of bandwidth, be a bridge. Thanks
2271)     for volunteering!

2272)     </p>

2273) 

2274)     <hr>

2275) 

2276) <a id="UpgradeOrMove"></a>

2277) <h3><a class="anchor" href="#UpgradeOrMove">I want to upgrade/move my relay. 
2278) How do I keep the same key?</a></h3>

2279) 
2280) <p>

2281)  When upgrading your Tor relay, or running it on a different computer, 
2282)  the important part is to keep the same nickname (defined in your torrc 
2283)  file) and the same identity key (stored in "keys/secret_id_key" in 
2284)  your DataDirectory).

2285) </p>
2286) <p>

2287) This means that if you're upgrading your Tor relay and you keep the same 
2288) torrc and the same DataDirectory, then the upgrade should just work and 
2289) your relay will keep using the same key. If you need to pick a new 
2290) DataDirectory, be sure to copy your old keys/secret_id_key over. 

2291) </p>
2292) 
2293)     <hr>
2294) 
2295) <a id="NTService"></a>

2296) <h3><a class="anchor" href="#NTService">How do I run my Tor relay as an NT 
2297) service?</a></h3>

2298) 
2299) <p>

2300)  You can run Tor as a service on all versions of Windows except Windows 
2301)  95/98/ME. This way you can run a Tor relay without needing to always have 
2302)  Vidalia running.

2303) </p>
2304) <p>

2305) If you've already configured your Tor to be a relay, please note that when 
2306) you enable Tor as a service, it will use a different DatagDirectory, and 
2307) thus will generate a different key. If you want to keep using the old key, 
2308) see the Upgrading your Tor relay FAQ entry for how to restore the old 
2309) identity key.

2310) </p>
2311) <p>
2312) To install Tor as a service, you can simply run:
2313) </p>
2314) <pre>
2315) tor --service install
2316) </pre>
2317) <p>

2318) A service called Tor Win32 Service will be installed and started. This 
2319) service will also automatically start every time Windows boots, unless 
2320) you change the Start-up type. An easy way to check the status of Tor, 
2321) start or stop the service, and change the start-up type is by running 
2322) services.msc and finding the Tor service in the list of currently 
2323) installed services.

2324) </p>
2325) <p>

2326) Optionally, you can specify additional options for the Tor service using 
2327) the -options argument. For example, if you want Tor to use C:\tor\torrc, 
2328) instead of the default torrc, and open a control port on port 9151, you 
2329) would run:

2330) </p>
2331) <pre>
2332) tor --service install -options -f C:\tor\torrc ControlPort 9151
2333) </pre>
2334) <p>
2335) You can also start or stop the Tor service from the command line by typing:
2336) </p>
2337) <pre>
2338)  tor --service start
2339) </pre>
2340) <p>
2341) or
2342) </p>
2343) <pre>
2344)  tor --service stop
2345) </pre>
2346) <p>
2347) To remove the Tor service, you can run the following command:
2348) </p>
2349) <pre>
2350) tor --service remove
2351) </pre>
2352) <p>

2353) If you are running Tor as a service and you want to uninstall Tor entirely, 
2354) be sure to run the service removal command (shown above) first before 
2355) running the uninstaller from "Add/Remove Programs". The uninstaller is 
2356) currently not capable of removing the active service.

2357) </p>
2358) 
2359) <hr>
2360) 
2361) <a id="VirtualServer"></a>

2362) <h3><a class="anchor" href="#VirtualServer">Can I run a Tor relay from my 
2363) virtual server account?</a></h3>

2364) 
2365) <p>

2366) Some ISPs are selling "vserver" accounts that provide what they call a 
2367) virtual server -- you can't actually interact with the hardware, and 
2368) they can artificially limit certain resources such as the number of file 
2369) descriptors you can open at once. Competent vserver admins are able to 
2370) configure your server to not hit these limits. For example, in SWSoft's 
2371) Virtuozzo, investigate /proc/user_beancounters. Look for "failcnt" in 
2372) tcpsndbuf, tcprecvbuf, numothersock, and othersockbuf. Ask for these to 
2373) be increased accordingly. Some users have seen settings work well as follows: 

2374) <p>

2375) <table border="1">

2376) <tr>
2377) <td>
2378) <i>resource</i>
2379) </td>
2380) <td>
2381) <i>held</i>
2382) </td>
2383) <td>
2384) <i>maxheld</i>
2385) </td>
2386) <td>
2387) <i>barrier</i>
2388) </td>
2389) <td>
2390) <i>limit</i>
2391) </td>
2392) <td>
2393) <i>failcnt</i>
2394) </td>
2395) </tr>
2396) <tr>
2397) <td>
2398) tcpsndbuf
2399) </td>
2400) <td>
2401) 46620
2402) </td>
2403) <td>
2404) 48840
2405) </td>
2406) <td>
2407) 3440640
2408) </td>
2409) <td>
2410) 5406720
2411) </td>
2412) <td>
2413) 0
2414) </td>
2415) </tr>
2416) <tr>
2417) <td>
2418) tcprcvbuf
2419) </td>
2420) <td>
2421) 0
2422) </td>
2423) <td>
2424) 2220
2425) </td>
2426) <td>
2427) 3440640
2428) </td>
2429) <td>
2430) 5406720
2431) </td>
2432) <td>
2433) 0
2434) </td>
2435) </tr>
2436) <tr>
2437) <td>
2438) othersockbuf
2439) </td>
2440) <td>
2441) 243516
2442) </td>
2443) <td>
2444) 260072
2445) </td>
2446) <td>
2447) 2252160
2448) </td>
2449) <td>
2450) 4194304
2451) </td>
2452) <td>
2453) 0
2454) </td>
2455) </tr>
2456) <tr>
2457) <td>
2458) numothersock
2459) </td>
2460) <td>
2461) 151
2462) </td>
2463) <td>
2464) 153
2465) </td>
2466) <td>
2467) 720
2468) </td>
2469) <td>
2470) 720
2471) </td>
2472) <td>
2473) 0
2474) </td>
2475) </tr>
2476) </table>
2477) <p>
2478)  Xen, Virtual Box and VMware virtual servers have no such limits normally.
2479) </p>
2480) <p>

2481) If the vserver admin will not increase system limits another option is 
2482) to reduce the memory allocated to the send and receive buffers on TCP 
2483) connections Tor uses. An experimental feature to constrain socket buffers 
2484) has recently been added. If your version of Tor supports it, set 
2485) "ConstrainedSockets 1" in your configuration. See the tor man page for 
2486) additional details about this option.

2487) </p>
2488) <p>

2489) Unfortunately, since Tor currently requires you to be able to connect to 
2490) all the other Tor relays, we need you to be able to use at least 1024 file 
2491) descriptors. This means we can't make use of Tor relays that are crippled 
2492) in this way.

2493) </p>
2494) <p>

2495) We hope to fix this in the future, once we know how to build a Tor network 
2496) with restricted topologies -- that is, where each node connects to only a 
2497) few other nodes. But this is still a long way off.

2498) </p>
2499) 

2500) <hr>
2501) 

2502) <a id="MultipleRelays"></a>

2503) <h3><a class="anchor" href="#MultipleRelays">I want to run more than one
2504) relay.</a></h3>

2505) 
2506) <p>
2507) Great. If you want to run several relays to donate more to the network,
2508) we're happy with that. But please don't run more than a few dozen on
2509) the same network, since part of the goal of the Tor network is dispersal
2510) and diversity.
2511) </p>
2512) 
2513) <p>
2514) If you do decide to run more than one relay, please set the "MyFamily"

2515) config option in the <a href="#torrc">torrc</a> of each relay, listing
2516) all the relays (comma-separated) that are under your control:

2517) </p>
2518) 
2519) <pre>
2520)     MyFamily $fingerprint1,$fingerprint2,$fingerprint3
2521) </pre>
2522) 
2523) <p>
2524) where each fingerprint is the 40 character identity fingerprint (without

2525) spaces). You can also list them by nickname, but fingerprint is safer.
2526) Be

2527) sure to prefix the digest strings with a dollar sign ('$') so that the
2528) digest is not confused with a nickname in the config file.
2529) </p>
2530) 
2531) <p>
2532) That way clients will know to avoid using more than one of your relays
2533) in a single circuit. You should set MyFamily if you have administrative
2534) control of the computers or of their network, even if they're not all in
2535) the same geographic location.
2536) </p>
2537) 
2538)     <hr>
2539) 

2540)     <a id="WrongIP"></a>

2541)     <h3><a class="anchor" href="#WrongIP">My relay is picking the wrong 
2542)     IP address.</a></h3>

2543)     <p>

2544)  Tor guesses its IP address by asking the computer for its hostname, and 
2545)  then resolving that hostname. Often people have old entries in their 
2546)  /etc/hosts file that point to old IP addresses.

2547)     </p>
2548)     <p>

2549) If that doesn't fix it, you should use the "Address" config option to 
2550) specify the IP you want it to pick. If your computer is behind a NAT and 
2551) it only has an internal IP address, see the following FAQ entry on <a 
2552) href="https://www.torproject.org/docs/faq.html.en#RelayFlexible">dynamic 
2553) IP addresses</a>.

2554)     </p>
2555)     <p>

2556) Also, if you have many addresses, you might also want to set 
2557) "OutboundBindAddress" so external connections come from the IP you intend 
2558) to present to the world. 

2559)     </p>
2560) 
2561)     <hr>
2562) 
2563)     <a id="BehindANAT"></a>
2564)     <h3><a class="anchor" href="#BehindANAT">I'm behind a NAT/Firewall.</a></h3>
2565) 
2566)     <p>

2567) See <a>​http://portforward.com/</a> for directions on how to port forward with 
2568) your NAT/router device.

2569) </p>
2570) <p>

2571) If your relay is running on a internal net you need to setup port forwarding. 
2572) Forwarding TCP connections is system dependent but the firewalled-clients FAQ 
2573) entry offers some examples on how to do this.

2574) </p>
2575) <p>

2576) Also, here's an example of how you would do this on GNU/Linux if you're using 
2577) iptables:

2578) </p>
2579) <pre>
2580) /sbin/iptables -A INPUT -i eth0 -p tcp --destination-port 9001 -j ACCEPT
2581) </pre>
2582) <p>

2583) You may have to change "eth0" if you have a different external interface 
2584) (the one connected to the Internet). Chances are you have only one (except 
2585) the loopback) so it shouldn't be too hard to figure out. 

2586)     </p>
2587)     <hr>
2588) 

2589)     <a id="RelayMemory"></a>

2590)     <h3><a class="anchor" href="#RelayMemory">Why is my Tor relay using
2591) so much memory?</a></h3>

2592) 

2593)     <p>If your Tor relay is using more memory than you'd like, here are
2594) some

2595)     tips for reducing its footprint:
2596)     </p>

2597) 

2598)     <ol>
2599)     <li>If you're on Linux, you may be encountering memory fragmentation

2600)     bugs in glibc's malloc implementation. That is, when Tor releases
2601) memory
2602)     back to the system, the pieces of memory are fragmented so they're
2603) hard
2604)     to reuse. The Tor tarball ships with OpenBSD's malloc
2605) implementation,
2606)     which doesn't have as many fragmentation bugs (but the tradeoff is
2607) higher
2608)     CPU load). You can tell Tor to use this malloc implementation
2609) instead:

2610)     <tt>./configure --enable-openbsd-malloc</tt></li>

2611) 

2612)     <li>If you're running a fast relay, meaning you have many TLS
2613) connections

2614)     open, you are probably losing a lot of memory to OpenSSL's internal
2615)     buffers (38KB+ per socket). We've patched OpenSSL to <a

2616) 
2617) href="https://lists.torproject.org/pipermail/tor-dev/2008-June/001519.
2618) html">release

2619)     unused buffer memory more aggressively</a>. If you update to OpenSSL

2620)     1.0.0 or newer, Tor's build process will automatically recognize and
2621) use

2622)     this feature.</li>

2623) 

2624) <!-- Nickm says he's not sure this is still accurate
2625) 

2626)     <li>If you're running on Solaris, OpenBSD, NetBSD, or
2627)     old FreeBSD, Tor is probably forking separate processes
2628)     rather than using threads. Consider switching to a <a
2629)     href="<wikifaq>#WhydoesntmyWindowsorotherOSTorrelayrunwell">better
2630)     operating system</a>.</li>

2631) -->

2632)     <li>If you still can't handle the memory load, consider reducing the

2633)     amount of bandwidth your relay advertises. Advertising less
2634) bandwidth

2635)     means you will attract fewer users, so your relay shouldn't grow
2636)     as large. See the <tt>MaxAdvertisedBandwidth</tt> option in the man
2637)     page.</li>

2638) 

2639)     </ol>

2640) 

2641)     <p>

2642)     All of this said, fast Tor relays do use a lot of ram. It is not
2643) unusual

2644)     for a fast exit relay to use 500-1000 MB of memory.
2645)     </p>

2646) 

2647)     <hr>

2648) 

2649)     <a id="BetterAnonymity"></a>

2650)     <h3><a class="anchor" href="#BetterAnonymity">Do I get better anonymity 
2651)     if I run a relay?</a></h3>

2652) 

2653)     <p>

2654) Yes, you do get better anonymity against some attacks.
2655)     </p>
2656)     <p>

2657) The simplest example is an attacker who owns a small number of Tor relays. 
2658) He will see a connection from you, but he won't be able to know whether 
2659) the connection originated at your computer or was relayed from somebody else.

2660)     </p>
2661)     <p>

2662) There are some cases where it doesn't seem to help: if an attacker can 
2663) watch all of your incoming and outgoing traffic, then it's easy for him 
2664) to learn which connections were relayed and which started at you. (In 
2665) this case he still doesn't know your destinations unless he is watching 
2666) them too, but you're no better off than if you were an ordinary client.)

2667)     </p>
2668)     <p>

2669) There are also some downsides to running a Tor relay. First, while we 
2670) only have a few hundred relays, the fact that you're running one might 
2671) signal to an attacker that you place a high value on your anonymity. 
2672) Second, there are some more esoteric attacks that are not as 
2673) well-understood or well-tested that involve making use of the knowledge 
2674) that you're running a relay -- for example, an attacker may be able to 
2675) "observe" whether you're sending traffic even if he can't actually watch 
2676) your network, by relaying traffic through your Tor relay and noticing 
2677) changes in traffic timing.

2678)     </p>
2679)     <p>

2680) It is an open research question whether the benefits outweigh the risks. 
2681) A lot of that depends on the attacks you are most worried about. For 
2682) most users, we think it's a smart move. 

2683)     </p>

2684) 

2685)     <hr>

2686) 

2687)     <a id="RelayDonations"></a>

2688)     <h3><a class="anchor" href="#RelayDonations">Can I donate for a
2689)     relay rather than run my own?</a></h3>

2690) 
2691)     <p>

2692)     Sure! We recommend these non-profit charities that are happy to turn

2693)     your donations into better speed and anonymity for the Tor network:
2694)     </p>
2695)     <ul>
2696)     <li><a href="https://www.torservers.net/">torservers.net</a>
2697)     is a German charitable non-profit that runs a wide variety of

2698)     exit relays worldwide. They also like donations of bandwidth from
2699)     ISPs.</li>

2700)     <li><a

2701) href="https://www.noisebridge.net/wiki/Noisebridge_Tor">Noisebridge</a>

2702)     is a US-based 501(c)(3) non-profit that collects donations and turns

2703)     them into more US-based exit relay capacity.</li>
2704)     <li><a href="https://nos-oignons.net/">Nos Oignons</a> is a French
2705)     charitable non-profit that runs fast exit relays in France.</li>

2706)     </ul>
2707) 
2708)     <p>
2709)     These organizations are not the same as <a href="<page
2710)     donate/donate>">The Tor Project, Inc</a>, but we consider that a

2711)     good thing. They're both run by nice people who are part of the
2712)     Tor community.

2713)     </p>
2714) 
2715)     <p>
2716)     Note that there can be a tradeoff here between anonymity and

2717)     performance. The Tor network's anonymity comes in part from
2718) diversity,

2719)     so if you are in a position to run your own relay, you will be

2720)     improving Tor's anonymity more than by donating. At the same time
2721)     though, economies

2722)     of scale for bandwidth mean that combining many small donations into

2723)     several larger relays is more efficient at improving network

2724)     performance. Improving anonymity and improving performance are both
2725)     worthwhile goals, so however you can help is great!
2726)     </p>
2727) 
2728)     <hr>
2729) 

2730)     <a id="AccessHiddenServices"></a>
2731)     <h3><a class="anchor" href="#AccessHiddenServices">How do I access 
2732)     hidden services?</a></h3>
2733)     
2734)     <p>
2735)     Tor hidden services are named with a special top-level domain (TLD) 
2736)     name in DNS: .onion. Since the .onion TLD is not recognized by the 
2737)     official root DNS servers on the Internet, your application will not 
2738)     get the response it needs to locate the service. Currently, the Tor 
2739)     directory server provides this look-up service; and thus the look-up 
2740)     request must get to the Tor network. 
2741)     </p>
2742) 
2743) <p>
2744)  Therefore, your application <b>needs</b> to pass the .onion hostname to 
2745)  Tor directly. You can't try to resolve it to an IP address, since there 
2746)  <i>is</i> no corresponding IP address: the server is hidden, after all! 
2747) </p>
2748)     
2749)     <p>
2750)     So, how do you make your application pass the hostname directly to Tor? 
2751)     You can't use SOCKS 4, since SOCKS 4 proxies require an IP from the 
2752)     client (a web browser is an example of a SOCKS client). Even though 
2753)     SOCKS 5 can accept either an IP or a hostname, most applications 
2754)     supporting SOCKS 5 try to resolve the name before passing it to the 
2755)     SOCKS proxy. SOCKS 4a, however, always accepts a hostname: You'll need 
2756)     to use SOCKS 4a. 
2757)     </p>
2758)     
2759)     <p>
2760)     Some applications, such as the browsers Mozilla Firefox and Apple's 
2761)     Safari, support sending DNS queries to Tor's SOCKS 5 proxy. Most web 
2762)     browsers don't support SOCKS 4a very well, though. The workaround is 
2763)     to point your web browser at an HTTP proxy, and tell the HTTP proxy 
2764)     to speak to Tor with SOCKS 4a. We recommend Polipo as your HTTP proxy.
2765)     </p>
2766)     
2767)     <p>
2768)     For applications that do not support HTTP proxy, and so cannot use 
2769)     Polipo, <a href="http://www.freecap.ru/eng/">FreeCap</a> is an 
2770)     alternative. When using FreeCap set proxy protocol  to SOCKS 5 and under 
2771)     settings set DNS name resolving to remote. This 
2772)     will allow you to use almost any program with Tor without leaking DNS 
2773)     lookups and allow those same programs to access hidden services. 
2774)     </p>
2775)     
2776)     <p>
2777)     See also the <a href="#SocksAndDNS">question on DNS</a>. 
2778)     </p>    
2779)     
2780)     <hr>
2781) 
2782)     <a id="ProvideAHiddenService"></a>
2783)     <h3><a class="anchor" href="#ProvideAHiddenService">How do I provide a 
2784)     hidden service?</a></h3>
2785)     
2786)     <p>

2787)     See the <a href="https://www.torproject.org/docs/tor-hidden-service.html.en">

2788)     official hidden service configuration instructions</a>.
2789)     </p>
2790) 
2791)     <hr>
2792)     

2793)     <a id="WhoIsResponsible"></a>
2794)     <h3><a class="anchor" href="#WhoIsResponsible">Who is responsible 
2795)     for Tor?</a></h3>
2796) 
2797)     <p>
2798)     <a href="http://www.freehaven.net/~arma/cv.html">Roger Dingledine</a> and 
2799)     <a href="http://www.wangafu.net/~nickm/">Nick Mathewson</a> are the main 
2800)     developers of Tor. You can read more at 
2801)     <a href="https://www.torproject.org/about/corepeople">Tor's People 
2802)     page</a>. 
2803)     </p>
2804) 
2805)     <hr>
2806) 
2807)     <a id="VersionNumbers"></a>
2808)     <h3><a class="anchor" href="#VersionNumbers">What do these weird 
2809)     version numbers mean?</a></h3>
2810) 
2811)     <p>
2812)     Versions of Tor before 0.1.0 used a strange and hard-to-explain version scheme. Let's forget about those.
2813)     </p>
2814)     <p>
2815)     Starting with 0.1.0, versions all look like this: 
2816)     MAJOR.MINOR.MICRO(.PATCHLEVEL)(-TAG). The stuff in parenthesis is 
2817)     optional. MAJOR, MINOR, MICRO, and PATCHLEVEL are all numbers. Only one 
2818)     release is ever made with any given set of these version numbers. The 
2819)     TAG lets you know how stable we think the release is: "alpha" is pretty 
2820)     unstable; "rc" is a release candidate; and no tag at all means that we 
2821)     have a final release. If the tag ends with "-cvs", you're looking at 
2822)     a development snapshot that came after a given release. 
2823)     </p>
2824)     <p>
2825)     So for example, we might start a development branch with (say) 
2826)     0.1.1.1-alpha. The patchlevel increments consistently as the status 
2827)     tag changes, for example, as in: 0.1.1.2-alpha, 0.1.1.3-alpha, 
2828)     0.1.1.4-rc, 0.1.1.5-rc, etc. Eventually, we would release 0.1.1.6. 
2829)     The next stable release would be 0.1.1.7.
2830)     </p>
2831)     <p>
2832)     Why do we do it like this? Because every release has a unique 
2833)     version number, it is easy for tools like package manager to tell 
2834)     which release is newer than another. The tag makes it easy for users 
2835)     to tell how stable the release is likely to be. 
2836)     </p>
2837) 
2838)     <hr>
2839) 
2840)     <a id="PrivateTorNetwork"></a>
2841)     <h3><a class="anchor" href="#PrivateTorNetwork">How do I set up my 
2842)     own private Tor network?</a></h3>
2843)     
2844)     <p>
2845)     If you want to experiment locally with your own network, or you're 
2846)     cut off from the Internet and want to be able to mess with Tor still, 
2847)     then you may want to set up your own separate Tor network. 
2848)     </p>
2849)     <p>
2850)     To set up your own Tor network, you need to run your own authoritative 
2851)     directory servers, and your clients and relays must be configured so 
2852)     they know about your directory servers rather than the default public 
2853)     ones. 
2854)     </p>
2855)     <p>
2856)     Apart from the somewhat tedious method of manually configuring a couple 
2857)     of directory authorities, relays and clients there are two separate 
2858)     tools that could help. One is Chutney, the other is Shadow. 
2859)     </p>
2860)     <p>
2861)     <a href="https://gitweb.torproject.org/chutney.git">Chutney</a> is a 
2862)     tool for configuring, controlling and running tests on a 
2863)     testing Tor network. It requires that you have Tor and Python (2.5 or 
2864)     later) installed on your system. You can use Chutney to create a testing
2865)     network by generating Tor configuration files (torrc) and necssary keys 
2866)     (for the directory authorities). Then you can let Chutney start your Tor
2867)     authorities, relays and clients and wait for the network to bootstrap.
2868)     Finally, you can have Chutney run tests on your network to see which 
2869)     things work and which do not. Chutney is typically used for running a 
2870)     testing network with about 10 instances of Tor. Every instance of Tor 
2871)     binds to one or two ports on localhost (127.0.0.1) and all Tor 
2872)     communication is done over the loopback interface. The <a 
2873)     href="https://gitweb.torproject.org/chutney.git/blob/HEAD:/README">Chutney 
2874)     README</a> is a good starting point for getting it up and running. 
2875)     </p>
2876)     <p>
2877)     <a href="https://github.com/shadow/shadow">Shadow</a> is a network 
2878)     simulator that can run Tor through its Scallion plug-in. Although 
2879)     it's typically used for running load and performance tests on 
2880)     substantially larger Tor test networks than what's feasible with 
2881)     Chutney, it also makes for an excellent debugging tool since you can 
2882)     run completely deterministic experiments. A large Shadow network is on 
2883)     the size of thousands of instances of Tor, and you can run experiments 
2884)     out of the box using one of Shadow's several included scallion experiment 
2885)     configurations. Shadow can be run on any linux machine without root, 
2886)     and can also run on EC2 using a pre-configured image. Also, Shadow 
2887)     controls the time of the simulation with the effect that 
2888)     time-consuming tests can be done more efficiently than in an 
2889)     ordinary testing network. The <a 
2890)     href="https://github.com/shadow/shadow/wiki">Shadow wiki</a> and 
2891)     <a href="http://shadow.github.io/">Shadow website</a> are 
2892)     good places to get started. 
2893)     </p>
2894) 
2895)     <hr>
2896) 

2897)     <a id="UseTorWithJava"></a>
2898)     <h3><a class="anchor" href="#UseTorWithJava">How can I make my Java 

2899)     program use the Tor Network?</a></h3>
2900) 
2901)     <p>
2902)     The newest versions of Java now have SOCKS4/5 support built in. 
2903)     Unfortunately, the SOCKS interface is not very well documented and 
2904)     may still leak your DNS lookups. The safest way to use Tor is to 
2905)     interface the SOCKS protocol directly or go through an application-level 
2906)     proxy that speaks SOCKS4a. For an example and libraries that implement 
2907)     the SOCKS4a connection, go to Joe Foley's TorLib in the <a 
2908)     href="http://web.mit.edu/foley/www/TinFoil/">TinFoil Project</a>. 
2909)     </p>
2910) 
2911)     <p>
2912)     A fully Java implementation of the Tor client is now available as <a 
2913)     href="http://www.subgraph.com/orchid.html">Orchid</a>. We still consider 
2914)     Orchid to be experimental, so use with care. 
2915)     </p>
2916) 
2917)     <hr>
2918) 
2919) 
2920)     <a id="WhatIsLibevent"></a>
2921)     <h3><a class="anchor" href="#WhatIsLibevent">What is Libevent?</a></h3>
2922)     
2923)     <p>
2924)     When you want to deal with a bunch of net connections at once, you 
2925)     have a few options: 
2926)     </p>
2927)     <p>
2928)     One is multithreading: you have a separate micro-program inside the 
2929)     main program for each net connection that reads and writes to the 
2930)     connection as needed.This, performance-wise, sucks. 
2931)     </p>
2932)     <p>
2933)     Another is asynchronous network programming: you have a single main 
2934)     program that finds out when various net connections are ready to 
2935)     read/write, and acts accordingly.
2936)     </p>
2937)     <p>
2938)     The problem is that the oldest ways to find out when net connections 
2939)     are ready to read/write, suck. And the newest ways are finally fast, 
2940)     but are not available on all platforms. 
2941)     </p>
2942)     <p>
2943)     This is where Libevent comes in and wraps all these ways to find 
2944)     out whether net connections are ready to read/write, so that Tor 
2945)     (and other programs) can use the fastest one that your platform 
2946)     supports, but can still work on older platforms (these methods are 
2947)     all different depending on the platorm) So Libevent presents a 
2948)     consistent and fast interface to select, poll, kqueue, epoll, 
2949)     /dev/poll, and windows select. 
2950)     </p>
2951)     <p>
2952)     However, On the the Win32 platform (by Microsoft) the only good 
2953)     way to do fast IO on windows with hundreds of sockets is using 
2954)     overlapped IO, which is grossly unlike every other BSD sockets 
2955)     interface. 
2956)     </p>
2957)     <p>Libevent has <a href="http://www.monkey.org/~provos/libevent/">its 
2958)     own website</a>.
2959)     </p>
2960)     <hr>
2961) 
2962)     <a id="MyNewFeature"></a>
2963)     <h3><a class="anchor" href="#MyNewFeature">What do I need to do to get 
2964)     a new feature into Tor?</a></h3>
2965)     
2966)     <p>
2967)     For a new feature to go into Tor, it needs to be designed (explain what 
2968)     you think Tor should do), argued to be secure (explain why it's better 
2969)     or at least as good as what Tor does now), specified (explained at the 
2970)     byte level at approximately the level of detail in tor-spec.txt), and 
2971)     implemented (done in software). 
2972)     </p>
2973) 
2974)     <p>
2975)     You probably shouldn't count on other people doing all of these steps 
2976)     for you: people who are skilled enough to do this stuff generally 
2977)     have their own favorite feature requests.
2978)     </p>
2979) 
2980)     <hr>
2981) 

2982)     <a id="WhatProtectionsDoesTorProvide"></a>
2983)     <h3><a class="anchor" href="#WhatProtectionsDoesTorProvide">What 
2984)     protections does Tor provide?</a></h3>
2985)     
2986)     <p>

2987)     Internet communication is based on a store-and-forward model that 
2988)     can be understood in analogy to postal mail: Data is transmitted in 
2989)     blocks called IP datagrams or packets. Every packet includes a source 
2990)     IP address (of the sender) and a destination IP address (of the 
2991)     receiver), just as ordinary letters contain postal addresses of sender 
2992)     and receiver. The way from sender to receiver involves multiple hops of 
2993)     routers, where each router inspects the destination IP address and 
2994)     forwards the packet closer to its destination. Thus, every router 
2995)     between sender and receiver learns that the sender is communicating 
2996)     with the receiver. In particular, your local ISP is in the position to 
2997)     build a complete profile of your Internet usage. In addition, every 
2998)     server in the Internet that can see any of the packets can profile your 
2999)     behaviour. 

3000)     </p>
3001)     
3002)     <p>
3003)     The aim of Tor is to improve your privacy by sending your traffic through 
3004)     a series of proxies. Your communication is encrypted in multiple layers 
3005)     and routed via multiple hops through the Tor network to the final 
3006)     receiver. More details on this process can be found in the <a 
3007)     href="https://www.torproject.org/about/overview">Tor overview</a>. 
3008)     Note that all your local ISP can observe now is that you are 
3009)     communicating with Tor nodes. Similarly, servers in the Internet just 
3010)     see that they are being contacted by Tor nodes.
3011)     </p>
3012)     
3013)     <p>
3014)     Generally speaking, Tor aims to solve three privacy problems: 
3015)     </p>
3016)     
3017)     <p>
3018)     First, Tor prevents websites and other services from learning 
3019)     your location, which they can use to build databases about your 
3020)     habits and interests. With Tor, your Internet connections don't 
3021)     give you away by default -- now you can have the ability to choose, 
3022)     for each connection, how much information to reveal. 
3023)     </p>
3024)     
3025)     <p>
3026)     Second, Tor prevents people watching your traffic locally (such as 
3027)     your ISP) from learning what information you're fetching and where 
3028)     you're fetching it from. It also stops them from deciding what you're 
3029)     allowed to learn and publish -- if you can get to any part of the Tor 
3030)     network, you can reach any site on the Internet.     
3031)     </p>
3032) 
3033)     <p>
3034)     Third, Tor routes your connection through more than one Tor relay 
3035)     so no single relay can learn what you're up to. Because these relays 
3036)     are run by different individuals or organizations, distributing trust 
3037)     provides more security than the old <a href="#Torisdifferent">one hop proxy
3038)     </a> approach. 
3039)     </p>
3040)     
3041)     <p>
3042)     Note, however, that there are situations where Tor fails to solve these 
3043)     privacy problems entirely: see the entry below on <a 
3044)     href="#AttacksOnOnionRouting">remaining attacks</a>.    
3045)     </p>
3046)     
3047)     <hr>
3048)     
3049)     <a id="CanExitNodesEavesdrop"></a>
3050)     <h3><a class="anchor" href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop 
3051)     on communications? Isn't that bad?</a></h3>
3052)     
3053)     <p>
3054)     Yes, the guy running the exit node can read the bytes that come in and 
3055)     out there. Tor anonymizes the origin of your traffic, and it makes sure 
3056)     to encrypt everything inside the Tor network, but it does not magically 
3057)     encrypt all traffic throughout the Internet. 
3058)     </p>
3059)     
3060)     <p>
3061)     This is why you should always use end-to-end encryption such as SSL for 
3062)     sensitive Internet connections. (The corollary to this answer is that if 
3063)     you are worried about somebody intercepting your traffic and you're 
3064)     *not* using end-to-end encryption at the application layer, then something 
3065)     has already gone wrong and you shouldn't be thinking that Tor is the problem.) 
3066)     </p>
3067)     
3068)     <p>
3069)     Tor does provide a partial solution in a very specific situation, though. 
3070)     When you make a connection to a destination that also runs a Tor relay, 
3071)     Tor will automatically extend your circuit so you exit from that circuit. 
3072)     So for example if Indymedia ran a Tor relay on the same IP address as 
3073)     their website, people using Tor to get to the Indymedia website would 
3074)     automatically exit from their Tor relay, thus getting *better* encryption 
3075)     and authentication properties than just browsing there the normal way. 
3076)     </p>
3077) 
3078)     <p>
3079)     We'd like to make it still work even if the service is nearby the Tor 
3080)     relay but not on the same IP address. But there are a variety of 
3081)     technical problems we need to overcome first (the main one being "how 
3082)     does the Tor client learn which relays are associated with which 
3083)     websites in a decentralized yet non-gamable way?"). 
3084)     </p>
3085)             
3086)     <hr>
3087)     
3088)     <a id="ExitEnclaving"></a>
3089)     <h3><a class="anchor" href="#ExitEnclaving">What is Exit Enclaving?</a></h3>
3090) 
3091)     <p>
3092)     When a machine that runs a Tor relay also runs a public service, such as 
3093)     a webserver, you can configure Tor to offer Exit Enclaving to that 
3094)     service. Running an Exit Enclave for all of your services you wish to 
3095)     be accessible via Tor provides your users the assurance that they will 
3096)     exit through your server, rather than exiting from a randomly selected 
3097)     exit node that could be watched. Normally, a tor circuit would end at 
3098)     an exit node and then that node would make a connection to your service. 
3099)     Anyone watching that exit node could see the connection to your service, 
3100)     and be able to snoop on the contents if it were an unencrypted 
3101)     connection. If you run an Exit Enclave for your service, then the exit 
3102)     from the Tor network happens on the machine that runs your service, 
3103)     rather than on an untrusted random node. This works when Tor clients 
3104)     wishing to connect to this public service extend their their circuit 
3105)     to exit from the Tor relay running on that same host. For example, if 
3106)     the server at 1.2.3.4 runs a web server on port 80 and also acts as a 
3107)     Tor relay configured for Exit Enclaving, then Tor clients wishing to 
3108)     connect to the webserver will extend their circuit a fourth hop to exit 
3109)     to port 80 on the Tor relay running on 1.2.3.4. 
3110)     </p>
3111)     <p>
3112)     Exit Enclaving is disabled by default to prevent attackers from 
3113)     exploiting trust relationships with locally bound services. For 
3114)     example, often 127.0.0.1 will run services that are not designed to 
3115)     be shared with the entire world. Sometimes these services will also 
3116)     be bound to the public IP address, but will only allow connections if 
3117)     the source address is something trusted, such as 127.0.0.1. 
3118)     </p>
3119)     <p>
3120)     As a result of possible trust issues, relay operators must configure 
3121)     their exit policy to allow connections to themselves, but they should 
3122)     do so only when they are certain that this is a feature that they would 
3123)     like. Once certain, turning off the ExitPolicyRejectPrivate option will 
3124)     enable Exit Enclaving. An example configuration would be as follows: 
3125)     </p>
3126)     <pre>
3127)     ExitPolicy accept 1.2.3.4:80
3128)     ExitPolicy reject 127.0.0.1/8
3129)     ExitPolicyRejectPrivate 0
3130)     </pre>
3131)     <p>
3132)     This option should be used with care as it may expose internal network 
3133)     blocks that are not meant to be accessible from the outside world or 
3134)     the Tor network. Please tailor your ExitPolicy to reflect all netblocks 
3135)     that you want to prohibit access. 
3136)     </p>
3137)     <p>
3138)     This option should be used with care as it may expose internal network 
3139)     blocks that are not meant to be accessible from the outside world or 
3140)     the Tor network. Please tailor your ExitPolicy to reflect all netblocks 
3141)     that you want to prohibit access. 
3142)     </p>
3143)     <p>
3144)     While useful, this behavior may go away in the future because it is 
3145)     imperfect. A great idea but not such a great implementation. 
3146)     </p>
3147) 
3148)     <hr>
3149)     

3150)     <a id="KeyManagement"></a>

3151)     <h3><a class="anchor" href="#KeyManagement">Tell me about all the
3152) keys Tor uses.</a></h3>

3153) 

3154)     <p>
3155)     Tor uses a variety of different keys, with three goals in mind: 1)
3156)     encryption to ensure privacy of data within the Tor network, 2)
3157)     authentication so clients know they're