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5) #include "head.wmi" TITLE="Tor Project: FAQ" CHARSET="UTF-8"
6) <div id="content" class="clearfix">
7)   <div id="breadcrumbs">

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

9)     <a href="<page docs/documentation>">Documentation &raquo; </a>
10)     <a href="<page docs/faq>">FAQ</a>
11)   </div>
12)   <div id="maincol">
13)     <!-- PUT CONTENT AFTER THIS TAG -->
14)     <h1>Tor FAQ</h1>

15)     <hr>

16) 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

43)     </ul>

44) 

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

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

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

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

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

59)     </ul>

60) 

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

63) 

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

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

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

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

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

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

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

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

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

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

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

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

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

88) tells

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

122)     </ul>

123) 

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

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

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

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

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

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

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

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

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

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

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

156)     </ul>

157) 

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

163) 

164)     <p>Anonymity and Security:</p>
165)     <ul>

166)     <li><a href="#WhatProtectionsDoesTorProvide">What protections does Tor 
167)     provide?</a></li>
168)     <li><a href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop on 
169)     communications? Isn't that bad? </a></li>
170)     <li><a href="#ExitEnclaving">What is Exit Enclaving?</a></li>

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

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

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

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

185)     </ul>

186) 

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

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

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

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

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

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

207)     </ul>

208) 

209)     <p>Abuse:</p>

210)     <ul>

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

213)     <li><a href="#RespondISP">How do I respond to my ISP about my exit
214)     relay?</a></li>
215)     </ul>

216) 

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

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

220) 

221)     <hr>

222) 

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

224) 

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

227) 

228)     <p>
229)     The name "Tor" can refer to several different components.
230)     </p>

231) 

232)     <p>

233)     The Tor software is a program you can run on your computer that
234) helps keep
235)     you safe on the Internet. Tor protects you by bouncing your
236) communications

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

238)     the world: it prevents somebody watching your Internet connection
239) from

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

241)     from learning your physical location. This set of volunteer relays
242) is
243)     called the Tor network. You can read more about how Tor works on the
244) <a

245)     href="<page about/overview>">overview page</a>.
246)     </p>

247) 

248)     <p>

249)     The Tor Project is a non-profit (charity) organization that
250) maintains

251)     and develops the Tor software.
252)     </p>

253) 

254)     <hr>

255) 

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

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

280) free wifi Internet.
281)     </p>
282)     <p>

283)     Simple proxy providers also create a single point of failure.  The
284) provider
285) knows who you are and where you browse on the Internet.  They can see
286) your
287) traffic as it passes through their server.  In some cases, they can even
288) see

289) inside your

290) encrypted traffic as they relay it to your banking site or to ecommerce
291) stores.

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

293) watching your traffic, injecting their own advertisements into your
294) traffic

295) stream, and recording your personal details.

296)     </p>
297)     <p>

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

314) packets between themselves.</p>

315)     <p>
316)     <dl>

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

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

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

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

333) e-commerce website, or encrypted mail connections, etc, it will only
334) know the
335) destination.  It won't be able to see the data inside the traffic
336) stream.  You

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

339)     </dl>
340)     </p>

341) 

342)     <hr>

343) 

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

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

347) 

348)     <p>

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

353)     </p>
354)     <p>
355)     There are plenty of other programs you can use with Tor,
356)     but we haven't researched the application-level anonymity

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

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

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

360)     specific applications</a>.

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

363) 

364)     <hr>

365) 

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

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

369) 

370)     <p>
371)     Because Tor is the onion routing network. When we were starting the
372)     new next-generation design and implementation of onion routing in
373)     2001-2002, we would tell people we were working on onion routing,
374)     and they would say "Neat. Which one?" Even if onion routing has
375)     become a standard household term, Tor was born out of the actual <a
376)     href="http://www.onion-router.net/">onion routing project</a> run by
377)     the Naval Research Lab.
378)     </p>

379) 

380)     <p>
381)     (It's also got a fine translation from German and Turkish.)
382)     </p>

383) 

384)     <p>

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

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

388)     spot people who haven't read any of our website (and have instead
389) learned
390)     everything they know about Tor from news articles) by the fact that
391) they

392)     spell it wrong.
393)     </p>

394) 

395)     <hr>

396) 

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

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

400) 

401)     <p>

402)     There is absolutely no backdoor in Tor. Nobody has asked us to put
403) one
404)     in, and we know some smart lawyers who say that it's unlikely that
405) anybody

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

409) 

410)     <p>
411)     We think that putting a backdoor in Tor would be tremendously

412)     irresponsible to our users, and a bad precedent for security
413) software

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

418) 

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

422)     computers, or something like that. Tor is open source, and you
423) should
424)     always check the source (or at least the diffs since the last
425) release)

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

432) 

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

435)     anonymity. We periodically find and fix anonymity-related bugs, so
436) make

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

439) 

440)     <hr>

441) 

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

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

445) 

446)     <p>
447)     Yes.
448)     </p>

449) 

450)     <p>

451)     The Tor software is <a href="https://www.fsf.org/">free
452) software</a>. This
453)     means we give you the rights to redistribute the Tor software,
454) either
455)     modified or unmodified, either for a fee or gratis. You don't have
456) to

457)     ask us for specific permission.
458)     </p>

459) 

460)     <p>

461)     However, if you want to redistribute the Tor software you must
462) follow our

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

464)     Essentially this means that you need to include our LICENSE file
465) along

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

468) 

469)     <p>

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

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

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

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

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

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

485)     </p>

486) 

487)     <p>

488)     Also, you should make sure not to confuse your readers about what
489) Tor is,
490)     who makes it, and what properties it provides (and doesn't provide).
491) See
492)     our <a href="<page docs/trademark-faq>">trademark FAQ</a> for
493) details.

494)     </p>

495) 

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

499)     changes. So if you distribute a particular version of the Tor
500) software, it
501)     may not be supported — or even work — six months later.
502) This

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

505) 

506)     <hr>

507) 

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

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

511) 

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

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

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

517)     <li>Read through the <a

518) 
519) href="https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk">
520) tor-talk

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

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

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

525)     <li>Send an email to <a

526) 
527) href="mailto:help@rt.torproject.org">help@rt.torproject.org</a>.</li>
528)     <li>If all else fails, try <a href="<page about/contact>">contacting
529) us</a> directly.</li>

530)     </ol>

531) 

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

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

535) 

536)     <hr>

537) 

538)     <a id="Forum"></a>
539)     <h3><a class="anchor" href="#Forum">Is there a Tor forum?</a></h3>
540) 
541)     <p>Not yet, but we're working on it. Most forum software is
542)     a disaster to maintain and keep secure, and at the same time
543)     too many of the Tor developers are spread too thin to be able

544)     to contribute enough to a forum.

545)     </p>
546) 
547)     <hr>
548) 

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

551) 

552)     <p>
553)     There are many reasons why the Tor network is currently slow.
554)     </p>

555) 

556)     <p>

557)     Before we answer, though, you should realize that Tor is never going
558) to
559)     be blazing fast. Your traffic is bouncing through volunteers'
560) computers
561)     in various parts of the world, and some bottlenecks and network
562) latency

563)     will always be present. You shouldn't expect to see university-style
564)     bandwidth through Tor.
565)     </p>

566) 

567)     <p>

568)     But that doesn't mean that it can't be improved. The current Tor
569) network
570)     is quite small compared to the number of people trying to use it,
571) and
572)     many of these users don't understand or care that Tor can't
573) currently

574)     handle file-sharing traffic load.
575)     </p>

576) 

577)     <p>
578)     For the much more in-depth answer, see <a

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

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

582)     to go with it.
583)     </p>

584) 

585)     <p>
586)     What can you do to help?
587)     </p>

588) 

589)     <ul>

590) 

591)     <li>

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

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

598) 

599)     <li>

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

602)     especially need people to help make it easier to configure your Tor
603)     as a relay. Also, we need help with clear simple documentation to
604)     walk people through setting it up.
605)     </li>

606) 

607)     <li>

608)     There are some bottlenecks in the current Tor network. Help us
609) design
610)     experiments to track down and demonstrate where the problems are,
611) and

612)     then we can focus better on fixing them.
613)     </li>

614) 

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

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

621)     get to spend more time on it.
622)     </li>

623) 

624)     <li>

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

629)     getinvolved/volunteer>">look at our volunteer page</a>.
630)     </li>

631) 

632)     <li>

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

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

636)     competition's websites discreetly, or to connect back to the home
637) servers
638)     when on the road without revealing affiliations? If your
639) organization has
640)     an interest in keeping the Tor network working, please contact them
641) about
642)     supporting Tor. Without sponsors, Tor is going to become even
643) slower.

644)     </li>

645) 

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

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

650)     cause</a>. It adds up!
651)     </li>

652) 

653)     </ul>

654) 

655)     <hr>

656) 

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

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

660) 
661)     <p>

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

668)     </p>
669) 
670)     <hr>
671) 

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

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

675) 

676)     <p>

677)     The Tor network's <a

678) 
679) href="https://metrics.torproject.org/network.html#networksize">several

680)     thousand</a> relays push <a
681)     href="https://metrics.torproject.org/network.html#bandwidth">over
682)     1GB per second on average</a>. We have <a

683) 
684) href="https://metrics.torproject.org/users.html#direct-users">several

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

687)     </p>

688) 

689)     <p>

690)     There are six main development/maintenance pushes that need
691) attention:

692)     </p>

693) 

694)     <ul>

695) 

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

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

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

703) 

704)     <li>

705)     User support: With this many users, a lot of people are asking
706) questions
707)     all the time, offering to help out with things, and so on. We need
708) good
709)     clean docs, and we need to spend some effort coordinating
710) volunteers.

711)     </li>

712) 

713)     <li>

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

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

717)     reminders to upgrade, and so on. The network itself is a commons,
718) and
719)     somebody needs to spend some energy making sure the relay operators
720) stay
721)     happy. We also need to work on stability on some platforms —
722) e.g.,

723)     Tor relays have problems on Win XP currently.

724)     </li>

725) 

726)     <li>

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

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

739) 

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

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

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

747) 

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

753)     critical <a href="<page getinvolved/volunteer>#Research">Tor
754) research questions</a>
755)     that will help us figure out how to make Tor secure against the
756) variety of
757)     attacks out there. Of course, there are more research questions
758) waiting

759)     behind these.
760)     </li>

761) 

762)     </ul>

763) 

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

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

768)     can keep up</a>.

769)     Now would be an excellent time to add a few more developers to the
770) effort

771)     so we can continue to grow the network.
772)     </p>

773) 

774)     <p>
775)     We are also excited about tackling related problems, such as
776)     censorship-resistance.
777)     </p>

778) 

779)     <p>

780)     We are proud to have <a href="<page about/sponsors>">sponsorship and
781) support</a>
782)     from the Omidyar Network, the International Broadcasting Bureau,
783) Bell
784)     Security Solutions, the Electronic Frontier Foundation, several
785) government

786)     agencies and research groups, and hundreds of private contributors.
787)     </p>

788) 

789)     <p>

790)     However, this support is not enough to keep Tor abreast of changes
791) in the
792)     Internet privacy landscape. Please <a href="<page
793) donate/donate>">donate</a>
794)     to the project, or <a href="<page about/contact>">contact</a> our
795) executive

796)     director for information on making grants or major donations.
797)     </p>

798) 

799)     <hr>
800) 

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

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

804) 
805)     <p>

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

810)     </p>
811)     <p>

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

819)     </p>
820)     <p>

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

823)     </p>
824)     <p>

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

830)     </p>
831)     
832)     <hr>
833)     
834)     <a id="IsItWorking"></a>

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

837) 
838)     <p>

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

842)     </p>
843)     <p>

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

850)     </p>
851)     <p>

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

855)     </p>
856)     <p>

857)     If you are behind a NAT or firewall, though, your IP address will be 
858)     within the range of 10.XXX.XXX.XXX, 192.168.XXX.XXX, or 172.16.XXX.XXX - 
859)     172.31.XXX.XXX, which is not your public IP address. In this case, you 
860)     should check your IP address with one of the sites above without using 
861)     Tor, and then check again using Tor to see whether your IP address has 
862)     changed. 

863)     </p>
864)     
865)     <hr>
866)     
867)     <a id="FTP"></a>
868)     <h3><a class="anchor" href="#FTP">How do I use my browser for ftp with Tor?
869)     </a></h3>
870) 

871)     <p>
872)     Use the Tor Browser Bundle. If you want a separate application for an 
873)     ftp client, we've heard good things about  FileZilla for Windows. You can 
874)     configure it to point to Tor as a "socks4a" proxy on "localhost" port 
875)     "9050". 
876)     </p>

877)     <hr>
878)     

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

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

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

882) 

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

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

886)     <hr>

887) 

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

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

891)     <p>

892)     <pre>

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

894)     The serial number is:

895) 06:DE:97:E5:1D:C3:9D:C2:64:8D:AC:72:DD:41:01:FC
896)     The SHA-1 fingerprint is: 1f9d306e8bfccfcb03981a71a27a9f5d1e0876ce

897)     The SHA-256 fingerprint is:

898) 3613d2b22a750094760c41ad19db52a4f05bdea80172e2578761ad967f7ed9aa

899) 

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

901)     The serial number is: 00:EF:A3
902)     The SHA-1 fingerprint is: 50af43db8438e67f305a3257d8ef198e8c42f13f

903)     </pre>

904)     </p>
905)     <hr>
906) 

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

908)     <h3><a class="anchor" href="#HowUninstallTor">How do I uninstall
909) Tor?</a></h3>
910) 
911)     <p>
912)     Tor Browser does not install itself in the classic sense of
913) applications. You just simply delete the folder or directory named "Tor
914) Browser" and it is removed from your system.
915)     </p>

916) 

917)     <p>

918)     If this is not related to Tor Browser, uninstallation depends
919) entirely on how you installed it and which operating system you
920)     have. If you installed a package, then hopefully your package has a
921) way to

922)     uninstall itself. The Windows packages include uninstallers. 

923)     </p>

924) 

925)     <p>
926)     For Mac OS X, follow the <a
927)     href="<page docs/tor-doc-osx>#uninstall">uninstall directions</a>.
928)     </p>

929) 

930)     <p>

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

935)     be pretty easy to notice things there.
936)     </p>

937) 

938)     <hr>

939) 

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

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

943) 

944)     <p>

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

947)     exactly the one that we intended you to get.
948)     </p>

949) 

950)     <p>
951)     Please read the <a

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

954)     </p>

955) 

956) <hr>
957) 
958) <a id="GetTor"></a>
959) <h3><a class="anchor" href="#GetTor">Your website is blocked in my
960) country. How do I download Tor?</a></h3>
961) 
962) <p>
963) Some government or corporate firewalls censor connections to Tor's
964) website. In those cases, you have three options. First, get it from

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

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

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

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

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

973) in the body of the email, it will reply with instructions. Note that
974) only a few webmail providers are supported, since they need to be able
975) to receive very large attachments.
976) </p>
977) 
978) <p>

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

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

983) </p>
984) 
985) <hr>

986) 

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

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

990) 

991)     <p>

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

994)     tor-win32-mingw-creation.txt</a>.
995)     </p>

996) 

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

999)     it. Most people just use the packages available on the <a
1000) href="<page

1001)     download/download>">download page</a>.)
1002)     </p>

1003) 

1004)     <hr>

1005) 

1006)     <a id="VirusFalsePositives"></a>

1007)     <h3><a class="anchor" href="#VirusFalsePositives">Why does my Tor
1008) executable appear to have a virus or spyware?</a></h3>

1009) 

1010)     <p>

1011)     Sometimes, overzealous Windows virus and spyware detectors trigger
1012) on some
1013)     parts of the Tor Windows binary. Our best guess is that these are
1014) false
1015)     positives — after all, the anti-virus and anti-spyware
1016) business is just a
1017)     guessing game anyway. You should contact your vendor and explain
1018) that you have
1019)     a program that seems to be triggering false positives. Or pick a
1020) better vendor.

1021)     </p>

1022) 

1023)     <p>
1024)     In the meantime, we encourage you to not just take our word for

1025)     it. Our job is to provide the source; if you're concerned, please do
1026) <a

1027)     href="#CompileTorWindows">recompile it yourself</a>.
1028)     </p>

1029) 

1030)     <hr>

1031) 

1032)     <a id="LiveCD"></a>

1033)     <h3><a class="anchor" href="#LiveCD">Is there a LiveCD or other
1034) bundle that includes Tor?</a></h3>

1035) 

1036)     <p>

1037)     Yes.  Use <a href="https://tails.boum.org/">The Amnesic Incognito

1038)     Live System</a> or <a href="<page projects/torbrowser>">the Tor
1039) Browser

1040)     Bundle</a>.

1041)     </p>

1042) 
1043) <hr>
1044) 

1045) <a id="TBBFlash"></a>

1046) <h3><a class="anchor" href="#TBBFlash">Why can't I view videos on
1047) YouTube

1048) and other Flash-based sites?</a></h3>

1049) 
1050) <p>

1051) YouTube and similar sites require third party browser plugins such as Flash.
1052) Plugins operate independently from Firefox and can perform
1053) activity on your computer that ruins your anonymity. This includes
1054) but is not limited to: <a href="http://decloak.net">completely disregarding
1055) proxy settings</a>, querying your <a

1056) href="http://forums.sun.com/thread.jspa?threadID=5162138&messageID=9618376">
1057) local IP address</a>, and <a

1058) href="http://epic.org/privacy/cookies/flash.html">storing their own
1059) cookies</a>. It is possible to use a LiveCD solution such as

1060) or <a href="https://tails.boum.org/">The Amnesic Incognito Live System</a> 
1061) that creates a secure, transparent proxy to protect you from proxy bypass, 
1062) however issues with local IP address discovery and Flash cookies still remain. 
1063) </p>

1064) 
1065) <p>

1066) <a href="https://www.youtube.com/html5">YouTube offers experimental HTML5 video
1067) support</a> for many of their videos. You can use their Advanced Search to

1068) find HTML5 videos.
1069) </p>
1070) 

1071) <hr>
1072) 

1073) <a id="Ubuntu"></a>
1074) <h3><a class="anchor" href="#Ubuntu">
1075) I'm using Ubuntu and I can't start Tor Browser</a></h3>
1076) <p>

1077) Ubuntu prevents its users from executing shell scripts by clicking them, 
1078) even when the file permissions are set correctly. For now you need to 
1079) start the Tor Browser from the command line by running </p>

1080) <pre>
1081) ./start-tor-browser
1082) </pre>
1083) <p>
1084) from inside the Tor Browser directory.
1085) </p>
1086) 
1087) <hr>
1088) 

1089) <a id="TBBSocksPort"></a>

1090) <h3><a class="anchor" href="#TBBSocksPort">

1091) I want to run another application through the Tor launched by Tor

1092) Browser Bundle.</a></h3>

1093) 
1094) <p>

1095) Typically Tor listens for Socks connections on port 9050. TBB listens

1096) on port 9150.

1097) The goal is to avoid conflicting with a "system" Tor install,

1098) so you can run a system Tor and TBB at the same time. We're <a
1099) href="https://trac.torproject.org/projects/tor/ticket/3948">working on
1100) a feature</a> where Tor will try the usual ports first and then back

1101) off to a random choice if they're already in use.

1102) </p>
1103) 
1104) <hr>
1105) 
1106) <a id="TBBPolipo"></a>
1107) <h3><a class="anchor" href="#TBBPolipo">I need an HTTP proxy. Where did
1108) Polipo go?</a></h3>
1109) 
1110) <p>
1111) In the past, Tor bundles included an HTTP proxy like Privoxy or Polipo,
1112) solely to work around a bug in Firefox that was finally fixed in Firefox
1113) 6. Now you don't need a separate HTTP proxy to use Tor, and in fact
1114) leaving it out makes you safer because Torbutton has better control over
1115) Firefox's interaction with websites.
1116) </p>
1117) 
1118) <p>
1119) If you are trying to use some external application with Tor, step zero

1120) should be to <a href="<page download/download>#warning">reread the set

1121) of warnings</a> for ways you can screw up. Step one should be to try

1122) to use a Socks proxy rather than an http proxy — Tor runs a Socks

1123) proxy on port 9050 on Windows, or <a href="#TBBSocksPort">see above</a>
1124) for OSX and Linux.
1125) </p>
1126) 
1127) <p>

1128) If that fails, feel free to install <a

1129) href="http://www.privoxy.org/">privoxy</a>.
1130) However, please realize that this approach is not recommended for novice
1131) users. Privoxy has an <a
1132) href="http://www.privoxy.org/faq/misc.html#TOR">example
1133) configuration</a> of Tor and Privoxy.

1134) </p>
1135) 
1136) <hr>
1137) 

1138) <a id="TBBOtherExtensions"></a>
1139) <h3><a class="anchor" href="#TBBOtherExtensions">Can I install other
1140) Firefox extensions?</a></h3>
1141) 
1142) <p>

1143) The Tor Browser is free software, so there is nothing preventing you from 
1144) modifying it any way you like. However, we do not recommend installing any 
1145) additional Firefox add-ons with the Tor Browser Bundle. Add-ons can break 
1146) your anonymity in a number of ways, including browser fingerprinting and 
1147) bypassing proxy settings.

1148) </p>

1149) <p>

1150) Some people have suggested we include ad-blocking software or 
1151) anti-tracking software with the Tor Browser Bundle. Right now, we do not 
1152) think that's such a good idea. The Tor Browser Bundle aims to provide 
1153) sufficient privacy that additional add-ons to stop ads and trackers are 
1154) not necessary. Using add-ons like these may cause some sites to break, which 
1155) <a href="https://www.torproject.org/projects/torbrowser/design/#philosophy">
1156) we don't want to do</a>. Additionally, maintaining a list of "bad" sites that 
1157) should be black-listed provides another opportunity to uniquely fingerprint 
1158) users. 

1159) </p>

1160) 

1161) <hr>
1162) 

1163) <a id="TBBJavaScriptEnabled"></a>

1164) <a id="TBBCanIBlockJS"></a>

1165) <h3><a class="anchor" href="#TBBJavaScriptEnabled">Why is NoScript
1166) configured to allow JavaScript by default in the Tor Browser Bundle?
1167) Isn't that unsafe?</a></h3>

1168) 
1169) <p>
1170) We configure NoScript to allow JavaScript by default in the Tor
1171) Browser Bundle because many websites will not work with JavaScript
1172) disabled.  Most users would give up on Tor entirely if a website
1173) they want to use requires JavaScript, because they would not know
1174) how to allow a website to use JavaScript (or that enabling
1175) JavaScript might make a website work).
1176) </p>
1177) 

1178) <p>
1179) There's a tradeoff here. On the one hand, we should leave
1180) JavaScript enabled by default so websites work the way
1181) users expect. On the other hand, we should disable JavaScript
1182) by default to better protect against browser vulnerabilities (<a

1183) href="https://blog.torproject.org/blog/tor-security-advisory-old-tor-browser-bundles-vulnerable">
1184) not just a theoretical concern!</a>). But there's a third issue: websites

1185) can easily determine whether you have allowed JavaScript for them,
1186) and if you disable JavaScript by default but then allow a few websites
1187) to run scripts (the way most people use NoScript), then your choice of
1188) whitelisted websites acts as a sort of cookie that makes you recognizable
1189) (and distinguishable), thus harming your anonymity.
1190) </p>

1191) 
1192) <p>

1193) Ultimately, we want the default Tor bundles to use
1194) a combination of firewalls (like the iptables rules
1195) in <a href="https://tails.boum.org/">Tails</a>) and <a
1196) href="https://trac.torproject.org/projects/tor/ticket/7680">sandboxes</a>
1197) to make JavaScript not so scary. In
1198) the shorter term, TBB 3.0 will hopefully <a
1199) href="https://trac.torproject.org/projects/tor/ticket/9387">allow users
1200) to choose their JavaScript settings more easily</a> &mdash; but the
1201) partitioning concern will remain.

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

1205) Until we get there, feel free to leave JavaScript on or off depending
1206) on your security, anonymity, and usability priorities.

1207) </p>
1208) 
1209) <hr>
1210) 

1211) <a id="TBBOtherBrowser"></a>
1212) <h3><a class="anchor" href="#TBBOtherBrowser">I want to use
1213) Chrome/IE/Opera/etc with Tor.</a></h3>
1214) 
1215) <p>
1216) Unfortunately, Torbutton only works with Firefox right now, and without
1217) <a href="https://www.torproject.org/torbutton/en/design/">Torbutton's
1218) extensive privacy fixes</a> there are many ways for websites or other

1219) attackers to recognize you, track you back to your IP address, and so
1220) on.

1221) In short, using any browser besides Tor Browser Bundle with Tor is a
1222) really bad idea.
1223) </p>
1224) 
1225) <p>
1226) We're working with the Chrome team to <a

1227) href="https://blog.torproject.org/blog/google-chrome-incognito-mode-tor-
1228) and-fingerprinting">fix
1229) some bugs and missing APIs in Chrome</a> so it will be possible to write
1230) a
1231) Torbutton for Chrome. No support for any other browser is on the
1232) horizon.

1233) </p>
1234) 
1235) <hr>
1236) 

1237) <a id="TorbuttonOtherBrowser"></a>
1238) <h3><a class="anchor" href="#TorbuttonOtherBrowser">
1239) Will Torbutton be available for other browsers?</a></h3>
1240) 
1241) <p>
1242)  We don't support IE, Opera or Safari and never plan to. There are too many 
1243)  ways that your privacy can go wrong with those browsers, and because of 
1244)  their closed design it is really hard for us to do anything to change these 
1245)  privacy problems.
1246) </p>
1247) <p>
1248) We are working with the Chrome people to modify Chrome's internals so that 
1249) we can eventually support it. But for now, Firefox is the only safe choice. 
1250) </p>
1251) 
1252) <hr>
1253) 
1254) <a id="NoDataScrubbing"></a>
1255) <h3><a class="anchor" href="#NoDataScrubbing">
1256) Does Tor remove personal information from the data my application sends?
1257) </a></h3>
1258) <p>
1259) No, it doesn't. You need to use a separate program that understands your 
1260) application and protocol and knows how to clean or "scrub" the data it 
1261) sends. Privoxy is an example of this for web browsing. But note that even 
1262) Privoxy won't protect you completely: you may still fall victim to viruses, 
1263) Java Script attacks, etc; and Privoxy can't do anything about text that you 
1264) type into forms. Be careful and be smart. 
1265) </p>
1266) 

1267) <hr>

1268) 

1269) <a id="TBBCloseBrowser"></a>

1270) <h3><a class="anchor" href="#TBBCloseBrowser">I want to leave Tor
1271) Browser

1272) Bundle running but close the browser.</a></h3>
1273) 
1274) <p>
1275) We're working on a way to make this possible on all platforms. Please
1276) be patient.
1277) </p>
1278) 
1279) <hr>
1280) 

1281) <a id="GoogleCAPTCHA"></a>
1282) <h3><a class="anchor" href="#GoogleCAPTCHA">Google makes me solve a
1283) CAPTCHA or tells me I have spyware installed.</a></h3>

1284) 
1285) <p>
1286) This is a known and intermittent problem; it does not mean that Google
1287) considers Tor to be spyware.
1288) </p>
1289) 
1290) <p>

1291) When you use Tor, you are sending queries through exit relays that are
1292) also

1293) shared by thousands of other users. Tor users typically see this message

1294) when many Tor users are querying Google in a short period of time.
1295) Google

1296) interprets the high volume of traffic from a single IP address (the exit
1297) relay you happened to pick) as somebody trying to "crawl" their website,
1298) so it slows down traffic from that IP address for a short time.
1299) </p>
1300) <p>
1301) An alternate explanation is that Google tries to detect certain
1302) kinds of spyware or viruses that send distinctive queries to Google
1303) Search. It notes the IP addresses from which those queries are received
1304) (not realizing that they are Tor exit relays), and tries to warn any
1305) connections coming from those IP addresses that recent queries indicate
1306) an infection.
1307) </p>
1308) 
1309) <p>

1310) To our knowledge, Google is not doing anything intentionally
1311) specifically

1312) to deter or block Tor use. The error message about an infected machine
1313) should clear up again after a short time.
1314) </p>
1315) 
1316) <p>
1317) Torbutton 1.2.5 (released in mid 2010) detects Google captchas and can
1318) automatically redirect you to a more Tor-friendly search engine such as

1319) DuckDuckGo, ixquick, or Bing.

1320) </p>
1321) 
1322) <hr />
1323) 

1324) <a id="ForeignLanguages"></a>
1325) <h3><a class="anchor" href="#ForeignLanguages">
1326) Why does Google show up in foreign languages?</a></h3>
1327) 
1328) <p>

1329)  Google uses "geolocation" to determine where in the world you are, so it 
1330)  can give you a personalized experience. This includes using the language 
1331)  it thinks you prefer, and it also includes giving you different results 
1332)  on your queries.

1333) </p>
1334) <p>

1335) If you really want to see Google in English you can click the link that 
1336) provides that. But we consider this a feature with Tor, not a bug --- the 
1337) Internet is not flat, and it in fact does look different depending on 
1338) where you are. This feature reminds people of this fact. The easy way to 
1339) avoid this "feature" is to use 
1340) <a href="https://google.com/ncr">https://google.com/ncr</a>.

1341) </p>
1342) <p>

1343) Note that Google search URLs take name/value pairs as arguments and one 
1344) of those names is "hl". If you set "hl" to "en" then Google will return 
1345) search results in English regardless of what Google server you have been 
1346) sent to. On a query this looks like: 
1347) </p>
1348) <pre>https://encrypted.google.com/search?q=online%20anonymity&hl=en

1349) </pre>

1350) <p>

1351) Another method is to simply use your country code for accessing Google. 
1352) This can be google.be, google.de, google.us and so on. 

1353) </p>
1354) <hr />

1355) <a id="GmailWarning"></a>

1356) <h3><a class="anchor" href="#GmailWarning">Gmail warns me that my

1357) account may have been compromised.</a></h3>

1358) 
1359) <p>
1360) Sometimes, after you've used Gmail over Tor, Google presents a
1361) pop-up notification that your account may have been compromised.
1362) The notification window lists a series of IP addresses and locations
1363) throughout the world recently used to access your account.
1364) </p>
1365) 
1366) <p>
1367) In general this is a false alarm: Google saw a bunch of logins from

1368) different places, as a result of running the service via Tor, and
1369) decided

1370) it was a good idea to confirm the account was being accessed by it's
1371) rightful owner.
1372) </p>
1373) 
1374) <p>
1375) Even though this may be a biproduct of using the service via tor,
1376) that doesn't mean you can entirely ignore the warning. It is
1377) <i>probably</i> a false positive, but it might not be since it is
1378) possible for someone to hijack your Google cookie.
1379) </p>
1380) 
1381) <p>
1382) Cookie hijacking is possible by either physical access to your computer
1383) or by watching your network traffic.  In theory only physical access
1384) should compromise your system because Gmail and similar services
1385) should only send the cookie over an SSL link. In practice, alas, it's <a

1386) href="http://fscked.org/blog/fully-automated-active-https-cookie-
1387) hijacking">

1388) way more complex than that</a>.
1389) </p>
1390) 
1391) <p>
1392) And if somebody <i>did</i> steal your google cookie, they might end
1393) up logging in from unusual places (though of course they also might
1394) not). So the summary is that since you're using Tor, this security
1395) measure that Google uses isn't so useful for you, because it's full of
1396) false positives. You'll have to use other approaches, like seeing if
1397) anything looks weird on the account, or looking at the timestamps for
1398) recent logins and wondering if you actually logged in at those times.
1399) </p>
1400) 
1401) <hr>
1402) 

1403) <a id="torrc"></a>

1404) <h3><a class="anchor" href="#torrc">I'm supposed to "edit my torrc".
1405) What does that mean?</a></h3>

1406) 
1407) <p>
1408) Tor installs a text file called torrc that contains configuration
1409) instructions for how your Tor program should behave. The default
1410) configuration should work fine for most Tor users. Users of Vidalia can
1411) make common changes through the Vidalia interface &mdash; only advanced
1412) users should need to modify their torrc file directly.
1413) </p>

1414) <p>

1415) Tor Browser Bundle users should edit your torrc through Vidalia. Open
1416) the
1417) Vidalia Control Panel. Choose Settings. Choose Advanced. Click the
1418) button

1419) labelled "Edit current torrc". Remember to make sure the checkbox for
1420) "Save Settings." is checked. Hit the Ok button and you are done.
1421) </p>

1422) <p>

1423) Otherwise, you will need to edit the file manually.

1424) The location of your torrc file depends on the way you installed Tor:
1425) </p>
1426) <ul>

1427) <li>If you installed Tor Browser Bundle, look for
1428) <code>Data/Tor/torrc</code> inside your Tor Browser Bundle directory.
1429) </li>

1430) <li>On Windows, if you installed a Tor bundle with Vidalia, you can
1431) find your torrc file in the Start menu under Programs -&gt; Vidalia
1432) Bundle -&gt; Tor, or you can find it by hand in <code>\Documents and
1433) Settings\<i>username</i>\Application Data\Vidalia\torrc</code>. If you
1434) installed Tor without Vidalia, you can find your torrc in the Start
1435) menu under Programs -&gt; Tor, or manually in either <code>\Documents
1436) and Settings\Application Data\tor\torrc</code> or <code>\Documents and
1437) Settings\<i>username</i>\Application Data\tor\torrc</code>.
1438) </li>
1439) <li>On OS X, if you use Vidalia, edit
1440) <code>~/.vidalia/torrc</code>. Otherwise, open your favorite text editor
1441) and load <code>/Library/Tor/torrc</code>.
1442) </li>
1443) <li>On Unix, if you installed a pre-built package, look for
1444) <code>/etc/tor/torrc</code> or <code>/etc/torrc</code> or consult your
1445) package's documentation.
1446) </li>
1447) <li>Finally, if you installed from source, you may not have a torrc
1448) installed yet: look in <code>/usr/local/etc/</code> and note that you

1449) may need to manually copy <code>torrc.sample</code> to
1450) <code>torrc</code>.

1451) </li>
1452) </ul>
1453) 
1454) <p>
1455) If you use Vidalia, be sure to exit both Tor and Vidalia before you edit

1456) your torrc file manually. Otherwise Vidalia might overwrite your
1457) changes.

1458) </p>
1459) 
1460) <p>
1461) Once you've changed your torrc, you will need to restart Tor for the
1462) changes to take effect. (For advanced users on OS X and Unix, note that

1463) you actually only need to send Tor a HUP signal, not actually restart
1464) it.)

1465) </p>
1466) 
1467) <p>
1468) For other configuration options you can use, look at the <a href="<page
1469) docs/tor-manual>">Tor manual page</a>. Remember, all lines beginning
1470) with # in torrc are treated as comments and have no effect on Tor's
1471) configuration.
1472) </p>
1473) 
1474) <hr>
1475) 

1476) <a id="Logs"></a>

1477) <h3><a class="anchor" href="#Logs">How do I set up logging, or see Tor's
1478) logs?</a></h3>

1479) 
1480) <p>

1481) If you installed a Tor bundle that includes Vidalia, then Vidalia has a

1482) window called "Message Log" that will show you Tor's log messages. Click
1483) on "Advanced" to see more details. You can click on "Settings" to change
1484) your log verbosity or save the messages to a file. You're all set.

1485) </p>
1486) 
1487) <p>
1488) If you're not using Vidalia, you'll have to go find the log files by

1489) hand. Here are some likely places for your logs to be:

1490) </p>
1491) 
1492) <ul>
1493) <li>On OS X, Debian, Red Hat, etc, the logs are in /var/log/tor/
1494) </li>

1495) <li>On Windows, there are no default log files currently. If you enable
1496) logs in your torrc file, they default to <code>\username\Application
1497) Data\tor\log\</code> or <code>\Application Data\tor\log\</code>
1498) </li>
1499) <li>If you compiled Tor from source, by default your Tor logs to <a
1500) href="http://en.wikipedia.org/wiki/Standard_streams">"stdout"</a>
1501) at log-level notice. If you enable logs in your torrc file, they
1502) default to <code>/usr/local/var/log/tor/</code>.

1503) </li>
1504) </ul>
1505) 
1506) <p>

1507) To change your logging setup by hand, <a href="#torrc">edit your
1508) torrc</a>

1509) and find the section (near the top of the file) which contains the
1510) following line:

1511) </p>
1512) 
1513) <pre>

1514) \## Logs go to stdout at level "notice" unless redirected by something
1515) \## else, like one of the below lines.

1516) </pre>

1517) 
1518) <p>

1519) For example, if you want Tor to send complete debug, info, notice, warn,

1520) and err level messages to a file, append the following line to the end
1521) of the section:
1522) </p>
1523) 
1524) <pre>
1525) Log debug file c:/program files/tor/debug.log
1526) </pre>
1527) 
1528) <p>

1529) Replace <code>c:/program files/tor/debug.log</code> with a directory
1530) and filename for your Tor log.

1531) </p>
1532) 
1533) <hr>
1534) 

1535) 
1536) <a id="LogLevel"></a>
1537) <h3><a class="anchor" href="#LogLevel">What log level should I use?</a></h3>
1538) 
1539) <p>

1540) There are five log levels (also called "log severities") you might see in 
1541) Tor's logs:

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

1545)     <li>"err": something bad just happened, and we can't recover. Tor will 
1546)     exit.</li>
1547)     <li>"warn": something bad happened, but we're still running. The bad 
1548)     thing might be a bug in the code, some other Tor process doing something 
1549)     unexpected, etc. The operator should examine the message and try to 
1550)     correct the problem.</li>

1551)     <li>"notice": something the operator will want to know about.</li>

1552)     <li>"info": something happened (maybe bad, maybe ok), but there's 
1553)     nothing you need to (or can) do about it.</li>

1554)     <li>"debug": for everything louder than info. It is quite loud indeed.</li> 
1555) </ul>
1556) 
1557) <p>

1558) Alas, some of the warn messages are hard for ordinary users to correct -- the 
1559) developers are slowly making progress at making Tor automatically react 
1560) correctly for each situation.

1561) </p>
1562) 
1563) <p>

1564) We recommend running at the default, which is "notice". You will hear about 
1565) important things, and you won't hear about unimportant things.

1566) </p>
1567) 
1568) <p>

1569) Tor relays in particular should avoid logging at info or debug in normal 
1570) operation, since they might end up recording sensitive information in 
1571) their logs. 

1572) </p>
1573) 

1574) <hr>
1575) 

1576) <a id="DoesntWork"></a>

1577) <h3><a class="anchor" href="#DoesntWork">I installed Tor but it's not
1578) working.</a></h3>

1579) 
1580) <p>

1581) Once you've got the Tor bundle up and running, the first question to
1582) ask is whether your Tor client is able to establish a circuit.

1583) </p>
1584) 
1585) <p>If Tor can establish a circuit, the onion icon in

1586) Vidalia will turn green (and if you're running Tor Browser Bundle, it
1587) will
1588) automatically launch a browser for you). You can also check in the
1589) Vidalia

1590) Control Panel to make sure it says "Connected to the Tor
1591) network!" under Status. For those not using Vidalia, check your <a

1592) href="#Logs">Tor logs</a> for

1593) a line saying that Tor "has successfully opened a circuit. Looks like
1594) client functionality is working."
1595) </p>
1596) 
1597) <p>
1598) If Tor can't establish a circuit, here are some hints:
1599) </p>
1600) 
1601) <ol>
1602) <li>Are you sure Tor is running? If you're using Vidalia, you may have
1603) to click on the onion and select "Start" to launch Tor.</li>
1604) <li>Check your system clock. If it's more than a few hours off, Tor will

1605) refuse to build circuits. For Microsoft Windows users, synchronize your
1606) clock under the clock -> Internet time tab. In addition, correct the

1607) day and date under the 'Date & Time' Tab. Also make sure your time
1608) zone is correct.</li>

1609) <li>Is your Internet connection <a href="#FirewallPorts">firewalled
1610) by port</a>, or do you normally need to use a <a

1611) href="<wikifaq>#MyInternetconnectionrequiresanHTTPorSOCKSproxy.">proxy</a>?

1612) </li>

1613) <li>Are you running programs like Norton Internet Security or SELinux
1614) that

1615) block certain connections, even though you don't realize they do? They
1616) could be preventing Tor from making network connections.</li>
1617) <li>Are you in China, or behind a restrictive corporate network firewall
1618) that blocks the public Tor relays? If so, you should learn about <a

1619) href="<page docs/bridges>">Tor bridges</a>.</li>

1620) <li>Check your <a href="#Logs">Tor logs</a>. Do they give you any hints
1621) about what's going wrong?</li>

1622) </ol>
1623) 
1624) <hr />
1625) 

1626) <a id="TorCrash"></a>
1627) <h3><a class="anchor" href="#TorCrash">My Tor keeps crashing.</a></h3>
1628) <p>
1629)  We want to hear from you! There are supposed to be zero crash bugs in Tor. 
1630)  This FAQ entry describes the best way for you to be helpful to us. But even 
1631)  if you can't work out all the details, we still want to hear about it, so 
1632)  we can help you track it down. 
1633) </p>
1634) <p>
1635) First, make sure you're using the latest version of Tor (either the latest 
1636) stable or the latest development version). 
1637) </p>
1638) <p>
1639) Second, make sure your version of libevent is new enough. We recommend at 
1640) least libevent 1.3a. 
1641) </p>
1642) <p>
1643) Third, see if there's already an entry for your bug in the <a 
1644) href="https://bugs.torproject.org/">Tor bugtracker</a>. If so, 
1645) check if there are any new details that you can add. 
1646) </p>
1647) <p>
1648) Fourth, is the crash repeatable? Can you cause the crash? Can 
1649) you isolate some of the circumstances or config options that 
1650) make it happen? How quickly or often does the bug show up? 
1651) Can you check if it happens with other versions of Tor, for 
1652) example the latest stable release? 
1653) </p>
1654) <p>
1655) Fifth, what sort of crash do you get? 
1656) </p>
1657) <ul>
1658) <li>
1659) Does your Tor log include an "assert failure"? If so, please 
1660) tell us that line, since it helps us figure out what's going on. 
1661) Tell us the previous couple of log messages as well, especially 
1662) if they seem important. 
1663) </li>
1664) <li>
1665) If it says "Segmentation fault - core dumped" then you need to 
1666) do a bit more to track it down. Look for a file like "core" or 
1667) "tor.core" or "core.12345" in your current directory, or in your 
1668) Data Directory. If it's there, run "gdb tor core" and then "bt", 
1669) and include the output. If you can't find a core, run "ulimit -c 
1670) unlimited", restart Tor, and try to make it crash again. (This core 
1671) thing will only work on Unix -- alas, tracking down bugs on Windows 
1672) is harder. If you're on Windows, can you get somebody to duplicate 
1673) your bug on Unix?)
1674) </li>
1675) <li>
1676) If Tor simply vanishes mysteriously, it probably is a segmentation 
1677) fault but you're running Tor in the background (as a daemon) so you 
1678) won't notice. Go look at the end of your log file, and look for a 
1679) core file as above. If you don't find any good hints, you should 
1680) consider running Tor in the foreground (from a shell) so you can 
1681) see how it dies. Warning: if you switch to running Tor in the foreground, 
1682) you might start using a different torrc file, with a different default 
1683) Data Directory; see the <a href="#UpgradeOrMove">relay-upgrade FAQ entry</a> 
1684) for details. 
1685) </li>
1686) <li>
1687) If it's still vanishing mysteriously, perhaps something else is killing it? 
1688) Do you have resource limits (ulimits) configured that kill off processes 
1689) sometimes? (This is especially common on OpenBSD.) On Linux, try running 
1690) "dmesg" to see if the out-of-memory killer removed your process. (Tor will 
1691) exit cleanly if it notices that it's run out of memory, but in some cases 
1692) it might not have time to notice.) In very rare circumstances, hardware 
1693) problems could also be the culprit. 
1694) </li>
1695) </ul>
1696) <p>
1697) Sixth, if the above ideas don't point out the bug, consider increasing your 
1698) log level to "loglevel debug". You can look at the log-configuration FAQ 
1699) entry for instructions on what to put in your torrc file. If it usually 
1700) takes a long time for the crash to show up, you will want to reserve a whole 
1701) lot of disk space for the debug log. Alternatively, you could just send 
1702) debug-level logs to the screen (it's called "stdout" in the torrc), and then 
1703) when it crashes you'll see the last couple of log lines it had printed. 
1704) (Note that running with verbose logging like this will slow Tor down 
1705) considerably, and note also that it's generally not a good idea security-wise 
1706) to keep logs like this sitting around.) 
1707) </p>
1708) 
1709) <hr />
1710) 

1711) <a id="VidaliaPassword"></a>

1712) <h3><a class="anchor" href="#VidaliaPassword">Tor/Vidalia prompts for a
1713) password at start.</a></h3>

1714) 
1715) <p>
1716) Vidalia interacts with the Tor software via Tor's "control port". The
1717) control port lets Vidalia receive status updates from Tor, request a new
1718) identity, configure Tor's settings, etc. Each time Vidalia starts Tor,
1719) Vidalia sets a random password for Tor's control port to prevent other
1720) applications from also connecting to the control port and potentially
1721) compromising your anonymity.
1722) </p>
1723) 
1724) <p>
1725) Usually this process of generating and setting a random control password
1726) happens in the background. There are three common situations, though,
1727) where Vidalia may prompt you for a password:
1728) </p>
1729) 
1730) <ol>
1731) <li>You're already running Vidalia and Tor. For example, this situation
1732) can happen if you installed the Vidalia bundle and now you're trying to
1733) run the Tor Browser Bundle. In that case, you'll need to close the old
1734) Vidalia and Tor before you can run this one.
1735) </li>
1736) <li>Vidalia crashed, but left Tor running with the last known random
1737) password. After you restart Vidalia, it generates a new random password,

1738) but Vidalia can't talk to Tor, because the random passwords are
1739) different.

1740) <br />

1741) If the dialog that prompts you for a control password has a Reset
1742) button,

1743) you can click the button and Vidalia will restart Tor with a new random
1744) control password.
1745) <br />
1746) If you do not see a Reset button, or if Vidalia is unable to restart
1747) Tor for you, you can still fix the problem manually. Simply go into your
1748) process or task manager, and terminate the Tor process. Then use Vidalia
1749) to restart Tor and all will work again.
1750) </li>
1751) <li>You had previously set Tor to run as a Windows NT service. When Tor
1752) is set to
1753) run as a service, it starts up when the system boots. If you configured
1754) Tor to start as a service through Vidalia, a random password was set
1755) and saved in Tor. When you reboot, Tor starts up and uses the random
1756) password it saved. You login and start up Vidalia. Vidalia attempts to
1757) talk to the already running Tor. Vidalia generates a random password,
1758) but it is different than the saved password in the Tor service.
1759) <br />
1760) You need to reconfigure Tor to not be a service. See the FAQ entry on

1761) <a href="#NTservice">running Tor as a

1762) Windows NT service</a>

1763) for more information on how to remove the Tor service.
1764) </li>
1765) </ol>
1766) 

1767)     <hr>

1768) 

1769)     <a id="ChooseEntryExit"></a>

1770)     <h3><a class="anchor" href="#ChooseEntryExit">Can I control which
1771) nodes (or country) are used for entry/exit?</a></h3>

1772) 

1773)     <p>

1774)     Yes. You can set preferred entry and exit nodes as well as
1775)     inform Tor which nodes you do not want to use.

1776)     The following options can be added to your config file <a
1777)     href="#torrc">"torrc"</a> or specified on the command line:

1778)     </p>
1779)     <dl>
1780)       <dt><tt>EntryNodes $fingerprint,$fingerprint,...</tt></dt>

1781)         <dd>A list of preferred nodes to use for the first hop in the
1782) circuit, if possible.

1783)         </dd>
1784)       <dt><tt>ExitNodes $fingerprint,$fingerprint,...</tt></dt>

1785)         <dd>A list of preferred nodes to use for the last hop in the
1786) circuit, if possible.

1787)         </dd>
1788)       <dt><tt>ExcludeNodes $fingerprint,$fingerprint,...</tt></dt>

1789)         <dd>A list of nodes to never use when building a circuit.

1790)         </dd>
1791)       <dt><tt>ExcludeExitNodes $fingerprint,$fingerprint,...</tt></dt>

1792)         <dd>A list of nodes to never use when picking an exit.

1793)             Nodes listed in <tt>ExcludeNodes</tt> are automatically in
1794) this list.

1795)         </dd>
1796)     </dl>
1797)     <p>

1798)     <em>We recommend you do not use these</em>

1799)     — they are intended for testing and may disappear in future
1800) versions.

1801)     You get the best security that Tor can provide when you leave the
1802)     route selection to Tor; overriding the entry / exit nodes can mess
1803)     up your anonymity in ways we don't understand.

1804)     </p>
1805)     <p>

1806)     Note also that not every circuit is used to deliver traffic outside of 
1807)     the Tor network. It is normal to see non-exit circuits (such as those 
1808)     used to connect to hidden services, those that do directory fetches, 
1809)     those used for relay reachability self-tests, and so on) that end at 
1810)     a non-exit node. To keep a node from being used entirely, see 
1811)     <tt>ExcludeNodes</tt> and <tt>StrictNodes</tt> in the 
1812)     <a href="<page docs/tor-manual>">manual</a>.

1813)     </p>
1814)     <p>

1815)     Instead of <tt>$fingerprint</tt> you can also specify a <a

1816) 
1817) href="https://secure.wikimedia.org/wikipedia/en/wiki/ISO_3166-1_alpha-2"
1818) >2

1819)     letter ISO3166 country code</a> in curly braces (for example <tt>{de}</tt>),

1820)     or an ip address pattern (for example 255.254.0.0/8), or a node
1821)     nickname. Make sure there are no spaces between the commas and the
1822)     list items.

1823)     </p>
1824)     <p>

1825)     If you want to access a service directly through Tor's Socks
1826) interface

1827)     (eg. using ssh via connect.c), another option is to set up an

1828)     internal mapping in your configuration file using
1829) <tt>MapAddress</tt>.

1830)     See the manual page for details.
1831)     </p>

1832) 

1833)     <hr>

1834) 

1835) <a id="FirewallPorts"></a>

1836) <h3><a class="anchor" href="#FirewallPorts">My firewall only allows a
1837) few outgoing ports.</a></h3>

1838) 
1839) <p>
1840) If your firewall works by blocking ports, then you can tell Tor to only

1841) use the ports that your firewall permits by adding "FascistFirewall 1"
1842) to

1843) your <a href="<page docs/faq>#torrc">torrc

1844) configuration file</a>, or by clicking "My firewall only lets me connect
1845) to certain ports" in Vidalia's Network Settings window.
1846) </p>
1847) 
1848) <p>
1849) By default, when you set this Tor assumes that your firewall allows only
1850) port 80 and port 443 (HTTP and HTTPS respectively). You can select a
1851) different set of ports with the FirewallPorts torrc option.
1852) </p>
1853) 
1854) <p>
1855) If you want to be more fine-grained with your controls, you can also
1856) use the ReachableAddresses config options, e.g.:
1857) </p>
1858) 
1859) <pre>
1860)   ReachableDirAddresses *:80
1861)   ReachableORAddresses *:443
1862) </pre>
1863) 
1864) <hr>

1865) 

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

1867)     <h3><a class="anchor" href="#ExitPorts">Is there a list of default exit 
1868)     ports?</a></h3>

1869)     <p>

1870) The default open ports are listed below but keep in mind that, any port or 
1871) ports can be opened by the relay operator by configuring it in torrc or 
1872) modifying the source code. But the default according to src/or/policies.c 
1873) from the source code release tor-0.2.4.16-rc is: 

1874)     </p>
1875)     <pre>
1876)   reject 0.0.0.0/8
1877)   reject 169.254.0.0/16
1878)   reject 127.0.0.0/8
1879)   reject 192.168.0.0/16
1880)   reject 10.0.0.0/8
1881)   reject 172.16.0.0/12
1882)   reject *:25
1883)   reject *:119
1884)   reject *:135-139
1885)   reject *:445
1886)   reject *:563
1887)   reject *:1214
1888)   reject *:4661-4666
1889)   reject *:6346-6429
1890)   reject *:6699
1891)   reject *:6881-6999
1892)   accept *:*
1893)     </pre>
1894)     <p>

1895)     A relay will block access to its own IP address, as well local network 
1896)     IP addresses. A relay always blocks itself by default. This prevents 
1897)     Tor users from accidentally accessing any of the exit operator's local 
1898)     services. 
1899)     </p>
1900) 
1901)     <hr>
1902) 
1903)     <a id="SocksAndDNS"></a>
1904)     <h3><a class="anchor" href="#SocksAndDNS">How do I check if my application that uses 
1905)     SOCKS is leaking DNS requests?</a></h3>
1906) 
1907)     <p>
1908)     These are two steps you need to take here. The first is to make sure 
1909)     that it's using the correct variant of the SOCKS protocol, and the 
1910)     second is to make sure that there aren't other leaks. 
1911)     </p>
1912) 
1913)     <p>
1914)     Step one: add "TestSocks 1" to your torrc file, and then watch your 
1915)     logs as you use your application. Tor will then log, for each SOCKS 
1916)     connection, whether it was using a 'good' variant or a 'bad' one. 
1917)     (If you want to automatically disable all 'bad' variants, set 
1918)     "SafeSocks 1" in your <a href="#torrc">torrc</a> file.) 
1919)     </p>
1920) 
1921)     <p>
1922)     Step two: even if your application is using the correct variant of 
1923)     the SOCKS protocol, there is still a risk that it could be leaking 
1924)     DNS queries. This problem happens in Firefox extensions that resolve 
1925)     the destination hostname themselves, for example to show you its IP 
1926)     address, what country it's in, etc. These applications may use a safe 
1927)     SOCKS variant when actually making connections, but they still do DNS 
1928)     resolves locally. If you suspect your application might behave like 
1929)     this, you should use a network sniffer like <a 
1930)     href="https://www.wireshark.org/">Wireshark</a> and look for 
1931)     suspicious outbound DNS requests. I'm afraid the details of how to look 
1932)     for these problems are beyond the scope of a FAQ entry though -- find 
1933)     a friend to help if you have problems. 

1934)     </p>
1935) 
1936)     <hr>
1937) 

1938)     <a id="HowDoIDecide"></a>
1939)     <h3><a class="anchor" href="#HowDoIDecide">How do I decide if I should 
1940)     run a relay?</a></h3>
1941)     <p>
1942)     We're looking for people with reasonably reliable Internet connections, 
1943)     that have at least 20 kilobytes/second each way. If that's you, please 
1944)     consider <a href="https://www.torproject.org/docs/tor-relay-debian">helping 
1945)     out</a>. 
1946)     </p>
1947)     
1948)     <hr>
1949)     
1950)     <a id="WhyIsntMyRelayBeingUsedMore"></a>
1951)     <h3><a class="anchor" href="#WhyIsntMyRelayBeingUsedMore">Why isn't my 
1952)     relay being used more?</a></h3>
1953)     <p>
1954)     If your relay is relatively new then give it time. Tor decides which 
1955)     relays it uses heuristically based on reports from Bandwidth 
1956)     Authorities. These authorities take measurements of your relay's 
1957)     capacity and, over time, directs more traffic there until it reaches 
1958)     an optimal load. The lifecycle of a new relay is explained in more 
1959)     depth in <a href="https://blog.torproject.org/blog/lifecycle-of-a-new-relay">
1960)     this blog post</a>.
1961)     </p>
1962)     <p>
1963)     If you've been running a relay for a while and still having issues 
1964)     then try asking on the <a href=
1965)     "https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays/">
1966)     tor-relays list</a>. 
1967)     </p>
1968)     
1969)     <hr>
1970) 

1971)     <a id="HighCapacityConnection"></a>    
1972)     <h3><a class="anchor" href="#HighCapacityConnection">How can I get Tor to fully 
1973)     make use of my high capacity connection?</a></h3>
1974)     
1975)     <p>
1976)     See <a href="http://archives.seul.org/or/relays/Aug-2010/msg00034.html">this 
1977)     tor-relays thread</a>.
1978)     </p>
1979)     
1980)     <hr>    
1981)     

1982)     <a id="RelayFlexible"></a>

1983)     <h3><a class="anchor" href="#RelayFlexible">How stable does my relay
1984) need to be?</a></h3>

1985) 

1986)     <p>
1987)     We aim to make setting up a Tor relay easy and convenient:
1988)     </p>

1989) 

1990)     <ul>
1991)     <li>Tor has built-in support for <a

1992)     href="<wikifaq>#WhatbandwidthshapingoptionsareavailabletoTorrelays">

1993)     rate limiting</a>. Further, if you have a fast
1994)     link but want to limit the number of bytes per
1995)     day (or week or month) that you donate, check out the <a

1996) 
1997) href="<wikifaq>#HowcanIlimitthetotalamountofbandwidthusedbymyTorrelay">
1998) hibernation

1999)     feature</a>.
2000)     </li>

2001)     <li>Each Tor relay has an <a href="#ExitPolicies">exit policy</a>
2002) that
2003)     specifies what sort of outbound connections are allowed or refused
2004) from
2005)     that relay. If you are uncomfortable allowing people to exit from
2006) your
2007)     relay, you can set it up to only allow connections to other Tor
2008) relays.

2009)     </li>
2010)     <li>It's fine if the relay goes offline sometimes. The directories
2011)     notice this quickly and stop advertising the relay. Just try to make
2012)     sure it's not too often, since connections using the relay when it
2013)     disconnects will break.
2014)     </li>
2015)     <li>We can handle relays with dynamic IPs just fine &mdash; simply
2016)     leave the Address config option blank, and Tor will try to guess.
2017)     </li>
2018)     <li>If your relay is behind a NAT and it doesn't know its public
2019)     IP (e.g. it has an IP of 192.168.x.y), you'll need to set up port

2020)     forwarding. Forwarding TCP connections is system dependent but

2021)     <a href="<wikifaq>#ImbehindaNATFirewall">this FAQ entry</a>

2022)     offers some examples on how to do this.
2023)     </li>
2024)     <li>Your relay will passively estimate and advertise its recent

2025)     bandwidth capacity, so high-bandwidth relays will attract more users
2026) than
2027)     low-bandwidth ones. Therefore having low-bandwidth relays is useful
2028) too.

2029)     </li>
2030)     </ul>

2031) 

2032)     <hr>

2033) 

2034)     <a id="ExitPolicies"></a>

2035)     <h3><a class="anchor" href="#ExitPolicies">I'd run a relay, but I
2036) don't want to deal with abuse issues.</a></h3>

2037) 

2038)     <p>
2039)     Great. That's exactly why we implemented exit policies.
2040)     </p>

2041) 

2042)     <p>
2043)     Each Tor relay has an exit policy that specifies what sort of

2044)     outbound connections are allowed or refused from that relay. The
2045) exit

2046)     policies are propagated to Tor clients via the directory, so clients
2047)     will automatically avoid picking exit relays that would refuse to
2048)     exit to their intended destination. This way each relay can decide
2049)     the services, hosts, and networks he wants to allow connections to,

2050)     based on abuse potential and his own situation. Read the FAQ entry
2051) on
2052)     <a href="<page docs/faq-abuse>#TypicalAbuses">issues you might
2053) encounter</a>

2054)     if you use the default exit policy, and then read Mike Perry's

2055)     <a href="<blog>tips-running-exit-node-minimal-harassment">tips

2056)     for running an exit node with minimal harassment</a>.
2057)     </p>

2058) 

2059)     <p>

2060)     The default exit policy allows access to many popular services

2061)     (e.g. web browsing), but <a
2062) href="<wikifaq>#Istherealistofdefaultexitports">restricts</a>

2063)     some due to abuse potential (e.g. mail) and some since
2064)     the Tor network can't handle the load (e.g. default
2065)     file-sharing ports). You can change your exit policy

2066)     using Vidalia's "Sharing" tab, or by manually editing your

2067)     <a href="<page docs/faq>#torrc">torrc</a>

2068)     file. If you want to avoid most if not all abuse potential, set it
2069) to
2070)     "reject *:*" (or un-check all the boxes in Vidalia). This setting
2071) means
2072)     that your relay will be used for relaying traffic inside the Tor
2073) network,

2074)     but not for connections to external websites or other services.
2075)     </p>

2076) 

2077)     <p>

2078)     If you do allow any exit connections, make sure name resolution
2079) works

2080)     (that is, your computer can resolve Internet addresses correctly).

2081)     If there are any resources that your computer can't reach (for
2082) example,

2083)     you are behind a restrictive firewall or content filter), please

2084)     explicitly reject them in your exit policy — otherwise Tor
2085) users

2086)     will be impacted too.
2087)     </p>

2088) 

2089)     <hr>

2090) 

2091)     <a id="DifferentComputer"></a>

2092)     <h3><a class="anchor" href="#DifferentComputer">I want to run my 
2093)     Tor client on a different computer than my applications.</a></h3>

2094)     <p>

2095)     By default, your Tor client only listens for applications that 
2096)     connect from localhost. Connections from other computers are 
2097)     refused. If you want to torify applications on different computers 
2098)     than the Tor client, you should edit your torrc to define 
2099)     SocksListenAddress 0.0.0.0 g and then restart (or hup) Tor. If you 
2100)     want to get more advanced, you can configure your Tor client on a 
2101)     firewall to bind to your internal IP but not your external IP.  

2102)     </p>
2103) 
2104)     <hr>
2105) 
2106)     <a id="ServerClient"></a>

2107)     <h3><a class="anchor" href="#ServerClient">Can I install Tor on a 
2108)     central server, and have my clients connect to it?</a></h3>
2109)     <p>
2110)      Yes. Tor can be configured as a client or a relay on another 
2111)      machine, and allow other machines to be able to connect to it 
2112)      for anonymity. This is most useful in an environment where many 
2113)      computers want a gateway of anonymity to the rest of the world. 
2114)      However, be forwarned that with this configuration, anyone within 
2115)      your private network (existing between you and the Tor 
2116)      client/relay) can see what traffic you are sending in clear text. 
2117)      The anonymity doesn't start until you get to the Tor relay. 
2118)      Because of this, if you are the controller of your domain and you 
2119)      know everything's locked down, you will be OK, but this configuration 
2120)      may not be suitable for large private networks where security is 
2121)      key all around.
2122)     </p>
2123)     <p>
2124) Configuration is simple, editing your torrc file's SocksListenAddress 
2125) according to the following examples:

2126)     </p>
2127)     <pre>

2128) 
2129)   #This provides local interface access only, 
2130)   #needs SocksPort to be greater than 0
2131)   SocksListenAddress 127.0.0.1 
2132) 
2133)   #This provides access to Tor on a specified interface
2134)   SocksListenAddress 192.168.x.x:9100 
2135) 
2136)   #Accept from all interfaces
2137)   SocksListenAddress 0.0.0.0:9100
2138)    </pre>

2139)     <p>

2140) You can state multiple listen addresses, in the case that you are 
2141) part of several networks or subnets.

2142)     </p>
2143)     <pre>
2144)   SocksListenAddress 192.168.x.x:9100 #eth0
2145)   SocksListenAddress 10.x.x.x:9100 #eth1
2146)     </pre>
2147)     <p>

2148) After this, your clients on their respective networks/subnets would specify 
2149) a socks proxy with the address and port you specified SocksListenAddress 
2150) to be. 

2151)     </p>
2152)     <p>

2153) Please note that the SocksPort configuration option gives the port ONLY for 
2154) localhost (127.0.0.1). When setting up your SocksListenAddress(es), you need 
2155) to give the port with the address, as shown above.

2156)     <p>

2157) If you are interested in forcing all outgoing data through the central Tor 
2158) client/relay, instead of the server only being an optional proxy, you may find 
2159) the program iptables (for *nix) useful. 

2160)     </p>
2161) 
2162)     <hr>
2163) 

2164)     <a id="JoinTheNetwork"></a>

2165)     <h3><a class="anchor" href="#JoinTheNetwork">So I can just configure a 
2166)     nickname and ORPort and join the network?</a></h3>

2167) 
2168)     <p>

2169)      Yes. You can join the network and be a useful relay just by configuring 
2170)      your Tor to be a relay and making sure it's reachable from the outside.

2171)     </p>
2172)     <p>
2173) 30 Seconds to a Tor Relay:
2174)     </p>
2175)     <ul><li>
2176)     Configure a Nickname: 
2177)     </li></ul>
2178)     <pre>
2179) Nickname ididnteditheconfig
2180)     </pre>

2181)     <ul><li>

2182)     Configure ORPort: 

2183)     </li></ul>

2184)     <pre>
2185) ORPort 9001
2186)     </pre>

2187)     <ul><li>

2188)     Configure Contact Info: 

2189)     </li></ul>

2190) 
2191)     <pre>
2192) ContactInfo human@…

2193)     </pre>
2194)     <ul><li>

2195)     Start Tor. Watch the log file for a log entry that states: "Self-testing 
2196)     indicates your ORPort is reachable from the outside. Excellent. Publishing 
2197)     server descriptor."

2198)     </li></ul>

2199) 
2200)     <hr />

2201) 

2202)     <a id="RelayOrBridge"></a>

2203)     <h3><a class="anchor" href="#RelayOrBridge">Should I be a normal
2204) relay or bridge relay?</a></h3>

2205) 

2206)     <p><a href="<page docs/bridges>">Bridge relays</a> (or "bridges" for
2207) short)
2208)     are <a href="<page docs/tor-doc-relay>">Tor relays</a> that aren't

2209)     listed in the public Tor directory.

2210)     That means that ISPs or governments trying to block access to the

2211)     Tor network can't simply block all bridges.

2212)     </p>

2213) 

2214)     <p>Being a normal relay vs being a bridge relay is almost the same
2215)     configuration: it's just a matter of whether your relay is listed

2216)     publicly or not.

2217)     </p>

2218) 

2219)     <p>

2220)     So bridges are useful a) for Tor users in oppressive regimes,

2221)     and b) for people who want an extra layer of security

2222)     because they're worried somebody will recognize that it's a public
2223)     Tor relay IP address they're contacting.

2224)     </p>

2225) 

2226)     <p>
2227)     Several countries, including China and Iran, have found ways to

2228)     detect and block connections to Tor bridges.

2229)     <a href="<page projects/obfsproxy>">Obfsproxy</a> bridges address

2230)     this by adding another layer of obfuscation.

2231)     </p>
2232) 

2233)     <p>So should you run a normal relay or bridge relay? If you have
2234) lots

2235)     of bandwidth, you should definitely run a normal relay.
2236)     If you're willing

2237)     to <a href="#ExitPolicies">be an exit</a>, you should definitely
2238)     run a normal relay, since we need more exits. If you can't be an
2239)     exit and only have a little bit of bandwidth, be a bridge. Thanks
2240)     for volunteering!

2241)     </p>

2242) 

2243)     <hr>

2244) 

2245) <a id="UpgradeOrMove"></a>

2246) <h3><a class="anchor" href="#UpgradeOrMove">I want to upgrade/move my relay. 
2247) How do I keep the same key?</a></h3>

2248) 
2249) <p>

2250)  When upgrading your Tor relay, or running it on a different computer, 
2251)  the important part is to keep the same nickname (defined in your torrc 
2252)  file) and the same identity key (stored in "keys/secret_id_key" in 
2253)  your DataDirectory).

2254) </p>
2255) <p>

2256) This means that if you're upgrading your Tor relay and you keep the same 
2257) torrc and the same DataDirectory, then the upgrade should just work and 
2258) your relay will keep using the same key. If you need to pick a new 
2259) DataDirectory, be sure to copy your old keys/secret_id_key over. 

2260) </p>
2261) 
2262)     <hr>
2263) 
2264) <a id="NTService"></a>

2265) <h3><a class="anchor" href="#NTService">How do I run my Tor relay as an NT 
2266) service?</a></h3>

2267) 
2268) <p>

2269)  You can run Tor as a service on all versions of Windows except Windows 
2270)  95/98/ME. This way you can run a Tor relay without needing to always have 
2271)  Vidalia running.

2272) </p>
2273) <p>

2274) If you've already configured your Tor to be a relay, please note that when 
2275) you enable Tor as a service, it will use a different DatagDirectory, and 
2276) thus will generate a different key. If you want to keep using the old key, 
2277) see the Upgrading your Tor relay FAQ entry for how to restore the old 
2278) identity key.

2279) </p>
2280) <p>
2281) To install Tor as a service, you can simply run:
2282) </p>
2283) <pre>
2284) tor --service install
2285) </pre>
2286) <p>

2287) A service called Tor Win32 Service will be installed and started. This 
2288) service will also automatically start every time Windows boots, unless 
2289) you change the Start-up type. An easy way to check the status of Tor, 
2290) start or stop the service, and change the start-up type is by running 
2291) services.msc and finding the Tor service in the list of currently 
2292) installed services.

2293) </p>
2294) <p>

2295) Optionally, you can specify additional options for the Tor service using 
2296) the -options argument. For example, if you want Tor to use C:\tor\torrc, 
2297) instead of the default torrc, and open a control port on port 9151, you 
2298) would run:

2299) </p>
2300) <pre>
2301) tor --service install -options -f C:\tor\torrc ControlPort 9151
2302) </pre>
2303) <p>
2304) You can also start or stop the Tor service from the command line by typing:
2305) </p>
2306) <pre>
2307)  tor --service start
2308) </pre>
2309) <p>
2310) or
2311) </p>
2312) <pre>
2313)  tor --service stop
2314) </pre>
2315) <p>
2316) To remove the Tor service, you can run the following command:
2317) </p>
2318) <pre>
2319) tor --service remove
2320) </pre>
2321) <p>

2322) If you are running Tor as a service and you want to uninstall Tor entirely, 
2323) be sure to run the service removal command (shown above) first before 
2324) running the uninstaller from "Add/Remove Programs". The uninstaller is 
2325) currently not capable of removing the active service.

2326) </p>
2327) 
2328) <hr>
2329) 
2330) <a id="VirtualServer"></a>

2331) <h3><a class="anchor" href="#VirtualServer">Can I run a Tor relay from my 
2332) virtual server account?</a></h3>

2333) 
2334) <p>

2335) Some ISPs are selling "vserver" accounts that provide what they call a 
2336) virtual server -- you can't actually interact with the hardware, and 
2337) they can artificially limit certain resources such as the number of file 
2338) descriptors you can open at once. Competent vserver admins are able to 
2339) configure your server to not hit these limits. For example, in SWSoft's 
2340) Virtuozzo, investigate /proc/user_beancounters. Look for "failcnt" in 
2341) tcpsndbuf, tcprecvbuf, numothersock, and othersockbuf. Ask for these to 
2342) be increased accordingly. Some users have seen settings work well as follows: 

2343) <p>

2344) <table border="1">

2345) <tr>
2346) <td>
2347) <i>resource</i>
2348) </td>
2349) <td>
2350) <i>held</i>
2351) </td>
2352) <td>
2353) <i>maxheld</i>
2354) </td>
2355) <td>
2356) <i>barrier</i>
2357) </td>
2358) <td>
2359) <i>limit</i>
2360) </td>
2361) <td>
2362) <i>failcnt</i>
2363) </td>
2364) </tr>
2365) <tr>
2366) <td>
2367) tcpsndbuf
2368) </td>
2369) <td>
2370) 46620
2371) </td>
2372) <td>
2373) 48840
2374) </td>
2375) <td>
2376) 3440640
2377) </td>
2378) <td>
2379) 5406720
2380) </td>
2381) <td>
2382) 0
2383) </td>
2384) </tr>
2385) <tr>
2386) <td>
2387) tcprcvbuf
2388) </td>
2389) <td>
2390) 0
2391) </td>
2392) <td>
2393) 2220
2394) </td>
2395) <td>
2396) 3440640
2397) </td>
2398) <td>
2399) 5406720
2400) </td>
2401) <td>
2402) 0
2403) </td>
2404) </tr>
2405) <tr>
2406) <td>
2407) othersockbuf
2408) </td>
2409) <td>
2410) 243516
2411) </td>
2412) <td>
2413) 260072
2414) </td>
2415) <td>
2416) 2252160
2417) </td>
2418) <td>
2419) 4194304
2420) </td>
2421) <td>
2422) 0
2423) </td>
2424) </tr>
2425) <tr>
2426) <td>
2427) numothersock
2428) </td>
2429) <td>
2430) 151
2431) </td>
2432) <td>
2433) 153
2434) </td>
2435) <td>
2436) 720
2437) </td>
2438) <td>
2439) 720
2440) </td>
2441) <td>
2442) 0
2443) </td>
2444) </tr>
2445) </table>
2446) <p>
2447)  Xen, Virtual Box and VMware virtual servers have no such limits normally.
2448) </p>
2449) <p>

2450) If the vserver admin will not increase system limits another option is 
2451) to reduce the memory allocated to the send and receive buffers on TCP 
2452) connections Tor uses. An experimental feature to constrain socket buffers 
2453) has recently been added. If your version of Tor supports it, set 
2454) "ConstrainedSockets 1" in your configuration. See the tor man page for 
2455) additional details about this option.

2456) </p>
2457) <p>

2458) Unfortunately, since Tor currently requires you to be able to connect to 
2459) all the other Tor relays, we need you to be able to use at least 1024 file 
2460) descriptors. This means we can't make use of Tor relays that are crippled 
2461) in this way.

2462) </p>
2463) <p>

2464) We hope to fix this in the future, once we know how to build a Tor network 
2465) with restricted topologies -- that is, where each node connects to only a 
2466) few other nodes. But this is still a long way off.

2467) </p>
2468) 

2469) <hr>
2470) 

2471) <a id="MultipleRelays"></a>

2472) <h3><a class="anchor" href="#MultipleRelays">I want to run more than one
2473) relay.</a></h3>

2474) 
2475) <p>
2476) Great. If you want to run several relays to donate more to the network,
2477) we're happy with that. But please don't run more than a few dozen on
2478) the same network, since part of the goal of the Tor network is dispersal
2479) and diversity.
2480) </p>
2481) 
2482) <p>
2483) If you do decide to run more than one relay, please set the "MyFamily"

2484) config option in the <a href="#torrc">torrc</a> of each relay, listing
2485) all the relays (comma-separated) that are under your control:

2486) </p>
2487) 
2488) <pre>
2489)     MyFamily $fingerprint1,$fingerprint2,$fingerprint3
2490) </pre>
2491) 
2492) <p>
2493) where each fingerprint is the 40 character identity fingerprint (without

2494) spaces). You can also list them by nickname, but fingerprint is safer.
2495) Be

2496) sure to prefix the digest strings with a dollar sign ('$') so that the
2497) digest is not confused with a nickname in the config file.
2498) </p>
2499) 
2500) <p>
2501) That way clients will know to avoid using more than one of your relays
2502) in a single circuit. You should set MyFamily if you have administrative
2503) control of the computers or of their network, even if they're not all in
2504) the same geographic location.
2505) </p>
2506) 
2507)     <hr>
2508) 

2509)     <a id="WrongIP"></a>

2510)     <h3><a class="anchor" href="#WrongIP">My relay is picking the wrong 
2511)     IP address.</a></h3>

2512)     <p>

2513)  Tor guesses its IP address by asking the computer for its hostname, and 
2514)  then resolving that hostname. Often people have old entries in their 
2515)  /etc/hosts file that point to old IP addresses.

2516)     </p>
2517)     <p>

2518) If that doesn't fix it, you should use the "Address" config option to 
2519) specify the IP you want it to pick. If your computer is behind a NAT and 
2520) it only has an internal IP address, see the following FAQ entry on <a 
2521) href="https://www.torproject.org/docs/faq.html.en#RelayFlexible">dynamic 
2522) IP addresses</a>.

2523)     </p>
2524)     <p>

2525) Also, if you have many addresses, you might also want to set 
2526) "OutboundBindAddress" so external connections come from the IP you intend 
2527) to present to the world. 

2528)     </p>
2529) 
2530)     <hr>
2531) 
2532)     <a id="BehindANAT"></a>
2533)     <h3><a class="anchor" href="#BehindANAT">I'm behind a NAT/Firewall.</a></h3>
2534) 
2535)     <p>

2536) See <a>​http://portforward.com/</a> for directions on how to port forward with 
2537) your NAT/router device.

2538) </p>
2539) <p>

2540) If your relay is running on a internal net you need to setup port forwarding. 
2541) Forwarding TCP connections is system dependent but the firewalled-clients FAQ 
2542) entry offers some examples on how to do this.

2543) </p>
2544) <p>

2545) Also, here's an example of how you would do this on GNU/Linux if you're using 
2546) iptables:

2547) </p>
2548) <pre>
2549) /sbin/iptables -A INPUT -i eth0 -p tcp --destination-port 9001 -j ACCEPT
2550) </pre>
2551) <p>

2552) You may have to change "eth0" if you have a different external interface 
2553) (the one connected to the Internet). Chances are you have only one (except 
2554) the loopback) so it shouldn't be too hard to figure out. 

2555)     </p>
2556)     <hr>
2557) 

2558)     <a id="RelayMemory"></a>

2559)     <h3><a class="anchor" href="#RelayMemory">Why is my Tor relay using
2560) so much memory?</a></h3>

2561) 

2562)     <p>If your Tor relay is using more memory than you'd like, here are
2563) some

2564)     tips for reducing its footprint:
2565)     </p>

2566) 

2567)     <ol>
2568)     <li>If you're on Linux, you may be encountering memory fragmentation

2569)     bugs in glibc's malloc implementation. That is, when Tor releases
2570) memory
2571)     back to the system, the pieces of memory are fragmented so they're
2572) hard
2573)     to reuse. The Tor tarball ships with OpenBSD's malloc
2574) implementation,
2575)     which doesn't have as many fragmentation bugs (but the tradeoff is
2576) higher
2577)     CPU load). You can tell Tor to use this malloc implementation
2578) instead:

2579)     <tt>./configure --enable-openbsd-malloc</tt></li>

2580) 

2581)     <li>If you're running a fast relay, meaning you have many TLS
2582) connections

2583)     open, you are probably losing a lot of memory to OpenSSL's internal
2584)     buffers (38KB+ per socket). We've patched OpenSSL to <a

2585) 
2586) href="https://lists.torproject.org/pipermail/tor-dev/2008-June/001519.
2587) html">release

2588)     unused buffer memory more aggressively</a>. If you update to OpenSSL

2589)     1.0.0 or newer, Tor's build process will automatically recognize and
2590) use

2591)     this feature.</li>

2592) 

2593)     <li>If you're running on Solaris, OpenBSD, NetBSD, or
2594)     old FreeBSD, Tor is probably forking separate processes
2595)     rather than using threads. Consider switching to a <a
2596)     href="<wikifaq>#WhydoesntmyWindowsorotherOSTorrelayrunwell">better
2597)     operating system</a>.</li>

2598) 

2599)     <li>If you still can't handle the memory load, consider reducing the

2600)     amount of bandwidth your relay advertises. Advertising less
2601) bandwidth

2602)     means you will attract fewer users, so your relay shouldn't grow
2603)     as large. See the <tt>MaxAdvertisedBandwidth</tt> option in the man
2604)     page.</li>

2605) 

2606)     </ol>

2607) 

2608)     <p>

2609)     All of this said, fast Tor relays do use a lot of ram. It is not
2610) unusual

2611)     for a fast exit relay to use 500-1000 MB of memory.
2612)     </p>

2613) 

2614)     <hr>

2615) 

2616)     <a id="BetterAnonymity"></a>

2617)     <h3><a class="anchor" href="#BetterAnonymity">Do I get better anonymity 
2618)     if I run a relay?</a></h3>

2619) 

2620)     <p>

2621) Yes, you do get better anonymity against some attacks.
2622)     </p>
2623)     <p>

2624) The simplest example is an attacker who owns a small number of Tor relays. 
2625) He will see a connection from you, but he won't be able to know whether 
2626) the connection originated at your computer or was relayed from somebody else.

2627)     </p>
2628)     <p>

2629) There are some cases where it doesn't seem to help: if an attacker can 
2630) watch all of your incoming and outgoing traffic, then it's easy for him 
2631) to learn which connections were relayed and which started at you. (In 
2632) this case he still doesn't know your destinations unless he is watching 
2633) them too, but you're no better off than if you were an ordinary client.)

2634)     </p>
2635)     <p>

2636) There are also some downsides to running a Tor relay. First, while we 
2637) only have a few hundred relays, the fact that you're running one might 
2638) signal to an attacker that you place a high value on your anonymity. 
2639) Second, there are some more esoteric attacks that are not as 
2640) well-understood or well-tested that involve making use of the knowledge 
2641) that you're running a relay -- for example, an attacker may be able to 
2642) "observe" whether you're sending traffic even if he can't actually watch 
2643) your network, by relaying traffic through your Tor relay and noticing 
2644) changes in traffic timing.

2645)     </p>
2646)     <p>

2647) It is an open research question whether the benefits outweigh the risks. 
2648) A lot of that depends on the attacks you are most worried about. For 
2649) most users, we think it's a smart move. 

2650)     </p>

2651) 

2652)     <hr>

2653) 

2654)     <a id="RelayDonations"></a>

2655)     <h3><a class="anchor" href="#RelayDonations">Can I donate for a
2656)     relay rather than run my own?</a></h3>

2657) 
2658)     <p>

2659)     Sure! We recommend these non-profit charities that are happy to turn

2660)     your donations into better speed and anonymity for the Tor network:
2661)     </p>
2662)     <ul>
2663)     <li><a href="https://www.torservers.net/">torservers.net</a>
2664)     is a German charitable non-profit that runs a wide variety of

2665)     exit relays worldwide. They also like donations of bandwidth from
2666)     ISPs.</li>

2667)     <li><a

2668) href="https://www.noisebridge.net/wiki/Noisebridge_Tor">Noisebridge</a>

2669)     is a US-based 501(c)(3) non-profit that collects donations and turns

2670)     them into more US-based exit relay capacity.</li>
2671)     <li><a href="https://nos-oignons.net/">Nos Oignons</a> is a French
2672)     charitable non-profit that runs fast exit relays in France.</li>

2673)     </ul>
2674) 
2675)     <p>
2676)     These organizations are not the same as <a href="<page
2677)     donate/donate>">The Tor Project, Inc</a>, but we consider that a

2678)     good thing. They're both run by nice people who are part of the
2679)     Tor community.

2680)     </p>
2681) 
2682)     <p>
2683)     Note that there can be a tradeoff here between anonymity and

2684)     performance. The Tor network's anonymity comes in part from
2685) diversity,

2686)     so if you are in a position to run your own relay, you will be

2687)     improving Tor's anonymity more than by donating. At the same time
2688)     though, economies

2689)     of scale for bandwidth mean that combining many small donations into

2690)     several larger relays is more efficient at improving network

2691)     performance. Improving anonymity and improving performance are both
2692)     worthwhile goals, so however you can help is great!
2693)     </p>
2694) 
2695)     <hr>
2696) 

2697)     <a id="AccessHiddenServices"></a>
2698)     <h3><a class="anchor" href="#AccessHiddenServices">How do I access 
2699)     hidden services?</a></h3>
2700)     
2701)     <p>
2702)     Tor hidden services are named with a special top-level domain (TLD) 
2703)     name in DNS: .onion. Since the .onion TLD is not recognized by the 
2704)     official root DNS servers on the Internet, your application will not 
2705)     get the response it needs to locate the service. Currently, the Tor 
2706)     directory server provides this look-up service; and thus the look-up 
2707)     request must get to the Tor network. 
2708)     </p>
2709) 
2710) <p>
2711)  Therefore, your application <b>needs</b> to pass the .onion hostname to 
2712)  Tor directly. You can't try to resolve it to an IP address, since there 
2713)  <i>is</i> no corresponding IP address: the server is hidden, after all! 
2714) </p>
2715)     
2716)     <p>
2717)     So, how do you make your application pass the hostname directly to Tor? 
2718)     You can't use SOCKS 4, since SOCKS 4 proxies require an IP from the 
2719)     client (a web browser is an example of a SOCKS client). Even though 
2720)     SOCKS 5 can accept either an IP or a hostname, most applications 
2721)     supporting SOCKS 5 try to resolve the name before passing it to the 
2722)     SOCKS proxy. SOCKS 4a, however, always accepts a hostname: You'll need 
2723)     to use SOCKS 4a. 
2724)     </p>
2725)     
2726)     <p>
2727)     Some applications, such as the browsers Mozilla Firefox and Apple's 
2728)     Safari, support sending DNS queries to Tor's SOCKS 5 proxy. Most web 
2729)     browsers don't support SOCKS 4a very well, though. The workaround is 
2730)     to point your web browser at an HTTP proxy, and tell the HTTP proxy 
2731)     to speak to Tor with SOCKS 4a. We recommend Polipo as your HTTP proxy.
2732)     </p>
2733)     
2734)     <p>
2735)     For applications that do not support HTTP proxy, and so cannot use 
2736)     Polipo, <a href="http://www.freecap.ru/eng/">FreeCap</a> is an 
2737)     alternative. When using FreeCap set proxy protocol  to SOCKS 5 and under 
2738)     settings set DNS name resolving to remote. This 
2739)     will allow you to use almost any program with Tor without leaking DNS 
2740)     lookups and allow those same programs to access hidden services. 
2741)     </p>
2742)     
2743)     <p>
2744)     See also the <a href="#SocksAndDNS">question on DNS</a>. 
2745)     </p>    
2746)     
2747)     <hr>
2748) 
2749)     <a id="ProvideAHiddenService"></a>
2750)     <h3><a class="anchor" href="#ProvideAHiddenService">How do I provide a 
2751)     hidden service?</a></h3>
2752)     
2753)     <p>

2754)     See the <a href="https://www.torproject.org/docs/tor-hidden-service.html.en">

2755)     official hidden service configuration instructions</a>.
2756)     </p>
2757) 
2758)     <hr>
2759)     

2760)     <a id="WhatProtectionsDoesTorProvide"></a>
2761)     <h3><a class="anchor" href="#WhatProtectionsDoesTorProvide">What 
2762)     protections does Tor provide?</a></h3>
2763)     
2764)     <p>
2765)      Internet communication is based on a store-and-forward model that 
2766)      can be understood in analogy to postal mail: Data is transmitted in 
2767)      blocks called IP datagrams or packets. Every packet includes a source 
2768)      IP address (of the sender) and a destination IP address (of the 
2769)      receiver), just as ordinary letters contain postal addresses of sender 
2770)      and receiver. The way from sender to receiver involves multiple hops of 
2771)      routers, where each router inspects the destination IP address and 
2772)      forwards the packet closer to its destination. Thus, every router 
2773)      between sender and receiver learns that the sender is communicating 
2774)      with the receiver. In particular, your local ISP is in the position to 
2775)      build a complete profile of your Internet usage. In addition, every 
2776)      server in the Internet that can see any of the packets can profile your 
2777)      behaviour. 
2778)     </p>
2779)     
2780)     <p>
2781)     The aim of Tor is to improve your privacy by sending your traffic through 
2782)     a series of proxies. Your communication is encrypted in multiple layers 
2783)     and routed via multiple hops through the Tor network to the final 
2784)     receiver. More details on this process can be found in the <a 
2785)     href="https://www.torproject.org/about/overview">Tor overview</a>. 
2786)     Note that all your local ISP can observe now is that you are 
2787)     communicating with Tor nodes. Similarly, servers in the Internet just 
2788)     see that they are being contacted by Tor nodes.
2789)     </p>
2790)     
2791)     <p>
2792)     Generally speaking, Tor aims to solve three privacy problems: 
2793)     </p>
2794)     
2795)     <p>
2796)     First, Tor prevents websites and other services from learning 
2797)     your location, which they can use to build databases about your 
2798)     habits and interests. With Tor, your Internet connections don't 
2799)     give you away by default -- now you can have the ability to choose, 
2800)     for each connection, how much information to reveal. 
2801)     </p>
2802)     
2803)     <p>
2804)     Second, Tor prevents people watching your traffic locally (such as 
2805)     your ISP) from learning what information you're fetching and where 
2806)     you're fetching it from. It also stops them from deciding what you're 
2807)     allowed to learn and publish -- if you can get to any part of the Tor 
2808)     network, you can reach any site on the Internet.     
2809)     </p>
2810) 
2811)     <p>
2812)     Third, Tor routes your connection through more than one Tor relay 
2813)     so no single relay can learn what you're up to. Because these relays 
2814)     are run by different individuals or organizations, distributing trust 
2815)     provides more security than the old <a href="#Torisdifferent">one hop proxy
2816)     </a> approach. 
2817)     </p>
2818)     
2819)     <p>
2820)     Note, however, that there are situations where Tor fails to solve these 
2821)     privacy problems entirely: see the entry below on <a 
2822)     href="#AttacksOnOnionRouting">remaining attacks</a>.    
2823)     </p>
2824)     
2825)     <hr>
2826)     
2827)     <a id="CanExitNodesEavesdrop"></a>
2828)     <h3><a class="anchor" href="#CanExitNodesEavesdrop">Can exit nodes eavesdrop 
2829)     on communications? Isn't that bad?</a></h3>
2830)     
2831)     <p>
2832)     Yes, the guy running the exit node can read the bytes that come in and 
2833)     out there. Tor anonymizes the origin of your traffic, and it makes sure 
2834)     to encrypt everything inside the Tor network, but it does not magically 
2835)     encrypt all traffic throughout the Internet. 
2836)     </p>
2837)     
2838)     <p>
2839)     This is why you should always use end-to-end encryption such as SSL for 
2840)     sensitive Internet connections. (The corollary to this answer is that if 
2841)     you are worried about somebody intercepting your traffic and you're 
2842)     *not* using end-to-end encryption at the application layer, then something 
2843)     has already gone wrong and you shouldn't be thinking that Tor is the problem.) 
2844)     </p>
2845)     
2846)     <p>
2847)     Tor does provide a partial solution in a very specific situation, though. 
2848)     When you make a connection to a destination that also runs a Tor relay, 
2849)     Tor will automatically extend your circuit so you exit from that circuit. 
2850)     So for example if Indymedia ran a Tor relay on the same IP address as 
2851)     their website, people using Tor to get to the Indymedia website would 
2852)     automatically exit from their Tor relay, thus getting *better* encryption 
2853)     and authentication properties than just browsing there the normal way. 
2854)     </p>
2855) 
2856)     <p>
2857)     We'd like to make it still work even if the service is nearby the Tor 
2858)     relay but not on the same IP address. But there are a variety of 
2859)     technical problems we need to overcome first (the main one being "how 
2860)     does the Tor client learn which relays are associated with which 
2861)     websites in a decentralized yet non-gamable way?"). 
2862)     </p>
2863)             
2864)     <hr>
2865)     
2866)     <a id="ExitEnclaving"></a>
2867)     <h3><a class="anchor" href="#ExitEnclaving">What is Exit Enclaving?</a></h3>
2868) 
2869)     <p>
2870)     When a machine that runs a Tor relay also runs a public service, such as 
2871)     a webserver, you can configure Tor to offer Exit Enclaving to that 
2872)     service. Running an Exit Enclave for all of your services you wish to 
2873)     be accessible via Tor provides your users the assurance that they will 
2874)     exit through your server, rather than exiting from a randomly selected 
2875)     exit node that could be watched. Normally, a tor circuit would end at 
2876)     an exit node and then that node would make a connection to your service. 
2877)     Anyone watching that exit node could see the connection to your service, 
2878)     and be able to snoop on the contents if it were an unencrypted 
2879)     connection. If you run an Exit Enclave for your service, then the exit 
2880)     from the Tor network happens on the machine that runs your service, 
2881)     rather than on an untrusted random node. This works when Tor clients 
2882)     wishing to connect to this public service extend their their circuit 
2883)     to exit from the Tor relay running on that same host. For example, if 
2884)     the server at 1.2.3.4 runs a web server on port 80 and also acts as a 
2885)     Tor relay configured for Exit Enclaving, then Tor clients wishing to 
2886)     connect to the webserver will extend their circuit a fourth hop to exit 
2887)     to port 80 on the Tor relay running on 1.2.3.4. 
2888)     </p>
2889)     <p>
2890)     Exit Enclaving is disabled by default to prevent attackers from 
2891)     exploiting trust relationships with locally bound services. For 
2892)     example, often 127.0.0.1 will run services that are not designed to 
2893)     be shared with the entire world. Sometimes these services will also 
2894)     be bound to the public IP address, but will only allow connections if 
2895)     the source address is something trusted, such as 127.0.0.1. 
2896)     </p>
2897)     <p>
2898)     As a result of possible trust issues, relay operators must configure 
2899)     their exit policy to allow connections to themselves, but they should 
2900)     do so only when they are certain that this is a feature that they would 
2901)     like. Once certain, turning off the ExitPolicyRejectPrivate option will 
2902)     enable Exit Enclaving. An example configuration would be as follows: 
2903)     </p>
2904)     <pre>
2905)     ExitPolicy accept 1.2.3.4:80
2906)     ExitPolicy reject 127.0.0.1/8
2907)     ExitPolicyRejectPrivate 0
2908)     </pre>
2909)     <p>
2910)     This option should be used with care as it may expose internal network 
2911)     blocks that are not meant to be accessible from the outside world or 
2912)     the Tor network. Please tailor your ExitPolicy to reflect all netblocks 
2913)     that you want to prohibit access. 
2914)     </p>
2915)     <p>
2916)     This option should be used with care as it may expose internal network 
2917)     blocks that are not meant to be accessible from the outside world or 
2918)     the Tor network. Please tailor your ExitPolicy to reflect all netblocks 
2919)     that you want to prohibit access. 
2920)     </p>
2921)     <p>
2922)     While useful, this behavior may go away in the future because it is 
2923)     imperfect. A great idea but not such a great implementation. 
2924)     </p>
2925) 
2926)     <hr>
2927)     

2928)     <a id="KeyManagement"></a>

2929)     <h3><a class="anchor" href="#KeyManagement">Tell me about all the
2930) keys Tor uses.</a></h3>

2931) 

2932)     <p>
2933)     Tor uses a variety of different keys, with three goals in mind: 1)
2934)     encryption to ensure privacy of data within the Tor network, 2)
2935)     authentication so clients know they're

2936)     talking to the relays they meant to talk to, and 3) signatures to
2937) make

2938)     sure all clients know the same set of relays.
2939)     </p>

2940) 

2941)     <p>

2942)     <b>Encryption</b>: first, all connections in Tor use TLS link
2943) encryption,

2944)     so observers can't look inside to see which circuit a given cell is

2945)     intended for. Further, the Tor client establishes an ephemeral
2946) encryption

2947)     key with each relay in the circuit; these extra layers of encryption
2948)     mean that only the exit relay can read

2949)     the cells. Both sides discard the circuit key when the circuit ends,

2950)     so logging traffic and then breaking into the relay to discover the

2951)     key won't work.

2952)     </p>

2953) 

2954)     <p>
2955)     <b>Authentication</b>:
2956)     Every Tor relay has a public decryption key called the "onion key".

2957)     Each relay rotates its onion key once a week.

2958)     When the Tor client establishes circuits, at each step it <a

2959) 
2960) href="<svnprojects>design-paper/tor-design.html#subsec:circuits">demands

2961)     that the Tor relay prove knowledge of its onion key</a>. That way
2962)     the first node in the path can't just spoof the rest of the path.

2963)     Because the Tor client chooses the path, it can make sure to get
2964)     Tor's "distributed trust" property: no single relay in the path can
2965)     know about both the client and what the client is doing.

2966)     </p>

2967) 

2968)     <p>
2969)     <b>Coordination</b>:

2970)     How do clients know what the relays are, and how do they know that
2971) they
2972)     have the right keys for them? Each relay has a long-term public
2973) signing
2974)     key called the "identity key". Each directory authority additionally
2975) has a

2976)     "directory signing key". The directory authorities <a