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5) #include "head.wmi" TITLE="Tor Project: Abuse 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-abuse>">Abuse FAQ</a>
11)   </div>
12)   <div id="maincol"> 
13)     <!-- PUT CONTENT AFTER THIS TAG -->
14)     <h1>Abuse FAQ</h1>
15)     #<!-- BEGIN SIDEBAR -->
16)     #<div class="sidebar-left">
17)     #<h3>Questions</h3>
18)     #<ul>
19)     #<li><a href="<page docs/faq-abuse>#WhatAboutCriminals">Doesn't Tor enable criminals to do bad things?</a></li>
20)     #<li><a href="<page docs/faq-abuse>#DDoS">What about distributed denial of service attacks?</a></li>
21)     #<li><a href="<page docs/faq-abuse>#WhatAboutSpammers">What about spammers?</a></li>
22)     #<li><a href="<page docs/faq-abuse>#HowMuchAbuse">Does Tor get much abuse?</a></li>
23)     #<li><a href="<page docs/faq-abuse>#TypicalAbuses">So what should I expect if I run an exit relay?</a></li>
24)     #<li><a href="<page docs/faq-abuse>#IrcBans">Tor is banned from the IRC network I want to use.</a></li>
25)     #<li><a href="<page docs/faq-abuse>#SMTPBans">Your nodes are banned from the mail server I want to use.</a></li>
26)     #<li><a href="<page docs/faq-abuse>#Bans">I want to ban the Tor network from my service.</a></li>
27)     #<li><a href="<page docs/faq-abuse>#TracingUsers">I have a compelling reason to trace a Tor user. Can you help?</a></li>
28)     #<li><a href="<page docs/faq-abuse>#RemoveContent">I want some content removed from a .onion address.</a></li>
29)     #<li><a href="<page docs/faq-abuse>#LegalQuestions">I have legal questions about Tor abuse.</a></li>
30)     #</ul>
31)     #</div>
32)     #<!-- END SIDEBAR -->

33)     #<hr>

34)     
35)     <a id="WhatAboutCriminals"></a>
36)     <h3><a class="anchor" href="#WhatAboutCriminals">Doesn't Tor enable criminals to do bad things?</a></h3>
37)     
38)     <p>Criminals can already do bad things. Since they're willing to
39)     break laws, they already have lots of options available that provide
40)     <em>better</em> privacy than Tor provides. They can steal cell phones,
41)     use them, and throw them in a ditch; they can crack into computers
42)     in Korea or Brazil and use them to launch abusive activities; they
43)     can use spyware, viruses, and other techniques to take control of
44)     literally millions of Windows machines around the world. </p>
45)     
46)     <p>Tor aims to provide protection for ordinary people who want to follow
47)     the law. Only criminals have privacy right now, and we need to fix that. </p>
48)     
49)     <p>Some advocates of anonymity explain that it's just a tradeoff &mdash;
50)     accepting the bad uses for the good ones &mdash; but there's more to it
51)     than that.
52)     Criminals and other bad people have the motivation to learn how to
53)     get good anonymity, and many have the motivation to pay well to achieve
54)     it. Being able to steal and reuse the identities of innocent victims
55)     (identify theft) makes it even easier. Normal people, on the other hand,
56)     don't have the time or money to spend figuring out how to get
57)     privacy online. This is the worst of all possible worlds. </p>
58)     
59)     <p>So yes, criminals could in theory use Tor, but they already have
60)     better options, and it seems unlikely that taking Tor away from the
61)     world will stop them from doing their bad things. At the same time, Tor
62)     and other privacy measures can <em>fight</em> identity theft, physical
63)     crimes like stalking, and so on. </p>
64)     
65)     <!--
66)     <a id="Pervasive"></a>
67)     <h3><a class="anchor" href="#Pervasive">If the whole world starts using
68)     Tor, won't civilization collapse?</a></h3>
69)     -->
70)     
71)     <a id="DDoS"></a>
72)     <h3><a class="anchor" href="#DDoS">What about distributed denial of service attacks?</a></h3>
73)     
74)     <p>Distributed denial of service (DDoS) attacks typically rely on having a group
75)     of thousands of computers all sending floods of traffic to a victim. Since
76)     the goal is to overpower the bandwidth of the victim, they typically send
77)     UDP packets since those don't require handshakes or coordination. </p>
78)     
79)     <p>But because Tor only transports correctly formed TCP streams, not
80)     all IP packets, you cannot send UDP packets over Tor. (You can't do
81)     specialized forms of this attack like SYN flooding either.) So ordinary
82)     DDoS attacks are not possible over Tor. Tor also doesn't allow bandwidth
83)     amplification attacks against external sites: you need to send in a byte
84)     for every byte that the Tor network will send to your destination. So
85)     in general, attackers who control enough bandwidth to launch an effective
86)     DDoS attack can do it just fine without Tor. </p>
87)     
88)     <a id="WhatAboutSpammers"></a>
89)     <h3><a class="anchor" href="#WhatAboutSpammers">What about spammers?</a></h3>
90)     
91)     <p>First of all, the default Tor exit policy rejects all outgoing
92)     port 25 (SMTP) traffic. So sending spam mail through Tor isn't going to
93)     work by default. It's possible that some relay operators will enable
94)     port 25 on their particular exit node, in which case that computer will
95)     allow outgoing mails; but that individual could just set up an open mail
96)     relay too, independent of Tor. In short, Tor isn't useful for spamming,
97)     because nearly all Tor relays refuse to deliver the mail. </p>
98)     
99)     <p>Of course, it's not all about delivering the mail. Spammers can use
100)     Tor to connect to open HTTP proxies (and from there to SMTP servers); to
101)     connect to badly written mail-sending CGI scripts; and to control their
102)     botnets &mdash; that is, to covertly communicate with armies of
103)     compromised computers that deliver the spam.
104)     </p>
105)     
106)     <p>
107)     This is a shame, but notice that spammers are already doing great
108)     without Tor. Also, remember that many of their more subtle communication
109)     mechanisms (like spoofed UDP packets) can't be used over Tor, because
110)     it only transports correctly-formed TCP connections.
111)     </p>
112)     
113)     <a id="ExitPolicies"></a>
114)     <h3><a class="anchor" href="#ExitPolicies">How do Tor exit policies work?</a></h3>
115)     
116)     <p>

117)     <a href="<wikifaq>#ExitPolicies">See the FAQ</a>

118)     </p>
119)     
120)     <a id="HowMuchAbuse"></a>
121)     <h3><a class="anchor" href="#HowMuchAbuse">Does Tor get much abuse?</a></h3>
122)     

123)     <p>Not much, in the grand scheme of things. The network has been running

124)     since October 2003, and it's only generated a handful of complaints. Of

125)     course, like all privacy-oriented networks on the net, it attracts its

126)     share of jerks. Tor's exit policies help separate the role of "willing
127)     to donate resources to the network" from the role of "willing to deal
128)     with exit abuse complaints," so we hope our network is more sustainable
129)     than past attempts at anonymity networks. </p>
130)     
131)     <p>Since Tor has

132)     <a href="<page about/torusers>">many good uses as

133)     well</a>, we feel that we're doing pretty well at striking a balance
134)     currently. </p>
135)     
136)     <a id="TypicalAbuses"></a>
137)     <h3><a class="anchor" href="#TypicalAbuses">So what should I expect if I run an exit relay?</a></h3>
138)     
139)     <p>If you run a Tor relay that allows exit connections (such as the
140)     default exit policy), it's probably safe to say that you will eventually
141)     hear from somebody. Abuse
142)     complaints may come in a variety of forms. For example: </p>
143)     <ul>
144)     <li>Somebody connects to Hotmail, and sends a ransom note to a
145)     company. The
146)     FBI sends you a polite email, you explain that you run a Tor relay,
147)     and they say "oh well" and leave you alone. [Port 80]</li>
148)     <li>Somebody tries to get you shut down by using Tor to connect to Google
149)     groups and post spam to Usenet, and then sends an angry mail to
150)     your ISP about how you're destroying the world. [Port 80]</li>
151)     <li>Somebody connects to an IRC network and makes a nuisance of
152)     himself. Your ISP gets polite mail about how your computer has been
153)     compromised; and/or your computer gets DDoSed. [Port 6667]</li>
154)     <li>Somebody uses Tor to download a Vin Diesel movie, and
155)     your ISP gets a DMCA takedown notice. See EFF's
156)     <a href="<page eff/tor-dmca-response>">Tor DMCA Response
157)     Template</a>, which explains why your ISP can probably ignore
158)     the notice without any liability. [Arbitrary ports]</li>
159)     </ul>
160)     
161)     <p>You might also find that your Tor relay's IP is blocked from accessing
162)     some Internet sites/services. This might happen regardless of your exit
163)     policy, because some groups don't seem to know or care that Tor has
164)     exit policies. (If you have a spare IP not used for other activities,
165)     you might consider running your Tor relay on it.) For example, </p>
166)     
167)     <ul>
168)     <li>Because of a few cases of anonymous jerks messing with its web
169)     pages, Wikipedia is currently blocking many Tor relay IPs from writing
170)     (reading still works). We're talking to Wikipedia about how they might
171)     control abuse while still providing access to anonymous contributors,
172)     who often have hot news or inside info on a topic but don't want to risk
173)     revealing their identities when publishing it (or don't want to reveal
174)     to local observers that they're accessing Wikipedia). Slashdot is also
175)     in the same boat.</li>
176)     
177)     <li>SORBS is putting some Tor relay IPs on their email
178)     blacklist as well. They do this because they passively detect whether your
179)     relay connects to certain IRC networks, and they conclude from this that
180)     your relay is capable of spamming. We tried to work with
181)     them to teach them that not all software works this way,
182)     but we have given up. We recommend you avoid them, and <a
183)     href="http://paulgraham.com/spamhausblacklist.html">teach your friends
184)     (if they use them) to avoid abusive blacklists too</a>.</li>
185)     
186)     </ul>
187)     
188)     <a id="IrcBans"></a>
189)     <h3><a class="anchor" href="#IrcBans">Tor is banned from the IRC network I want to use.</a></h3>
190)     
191)     <p>Sometimes jerks make use of Tor to troll IRC channels. This abuse
192)     results in IP-specific temporary bans ("klines" in IRC lingo), as the
193)     network operators try to keep the troll off of their network. </p>
194)     
195)     <p>This response underscores a fundamental flaw in IRC's security model:
196)     they assume that IP addresses equate to humans, and by banning the
197)     IP address they can ban the human. In reality this is not the case &mdash;
198)     many such trolls routinely make use of the literally millions of open
199)     proxies and compromised computers around the Internet. The IRC networks
200)     are fighting a losing battle of trying to block all these nodes,
201)     and an entire cottage industry of blacklists and counter-trolls has
202)     sprung up based on this flawed security model (not unlike the antivirus
203)     industry). The Tor network is just a drop in the bucket here. </p>
204)     
205)     <p>On the other hand, from the viewpoint of IRC server operators, security
206)     is not an all-or-nothing thing.  By responding quickly to trolls or
207)     any other social attack, it may be possible to make the attack scenario
208)     less attractive to the attacker.  And most individual IP addresses do
209)     equate to individual humans, on any given IRC network at any given time.
210)     The exceptions include NAT gateways which may be allocated access as
211)     special cases. While it's a losing battle to try to stop the use of open
212)     proxies, it's not generally a losing battle to keep klining a single
213)     ill-behaved IRC user until that user gets bored and goes away. </p>
214)     
215)     <p>But the real answer is to implement application-level auth systems,
216)     to let in well-behaving users and keep out badly-behaving users. This
217)     needs to be based on some property of the human (such as a password he
218)     knows), not some property of the way his packets are transported. </p>
219)     
220)     <p>Of course, not all IRC networks are trying to ban Tor nodes. After
221)     all, quite a few people use Tor to IRC in privacy in order to carry
222)     on legitimate communications without tying them to their real-world
223)     identity. Each IRC network needs to decide for itself if blocking a few
224)     more of the millions of IPs that bad people can use is worth losing the
225)     contributions from the well-behaved Tor users. </p>
226)     
227)     <p>If you're being blocked, have a discussion with the network operators
228)     and explain the issues to them. They may not be aware of the existence of
229)     Tor at all, or they may not be aware that the hostnames they're klining
230)     are Tor exit nodes.  If you explain the problem, and they conclude that
231)     Tor ought to be blocked, you may want to consider moving to a network that
232)     is more open to free speech.  Maybe inviting them to #tor on irc.oftc.net
233)     will help show them that we are not all evil people. </p>
234)     
235)     <p>Finally, if you become aware of an IRC network that seems to be
236)     blocking Tor, or a single Tor exit node, please put that information on <a

237)     href="<wiki>TheOnionRouter/BlockingIrc">The Tor

238)     IRC block tracker</a>
239)     so that others can share.  At least one IRC network consults that page
240)     to unblock exit nodes that have been blocked inadvertently. </p>
241)     
242)     <a id="SMTPBans"></a>
243)     <h3><a class="anchor" href="#SMTPBans">Your nodes are banned from the mail server I want to use.</a></h3>
244)     
245)     <p>Even though <a href="#WhatAboutSpammers">Tor isn't useful for
246)     spamming</a>, some over-zealous blacklisters seem to think that all
247)     open networks like Tor are evil &mdash; they attempt to strong-arm network
248)     administrators on policy, service, and routing issues, and then extract
249)     ransoms from victims. </p>
250)     
251)     <p>If your server administrators decide to make use of these
252)     blacklists to refuse incoming mail, you should have a conversation with
253)     them and explain about Tor and Tor's exit policies. </p>
254)     
255)     <a id="Bans"></a>
256)     <h3><a class="anchor" href="#Bans">I want to ban the Tor network from my service.</a></h3>
257)     
258)     <p>We're sorry to hear that. There are some situations where it makes
259)     sense to block anonymous users for an Internet service. But in many
260)     cases, there are easier solutions that can solve your problem while
261)     still allowing users to access your website securely.</p>
262)     
263)     <p>First, ask yourself if there's a way to do application-level decisions
264)     to separate the legitimate users from the jerks. For example, you might
265)     have certain areas of the site, or certain privileges like posting,
266)     available only to people who are registered. It's easy to build an
267)     up-to-date list of Tor IP addresses that allow connections to your
268)     service, so you could set up this distinction only for Tor users. This
269)     way you can have multi-tiered access and not have to ban every aspect
270)     of your service. </p>
271)     
272)     <p>For example, the <a
273)     href="http://freenode.net/policy.shtml#tor">Freenode IRC network</a>
274)     had a problem with a coordinated group of abusers joining channels and
275)     subtly taking over the conversation; but when they labelled all users
276)     coming from Tor nodes as "anonymous users," removing the ability of the
277)     abusers to blend in, the abusers moved back to using their open proxies
278)     and bot networks. </p>
279)     
280)     <p>Second, consider that hundreds of thousands of
281)     people use Tor every day simply for
282)     good data hygiene &mdash; for example, to protect against data-gathering
283)     advertising companies while going about their normal activities. Others
284)     use Tor because it's their only way to get past restrictive local
285)     firewalls. Some Tor users may be legitimately connecting
286)     to your service right now to carry on normal activities. You need to
287)     decide whether banning the Tor network is worth losing the contributions
288)     of these users, as well as potential future legitimate users. (Often
289)     people don't have a good measure of how many polite Tor users are
290)     connecting to their service &mdash; you never notice them until there's
291)     an impolite one.)</p>
292)     
293)     <p>At this point, you should also ask yourself what you do about other
294)     services that aggregate many users behind a few IP addresses. Tor is
295)     not so different from AOL in this respect.</p>
296)     
297)     <p>Lastly, please remember that Tor relays have <a

298)     href="<wikifaq>#ExitPolicies">individual exit policies</a>. Many Tor relays do

299)     not allow exiting connections at all. Many of those that do allow some
300)     exit connections might already disallow connections to
301)     your service. When you go about banning nodes, you should parse the
302)     exit policies and only block the ones that allow these connections;
303)     and you should keep in mind that exit policies can change (as well as
304)     the overall list of nodes in the network).</p>
305)     
306)     <p>If you really want to do this, we provide a
307)     <a href="https://check.torproject.org/cgi-bin/TorBulkExitList.py">Tor
308)     exit relay list</a> or a
309)     <a href="<page projects/tordnsel>">DNS-based list you can query</a>.
310)     </p>
311)     
312)     <p>
313)     (Some system administrators block ranges of IP addresses because of
314)     official policy or some abuse pattern, but some have also asked about
315)     whitelisting Tor exit relays because they want to permit access to their
316)     systems only using Tor. These scripts are usable for whitelisting as well.)
317)     </p>
318)     
319)     <a id="TracingUsers"></a>
320)     <h3><a class="anchor" href="#TracingUsers">I have a compelling reason to trace a Tor user. Can you help?</a></h3>
321)     
322)     <p>
323)     There is nothing the Tor developers can do to trace Tor users. The same
324)     protections that keep bad people from breaking Tor's anonymity also
325)     prevent us from figuring out what's going on.
326)     </p>
327)     
328)     <p>
329)     Some fans have suggested that we redesign Tor to include a <a

330)     href="<wikifaq>#Backdoor">backdoor</a>.