Abuse FAQ

Great. That's exactly why we implemented exit policies.

Each Tor relay has an exit policy that specifies what sort of outbound connections are allowed or refused from that relay. The exit policies are propagated to Tor clients via the directory, so clients will automatically avoid picking exit relays that would refuse to exit to their intended destination. This way each relay can decide the services, hosts, and networks it wants to allow connections to, based on abuse potential and its own situation. Read the Support entry on issues you might encounter if you use the default exit policy, and then read Mike Perry's tips for running an exit node with minimal harassment.

The default exit policy allows access to many popular services (e.g. web browsing), but restricts some due to abuse potential (e.g. mail) and some since the Tor network can't handle the load (e.g. default file-sharing ports). You can change your exit policy by editing your torrc file. If you want to avoid most if not all abuse potential, set it to "reject *:*". This setting means that your relay will be used for relaying traffic inside the Tor network, but not for connections to external websites or other services.

If you do allow any exit connections, make sure name resolution works (that is, your computer can resolve Internet addresses correctly). If there are any resources that your computer can't reach (for example, you are behind a restrictive firewall or content filter), please explicitly reject them in your exit policy otherwise Tor users will be impacted too.

Tor's mission is to advance human rights with free and open-source technology, empowering users to defend against mass surveillance and internet censorship. We hate that there are some people who use Tor for nefarious purposes, and we condemn the misuse and exploitation of our technology for criminal activity.

It's essential to understand that criminal intent lies with the individuals and not the tools they use. Just like other widely available technology, Tor can be used by individuals with criminal intent. And because of other options they can use it seems unlikely that taking Tor away from the world will stop them from engaging in criminal activity. At the same time, Tor and other privacy measures can fight identity theft, physical crimes like stalking, and be used by law enforcement to investigate crime and help support survivors.

Distributed denial of service (DDoS) attacks typically rely on having a group of thousands of computers all sending floods of traffic to a victim. Since the goal is to overpower the bandwidth of the victim, they typically send UDP packets since those don't require handshakes or coordination.

But because Tor only transports correctly formed TCP streams, not all IP packets, you cannot send UDP packets over Tor. (You can't do specialized forms of this attack like SYN flooding either.) So ordinary DDoS attacks are not possible over Tor. Tor also doesn't allow bandwidth amplification attacks against external sites: you need to send in a byte for every byte that the Tor network will send to your destination. So in general, attackers who control enough bandwidth to launch an effective DDoS attack can do it just fine without Tor.

First of all, the default Tor exit policy rejects all outgoing port 25 (SMTP) traffic. So sending spam mail through Tor isn't going to work by default. It's possible that some relay operators will enable port 25 on their particular exit node, in which case that computer will allow outgoing mails; but that individual could just set up an open mail relay too, independent of Tor. In short, Tor isn't useful for spamming, because nearly all Tor relays refuse to deliver the mail.

Of course, it's not all about delivering the mail. Spammers can use Tor to connect to open HTTP proxies (and from there to SMTP servers); to connect to badly written mail-sending CGI scripts; and to control their botnets — that is, to covertly communicate with armies of compromised computers that deliver the spam.

This is a shame, but notice that spammers are already doing great without Tor. Also, remember that many of their more subtle communication mechanisms (like spoofed UDP packets) can't be used over Tor, because it only transports correctly-formed TCP connections.

Tor has implemented exit policies. Each Tor relay has an exit policy that specifies what sort of outbound connections are allowed or refused from that relay. This way each relay can decide the services, hosts, and networks it wants to allow connections to, based on abuse potential and its own situation. We also have a dedicated team, Network Health, to investigate bad relay behavior and kick them out of the network.

It is important to note that while we can combat some type of abuse like bad relays in our network, we can't see or manage what users do on the network and that is by design. This design overwhelmingly allows for beneficial uses by providing human rights activists, journalists, domestic violence survivors, whistleblowers, law enforcement officers, and many others with as much privacy and anonymity as possible. Learn more about our users and Tor's beneficial use cases here.

If you run a Tor relay that allows exit connections (such as the default exit policy), it's probably safe to say that you will eventually hear from somebody. Abuse complaints may come in a variety of forms. For example:

  • Somebody connects to Hotmail, and sends a ransom note to a company. The FBI sends you a polite email, you explain that you run a Tor relay, and they say "oh well" and leave you alone. [Port 80]
  • Somebody tries to get you shut down by using Tor to connect to Google groups and post spam to Usenet, and then sends an angry mail to your ISP about how you're destroying the world. [Port 80]
  • Somebody connects to an IRC network and makes a nuisance of himself. Your ISP gets polite mail about how your computer has been compromised; and/or your computer gets DDoSed. [Port 6667]
  • Somebody uses Tor to download a Vin Diesel movie, and your ISP gets a DMCA takedown notice. See EFF's Tor DMCA Response Template, which explains why your ISP can probably ignore the notice without any liability. [Arbitrary ports]

Some hosting providers are friendlier than others when it comes to Tor exits. For a listing see the good and bad ISPs wiki.

For a complete set of template responses to different abuse complaint types, see the collection of templates. You can also proactively reduce the amount of abuse you get by following these tips for running an exit node with minimal harassment and running a reduced exit policy.

You might also find that your Tor relay's IP is blocked from accessing some Internet sites/services. This might happen regardless of your exit policy, because some groups don't seem to know or care that Tor has exit policies. (If you have a spare IP not used for other activities, you might consider running your Tor relay on it.) In general, it's advisable not to use your home internet connection to provide a Tor relay.

A collection of templates for successfully responding to ISPs is collected here.

Sometimes jerks make use of Tor to troll IRC channels. This abuse results in IP-specific temporary bans ("klines" in IRC lingo), as the network operators try to keep the troll off of their network.

This response underscores a fundamental flaw in IRC's security model: they assume that IP addresses equate to humans, and by banning the IP address they can ban the human. In reality, this is not the case — many such trolls routinely make use of the literally millions of open proxies and compromised computers around the Internet. The IRC networks are fighting a losing battle of trying to block all these nodes, and an entire cottage industry of blocklists and counter-trolls has sprung up based on this flawed security model (not unlike the antivirus industry). The Tor network is just a drop in the bucket here.

On the other hand, from the viewpoint of IRC server operators, security is not an all-or-nothing thing. By responding quickly to trolls or any other social attack, it may be possible to make the attack scenario less attractive to the attacker. And most individual IP addresses do equate to individual humans, on any given IRC network at any given time. The exceptions include NAT gateways which may be allocated access as special cases. While it's a losing battle to try to stop the use of open proxies, it's not generally a losing battle to keep klining a single ill-behaved IRC user until that user gets bored and goes away.

But the real answer is to implement application-level auth systems, to let in well-behaving users and keep out badly-behaving users. This needs to be based on some property of the human (such as a password they know), not some property of the way their packets are transported.

Of course, not all IRC networks are trying to ban Tor nodes. After all, quite a few people use Tor to IRC in privacy in order to carry on legitimate communications without tying them to their real-world identity. Each IRC network needs to decide for itself if blocking a few more of the millions of IPs that bad people can use is worth losing the contributions from the well-behaved Tor users.

If you're being blocked, have a discussion with the network operators and explain the issues to them. They may not be aware of the existence of Tor at all, or they may not be aware that the hostnames they're klining are Tor exit nodes. If you explain the problem, and they conclude that Tor ought to be blocked, you may want to consider moving to a network that is more open to free speech. Maybe inviting them to #tor on irc.oftc.net will help show them that we are not all evil people.

Finally, if you become aware of an IRC network that seems to be blocking Tor, or a single Tor exit node, please put that information on The Tor IRC block tracker so that others can share. At least one IRC network consults that page to unblock exit nodes that have been blocked inadvertently.

Even though Tor isn't useful for spamming, some over-zealous blocklisters seem to think that all open networks like Tor are evil — they attempt to strong-arm network administrators on policy, service, and routing issues, and then extract ransoms from victims.

If your server administrators decide to make use of these blocklists to refuse incoming mail, you should have a conversation with them and explain about Tor and Tor's exit policies.

We're sorry to hear that. There are some situations where it makes sense to block anonymous users for an Internet service. But in many cases, there are easier solutions that can solve your problem while still allowing users to access your website securely.

First, ask yourself if there's a way to do application-level decisions to separate the legitimate users from the jerks. For example, you might have certain areas of the site, or certain privileges like posting, available only to people who are registered. It's easy to build an up-to-date list of Tor IP addresses that allow connections to your service, so you could set up this distinction only for Tor users. This way you can have multi-tiered access and not have to ban every aspect of your service.

For example, the Freenode IRC network had a problem with a coordinated group of abusers joining channels and subtly taking over the conversation; but when they labeled all users coming from Tor nodes as "anonymous users", removing the ability of the abusers to blend in, the abusers moved back to using their open proxies and bot networks.

Second, consider that hundreds of thousands of people use Tor every day simply for good data hygiene — for example, to protect against data-gathering advertising companies while going about their normal activities. Others use Tor because it's their only way to get past restrictive local firewalls. Some Tor users may be legitimately connecting to your service right now to carry on normal activities. You need to decide whether banning the Tor network is worth losing the contributions of these users, as well as potential future legitimate users. (Often people don't have a good measure of how many polite Tor users are connecting to their service — you never notice them until there's an impolite one.)

At this point, you should also ask yourself what you do about other services that aggregate many users behind a few IP addresses. Tor is not so different from AOL in this respect.

Lastly, please remember that Tor relays have individual exit policies. Many Tor relays do not allow exiting connections at all. Many of those that do allow some exit connections might already disallow connections to your service. When you go about banning nodes, you should parse the exit policies and only block the ones that allow these connections; and you should keep in mind that exit policies can change (as well as the overall list of nodes in the network).

If you really want to do this, we provide a Tor exit relay list or a DNS-based list you can query.

(Some system administrators block ranges of IP addresses because of official policy or some abuse pattern, but some have also asked about allowing Tor exit relays because they want to permit access to their systems only using Tor. These scripts are usable for allowlisting as well.)

There is nothing the Tor developers can do to trace Tor users. The same protections that keep bad people from breaking Tor's anonymity also prevent us from figuring out what's going on.

Some fans have suggested that we redesign Tor to include a backdoor. There are two problems with this idea. First, it technically weakens the system too far. Having a central way to link users to their activities is a gaping hole for all sorts of attackers; and the policy mechanisms needed to ensure correct handling of this responsibility are enormous and unsolved. Second, the bad people aren't going to get caught by this anyway, since they will use other means to ensure their anonymity (identity theft, compromising computers and using them as bounce points, etc).

This ultimately means that it is the responsibility of site owners to protect themselves against compromise and security issues that can come from anywhere. This is just part of signing up for the benefits of the Internet. You must be prepared to secure yourself against the bad elements, wherever they may come from. Tracking and increased surveillance are not the answer to preventing abuse.

But remember that this doesn't mean that Tor is invulnerable. Traditional police techniques can still be very effective against Tor, such as investigating means, motive, and opportunity, interviewing suspects, writing style analysis, technical analysis of the content itself, sting operations, keyboard taps, and other physical investigations. The Tor Project is also happy to work with everyone including law enforcement groups to train them how to use the Tor software to safely conduct investigations or anonymized activities online.

The Tor Project does not host, control, nor have the ability to discover the owner or location of a .onion address. The .onion address is an address from an onion service. The name you see ending in .onion is an onion service descriptor. It's an automatically generated name which can be located on any Tor relay or client anywhere on the Internet. Onion services are designed to protect both the user and service provider from discovering who they are and where they are from. The design of onion services means the owner and location of the .onion site is hidden even from us.

But remember that this doesn't mean that onion services are invulnerable. Traditional police techniques can still be very effective against them, such as interviewing suspects, writing style analysis, technical analysis of the content itself, sting operations, keyboard taps, and other physical investigations.

If you have a complaint about child abuse materials, you may wish to report it to the National Center for Missing and Exploited Children, which serves as a national coordination point for investigation of child pornography: http://www.missingkids.com/. We do not view links you report.

We take abuse seriously. Activists and law enforcement use Tor to investigate abuse and help support survivors. We work with them to help them understand how Tor can help their work. In some cases, technological mistakes are being made and we help to correct them. Because some people in survivors' communities embrace stigma instead of compassion, seeking support from fellow victims requires privacy-preserving technology.

Our refusal to build backdoors and censorship into Tor is not because of a lack of concern. We refuse to weaken Tor because it would harm efforts to combat child abuse and human trafficking in the physical world, while removing safe spaces for victims online. Meanwhile, criminals would still have access to botnets, stolen phones, hacked hosting accounts, the postal system, couriers, corrupt officials, and whatever technology emerges to trade content. They are early adopters of technology. In the face of this, it is dangerous for policymakers to assume that blocking and filtering is sufficient. We are more interested in helping efforts to halt and prevent child abuse than helping politicians score points with constituents by hiding it. The role of corruption is especially troubling; see this United Nations report on The Role of Corruption in Trafficking in Persons.

Finally, it is important to consider the world that children will encounter as adults when enacting policy in their name. Will they thank us if they are unable to voice their opinions safely as adults? What if they are trying to expose a failure of the state to protect other children?