What is Hyphanet?

Hyphanet is a platform for censorship-resistant communication and publishing. It is designed to ensure true freedom of communication over the Internet. It allows anybody to publish and read information with complete anonymity. Nobody controls Hyphanet, not even its creators, meaning that the system is not vulnerable to manipulation or shutdown. Hyphanet is also very efficient in how it deals with information, adaptively replicating content in response to demand. For more information, see What is Hyphanet?

How is Hyphanet different to Tor? Can I access Google/Facebook/etc through Hyphanet?

Hyphanet is a self-contained network, while Tor allows accessing the web anonymously, as well as using "hidden services" (anonymous web servers). Hyphanet is not a proxy: You cannot connect to services like Google or Facebook using Hyphanet. However, Hyphanet has websites, filesharing, forums, chat, microblogging, email etc, all anonymous and hosted within Hyphanet.

Hyphanet is a distributed datastore, so once content is uploaded to Hyphanet, it will remain on Hyphanet forever, as long as it remains popular, without fear of censorship or denial of service attacks, and without needing to run your own web server and keep it online constantly.

The other big difference is that Hyphanet has the "darknet" or Friend to Friend mode, where your Hyphanet node (software on your computer) only connects to the Hyphanet nodes run by your friends, i.e. people you know (and maybe to their friends, to speed things up). This makes blocking Hyphanet, e.g. on a national firewall, extremely difficult.

However, most people currently use Hyphanet in "opennet" mode (that is, connecting automatically to whoever the network assigns, rather than connecting only to their friends). This is much less secure than using Hyphanet in "darknet" mode, and is relatively easy to block, as it does have some central servers ("seed nodes").

Hyphanet has many unsolved problems, and is still experimental. Our objective for Hyphanet is to build a global friend-to-friend darknet, which would be extremely difficult to block, and would provide very strong anonymity and censorship resistance. This will require further work on Hyphanet, on usability, speed and security, but above all it is a techno-social experiment: Will people know enough friends who are willing to use Hyphanet to make such an anonymous friend-to-friend network possible? This is why Hyphanet supports "opennet" mode: to let people try it out before they ask their friends to connect.

Tor is a little less experimental, and arguably is an easier problem; it may provide better anonymity today, provided that it isn't blocked, and of course, Tor lets you access the internet as a whole, whereas on Hyphanet you can only access Hyphanet content. However if you can use a large enough darknet, Hyphanet already provides an interesting level of censorship resistance, DoS resistance and anonymity.

Using the internet "anonymously" is not necessarily easy: Connecting to Facebook through Tor doesn't prevent Facebook from knowing pretty much everything about you, and connecting to your (non-HTTPS) webmail account through Tor may mean the person running the proxy ("exit node") can steal your webmail account password.

Hyphanet is a separate network, which does things differently, because there are no central servers. This is why we don't support Javascript, server-side scripting etc on freesites: Everything must be rewritten to work on a distributed network. But the advantage is there is no single server which can be compelled to hand over your private communications or which can be shut down.

There are still risks, for example, talking about your home town or internet provider on an anonymous forum, or downloading files which Hyphanet can't make safe such as PDFs or word processor documents (Hyphanet will warn you about this). Also, for web content in particular, it may be easier to upload it to Hyphanet than set up a hidden server on Tor; you don't need to keep your node online for your content to be available, you don't need to figure out how to configure it safely, and most important, if you go away your site will still be available.


Tor (or I2P):

Hyphanet in general:

Hyphanet in darknet mode: (friend to friend: connects only to your friends' nodes)

Hyphanet in opennet mode: (connect automatically even if you don't know anyone on Hyphanet)

Unfortunately most people use Hyphanet in opennet mode currently. The big question is can we build a global friend-to-friend darknet? Join us and find out!

PS for an example of how dependant Tor is on centralised hidden services, see this bust. Half the hidden services on Tor were using a single hosting service, whose owner has now been arrested. While we don't approve of these sites, it does illustrate the point: A centralised network is a vulnerable network. Unfortunately, decentralised networks are hard, but in the long run they are more secure.

Who is behind Hyphanet?

Hyphanet grew out of a design for an anonymous publication system created by Ian Clarke while a student at the University of Edinburgh, Scotland. Since then many other people have contributed towards making Ian's proposal a reality.

If authors are anonymous how can you trust information?

Cryptographic signing of information allows people to prove authorship, this technique is frequently used to authenticate authorship of emails. Moreover, you can actually sign information while remaining anonymous, thus having an anonymous persona. You can prove that you wrote different pieces of information on Hyphanet, without revealing your identity. In this way you can build up an anonymous reputation for reliability.

Do I have to donate disk space and bandwidth?

You aren't really donating in the sense that you lose the disk space and the bandwidth; but you aren't really sharing either (at least not the same way as with filesharing programs). It is more like pitching in to the common Hyphanet resource pool.

I don't have to donate anything when using filesharing application X and I get to leech more.

Do you get to do that anonymously? Hyphanet is designed with anonymity in mind, performance comes second.

All my friends donate very little space and bandwidth. Should I donate more?

If you are happy with what you are getting then no. But if you want more you should consider donating more and running your node as close to 24x7 as possible, and you should ask your friends to do the same.

If I donate a lot will my experience improve significantly?

Your experience will definitely get better, but for a really great improvement we need more people to start thinking like you. Bandwidth counts more than diskspace.

We don't currently know of any prosecutions for merely using Hyphanet. Some people claim that the DADVSI makes Hyphanet illegal in France; the German data retention law might have required logging, but was struck down. Also, the German supreme court has found that not securing your wifi properly makes you responsible for other people's downloads over it; this might or might not be extended to prohibiting anonymous peer to peer filesharing such as Hyphanet. ACTA might have wide-ranging effects, including on Hyphanet, should it pass, and similar laws such as IPRED2 have been tried in the past. There have also been attempts to force peer to peer systems to provide wiretapping capabilities in the USA, and there are worrying developments in the UK that might result in it being blocked, but not being made illegal per se. As far as we know none of these things - apart from the first two - have passed. Many of these are arguable either way (depending on how broadly the legislation is applied) and will have to be decided in caselaw. The law can be an ass sometimes. You can read the EFF's (US-centric) advice to peer to peer developers here. If you need legal advice, talk to a lawyer. Also read the next section especially if you are in China; blocking the protocol may suggest the authorities don't like us!

Is Hyphanet blocked by national firewalls?

The Chinese national firewall (Golden Shield) has blocked our website for many years, and was observed in 2005 to block the 0.5 protocol as well. This suggests China doesn't like us, so be careful if you run Hyphanet in China. Some other countries (e.g. France) are known to be hostile to peer to peer, and may eventually force ISPs to block peer to peer networks (but right now Hyphanet works fine in France and we have many French users!).

Technically, Hyphanet 0.7 has some minimal defences against blocking; the protocol is relatively hard to identify (we are working on "transport plugins", which would make it much harder to detect Hyphanet. Hyphanet supports a darknet mode (i.e. only connecting to your friends) which makes automated harvesting and blocking of nodes very difficult. Note that many mobile internet providers block all peer to peer networks along with other content, and many corporate or academic networks may block Hyphanet (but even if they don't, see you shouldn't run Hyphanet at work for non-work purposes!).

There has been discussion in the US and UK of legislation to require backdoors and presumably blocking of anything that can't be backdoored. This is unlikely to pass, especially in the US, where similar laws have been proposed periodically and are probably unconstitutional. However, even if the government came to us and demanded a back door, we would be legally unable to secretly distribute a trojan'ed build, because Hyphanet is open source, numerous people have contributed code to it, so legally we have to give you the source code, including that for any government mandated back doors - which wouldn't be secret for long! If this happened it is likely that Hyphanet Project Incorporated, the non-profit organisation that runs this website and handles donations, would shut down, but the Hyphanet network itself would live on just fine, the only difference being not being able to pay full time developers as easily.

See net neutrality and the EFF or equivalent organisations in your country for the politics of all this and how you can stop such laws.

Can I get trouble if I run a node?

This is related to "Is Hyphanet legal?". We have done everything we can to make it extremely difficult for any sane legal system to justify punishing someone for running a Hyphanet node, and there is little precedent for such action in today's developed countries. Many legal systems recognize the importance of freedom of speech, which is Hyphanet's core goal. Having said that, there is risk in doing anything that your government might not agree with; you should make an informed decision as to whether to take that risk. Furthermore, your ISP or hosting provider may have a problem with Hyphanet. At least one French hosting provider has been known to ban Hyphanet ( along with Tor and others) from their servers; please read your terms and conditions to make sure you are allowed to run Hyphanet. Note also that Hyphanet can use rather a lot of bandwidth, at least 20GB/month, and this may be a problem on a cheap or shared connection. And of course running it at work could get you into trouble too, unless it's for work purposes!

There are some excellent thoughts on this subject on the Philosophy page. Specific copyright-related laws may be a problem, please read Is Hyphanet legal? and Is Hyphanet blocked by national firewalls?.

What about child porn, offensive content or terrorism?

While most people wish that child pornography and terrorism did not exist, humanity should not be deprived of their freedom to communicate just because of how a very small number of people might use that freedom.

I don't want my node to be used to harbor child porn, offensive content, or terrorism. What can I do?

This is a problem that sadly any censorship-resistance tool faces. If the capacity to remove content existed, it might only be used to remove things one finds offensive, but it could be used to remove anything. From a technological point of view one cannot have censorship-resistance with exceptions. Hyphanet is merely a tool that by itself doesn't do anything to promote offensive content. How people choose to use the tool is their sole responsibility. As a communication medium, Hyphanet cannot be considered responsible for what people use it for — just like Internet Service Providers, telecoms, or postal services cannot be held responsible for their users either.

Note that files are encrypted and split into pieces. They are not stored on your machine in their entirety. Your instance of Hyphanet will likely have very few encrypted pieces of a given file, if any. These pieces cannot be used as parts of the file they were made from without additional information. Reassembling a file requires knowing both what pieces to use and the key to decrypt them, neither of which is included with each piece.

How about encryption export restrictions?

The Hyphanet Project has notified the US authorities that it will be exporting crypto. As long as your country doesn't prohibit the use of encryption you are fine. Further, there is now an exception in the export laws for software doing exactly what Hyphanet does! However, Oracle limits the encryption strength available on the JVM that runs Hyphanet; you should install the Unlimited Strength Policy Files for Java if possible to improve performance. Hyphanet will however work even without this, by using its built-in encryption code.

I have nothing to hide and don't need anonymity. Is there anything else Hyphanet can offer?

Yes, in fact even without the anonymity feature Hyphanet is very useful because of the unique way it handles content distribution and information load. In simple terms that means you can publish a website without worrying about how big the site will be and without having to put someone else's ad banners on it. While it is unlikely that freesites will ever load faster than regular websites, they do adapt to sudden surges of visitors better ( which often happen when relatively unknown sites get linked to from a big site), and reasonable download speeds for big files are feasible too. Just don't expect very low latency.


How do I use this software? I downloaded it, but when I run it there's no GUI.

Fred (the Hyphanet REference Daemon) runs as a daemon, or service, in the background. You normally talk to it through a Hyphanet client. One built-in client is fproxy, which lets you talk to Hyphanet with a web browser. Hyphanet should have installed a Browse Hyphanet shortcut on the desktop and/or the start menu, or a system tray icon (rabbit) with an Open Hyphanet menu item. Failing that, point your web browser to for the gateway page. Try clicking the various links in the bookmark list to reach an initial set of sites.

Why is Hyphanet so slow?

When you first install Hyphanet, it will be slow, and you may see Data Not Found or Route Not Found errors for freesites. This is normal, and Hyphanet will speed up significantly over time. For best performance you should try to run Hyphanet as close to 24 hours a day as possible. This is why we install Hyphanet as a service.

Please bear in mind that Hyphanet is inherently high latency: it can take a while to (for example) load a page for the first time, even if it is capable of reasonable speeds (as anonymous systems go!) for large popular files. You can also improve performance for freesite browsing by using a separate browser and increasing its connection limit. You should also set the datastore size and bandwidth limit as high as possible. But protecting your anonymity does cost a certain amount of performance. You can configure how much to a degree by changing the security levels on the page under Configuration.

Is Hyphanet searchable?

Yes, there are a few different search mechanisms. To search the Hyphanet web (freesites), you should be able to just use the search box on the homepage, or go to Search Hyphanet on the Browse submenu. If it's not there, go to the Plugins page under Configuration, and load the Library plugin. Alternatively, Frost and Thaw also provide searching for messages and files. Note that searching on Hyphanet is a good deal more difficult than on other networks because of Hyphanet's different architecture and design goals.

How do I get Hyphanet working with a Firewall/NAT?

Mostly, Hyphanet should just work with a NAT. However, you should forward the ports manually if you can. Click on the Connectivity page. At the top you will see a list of ports used by the node. You should forward (for UDP) the Darknet FNP and Opennet FNP ports. You may need to look up your router's documentation to figure out how to do this. Hyphanet should have forwarded them itself through Universal Plug and Play, but this doesn't always work (and it never works if you don't have the UPnP plugin loaded, or have one router behind another).

If you have a dyndns address or other domain name pointing to the computer you run your Hyphanet node on, tell the node about it. Go to the core settings config page (in advanced mode), and find the option "IP address override". Put your domain name in that box, and apply the settings.

Do I need a permanent Internet connection to run a node?

No, but it is preferred. You can run the software and test it from a "transient" connection (e.g. dial up/mobile modem), but for the network as a whole to be most useful, we will need as many permanent nodes as possible ( most cable modem or DSL setups are sufficiently "permanent" for this). A later version of Hyphanet may take better advantage of transient nodes.

Why does Hyphanet only download 1 or 2 files at a time?

Many browsers limit the number of simultaneous connections to something far too low for efficiently browsing Hyphanet (since Hyphanet pages often have much higher latency than web pages). This can usually be reconfigured. For example, for Mozilla Firefox, type about:config in the address field of the browser and replace the value of the following settings to the one stated. Filter on "connections" to get only the relevant settings:

network.http.max-connections 200  
network.http.max-connections-per-server 200  
network.http.max-persistent-connections-per-proxy 200  
network.http.max-persistent-connections-per-server 200

Note that these settings will cause mozilla to use more connections for all your browsing, which may not be desirable from a network congestion point of view. But you should ideally be using a separate browser for Hyphanet anyway, for best security.

Why can't Hyphanet store data permanently?

Because we can't find a way to do this without compromising Hyphanet's other goals. For example, people often suggest that someone's node could just never drop data they want to cache permanently. This, however, won't work because even if the data is still available on their node, there is no way to ensure that requests for that data will be routed to that node. We have considered many other ways that Hyphanet could store data permanently, but they either won't work, or compromise Hyphanet's core goals of anonymity, and scalability.

Content which is popular should persist indefinitely, for example most freesites linked from the main indexes are still retrievable years later (at least their front pages are). If the content isn't very popular the best way to keep it available is to regularly re-insert (re-upload) it. An interesting option is the "Keepalive" plugin, which will do this for you - even if you didn't upload the file/site in the first place. Improvements are planned, such as a special kind of request that allows us to probe whether a file is available from a random point on the network.

Why is Hyphanet implemented in Java?

Opinions differ about the choice of Java for the reference implementation of Hyphanet (even among the core developers). Ian Clarke and several other developers are Java proponents and the choice for Java was made. Even if everybody could be convinced to switch to a different language reimplementing the current Hyphanet protocol would be quite a big task, and take up a significant amount of time, while there is only a limited amount of developer-time available. Flame wars on the development list about the language choice aren't welcome, people willing to implement Hyphanet in other languages however are very much encouraged to try. Don't underestimate the amount of work however.

How do I allow connections to FProxy from other computers?

If you want everyone to be able to use your node you have the following options:

In both cases change the following parameters:


Of course, this leaves your node wide open, unless you control access with a firewall of some sort. If you'd prefer to use access controls within Hyphanet, then you can use lines like this:


Or even (find your IP address from ipconfig/ifconfig/winipcfg and substitute it for


And if you want to grant full access (i.e. change config settings, restart, etc) to the node (WARNING: Be very careful who you give full fproxy access to!):


What's new? Is there a changelog?

On every new build, a brief summary of all the main changes is posted to the support and devl lists and the eng.freenet board on Freetalk. This is usually relayed to FMS and Frost too. Alternatively, for a much more detailed view, check out the git repositories. Also, you should check the developer blogs (from the default bookmarks, or over the web, e.g. toad), but be warned they are often not regularly updated and frequently go off on rants on unrelated topics!

Why are there so many messages in my logfile with a backtrace attached?

Hyphanet logs messages excessively during normal operation. It's something we're aware of and are working on.

I have Kaspersky anti-virus, and Hyphanet doesn't install, or shows "Download/upload queue database corrupted!"

Kaspersky can be a problem with Hyphanet. See here. We recommend you turn off Kaspersky during install and during node startup, and exclude the directory you installed Hyphanet in (most likely C:\Program Files\Hyphanet or C:\Program Files (x86)\Hyphanet).

I set a password and now I forgot it, what can I do?

The password protects your downloads and uploads and the client-cache (cache of what you've recently browsed on Hyphanet). It is stored in the file master.keys. There is no way to recover the password, but if you forget it you can wipe your downloads and uploads and the client cache by securely deleting the file master.keys. See the question on private data and local security for more information.

Hyphanet keeps complaining about clock skew

Hyphanet will have problems if your clock is constantly being rewound. Usually this happens when something is resetting your clock regularly in big jumps. On Linux, you should run ntpd to make sure your clock isn't too far off (this isn't vital but it's helpful), but if you see clock skew errors, try adding the -x option to it to avoid big backwards jumps. Also, running ntpdate on startup so there is one big jump before Hyphanet starts is a good idea. This can also happen on Windows sometimes, let us know how you managed to fix it ... generally it's not all that serious though, especially if big jumps in the clock are only once a day.


If I publish something in Hyphanet, how will people find it? Don't they have to know the key I used?

Yes, people will have to know what key you used to publish your information. This means you will have to announce your key in some way.

The most common way to do this is to send a message, containing your key and brief description of your information, to the author of one of the existing Hyphanet sites. Most of the "portal" sites which are linked from the Hyphanet web interface (fproxy) read the Freetalk or FMS forums, and there are boards specifically for announcing sites (usually the boards are called "sites"!). You could also send your key to people by using the Hyphanet mailing lists, in the IRC channel ( #freenet), by private e-mail, or by advertising your Hyphanet site on your World Wide Web site. If you're feeling extravagant, you could even try skywriting it. (Graffiti is not recommended, for legal reasons.)

How do I publish a Content Hash Key (CHK)?

A Content Hash Key is based on the actual content contained within it - and as such, the key will only be known after it has been inserted into Hyphanet. To insert a CHK, simply insert it as "CHK@", Hyphanet will tell you what the actual CHK is once the insertion completes.

Can Hyphanet documents be updated / deleted?

Currently, a document posted to freenet with the same name as one already present may actually serve to propagate the existing document. there is also currently no means of deleting a document from freenet. documents that are never requested are eventually removed through disuse.

however, you can use an updatable subspace key (usk) to provide a form of updatable freesite: your node will automatically look for later editions of the site (after you visit it, or always if you bookmark it), and show you the latest version. you can force it to search for the latest version by changing the number at the end of the key to negative.


I have this great idea...

Good! First step: read the mailing list archives. Odds are good that someone else had the same idea and discussed it with the group. Either a flaw was found in the idea, or perhaps it was decided to postpone implementing the idea until later. Some examples of ideas already discussed are storing information by content hash, key redirection, signed keys/data, use of UDP, server discovery, URLs, document versioning, and others. If you don't see the idea discussed in the archives, by all means bring it up in the appropriate mailing list.

Can I contribute to the Hyphanet Project?

Absolutely. Even if you don't have the time or skills to become a co-developer of the project, you can contribute in other ways:

If you are a developer, you can help by working on Hyphanet itself, or by creating other applications to run on Hyphanet. External applications (such as FMS, the main forums system used on Hyphanet) use the Hyphanet Client Protocol to talk to Fred. Another possibility is writing plugins - these are written in Java and run in Hyphanet's JVM, and can be bundled with Hyphanet when they are ready. A popular plugin is Sone, which is a microblogging/social app over Hyphanet. You can see how to install FMS and Sone on e.g. the Hyphanet Social Networking Guide freesite.

If you want to work on Hyphanet itself, see:

Improvements to this website, fixes for spelling/grammar mistakes, new ideas (see the previous answer), are all welcome. You may find the wiki helpful.

If you have any questions about contributing, please contact us, via the developers mailing list, the chat channel, the support mailing list or anonymously via the freenet board on FMS.

Last but not least you can donate to support our paid developer(s) and cover server costs.

How can I access the code and website?

See our GitHub repository.

What tools do I need to help develop?

Building Hyphanet requires JDK 1.8 or later. You can download the source tarballs on the download page for a specific build, or use git to get an up to date copy of the source, see here for details. Further instructions for building and deploying the server are included with the code itself. Generally speaking, joining our IRC channel is a good idea: #freenet on

Is there a Help Site that goes deeper into the questions newbies may have about Hyphanet, and where people can contribute too?

Have a look at our wiki. An older wiki, which is now read-only, but has a fair amount of content so is sometimes helpful is here. There are also several implementations of wiki's over Hyphanet. The most recent one is called Jfniki. There is a link in the default bookmarks on the Browse Hyphanet page after you install Hyphanet.

Where can I report bugs?

You can use our bug tracking system hosted by MantisHub or send a mail to our support mailing list.

I'm a theoretical computer scientist/mathematician, how can I help?

See here.


Can I use my regular browser to browse Hyphanet?

Hyphanet has a web interface: much of the content on Hyphanet is in the form of "freesites", and downloads, configuration and friend connections can be managed from the web interface. However, because of weaknesses in current browsers, we strongly recommend that you use a separate browser for Hyphanet. Specifically, browser history stealing, in all its forms, is a major threat if you share a browser between Hyphanet and the WWW at large: malicious web pages will be able to probe which freesites you have visited, and report this information to their owners.

Privacy/incognito mode may be sufficient, and Windows tray app will start a browser running in this mode.

Won't attack X break Hyphanet's anonymity?

Short answer: Probably, on opennet. Maybe, on darknet.

Long answer:

Hyphanet has a different threat model to Tor and the Mixmaster remailers. Hyphanet is designed to resist censorship: The network must therefore be robust, and content must be distributed without requiring a central server, whether anonymous or not. Anonymity is important for requesters and especially for those who upload content in the first place. The typical example is a corporate or government whistleblower. Generally to find the originator of some content, the attacker must be able to predict the data in advance, must be able to move across the network relatively quickly, and must be able to perform the attack while the data is being inserted; after that, it is distributed across the network and is much harder to trace, and the originator may have left the network. However, if by chance or by overwhelming force the attacker is connected to the whistleblower (or e.g. seizes the computers of everyone on the network), he may be able to identify this much more quickly. All of this is vastly more difficult on a darknet, where everyone connects only to their friends, where it is very hard for an attacker to find nodes, and where to connect to a given node he must social engineer its operator! Hyphanet does support opennet mode (plug and play), but darknet is far more secure, and far more difficult to block on a national firewall.

Tor on the other hand is designed to anonymise real-time data streams, on the assumption that the list of nodes can be public, that there is a free world where nodes can be operated safely, that the authors of controversial content will be able to either host (hidden) web servers themselves or upload it to other (hidden, but usually centralised) storage systems, and so on. And Tor has a concept of a "client", which is somebody who uses the service without providing any value to it; on Hyphanet, every node relays data for its neighbours. Hence the attacks on Hyphanet are completely different to the attacks on Tor. Both compromise to some degree to enable more or less real-time performance.

If you can use the darknet, trust your friends, don't reinsert files, always use the "Insert a random, safe key" option, and change your anonymous identity after some volume of inserts, you should be relatively safe using Hyphanet. However this has not yet been quantified. If you can connect, build up some trust in your anonymous persona, insert your controversial content, and then disappear, again, you are better off with Hyphanet, especially if the content is a website (but if you are connecting on opennet, beware of seednode compromises). In some other cases, Tor is better.

We are still working on Hyphanet's security and there are major security enhancements which have not yet been implemented, most of which will go in before 1.0. Cryptographic tunnels similar to Tor's onion routing are one possibility, which would greatly reduce the impact of many of the below attacks, but there are several other enhancements planned, both to anonymity and to network robustness/undetectability.

Major known attacks:

In the interests of giving would-be users as much information as possible, and on the assumption that any serious attacker would do their homework, here are the major classes of attack on Hyphanet we are presently aware of:

More information on the current practical state of Hyphanet security is available here.

Is Hyphanet vulnerable to flooding attacks?

Short answer: no.

Long answer:

We don't think so. Aside from protecting freedom of speech, Hyphanet is also designed to be an efficient dynamic caching system. If information is requested a lot from a limited number of nodes, the nodes that the requests pass through will cache the information, lowering the load on the network. If information is inserted on a limited set of nodes and then subsequently requested a lot from a separate set of nodes, with repetition, the sets will close in on one another in the network topology until they are "neighbors" and only the originally targeted nodes are suffering from the attack.

In other words, in order to harm Hyphanet with a flood you need to consistently change your point of entry into the network and continually insert and request new data, and you will still only increase the workload for the network that is linear to your own. Given an immense will and capacity greater than the total of the entire network, it is possible to cripple any public network (including the Internet itself) with floods, but it is our intention to always keep Hyphanet as resistant to this as theoretically possible.

Curiously enough, the above analysis only applies to Opennet. On Darknet, you might have a little more success, although it would be much harder to change your entry point in any significant way. Nonetheless, you have a reasonably low bandwidth multiplier (the total number of nodes visited, around 20 on average), and you are severely limited by the number of nodes you can connect to, which will be low on a darknet.

Why hash keys and encrypt data when a node operator could identify them (the data) anyway if he tried?

Hashing the key and encrypting the data is not meant a method to keep Hyphanet Node operators from being able to figure out what type of information is in their nodes if they really want to (after all, they can just find the key in the same way as someone who requests the information would) but rather to keep operators from having to know what information is in their nodes if they don't want to. This distinction is more a legal one than a technical one. It is not realistic to expect a node operator to try to continually collect and/ or guess possible keys and then check them against the information in his node (even if such an attack is viable from a security perspective), so a sane society is less likely to hold an operator liable for such information on the network.

What about hostile "cancer" nodes within the network?

The existence of malicious nodes within the network is the most difficult problem that a distributed network must face, and has been the bane of many previous ideas. Many systems (such as multiplayer gaming networks) try to avoid malicious nodes by keeping the protocol and code closed, but we have yet to see an example of that working in the long run. And anyway it is opposed to Hyphanet's philosophy.

Hyphanet is based on a balance of positive and negative feedback loops that bring requests for information to a node when it is functioning well, and keep requests away from it when it is not. The key to avoiding "cancers" is (as in the body) to make sure these loops can correctly identify even the most carefully designed malicious node and not keep sending requests to it. This issue is not fully dealt with by the current test code, but you can rest assured that a number of possible solutions have been on the table and discussed for some time now. Several have been implemented (enforcing hashes or signatures on content, per node failure tables, backing off from a node that causes timeouts ...)

What about attack Y?

Hyphanet is still in testing and there are bound to be attacks found that we have not dealt with yet. So if you do manage to figure out a truly new kind of attack, we are interested in hearing about it. Please keep in mind what Hyphanet is and what it is not, however. No single network can offer everybody everything, and there are security issues that Hyphanet, by its nature, may not deal with to extent you might wish. If this upsets you, all of our code is freely available, so you are free to take as much of it as you like and write your own distributed network that suits your desires.

What private data does Hyphanet store? How do I get rid of it? How can I secure my computer so I am safe when running Hyphanet?

First of all, we strongly suggest that you install Hyphanet inside an encrypted drive using, for example, Veracrypt. It is not possible for Hyphanet to prevent all leaks of private data, especially if you download media files etc. Even if you only browse freesites and use the chat plugins, there will still be potentially incriminating data in your swapfile, which needs to be encrypted (on recent versions of Windows you could try the command "fsutil behavior set encryptpagingfile 1", but really the solution is to encrypt your whole system including swap). It is also essential that you use your web browser in privacy mode, or with cache and history turned off; we try to do this if you launch Hyphanet via the rabbit icon, but there are no guarantees as unfortunately this functionality seems buggy in current web browsers. Browser plugins could also be a problem, and you should use a separate browser for Hyphanet if in any doubt. Be careful with the files you download from Hyphanet - not only could anyone seizing your computer see you have them (media files are likely to be written to disk even if you open them directly in your web browser and never save them), but also they could contain threats to anonymity themselves, such as calling back to a malicious website etc; this is possible in for instance PDFs and some video formats. Hyphanet tries to warn you about this when it can't filter out such malicious content: Currently it can only filter HTML pages, GIF/PNG/JPEG images and CSS, and MP3s, but we will add support for Ogg soon and other formats later. And of course there are many other threats - you should take standard security precautions, such as not running operating systems that are no longer updated, not running software not from a trustworthy source, using appropriate security software etc (if you have a firewall make sure it allows the two UDP ports Hyphanet needs through).

Because not all users will have installed encrypted drives at the time when they first install Hyphanet, Hyphanet itself attempts to encrypt all the potentially incriminating data that it stores on disk. Details are below but as explained, leaks are inevitable: you really should encrypt your disks!

The main datastore does not store data you request or insert (or that is requested or inserted by nearby nodes), because it can be probed by other nodes: This was introduced to fix this attack publicised by The Register. Hyphanet has a separate client-cache, which stores data which you have recently requested to avoid having to go back to the network every time (which would not only reduce speed but also security, by giving attackers more opportunities to see your requests). Also, Hyphanet stores the list of your downloads and uploads (which you can see on the Filesharing menu), their current progress, and various other data, in the file node.db4o (or node.db4o.crypt). The actual data is kept in the persistent-temp- directory. Unless you set the physical security level to LOW, this data is encrypted. At MAXIMUM, the encryption keys are never written to disk, so the data is effectively wiped on restarting the node; otherwise the encryption keys are stored in a file called master.keys (on HIGH this is passworded). You can wipe the data by either using the panic button on the downloads/uploads page or by securely deleting master.keys. Hyphanet also creates temporary files for other requests, which are also encrypted unless physical seclevel is LOW, which are in temp-. Also, some plugins may create their own data files, which may contain for instance messages you have posted or downloaded from chat forums, and currently bookmarks and recently completed files are stored in plain text. It is our intention to move these into node.db4o or store them in separate encrypted databases, as soon as we have automatic backups for node.db4o. See here for details on some of the files.

Windows SmartScreen filter warns the Hyphanet installer might put my PC at risk. What's going on?

SmartScreen is sometimes incorrect in classifying a file as dangerous. We believe our installer is not infected with malicious software, and if you are a developer you can check the installer source code here.

Yes. There is one such instance that we know of. United States law enforcement can identify anonymous users of Hyphanet and Tor. Without further information we do not know how they did this, but we suspect it affects people using the network security level "normal" or lower. It is reasonable to assume that other governments have access to the same technology, which is provided by private contractors. If you are concerned about governments, you should use Hyphanet's capacity to connect only to users you trust, ("high" network security level or higher) and bear in mind that no anonymity technology provides perfect protection.

While we applaud law enforcement's apparent success in apprehending suspects allegedly sharing child abuse images, any security flaws they may have used are not limited to such noble usage. Many governments persecute and prosecute political dissidents for legitimate speech published online. Therefore we hope to discover and fix these flaws to protect those who fight for human rights, against corruption, for a peaceful future, and for other legitimate goals.

Additional information sources

Mailing lists

These are the mailing lists that can be used for support or general information about Hyphanet.


Get Support

You can find information about installing Hyphanet in the Wiki especially in the Installing Hyphanet and FAQ.

When Hyphanet is already installed you may get support in FMS forum.

When writing your support request, please make sure you include a full description of the problem, your current version of Java, your operating system and current Hyphanet version.

Chat with us

Many of the developers and users of Hyphanet are on the IRC channel #freenet on

Chat with us