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Table of Contents
Note: This TOC is generated manually as Github does not do it automatically
- What is Freenet?
- How is Freenet different to Tor? Can I access Google/Facebook/etc through Freenet?
- Who is behind Freenet?
- If authors are anonymous how can you trust information?
- I have nothing to hide and don't need anonymity. Is there anything else Freenet can offer?
- Do I have to donate disk space and bandwidth?
- I don't have to donate anything when using filesharing application X and I get to leech more.
- All my friends donate very little space and bandwidth. Should I donate more?
- If I donate a lot will my experience improve significantly?
- What is FProxy? What is Fred?
- How do I use this software? I downloaded it, but when I run it there's no GUI.
- What's new? Is there a changelog?
- Why is Freenet so slow?
- Is Freenet searchable?
- Why does Freenet only download 1 or 2 files at a time?
- How do I allow connections to FProxy from other computers?
- Why are there so many messages in my logfile with a backtrace attached?
- I have Kaspersky anti-virus, and Freenet doesn't install, or shows "Download/upload queue database corrupted!"
- I set a password and now I forgot it, what can I do?
- Freenet keeps complaining about clock skew
- Windows SmartScreen filter warns the Freenet installer might put my PC at risk. What's going on?
- Publishing on Freenet
Legal and liability questions
- Is Freenet legal?
- Can I get trouble if I run a node?
- Has anyone ever faced legal trouble for their anonymous activities conducted on Freenet?
- What about copyright?
- What about child porn, offensive content or terrorism?
- How about encryption export restrictions?
- I don't want my node to be used to harbor child porn, offensive content, or terrorism. What can I do?
- Connecting to the network
- Can I use my regular browser to browse Freenet?
- Won't attack X break Freenet's anonymity?
- Is Freenet vulnerable to flooding attacks?
- Why hash keys and encrypt data when a node operator could identify them (the data) anyway if he tried?
- What about hostile "cancer" nodes within the network?
- What about attack Y?
- What private data does Freenet store? How do I get rid of it? How can I secure my computer so I am safe when running Freenet?
- I have this great idea....
- Can I contribute to the Freenet Project?
- How can I access the code and website?
- What tools do I need to help develop?
- Is there a Help Site that goes deeper into the questions newbies may have about Freenet, and where people can contribute too?
- Where can I report bugs?
- I'm a theoretical computer scientist/mathematician, how can I help?
- Technical details
What is Freenet?
Freenet 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 Freenet, not even its creators, meaning that the system is not vulnerable to manipulation or shutdown. Freenet is also very efficient in how it deals with information, adaptively replicating content in response to demand. For more information, see What is Freenet?
How is Freenet different to Tor? Can I access Google/Facebook/etc through Freenet?
Freenet is a self-contained network, while Tor allows accessing the web anonymously, as well as using "hidden services" (anonymous web servers). Freenet is not a proxy: You cannot connect to services like Google or Facebook using Freenet. However, Freenet has websites, filesharing, forums, chat, microblogging, email etc, all anonymous and hosted within Freenet.
Freenet is a distributed datastore, so once content is uploaded to Freenet, it will remain on Freenet 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 Freenet has the "darknet" or Friend to Friend mode, where your Freenet node (software on your computer) only connects to the Freenet nodes run by your friends, i.e. people you know (and maybe to their friends, to speed things up). This makes blocking Freenet, e.g. on a national firewall, extremely difficult.
However, most people currently use Freenet 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 Freenet in "darknet" mode, and is relatively easy to block, as it does have some central servers ("seed nodes").
Freenet has many unsolved problems, and is still experimental. Our objective for Freenet 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 Freenet, on usability, speed and security, but above all it is a techno-social experiment: Will people know enough friends who are willing to use Freenet to make such an anonymous friend-to-friend network possible? This is why Freenet 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 Freenet you can only access Freenet content. However if you can use a large enough darknet, Freenet 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.
There are still risks, for example, talking about your home town or internet provider on an anonymous forum, or downloading files which Freenet can't make safe such as PDFs or word processor documents (Freenet will warn you about this). Also, for web content in particular, it may be easier to upload it to Freenet 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):
- Lets you access the Internet (but be careful!).
- Lets you access anonymous web servers and other services.
- Lets you host anonymous web servers, which need to be kept online, and can be DoS'ed, but can run any dynamic or server-side content you want.
- Provides reasonable anonymity
- Has been blocked by several countries, with varying success. Even its hidden bridges can be harvested and blocked with moderate effort.
- Is somewhat centralised
- Is more mature and has more users and developers
Freenet in general:
- Only lets you access content uploaded to Freenet, including (static) websites, email, filesharing, forums, microblogging, etc. All of which are anonymous (or pseudonymous i.e. you create an untraceable identity).
- Hosts content in a distributed way: You don't know what your node is storing, any given content is distributed across many nodes.
- Ensures that popular content will be available forever.
- Is older than Tor, but more experimental (arguably it's a harder task).
Freenet in darknet mode: (friend to friend: connects only to your friends' nodes)
- Is very hard to block, and this can be improved further with transport plugins.
- Provides good anonymity, and with a bit more work it could provide very strong anonymity (PISCES tunnels).
- Is fully decentralised: No central servers at all.
Freenet in opennet mode: (connect automatically even if you don't know anyone on Freenet)
- Is relatively easy to block.
- Provides limited anonymity
- Is somewhat centralised
Unfortunately most people use Freenet 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 Freenet?
Freenet 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 Freenet, without revealing your identity. In this way you can build up an anonymous reputation for reliability.
I have nothing to hide and don't need anonymity. Is there anything else Freenet can offer?
Yes, in fact even without the anonymity feature Freenet 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.
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 Freenet 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? Freenet 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.
What is FProxy? What is Fred?
Fred is the Freenet REference Daemon. It is the software that runs all Freenet nodes (computers on the Freenet network). FProxy is the part of Fred that provides a web browser interface; it is used both to configure and control Fred, and to view files and freesites that are on Freenet.
How do I use this software? I downloaded it, but when I run it there's no GUI.
Fred (the Freenet REference Daemon) runs as a daemon, or service, in the background. You normally talk to it through a Freenet client. One built-in client is fproxy, which lets you talk to Freenet with a web browser. Freenet should have installed a Browse Freenet shortcut on the desktop and/or the start menu, or a system tray icon (rabbit) with an Open Freenet menu item. Failing that, point your web browser to 2 for the gateway page. Try clicking the various links in the "Freesite subscriptions" panel to reach some of the popular Freenet index sites.
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 is Freenet so slow?
When you first install Freenet, it will be slow, and you may see Data Not Found or Route Not Found errors for freesites. This is normal, and Freenet will speed up significantly over time. For best performance you should try to run Freenet as close to 24 hours a day as possible. This is why we install Freenet as a service.
Please bear in mind that Freenet 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 Freenet searchable?
Yes, there are a few different search mechanisms. To search the Freenet web (freesites), you should be able to just use the search box on the homepage, or go to Search Freenet 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 Freenet is a good deal more difficult than on other networks because of Freenet's different architecture and design goals.
Why does Freenet 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 Freenet (since Freenet 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 Freenet anyway, for best security.
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:
Go to the web interface configuration page and enable advanced mode Stop your node and edit freenet.ini manually
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 Freenet, then you can use lines like this:
Or even (find your IP address from ipconfig/ifconfig/winipcfg and substitute it for 192.168.1.1):
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!):
Why are there so many messages in my logfile with a backtrace attached?
Freenet logs messages excessively during normal operation. It's something we're aware of and are working on.
I have Kaspersky anti-virus, and Freenet doesn't install, or shows "Download/upload queue database corrupted!"
Kaspersky can be a problem with Freenet. See here. We recommend you turn off Kaspersky during install and during node startup, and exclude the directory you installed Freenet in (most likely
C:\Program Files\Freenet or
C:\Program Files (x86)\Freenet).
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 Freenet). 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.
Freenet keeps complaining about clock skew
Freenet 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 Freenet 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.
Windows SmartScreen filter warns the Freenet 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.
Publishing on Freenet
If I publish something in Freenet, 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 Freenet sites. Most of the "portal" sites which are linked from the Freenet 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 Freenet mailing lists, in the IRC channel (chat.freenode.net #freenet), by private e-mail, or by advertising your Freenet 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 Freenet. To insert a CHK, simply insert it as "CHK@", Freenet will tell you what the actual CHK is once the insertion completes.
Can Freenet 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.
Legal and liability questions
Is Freenet legal?
We don't currently know of any prosecutions for merely using Freenet. Some people claim that the DADVSI makes Freenet 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 Freenet. ACTA might have wide-ranging effects, including on Freenet, 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!
Can I get trouble if I run a node?
This is related to "Is Freenet legal?". We have done everything we can to make it extremely difficult for any sane legal system to justify punishing someone for running a Freenet 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 Freenet'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 Freenet. At least one French hosting provider has been known to ban Freenet ( along with Tor and others) from their servers; please read your terms and conditions to make sure you are allowed to run Freenet. Note also that Freenet 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!
Has anyone ever faced legal trouble for their anonymous activities conducted on Freenet?
Yes. There is one such instance that we know of. United States law enforcement can identify anonymous users of Freenet 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 Freenet's capacity to connect only to users you trust, (Darknet, the "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.
What about copyright?
There are some excellent thoughts on this subject on the Philosophy page. Specific copyright-related laws may be a problem, please read Is Freenet legal? and Is Freenet 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.
How about encryption export restrictions?
The Freenet 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 Freenet does! However, Oracle limits the encryption strength available on the JVM that runs Freenet; you should install the Unlimited Strength Policy Files for Java if possible to improve performance. Freenet will however work even without this, by using its built-in encryption code.
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. Freenet 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, Freenet 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 Freenet 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.
Connecting to the network
How do I get Freenet working with a Firewall/NAT?
Mostly, Freenet 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. Freenet 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 Freenet 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 Freenet may take better advantage of transient nodes.
Is Freenet 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 Freenet 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 Freenet works fine in France and we have many French users!).
Technically, Freenet 0.7 has some minimal defenses against blocking; the protocol is relatively hard to identify (we are working on "transport plugins", which would make it much harder to detect Freenet. Freenet 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 Freenet (but even if they don't, see you shouldn't run Freenet 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 Freenet 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 Freenet Project Incorporated, the non-profit organization that runs this website and handles donations, would shut down, but the Freenet network itself would live on just fine, the only difference being not being able to pay full time developers as easily.
What is darknet?
A darknet, for Freenet purposes, is a network where node connections are created manually by the users of the nodes via invitations. These connections should be made on the basis of mutual trust, friendship, or acquaintance. If they are, then the network should have a small world topology and routing will work, especially since darknet peers are more or less permanent. If the connections are made completely at random, then the network topology will be wrong, and routing will not work.
In darknet mode, Freenet uses location swapping to create a routable network. Unlike opennet, darknet connections are outside of the control of the node. However, the underlying social network will have the correct topology, and so will the resultant darknet. Location swapping is used to assign routable location to nodes on the network.
What is opennet?
An opennet, for Freenet purposes, is a network where connections are automatically created by the node. The node comes prepackaged with a list of seed nodes to which the node may connect. Once a connection is established between the node and the seed nodes, the seed nodes provide a list of more nodes to connect to, and they do they same, etc. This process happens continually while the node is running, without any user intervention.
Security: How should I connect to the network?
Though opennet is much easier for the user (compared to creating connections in a darknet), it is vulnerable to harvesting, and therefore can be blocked very easily.
This was a known problem with Freenet 0.5, and it led to it being blocked by the Chinese firewall.
A darknet is not harvestable because your node reference will never be passed on by the network to any other node. Therefore, an attacker running a darknet node can only see those nodes which he has managed to get invitations to connect to.
Consequently, you are vulnerable primarily to the nodes you are connected to. Thus, it is a good idea to only connect to people you trust, if this is possible.
Where is my data stored?
See Program files.
Can I use my regular browser to browse Freenet?
Freenet has a web interface: much of the content on Freenet 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 Freenet. Specifically, browser history stealing, in all its forms, is a major threat if you share a browser between Freenet 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 Freenet's anonymity?
Short answer: Probably, on opennet. Maybe, on darknet.
Freenet has a different threat model to Tor and the Mixmaster remailers. Freenet 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! Freenet 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 Freenet, every node relays data for its neighbours. Hence the attacks on Freenet 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 Freenet. 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 Freenet, 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 Freenet'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 Freenet we are presently aware of:
Simply by running some powerful Freenet nodes, an attacker can identify most of the opennet (Strangers network) relatively easily. These nodes can then be attacked one by one (subject to resources), their traffic analysed, or simply be blocked on a national firewall. Connecting only to friends (darknet) largely solves this problem. ISPs may be able to identify Freenet nodes with some effort, although we make this fairly difficult: Freenet's current protocol is designed to be hard to detect, and steganography will be introduced at some point. However, traffic flow analysis, or brute-force blocking of all peer to peer traffic (e.g. traffic between IP addresses marked as "consumer" rather than "business"), both of which would hit a lot of things other than Freenet, would likely be effective for quite some time.
Unless a node only connects to friends, it will have to connect to the opennet "seednodes" to announce itself and get initial peers to connect to. At the moment there are relatively few seednodes and the list is maintained manually. The seednodes could be blocked easily by a national firewall etc, but also, there is little to prevent attackers from setting up their own seednodes and submitting them, and then "capturing" any new Freenet users who connect to their nodes, in order to observe their traffic etc. Freenet will try to announce to multiple seednodes, but see the below section on "correlation attacks", which generally are feasible with only a single connection to the target. So this is a question of resources - if the attacker has the resources to surveil all new Freenet nodes, he has a good chance of pulling it off. In future we may have more seednodes, and only reveal a small proportion of them to each node, as Tor does with its hidden bridges, but that will not prevent attackers from creating lots of malicious seednodes and getting them into the official lists, and it will likely still be possible to block all the seednodes with some effort (something similar has already happened to Tor hidden bridges in China). Combined with harvesting and adaptive search attacks, this attack explains why opennet is regarded by many core developers as hopelessly insecure. If you want good security you need to connect only to friends. Hit and run inserts are possible, and can be relatively safe in terms of many of the other attacks, but you are taking the risk that the opennet seednode you connect to may be malicious.
If you are connected to a node, and can recognise the keys being requested (probably because it was posted publicly), you can show statistically that the node in question probably requested it, based on the proportion of the keys requested from that node, the locations of nearby nodes, the HTL on the requests and so on. This will be largely eliminated by tunnels (but these will be quite expensive so may need to be turned off by default except for predictable blocks), but in any case it requires a rather powerful attacker compared to the next attack... Note also that if you only connect to your friends, a remote attacker will have to either co-opt your friends or social engineer you into giving them a connection; either way, connecting to the entire network this way is rather expensive: If they already suspect you personally they'll probably bug your keyboard rather than trying to connect to your Freenet node!
If you want to find the author of some content, and you can predict the exact keys which will be inserted, and you are able to connect to new nodes at will, you may be able to listen out for the keys, guess where they must have come from, connect to nodes near there, and if your guess is correct, get more keys which gives you a more accurate fix on the originator, so the attack gets faster and faster and eventually converges on the originator. This attack is most powerful with inserts of big, predictable files, but the "Insert a random, safe key" option will make the keys unpredictable even if the content is guessable, by using random encryption keys. The downside is it produces a different key each time for the same file, and you can never safely reinsert the same file to the same key. Given that Freenet's data persistence is currently relatively poor, this is a problem. Anyway, if you can use the random keys option, the attacker is unable to move towards you until after you announce the file: Most of his samples will come not from the actual content inserts but from chat posts. There are far fewer of these, and changing your pseudonymous identity periodically will help, provided the attacker cannot easily connect the new identity to the old one. Using a dedicated identity for posting sensitive content, which doesn't chat too much, again will help. Another thing which makes a huge difference is connecting only to your friends (i.e. using darknet): This makes it extremely difficult for an attacker to get new connections closer to where he thinks you must be, just as it helps with correlation attacks. So the biggest problems with this attack are 1) Files which are not very popular fall off Freenet relatively quickly, so need to be reinserted, but it is not safe to reinsert to the same key (this is why we have the "Insert a canonical key" option, for those who don't care about attacks), and 2) Chat can still be attacked. Tunnels will help to deal with both problems, and by default will only be used for predictable keys so can be relatively slow without this causing problems in practice. Also there is work going on on various techniques to allow users to do reinserts safely via for example preventing the attacker from seeing requests started before he connected. Another important point is this only works if the source is uploading new content, or chatting, regularly; creating and bootstrapping a new pseudonymous identity over a short period, doing a single insert (of any size) with the safe random key option, and announcing it, should be relatively safe from this attack, even on opennet - but see the section above on bootstrapping attacks.
Freenet provides minimal protection against global traffic analysis (basic message padding etc); if the attacker also has nodes on the network, the extra data will likely be helpful. We certainly do not guarantee that it is impossible to trace data transfers from one node to the next with detailed traffic data, however it is hoped that this will fall down on the busier nodes. One day we will implement steganographic transports and/or constant bitrate links as an option for more paranoid users. Note that on Tor-style networks, global traffic analysis will defeat the network completely: all that is needed is to observe both the entry and exit points.
It is possible to attack the location swapping algorithm, and thereby disrupt routing on friend-to-friend networks. This has been demonstrated by the authors of the Pitch Black paper. We are working on a solution, but sadly at the moment most users use opennet.
More information on the current practical state of Freenet security is available here.
Is Freenet vulnerable to flooding attacks?
Short answer: no.
We don't think so. Aside from protecting freedom of speech, Freenet 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 Freenet 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 Freenet 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 Freenet 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 Freenet's philosophy.
Freenet 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?
Freenet 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 Freenet is and what it is not, however. No single network can offer everybody everything, and there are security issues that Freenet, 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 Freenet store? How do I get rid of it? How can I secure my computer so I am safe when running Freenet?
First of all, we strongly suggest that you install Freenet inside an encrypted drive using, for example, Truecrypt. It is not possible for Freenet 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 Freenet 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 Freenet if in any doubt. Be careful with the files you download from Freenet - 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. Freenet 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 Freenet needs through).
Because not all users will have installed encrypted drives at the time when they first install Freenet, Freenet 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 publicized by The Register. Freenet 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, Freenet 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. Freenet 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.
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 Freenet 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:
- Help test Freenet by installing and configuring the server software on your machine.
- Install the client software on your machine to test retrieving information and publishing your own.
- Work on the Freenet web site (including the FAQ).
- Contribute your ideas to the discussion lists.
- Translate the user interface into another language.
If you are a developer, you can help by working on Freenet itself, or by creating other applications to run on Freenet. External applications (such as FMS, the main forums system used on Freenet) use the Freenet Client Protocol to talk to Fred. Another possibility is writing plugins - these are written in Java and run in Freenet's JVM, and can be bundled with Freenet when they are ready. A popular plugin is Sone, which is a microblogging/social app over Freenet. You can see how to install FMS and Sone on e.g. the Freenet Social Networking Guide freesite.
If you want to work on Freenet itself, see here to get the source code.
Improvements to this website, fixes for spelling/grammar mistakes, new ideas (see the previous answer), are all welcome. You may find the wiki helpful.
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 Freenet requires JDK 1.6 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.
Is there a Help Site that goes deeper into the questions newbies may have about Freenet, 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 Freenet. The most recent one is called Jfniki. There is a link in the default bookmarks on the Browse Freenet page after you install Freenet.
Where can I report bugs?
I'm a theoretical computer scientist/mathematician, how can I help?
Why can't Freenet store data permanently?
Because we can't find a way to do this without compromising Freenet'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 Freenet could store data permanently, but they either won't work, or compromise Freenet'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 Freenet implemented in Java?
Opinions differ about the choice of java for the reference implementation of Freenet (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 Freenet 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 Freenet in other languages however are very much encouraged to try. Don't underestimate the amount of work however.