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118-507: Hyphanet (until mid-2023: Freenet ) is a peer-to-peer platform for censorship -resistant, anonymous communication. It uses a decentralized distributed data store to keep and deliver information, and has a suite of free software for publishing and communicating on the Web without fear of censorship. Both Freenet and some of its associated tools were originally designed by Ian Clarke , who defined Freenet's goal as providing freedom of speech on

236-659: A content-addressable , peer-to-peer method of storing and sharing hypermedia distribution protocol, with nodes in the IPFS network forming a distributed file system . Jami is a peer-to-peer chat and SIP app. JXTA is a peer-to-peer protocol designed for the Java platform . Netsukuku is a Wireless community network designed to be independent from the Internet. Open Garden is a connection-sharing application that shares Internet access with other devices using Wi-Fi or Bluetooth. Resilio Sync

354-493: A heuristic routing algorithm where each node had no fixed location, and routing was based on which node had served a key closest to the key being fetched (in version 0.3) or which is estimated to serve it faster (in version 0.5). In either case, new connections were sometimes added to downstream nodes (i.e. the node that answered the request) when requests succeeded, and old nodes were discarded in least recently used order (or something close to it). Oskar Sandberg's research (during

472-608: A server experiences an increase in load it redirects incoming peers to other peers who have agreed to mirror the content, thus off-loading balance from the server. All of the information is retained at the server. This system makes use of the fact that the bottleneck is most likely in the outgoing bandwidth than the CPU , hence its server-centric design. It assigns peers to other peers who are 'close in IP ' to its neighbors [same prefix range] in an attempt to use locality. If multiple peers are found with

590-489: A small-world structure. Other modifications include switching from TCP to UDP , which allows UDP hole punching along with faster transmission of messages between peers in the network. Freenet 0.7.5, released on 12 June 2009, offers a variety of improvements over 0.7. These include reduced memory usage, faster insert and retrieval of content, significant improvements to the FProxy web interface used for browsing freesites, and

708-545: A virus originating from Winny affected the computer of a co-pilot. Perhaps the largest Winny-related leak was that of the Okayama Prefectural Police Force , whose computer leaked data about around 1,500 investigations. This information included sensitive data such as the names of sex crime victims, and is the largest amount of information held by Japanese police to have ever leaked online. On November 28, 2003, two Japanese users of Winny, Yoshihiro Inoue,

826-552: A 41-year-old self-employed businessman from Takasaki , Gunma Prefecture and an unemployed 19-year-old from Matsuyama , were arrested by the Kyoto Prefectural Police. They were accused of sharing copyrighted material via Winny and admitted to their crimes. Shortly following the two users' arrests, Kaneko also had his home searched and had the source code of Winny confiscated by the Kyoto Police. On May 10, 2004, Kaneko

944-495: A P2P network are more stable and available than files on central networks. In a centralized network, a simple loss of connection between the server and clients can cause a failure, but in P2P networks, the connections between every node must be lost to cause a data-sharing failure. In a centralized system, the administrators are responsible for all data recovery and backups, while in P2P systems, each node requires its backup system. Because of

1062-534: A P2P network requires that at least one node in the network has the requested data, and that node must be able to connect to the node requesting the data. This requirement is occasionally hard to meet because users may delete or stop sharing data at any point. In a P2P network, the community of users is entirely responsible for deciding which content is available. Unpopular files eventually disappear and become unavailable as fewer people share them. Popular files, however, are highly and easily distributed. Popular files on

1180-409: A centralized functionality but benefit from the decentralized aggregation of nodes provided by unstructured networks. CoopNet (Cooperative Networking) was a proposed system for off-loading serving to peers who have recently downloaded content, proposed by computer scientists Venkata N. Padmanabhan and Kunwadee Sripanidkulchai, working at Microsoft Research and Carnegie Mellon University . When

1298-602: A combination of peer-to-peer and client–server models. A common hybrid model is to have a central server that helps peers find each other. Spotify was an example of a hybrid model [until 2014]. There are a variety of hybrid models, all of which make trade-offs between the centralized functionality provided by a structured server/client network and the node equality afforded by the pure peer-to-peer unstructured networks. Currently, hybrid models have better performance than either pure unstructured networks or pure structured networks because certain functions, such as searching, do require

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1416-850: A direct result of the anonymity requirements, the node requesting content does not normally connect directly to the node that has it; instead, the request is routed across several intermediaries, none of which know which node made the request or which one had it. As a result, the total bandwidth required by the network to transfer a file is higher than in other systems, which can result in slower transfers, especially for infrequently accessed content. Since version 0.7, Freenet offers two different levels of security: opennet and darknet. With opennet, users connect to arbitrary other users. With darknet, users connect only to "friends" with whom they previously exchanged public keys , named node-references. Both modes can be used together. Freenet's founders argue that true freedom of speech comes only with true anonymity and that

1534-439: A distributed messaging system that is often described as an early peer-to-peer architecture, was established. It was developed in 1979 as a system that enforces a decentralized model of control. The basic model is a client–server model from the user or client perspective that offers a self-organizing approach to newsgroup servers. However, news servers communicate with one another as peers to propagate Usenet news articles over

1652-448: A few friends using the network to get the performance from having sufficient connections while still receiving some of the security benefits of darknet connections. This also means that small darknets where some users also have opennet connections are fully integrated into the whole Freenet network, allowing all users access to all content, whether they run opennet, darknet, or a hybrid of the two, except for darknet pockets connected only by

1770-668: A given time. Trustworthiness of sources is a potential security threat that can be seen with peer-to-peer systems. A study ordered by the European Union found that illegal downloading may lead to an increase in overall video game sales because newer games charge for extra features or levels. The paper concluded that piracy had a negative financial impact on movies, music, and literature. The study relied on self-reported data about game purchases and use of illegal download sites. Pains were taken to remove effects of false and misremembered responses. Peer-to-peer applications present one of

1888-491: A key. This is unlike most other P2P networks where node administrators can employ a ratio system, where users have to share a certain amount of content before they can download. Freenet may also be considered a small world network . The Freenet protocol is intended to be used on a network of complex topology, such as the Internet ( Internet Protocol ). Each node knows only about some number of other nodes that it can reach directly (its conceptual "neighbors"), but any node can be

2006-405: A large distributed, variable-size network of peer nodes. Some nodes are end user nodes, from which documents are requested and presented to human users. Other nodes serve only to route data. All nodes communicate with each other identically – there are no dedicated "clients" or "servers". It is not possible for a node to rate another node except by its capacity to insert and fetch data associated with

2124-478: A large number of smaller bugfixes, performance enhancements, and usability improvements. Version 0.7.5 also shipped with a new version of the Windows installer. As of build 1226, released on 30 July 2009, features that have been written include significant security improvements against both attackers acting on the network and physical seizure of the computer running the node. As of build 1468, released on 11 July 2015,

2242-431: A layer of strong encryption, and no reliance on centralized structures . This allows users to publish anonymously or retrieve various kinds of information. Freenet has been under continuous development since 2000. Freenet 0.7, released on 8 May 2008, is a major re-write incorporating a number of fundamental changes. The most fundamental change is support for darknet operation. Version 0.7 offered two modes of operation:

2360-426: A mode in which it connects only to friends, and an opennet-mode in which it connects to any other Freenet user. Both modes can be run simultaneously. When a user switches to pure darknet operation, Freenet becomes very difficult to detect from the outside. The transport layer created for the darknet mode allows communication over restricted routes as commonly found in mesh networks , as long as these connections follow

2478-807: A more psychological and information-processing direction. Some peer-to-peer networks (e.g. Freenet ) place a heavy emphasis on privacy and anonymity —that is, ensuring that the contents of communications are hidden from eavesdroppers, and that the identities/locations of the participants are concealed. Public key cryptography can be used to provide encryption , data validation , authorization, and authentication for data/messages. Onion routing and other mix network protocols (e.g. Tarzan) can be used to provide anonymity. Perpetrators of live streaming sexual abuse and other cybercrimes have used peer-to-peer platforms to carry out activities with anonymity. Although peer-to-peer networks can be used for legitimate purposes, rights holders have targeted peer-to-peer over

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2596-399: A neighbor to any other; no hierarchy or other structure is intended. Each message is routed through the network by passing from neighbor to neighbor until it reaches its destination. As each node passes a message to a neighbor, it does not know whether the neighbor will forward the message to another node, or is the final destination or original source of the message. This is intended to protect

2714-467: A new peer-to-peer application, Share , was developed to be a successor. Since August 2003, several worms called " Antinny " have spread on the Winny network. Some versions of Antinny work as follows: Some people have uploaded their information unwittingly from their computers because of Antinny. That information includes governmental documents, information about customers, and people's private files. Once

2832-410: A peer wants to find a desired piece of data in the network, the search query must be flooded through the network to find as many peers as possible that share the data. Flooding causes a very high amount of signaling traffic in the network, uses more CPU /memory (by requiring every peer to process all search queries), and does not ensure that search queries will always be resolved. Furthermore, since there

2950-477: A peer-to-peer network in conjunction with streaming servers to stream audio and video to their clients. Peercasting is employed for multicasting streams. Additionally, a project called LionShare , undertaken by Pennsylvania State University , MIT, and Simon Fraser University , aims to facilitate file sharing among educational institutions globally. Another notable program, Osiris , enables users to create anonymous and autonomous web portals that are distributed via

3068-461: A peer-to-peer network. Dat is a distributed version-controlled publishing platform. I2P , is an overlay network used to browse the Internet anonymously . Unlike the related I2P, the Tor network is not itself peer-to-peer ; however, it can enable peer-to-peer applications to be built on top of it via onion services . The InterPlanetary File System (IPFS) is a protocol and network designed to create

3186-449: A proprietary peer-to-peer technology called "Delivery Optimization" to deploy operating system updates using end-users' PCs either on the local network or other PCs. According to Microsoft's Channel 9, this led to a 30%-50% reduction in Internet bandwidth usage. Artisoft's LANtastic was built as a peer-to-peer operating system where machines can function as both servers and workstations simultaneously. Hotline Communications Hotline Client

3304-518: A second file with the same name can cause collisions. USKs resolve this by adding a version number to the keys which is also used for providing update notification for keys registered as bookmarks in the web interface. Another subtype of the SSK is the Keyword Signed Key, or KSK, in which the key pair is generated in a standard way from a simple human-readable string. Inserting a document using a KSK allows

3422-545: A single hybrid node. Unlike many other P2P applications Freenet does not provide comprehensive functionality itself. Freenet is modular and features an API called Freenet Client Protocol (FCP) for other programs to use to implement services such as message boards , file sharing, or online chat . Freenet Messaging System (FMS) Frost Sone Peer-to-peer Peers make a portion of their resources, such as processing power, disk storage, or network bandwidth , directly available to other network participants, without

3540-444: A small-world network (which includes both opennet and darknet style Freenet networks), when ignoring the caching which could improve the scalability for popular content. However, this scalability is difficult to test without a very large network. Furthermore, the security features inherent to Freenet make detailed performance analysis (including things as simple as determining the size of the network) difficult to do accurately. As of now,

3658-818: A survey in June 2018 suggesting that Winny was still the most popular p2p network in Japan ahead of Perfect Dark (P2P) and Share (P2P) with approximately 45,000 nodes connecting each day over Golden Week. The number of nodes on Winny appears to be holding steady compared with 2015. Kaneko first announced Winny on the Download Software board of the 2channel ( 2ch for short) Japanese bulletin board site. Since 2channel users often refer to anonymous users by their post numbers, Kaneko came to be known as "Mr. 47" ("47-Shi", or 47氏 in Japanese), or just "47". After Winny's development stopped,

Hyphanet - Misplaced Pages Continue

3776-469: A user must add an encrypted node list in order to connect to other nodes on the network. Users choose three cluster words which symbolize their interests, and then Winny connects to other nodes which share these cluster words, downloading and storing encrypted data from cache of these neighbors in a distributed data store . If users want a particular file, they set up triggers (keywords), and Winny will download files marked by these triggers. The encryption

3894-676: Is a directory-syncing app. Research includes projects such as the Chord project , the PAST storage utility , the P-Grid , and the CoopNet content distribution system . Secure Scuttlebutt is a peer-to-peer gossip protocol capable of supporting many different types of applications, primarily social networking . Syncthing is also a directory-syncing app. Tradepal l and M-commerce applications are designed to power real-time marketplaces. The U.S. Department of Defense

4012-552: Is also known to have uploaded fake music and movies to P2P networks in order to deter illegal file sharing. Consequently, the P2P networks of today have seen an enormous increase of their security and file verification mechanisms. Modern hashing , chunk verification and different encryption methods have made most networks resistant to almost any type of attack, even when major parts of the respective network have been replaced by faked or nonfunctional hosts. The decentralized nature of P2P networks increases robustness because it removes

4130-671: Is conducting research on P2P networks as part of its modern network warfare strategy. In May 2003, Anthony Tether , then director of DARPA , testified that the United States military uses P2P networks. WebTorrent is a P2P streaming torrent client in JavaScript for use in web browsers , as well as in the WebTorrent Desktop standalone version that bridges WebTorrent and BitTorrent serverless networks. Microsoft , in Windows 10 , uses

4248-501: Is essentially random. In opennet connections are established by a join request which provides an optimized network structure if the existing network is already optimized. So the data in a newly started Freenet will be distributed somewhat randomly. As location swapping (on darknet) and path folding (on opennet) progress, nodes which are close to one another will increasingly have close locations, and nodes which are far away will have distant locations. Data with similar keys will be stored on

4366-409: Is high. Therefore, the community should work together to get these features in open-source software. This would reduce the need for custom simulators, and hence increase repeatability and reputability of experiments." Popular simulators that were widely used in the past are NS2, OMNeT++, SimPy, NetLogo, PlanetLab, ProtoPeer, QTM, PeerSim, ONE, P2PStrmSim, PlanetSim, GNUSim, and Bharambe. Besides all

4484-416: Is made possible by the fact that human relationships tend to form small-world networks, a property that can be exploited to find short paths between any two people. The work is based on a speech given at DEF CON 13 by Ian Clarke and Swedish mathematician Oskar Sandberg . Furthermore, the routing algorithm is capable of routing over a mixture of opennet and darknet connections, allowing people who have only

4602-442: Is no correlation between a peer and the content managed by it, there is no guarantee that flooding will find a peer that has the desired data. Popular content is likely to be available at several peers and any peer searching for it is likely to find the same thing. But if a peer is looking for rare data shared by only a few other peers, then it is highly unlikely that the search will be successful. In structured peer-to-peer networks

4720-535: Is no notion of semantic closeness when speaking of key closeness. Therefore, there will be no correlation between key closeness and similar popularity of data as there might be if keys did exhibit some semantic meaning, thus avoiding bottlenecks caused by popular subjects. There are two main varieties of keys in use on Freenet, the Content Hash Key (CHK) and the Signed Subspace Key (SSK). A subtype of SSKs

4838-507: Is no structure globally imposed upon them, unstructured networks are easy to build and allow for localized optimizations to different regions of the overlay. Also, because the role of all peers in the network is the same, unstructured networks are highly robust in the face of high rates of "churn"—that is, when large numbers of peers are frequently joining and leaving the network. However, the primary limitations of unstructured networks also arise from this lack of structure. In particular, when

Hyphanet - Misplaced Pages Continue

4956-444: Is not retrieved regularly (see also Effect ). While users can insert data into the network, there is no way to delete data. Due to Freenet's anonymous nature the original publishing node or owner of any piece of data is unknown. The only way data can be removed is if users don't request it. Typically, a host computer on the network runs the software that acts as a node, and it connects to other hosts running that same software to form

5074-406: Is not subject to the control of any one individual or organization, including the designers of Freenet. The codebase size is over 192,000 lines of code . Information stored on Freenet is distributed around the network and stored on several different nodes. Encryption of data and relaying of requests makes it difficult to determine who inserted content into Freenet, who requested that content, or where

5192-514: Is that peer-to-peer applications act as servers as well as clients, meaning that they can be more vulnerable to remote exploits . Since each node plays a role in routing traffic through the network, malicious users can perform a variety of "routing attacks", or denial of service attacks. Examples of common routing attacks include "incorrect lookup routing" whereby malicious nodes deliberately forward requests incorrectly or return false results, "incorrect routing updates" where malicious nodes corrupt

5310-416: Is that results must be reproducible so that other researchers can replicate, validate, and extend existing work." If the research cannot be reproduced, then the opportunity for further research is hindered. "Even though new simulators continue to be released, the research community tends towards only a handful of open-source simulators. The demand for features in simulators, as shown by our criteria and survey,

5428-492: Is the Updatable Subspace Key (USK) which adds versioning to allow secure updating of content. A CHK is a SHA-256 hash of a document (after encryption, which itself depends on the hash of the plaintext) and thus a node can check that the document returned is correct by hashing it and checking the digest against the key. This key contains the meat of the data on Freenet. It carries all the binary data building blocks for

5546-578: Is typically several GB (or more). Files on Freenet are typically split into multiple small blocks, with duplicate blocks created to provide redundancy . Each block is handled independently, meaning that a single file may have parts stored on many different nodes. Information flow in Freenet is different from networks like eMule or BitTorrent ; in Freenet: Two advantages of this design are high reliability and anonymity. Information remains available even if

5664-505: Is used in many protocols such as BitTorrent file sharing over the Internet and in personal networks like Miracast displaying and Bluetooth radio. The concept has inspired new structures and philosophies in many areas of human interaction. In such social contexts, peer-to-peer as a meme refers to the egalitarian social networking that has emerged throughout society, enabled by Internet technologies in general. While P2P systems had previously been used in many application domains,

5782-437: Is used, so that seldom-used data will tend to be on just a few nodes which specialize in providing that data, and frequently used items will be spread widely throughout the network. This automatic mirroring counteracts the times when web traffic becomes overloaded, and due to a mature network's intelligent routing, a network of size n should require only log( n ) time to retrieve a document on average. Keys are hashes : there

5900-505: The RIAA , MPAA , and entertainment industry to filter out copyrighted content. Although server-client networks are able to monitor and manage content availability, they can have more stability in the availability of the content they choose to host. A client should not have trouble accessing obscure content that is being shared on a stable centralized network. P2P networks, however, are more unreliable in sharing unpopular files because sharing files in

6018-489: The University of Edinburgh , which he completed as a graduation requirement in the summer of 1999. Ian Clarke's resulting unpublished report "A distributed decentralized information storage and retrieval system" (1999) provided foundation for the seminal paper written in collaboration with other researchers, "Freenet: A Distributed Anonymous Information Storage and Retrieval System" (2001). According to CiteSeer , it became one of

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6136-471: The YaCy . Some prominent research projects include the Chord project , Kademlia , PAST storage utility , P-Grid , a self-organized and emerging overlay network, and CoopNet content distribution system . DHT-based networks have also been widely utilized for accomplishing efficient resource discovery for grid computing systems, as it aids in resource management and scheduling of applications. Hybrid models are

6254-407: The broadcasting -like structure of the web as it has developed over the years. As a precursor to the Internet, ARPANET was a successful peer-to-peer network where "every participating node could request and serve content". However, ARPANET was not self-organized, and it could not "provide any means for context or content-based routing beyond 'simple' address-based routing." Therefore, Usenet ,

6372-422: The single point of failure that can be inherent in a client–server based system. As nodes arrive and demand on the system increases, the total capacity of the system also increases, and the likelihood of failure decreases. If one peer on the network fails to function properly, the whole network is not compromised or damaged. In contrast, in a typical client–server architecture, clients share only their demands with

6490-598: The "freeloader problem"). Freeloading can have a profound impact on the network and in some cases can cause the community to collapse. In these types of networks "users have natural disincentives to cooperate because cooperation consumes their own resources and may degrade their own performance". Studying the social attributes of P2P networks is challenging due to large populations of turnover, asymmetry of interest and zero-cost identity. A variety of incentive mechanisms have been implemented to encourage or even force nodes to contribute resources. Some researchers have explored

6608-522: The 365 different computer viruses that were tested for. Corrupted data can also be distributed on P2P networks by modifying files that are already being shared on the network. For example, on the FastTrack network, the RIAA managed to introduce faked chunks into downloads and downloaded files (mostly MP3 files). Files infected with the RIAA virus were unusable afterwards and contained malicious code. The RIAA

6726-544: The Chinese authorities on the mainland. It was reported that in 2002 Freenet China had several thousand dedicated users. However, Freenet opennet traffic was blocked in China around the 2010s. The Freenet file sharing network stores documents and allows them to be retrieved later by an associated key, as is now possible with protocols such as HTTP . The network is designed to be highly survivable. The system has no central servers and

6844-478: The Freenet core stopped using the db4o database and laid the foundation for an efficient interface to the Web of Trust plugin which provides spam resistance. Freenet has always been free software, but until 2011 it required users to install Java . This problem was solved by making Freenet compatible with OpenJDK , a free and open source implementation of the Java Platform. On 11 February 2015, Freenet received

6962-443: The Freenet network. In this way, it is more similar to Tor's onion services than to anonymous proxy software like Tor's proxy . Freenet's focus lies on free speech and anonymity. Because of that, Freenet acts differently at certain points that are (directly or indirectly) related to the anonymity part. Freenet attempts to protect the anonymity of both people inserting data into the network (uploading) and those retrieving data from

7080-415: The Freenet network. The simplest is via FProxy, which is integrated with the node software and provides a web interface to content on the network. Using FProxy, a user can browse freesites (websites that use normal HTML and related tools, but whose content is stored within Freenet rather than on a traditional web server). The web interface is also used for most configuration and node management tasks. Through

7198-433: The Internet with strong anonymity protection. The distributed data store of Freenet is used by many third-party programs and plugins to provide microblogging and media sharing, anonymous and decentralised version tracking, blogging, a generic web of trust for decentralized spam resistance , Shoeshop for using Freenet over sneakernet , and many more. The origin of Freenet can be traced to Ian Clarke's student project at

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7316-636: The Internet, and direct people towards a client–server -based application architecture. The client–server model provides financial barriers-to-entry to small publishers and individuals, and can be less efficient for sharing large files. As a reaction to this bandwidth throttling , several P2P applications started implementing protocol obfuscation, such as the BitTorrent protocol encryption . Techniques for achieving "protocol obfuscation" involves removing otherwise easily identifiable properties of protocols, such as deterministic byte sequences and packet sizes, by making

7434-562: The P2P system independent from the physical network topology. Based on how the nodes are linked to each other within the overlay network, and how resources are indexed and located, we can classify networks as unstructured or structured (or as a hybrid between the two). Unstructured peer-to-peer networks do not impose a particular structure on the overlay network by design, but rather are formed by nodes that randomly form connections to each other. ( Gnutella , Gossip , and Kazaa are examples of unstructured P2P protocols). Because there

7552-526: The SUMA-Award for "protection against total surveillance". Freenet served as the model for the Japanese peer to peer file-sharing programs Winny , Share and Perfect Dark , but this model differs from p2p networks such as Bittorrent and emule . Freenet separates the underlying network structure and protocol from how users interact with the network; as a result, there are a variety of ways to access content on

7670-496: The United States, over conflicts with copyright law. Two major cases are Grokster vs RIAA and MGM Studios, Inc. v. Grokster, Ltd. . In the last case, the Court unanimously held that defendant peer-to-peer file sharing companies Grokster and Streamcast could be sued for inducing copyright infringement. The P2PTV and PDTP protocols are used in various peer-to-peer applications. Some proprietary multimedia applications leverage

7788-415: The above stated facts, there has also been work done on ns-2 open source network simulators. One research issue related to free rider detection and punishment has been explored using ns-2 simulator here. Winny Winny (also known as WinNY ) is a Japanese peer-to-peer (P2P) file-sharing program developed by Isamu Kaneko, a research assistant at the University of Tokyo in 2002. Like Freenet ,

7906-411: The anonymity of users and publishers. Each node maintains a data store containing documents associated with keys, and a routing table associating nodes with records of their performance in retrieving different keys. The Freenet protocol uses a key-based routing protocol, similar to distributed hash tables . The routing algorithm changed significantly in version 0.7. Prior to version 0.7, Freenet used

8024-519: The answered download requests on the gnutella network contained some form of malware, whereas only 3% of the content on OpenFT contained malware. In both cases, the top three most common types of malware accounted for the large majority of cases (99% in gnutella, and 65% in OpenFT). Another study analyzing traffic on the Kazaa network found that 15% of the 500,000 file sample taken were infected by one or more of

8142-447: The availability of files being shared. If the administrators decide to no longer distribute a file, they simply have to remove it from their servers, and it will no longer be available to users. Along with leaving the users powerless in deciding what is distributed throughout the community, this makes the entire system vulnerable to threats and requests from the government and other large forces. For example, YouTube has been pressured by

8260-585: The beneficial uses of Freenet outweigh its negative uses. Their view is that free speech, in itself, is not in contradiction with any other consideration—the information is not the crime. Freenet attempts to remove the possibility of any group imposing its beliefs or values on any data. Although many states censor communications to different extents, they all share one commonality in that a body must decide what information to censor and what information to allow. What may be acceptable to one group of people may be considered offensive or even dangerous to another. In essence,

8378-445: The benefits of enabling virtual communities to self-organize and introduce incentives for resource sharing and cooperation, arguing that the social aspect missing from today's P2P systems should be seen both as a goal and a means for self-organized virtual communities to be built and fostered. Ongoing research efforts for designing effective incentive mechanisms in P2P systems, based on principles from game theory, are beginning to take on

8496-503: The cases the file sharing technology was ruled to be legal as long as the developers had no ability to prevent the sharing of the copyrighted material. To establish criminal liability for the copyright infringement on peer-to-peer systems, the government must prove that the defendant infringed a copyright willingly for the purpose of personal financial gain or commercial advantage. Fair use exceptions allow limited use of copyrighted material to be downloaded without acquiring permission from

8614-453: The concept was popularized by file sharing systems such as the music-sharing application Napster . The peer-to-peer movement allowed millions of Internet users to connect "directly, forming groups and collaborating to become user-created search engines, virtual supercomputers, and filesystems". The basic concept of peer-to-peer computing was envisioned in earlier software systems and networking discussions, reaching back to principles stated in

8732-473: The content (especially with protocols such as Bittorrent that require users to share, refer a performance measurement study ). This property is one of the major advantages of using P2P networks because it makes the setup and running costs very small for the original content distributor. Peer-to-peer file sharing networks such as Gnutella , G2 , and the eDonkey network have been useful in popularizing peer-to-peer technologies. These advancements have paved

8850-401: The content to be delivered to the client for reassembly and decryption. The CHK is unique by nature and provides tamperproof content. A hostile node altering the data under a CHK will immediately be detected by the next node or the client. CHKs also reduce the redundancy of data since the same data will have the same CHK and when multiple sites reference the same large files, they can reference to

8968-458: The content was stored. This protects the anonymity of participants, and also makes it very difficult to censor specific content. Content is stored encrypted, making it difficult for even the operator of a node to determine what is stored on that node. This provides plausible deniability ; which, in combination with request relaying, means that safe harbor laws that protect service providers may also protect Freenet node operators. When asked about

9086-504: The core issues in the network neutrality controversy. Internet service providers ( ISPs ) have been known to throttle P2P file-sharing traffic due to its high- bandwidth usage. Compared to Web browsing, e-mail or many other uses of the internet, where data is only transferred in short intervals and relative small quantities, P2P file-sharing often consists of relatively heavy bandwidth usage due to ongoing file transfers and swarm/network coordination packets. In October 2007, Comcast , one of

9204-731: The darknet (a subset of the global social network) is a small-world network, and nodes constantly attempt to swap locations (using the Metropolis–Hastings algorithm ) in order to minimize their distance to their neighbors. If the network actually is a small-world network, Freenet should find data reasonably quickly; ideally on the order of O ( [ l o g ( n ) ] 2 ) {\displaystyle O\left(\left[log\left(n\right)\right]^{2}\right)} hops in Big O notation . However, it does not guarantee that data will be found at all. Eventually, either

9322-474: The data look as if it were random. The ISP's solution to the high bandwidth is P2P caching , where an ISP stores the part of files most accessed by P2P clients in order to save access to the Internet. Researchers have used computer simulations to aid in understanding and evaluating the complex behaviors of individuals within the network. "Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process

9440-402: The development of version 0.7) shows that this "path folding" is critical, and that a very simple routing algorithm will suffice provided there is path folding. The disadvantage of this is that it is very easy for an attacker to find Freenet nodes, and connect to them, because every node is continually attempting to find new connections. In version 0.7, Freenet supports both "opennet" (similar to

9558-481: The document is found or the hop limit is exceeded. The terminal node sends a reply that makes its way back to the originator along the route specified by the intermediate nodes' records of pending requests. The intermediate nodes may choose to cache the document along the way. Besides saving bandwidth, this also makes documents harder to censor as there is no one "source node". Initially, the locations in darknet are distributed randomly. This means that routing of requests

9676-575: The document to be retrieved and decrypted if and only if the requester knows the human-readable string; this allows for more convenient (but less secure) URIs for users to refer to. A network is said to be scalable if its performance does not deteriorate even if the network is very large. The scalability of Freenet is being evaluated, but similar architectures have been shown to scale logarithmically. This work indicates that Freenet can find data in O ( log 2 ⁡ n ) {\displaystyle O(\log ^{2}n)} hops on

9794-449: The entire group of network servers. The same consideration applies to SMTP email in the sense that the core email-relaying network of mail transfer agents has a peer-to-peer character, while the periphery of Email clients and their direct connections is strictly a client-server relationship. In May 1999, with millions more people on the Internet, Shawn Fanning introduced the music and file-sharing application called Napster. Napster

9912-532: The first Request for Comments , RFC 1. Tim Berners-Lee 's vision for the World Wide Web was close to a P2P network in that it assumed each user of the web would be an active editor and contributor, creating and linking content to form an interlinked "web" of links. The early Internet was more open than the present day, where two machines connected to the Internet could send packets to each other without firewalls and other security measures. This contrasts with

10030-622: The information is uploaded, it is difficult to delete. Recently, highly publicized cases of sensitive file uploading have come to light in Japan's media. In particular, a defense agency was forced to admit that classified information from the Maritime Self Defense Force was uploaded by a computer with Winny software installed on it. Following this, All Nippon Airways suffered an embarrassing leak of passwords for security-access areas in 29 airports across Japan. A similar incident occurred with JAL Airlines on 17 December 2005, after

10148-423: The involvement with sharing copyrighted material. Peer-to-peer networking involves data transfer from one user to another without using an intermediate server. Companies developing P2P applications have been involved in numerous legal cases, primarily in the United States, primarily over issues surrounding copyright law. Two major cases are Grokster vs RIAA and MGM Studios, Inc. v. Grokster, Ltd. In both of

10266-462: The key's hash is turned into another number in the same range, and the request is routed to the node whose location is closest to the key. This goes on until some number of hops is exceeded, there are no more nodes to search, or the data is found. If the data is found, it is cached on each node along the path. So there is no one source node for a key, and attempting to find where it is currently stored will result in it being cached more widely. Essentially

10384-402: The lack of central authority in P2P networks, forces such as the recording industry, RIAA , MPAA , and the government are unable to delete or stop the sharing of content on P2P systems. In P2P networks, clients both provide and use resources. This means that unlike client–server systems, the content-serving capacity of peer-to-peer networks can actually increase as more users begin to access

10502-427: The largest broadband Internet providers in the United States, started blocking P2P applications such as BitTorrent . Their rationale was that P2P is mostly used to share illegal content, and their infrastructure is not designed for continuous, high-bandwidth traffic. Critics point out that P2P networking has legitimate legal uses, and that this is another way that large providers are trying to control use and content on

10620-500: The most frequently cited computer science articles in 2002. Freenet can provide anonymity on the Internet by storing small encrypted snippets of content distributed on the computers of its users and connecting only through intermediate computers which pass on requests for content and sending them back without knowing the contents of the full file. This is similar to how routers on the Internet route packets without knowing anything about files ‍ — except Freenet has caching,

10738-474: The need for central coordination by servers or stable hosts. Peers are both suppliers and consumers of resources, in contrast to the traditional client–server model in which the consumption and supply of resources are divided. While P2P systems had previously been used in many application domains , the architecture was popularized by the Internet file sharing system Napster , originally released in 1999. P2P

10856-482: The network (downloading). Unlike file sharing systems, there is no need for the uploader to remain on the network after uploading a file or group of files. Instead, during the upload process, the files are broken into chunks and stored on a variety of other computers on the network. When downloading, those chunks are found and reassembled. Every node on the Freenet network contributes storage space to hold files and bandwidth that it uses to route requests from its peers. As

10974-526: The network using a hash table : that is, ( key , value ) pairs are stored in the DHT, and any participating node can efficiently retrieve the value associated with a given key. However, in order to route traffic efficiently through the network, nodes in a structured overlay must maintain lists of neighbors that satisfy specific criteria. This makes them less robust in networks with a high rate of churn (i.e. with large numbers of nodes frequently joining and leaving

11092-549: The network). More recent evaluation of P2P resource discovery solutions under real workloads have pointed out several issues in DHT-based solutions such as high cost of advertising/discovering resources and static and dynamic load imbalance. Notable distributed networks that use DHTs include Tixati , an alternative to BitTorrent's distributed tracker, the Kad network , the Storm botnet , and

11210-424: The network, and can make it difficult for an attacker (such as an oppressive government) to even determine that a user is running Freenet in the first place. The core innovation in Freenet 0.7 is to allow a globally scalable darknet, capable (at least in theory) of supporting millions of users. Previous darknets, such as WASTE , have been limited to relatively small disconnected networks. The scalability of Freenet

11328-550: The network. This model of network arrangement differs from the client–server model where communication is usually to and from a central server. A typical example of a file transfer that uses the client-server model is the File Transfer Protocol (FTP) service in which the client and server programs are distinct: the clients initiate the transfer, and the servers satisfy these requests. Peer-to-peer networks generally implement some form of virtual overlay network on top of

11446-431: The old algorithms, but simpler), and "darknet" (all node connections are set up manually, so only your friends know your node's IP address). Darknet is less convenient, but much more secure against a distant attacker. This change required major changes in the routing algorithm. Every node has a location, which is a number between 0 and 1. When a key is requested, first the node checks the local data store. If it's not found,

11564-437: The overlay is organized into a specific topology, and the protocol ensures that any node can efficiently search the network for a file/resource, even if the resource is extremely rare. The most common type of structured P2P networks implement a distributed hash table (DHT), in which a variant of consistent hashing is used to assign ownership of each file to a particular peer. This enables peers to search for resources on

11682-435: The physical network topology, where the nodes in the overlay form a subset of the nodes in the physical network. Data is still exchanged directly over the underlying TCP/IP network, but at the application layer peers can communicate with each other directly, via the logical overlay links (each of which corresponds to a path through the underlying physical network). Overlays are used for indexing and peer discovery, and make

11800-438: The publisher node goes offline, and is anonymously spread over many hosting nodes as encrypted blocks, not entire files. The key disadvantage of the storage method is that no one node is responsible for any chunk of data. If a piece of data is not retrieved for some time and a node keeps getting new data, it will drop the old data sometime when its allocated disk space is fully used. In this way Freenet tends to 'forget' data which

11918-411: The purpose of Freenet is to ensure that no one is allowed to decide what is acceptable. Reports of Freenet's use in authoritarian nations is difficult to track due to the very nature of Freenet's goals. One group, Freenet China , used to introduce the Freenet software to Chinese users starting from 2001 and distribute it within China through e-mails and on disks after the group's website was blocked by

12036-401: The rights holders. These documents are usually news reporting or under the lines of research and scholarly work. Controversies have developed over the concern of illegitimate use of peer-to-peer networks regarding public safety and national security. When a file is downloaded through a peer-to-peer network, it is impossible to know who created the file or what users are connected to the network at

12154-455: The routing tables of neighboring nodes by sending them false information, and "incorrect routing network partition" where when new nodes are joining they bootstrap via a malicious node, which places the new node in a partition of the network that is populated by other malicious nodes. The prevalence of malware varies between different peer-to-peer protocols. Studies analyzing the spread of malware on P2P networks found, for example, that 63% of

12272-607: The ruling. On October 8, 2009, the guilty verdict was overturned by the Osaka High Court. On December 20, 2011, Kaneko was cleared of all charges after the Supreme Court of Japan agreed that the prosecution could not prove that he had any intention to promote the software for illegal use. Japanese heavy metal band, Maximum the Hormone referenced the software in their song "A-L-I-E-N" by satirically urging listeners to stop using

12390-441: The same file it designates that the node choose the fastest of its neighbors. Streaming media is transmitted by having clients cache the previous stream, and then transmit it piece-wise to new nodes. Peer-to-peer systems pose unique challenges from a computer security perspective. Like any other form of software , P2P applications can contain vulnerabilities . What makes this particularly dangerous for P2P software, however,

12508-528: The same CHK. SSKs are based on public-key cryptography. Currently Freenet uses the DSA algorithm. Documents inserted under SSKs are signed by the inserter, and this signature can be verified by every node to ensure that the data is not tampered with. SSKs can be used to establish a verifiable pseudonymous identity on Freenet, and allow for multiple documents to be inserted securely by a single person. Files inserted with an SSK are effectively immutable , since inserting

12626-444: The same node. The result is that the network will self-organize into a distributed, clustered structure where nodes tend to hold data items that are close together in key space. There will probably be multiple such clusters throughout the network, any given document being replicated numerous times, depending on how much it is used. This is a kind of " spontaneous symmetry breaking ", in which an initially symmetric state (all nodes being

12744-417: The same process is used to insert a document into the network: the data is routed according to the key until it runs out of hops, and if no existing document is found with the same key, it is stored on each node. If older data is found, the older data is propagated and returned to the originator, and the insert "collides". But this works only if the locations are clustered in the right way. Freenet assumes that

12862-407: The same, with random initial keys for each other) leads to a highly asymmetric situation, with nodes coming to specialize in data that has closely related keys. There are forces which tend to cause clustering (shared closeness data spreads throughout the network), and forces that tend to break up clusters (local caching of commonly used data). These forces will be different depending on how often data

12980-484: The scalability of Freenet has yet to be tested. As of version 0.7, Freenet supports both "darknet" and "opennet" connections. Opennet connections are made automatically by nodes with opennet enabled, while darknet connections are manually established between users that know and trust each other. Freenet developers describe the trust needed as "will not crack their Freenet node". Opennet connections are easy to use, but darknet connections are more secure against attackers on

13098-415: The system, but not their resources. In this case, as more clients join the system, fewer resources are available to serve each client, and if the central server fails, the entire network is taken down. There are both advantages and disadvantages in P2P networks related to the topic of data backup , recovery, and availability. In a centralized network, the system administrators are the only forces controlling

13216-449: The topic, Freenet developers defer to the EFF discussion which says that not being able to filter anything is a safe choice. Like Winny , Share and Perfect Dark , Freenet not only transmits data between nodes but actually stores them, working as a huge distributed cache. To achieve this, each node allocates some amount of disk space to store data; this is configurable by the node operator, but

13334-445: The use of separate applications or plugins loaded into the node software, users can interact with the network in other ways, such as forums similar to web forums or Usenet or interfaces more similar to traditional P2P "filesharing" interfaces. While Freenet provides an HTTP interface for browsing freesites, it is not a proxy for the World Wide Web ; Freenet can be used to access only the content that has been previously inserted into

13452-554: The way for Peer-to-peer content delivery networks and services, including distributed caching systems like Correli Caches to enhance performance. Furthermore, peer-to-peer networks have made possible the software publication and distribution, enabling efficient sharing of Linux distribution and various games though file sharing networks. Peer-to-peer networking involves data transfer from one user to another without using an intermediate server. Companies developing P2P applications have been involved in numerous legal cases, primarily in

13570-534: Was arrested for suspected conspiracy to encourage copyright infringement by the High-tech Crime Taskforce of the Kyoto Prefectural Police. Kaneko was released on bail on June 1, 2004. The court hearings started in September 2004 at Kyoto district court. On December 13, 2006, Kaneko was convicted of assisting copyright violations and sentenced to pay a fine of ¥ 1.5 million (about US$ 13,200). He appealed

13688-601: Was built with decentralized servers and tracker software dedicated to any type of files and continues to operate today. Cryptocurrencies are peer-to-peer-based digital currencies that use blockchains Cooperation among a community of participants is key to the continued success of P2P systems aimed at casual human users; these reach their full potential only when large numbers of nodes contribute resources. But in current practice, P2P networks often contain large numbers of users who utilize resources shared by other nodes, but who do not share anything themselves (often referred to as

13806-474: Was meant to provide anonymity, but Winny also included bulletin boards where users would announce uploads, and the IP address of posters could be discovered through these boards. While Freenet was implemented in Java , Winny was implemented as a Windows C++ application. The software takes its name from WinMX , where the M and the X are each advanced one letter in the Latin alphabet, to N and Y. Netagent published

13924-403: Was the beginning of peer-to-peer networks, as we know them today, where "participating users establish a virtual network, entirely independent from the physical network, without having to obey any administrative authorities or restrictions". A peer-to-peer network is designed around the notion of equal peer nodes simultaneously functioning as both "clients" and "servers" to the other nodes on

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