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| GNUnet | |
|---|---|
 | |
 GNUnet with theGTK+ user interface | |
| Developer | GNUnete.V.[1] |
| Initial release | November 5, 2001; 24 years ago (2001-11-05) |
| Stable release | 0.26.0[2]  / 15 November 2025 |
| Repository | |
| Written in | C[3] |
| Operating system | official:Free software operating systems (Linux,FreeBSD,NetBSD,OpenBSD); unofficial: Other operating systems (OS X,Windows) |
| Available in | Spanish, English, Russian, German, French |
| Type | Anonymous P2P,Friend-to-friend |
| License | 2018:AGPL-3.0-or-later[a][4] 2007:GPL-3.0-or-later[b] 2001:GPL-2.0-or-later[c] |
| Website | gnunet |
| Part ofa series on |
| File sharing |
|---|
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Video on demand sites |
File sharing networks |
Streaming programs |
Anonymous file sharing |
Development and societal aspects |
GNUnet is asoftware framework fordecentralized,peer-to-peernetworking and an officialGNU package. The framework offerslink encryption,peer discovery,resource allocation, communication over many transports (such asTCP,UDP,HTTP,HTTPS,WLAN andBluetooth) and various basicpeer-to-peer algorithms forrouting,multicast and network size estimation.[5][6]
GNUnet's basic network topology is that of amesh network. GNUnet includes adistributed hash table (DHT) which is arandomized variant ofKademlia that can still efficiently route insmall-world networks. GNUnet offers a "F2F topology" option for restricting connections to only the users' trusted friends. The users' friends' own friends (and so on) can then indirectly exchange files with the users' computer, never using its IP address directly.
GNUnet usesUniform resource identifiers (not approved byIANA, although an application has been made).[when?] GNUnet URIs consist of two major parts: the module and the module specific identifier. A GNUnet URI is of formgnunet://module/identifier wheremodule is the module name andidentifier is a module specific string.
The primary codebase is written inC, but there arebindings in other languages to produce an API for developing extensions in those languages. GNUnet is part of theGNU Project. It has gained interest in thehacker community after thePRISM revelations.[7]
GNUnet consists of several subsystems, of which essential ones are Transport and Core subsystems.[8] Transport subsystem provides insecure link-layer communications, while Core provides peer discovery and encryption.[9] On top of the core subsystem various applications are built.
GNUnet includes various P2P applications in the main distribution of the framework, including filesharing, chat and VPN; additionally, a few external projects (such as secushare) are also extending the GNUnet infrastructure.
GNUnet is unrelated to the olderGnutella P2P protocol. Gnutella is not an official GNU project, while GNUnet is.[10]
Originally, GNUnet usedUDP for underlying transport.[11] The GNUnet transport subsystem were expanded to included additional options, such as TCP and SMTP.[12] Support for the latter was later dropped due to a lack of maintenance.[13]
The communication port, officially registered atIANA, is 2086 (tcp +udp).[14]
GNUnet provides trust system based on an excess-based economic model.[15] The idea of employing an economic system is taken from theMojoNation network.[16]
GNUnet network has no trusted entities so it is impossible to maintain a globalreputation. Instead, each peer maintains its owntrust for each of its local links.
When resources, such as bandwidth and CPU time, are in excess, the peer provides them to all requesting neighbors without reducing trust or otherwise charging them. When a node is under stress, it denies requests of those neighbors that it trusts less and charges others by reducing their trust.
The primary application at this point isanonymous,censorship-resistant file-sharing, allowing users to anonymously publish or retrieve information of all kinds. The GNUnet protocol which provides anonymity is called GAP (GNUnet anonymity protocol).[17] GNUnet FS can additionally make use ofGNU libextractor to automatically annotate shared files withmetadata.
Files shared with GNUnet are ECRS (Encoding for Censorship-Resistant Sharing) coded.[18]
All content is represented as GBlocks. Each GBlock contains 1024 bytes. There are several types of GBlocks, each of them serves a particular purpose. Any GBlock is uniquely identified by itsRIPEMD-160 hash.
DBlocks store actual file contents and nothing else. File is split at 1024 byte boundaries and resulting chunks are stored in DBlocks. DBlocks are linked together intoMerkle tree by means of IBlocks that store DBlock identifiers.
Blocks are encrypted with a symmetric key derived from when they are stored in the network.
GNUnet Anonymity Protocol consists of queries and replies. Depending on load of the forwarding node, messages are forwarded to zero or more nodes.
Queries are used to search for content and request data blocks.
Query contains resource identifier, reply address, priority and TTL (Time-to-Live).
Resource identifier of datum is a triple-hash.[19] Peer that replies to query providesto prove that it indeed has the requested resource without providing to intermediate nodes, so intermediate nodes can't decrypt.
Reply address is the major difference compared toFreenet protocol. While in Freenet reply always propagates back using the same path as the query, in GNUnet the path may be shorter. Peer receiving a query may drop it,forward it without rewriting reply address orindirect it by replacing reply address with its own address. By indirecting queries peer providescover traffic for its own queries, while by forwarding them peer avoids being a link in reply propagation and preserves its bandwidth. This feature allows the user to trade anonymity for efficiency. User can specify an anonymity level for each publish, search and download operation. An anonymity level ofzero can be used to select non-anonymous file-sharing. GNUnet's DHT infrastructure is only used if non-anonymous file-sharing is specified. The anonymity level determines how much cover traffic a peer must have to hide the user's own actions.
Priority specifies how much of its trust user wants to spend in case of a resource shortage.
TTL is used to prevent queries from staying in the network for too long.
Thefs moduleidentifier consists of eitherchk,sks,ksk orloc followed by a slash and a category specific value. Most URIs contain hashes, which are encoded inbase32hex.[20]
gnunet://fs/chk/[file hash].[query hash].[file size in bytes]gnunet://fs/sks/NAMESPACE/IDENTIFIERgnunet://fs/ksk/KEYWORD[+KEYWORD]*gnunet://fs/loc/PEER/QUERY.TYPE.KEY.SIZEA type of GNUnet filesharing URI pointing to a specific copy ofGNU GPL license text:gnunet://fs/chk/9E4MDN4VULE8KJG6U1C8FKH5HA8C5CHSJTILRTTPGK8MJ6VHORERHE68JU8Q0FDTOH1DGLUJ3NLE99N0ML0N9PIBAGKG7MNPBTT6UKG.1I823C58O3LKS24LLI9KB384LH82LGF9GUQRJHACCUINSCQH36SI4NF88CMAET3T3BHI93D4S0M5CC6MVDL1K8GFKVBN69Q6T307U6O.17992
Another type of GNUnet filesharing URI, pointing to the search results of a search with keyword "gpl":gnunet://fs/ksk/gpl
GNUnet includes an implementation of the GNU Name System (GNS), a decentralized and censorship-resistant replacement forDNS. In GNS, each user manages their ownzones and can delegate subdomains to zones managed by other users. Lookups of records defined by other users are performed using GNUnet's DHT.[21] GNS was standardized inRFC 9498 in 2023. The GANA registry manages the ".alt"top-level domain in GNS.[22]
GNUnet can tunnel IP traffic over the peer-to-peer network. If necessary, GNUnet can perform IPv4-IPv6protocol translation in the process. GNUnet provides aDNS Application-level gateway to proxy DNS requests and map addresses to the desired address family as necessary. This way, GNUnet offers a possible technology to facilitateIPv6 transition. Furthermore, in combination with GNS, GNUnet's protocol translation system can be used to access hidden services — IP-based services that run locally at some peer in the network and which can only be accessed by resolving a GNS name.
Gabor X Toth published in early September 2013 a thesis[23] to present the design of asocial messaging service for the GNUnet peer-to-peer framework that offers scalability, extensibility, and end-to-end encrypted communication. The scalability property is achieved through multicast message delivery, while extensibility is made possible by usingPSYC (Protocol for SYnchronous Conferencing), which provides an extensibleRPC (Remote Procedure Call) syntax that can evolve over time without having to upgrade the software on all nodes in the network. Another key feature provided by the PSYC layer are stateful multicast channels, which are used to store e.g. user profiles. End-to-end encrypted communication is provided by the mesh service of GNUnet, upon which the multicast channels are built. Pseudonymous users and social places in the system have cryptographical identities — identified by their public key — these are mapped to human memorable names using GNS (GNU Name System), where each pseudonym has a zone pointing to its places.
That is the required building block for turning the GNUnet framework into a fullypeer-to-peer social networking platform.
A chat has been implemented in the CADET module,[24] for which aGTK interface forGNOME exists,[25] specifically designed for the emerging Linux phones (such as theLibrem 5 or thePinePhone).[26]
GNUnet is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
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