GNUnet is a
software framework
In computer programming, a software framework is a software abstraction that provides generic functionality which developers can extend with custom code to create applications. It establishes a standard foundation for building and deploying soft ...
for
decentralized
Decentralization or decentralisation is the process by which the activities of an organization, particularly those related to planning and decision-making, are distributed or delegated away from a central, authoritative location or group and gi ...
,
peer-to-peer
Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network, forming a peer-to-peer network of Node ...
networking and an official
GNU
GNU ( ) is an extensive collection of free software (394 packages ), which can be used as an operating system or can be used in parts with other operating systems. The use of the completed GNU tools led to the family of operating systems popu ...
package. The framework offers
link encryption,
peer discovery,
resource allocation
In economics, resource allocation is the assignment of available resources to various uses. In the context of an entire economy, resources can be allocated by various means, such as markets, or planning.
In project management, resource allocatio ...
, communication over many transports (such as
TCP,
UDP,
HTTP
HTTP (Hypertext Transfer Protocol) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, wher ...
,
HTTPS
Hypertext Transfer Protocol Secure (HTTPS) is an extension of the Hypertext Transfer Protocol (HTTP). It uses encryption for secure communication over a computer network, and is widely used on the Internet. In HTTPS, the communication protoc ...
,
WLAN
A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office buildin ...
and
Bluetooth
Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is li ...
) and various basic
peer-to-peer
Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network, forming a peer-to-peer network of Node ...
algorithms for
routing
Routing is the process of selecting a path for traffic in a Network theory, network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched ...
,
multicast
In computer networking, multicast is a type of group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast differs from ph ...
and network size estimation.
GNUnet's basic network topology is that of a
mesh network. GNUnet includes a
distributed hash table
A distributed hash table (DHT) is a Distributed computing, distributed system that provides a lookup service similar to a hash table. Key–value pairs are stored in a DHT, and any participating node (networking), node can efficiently retrieve the ...
(DHT) which is a
randomized variant of
Kademlia
Kademlia is a distributed hash table for decentralized peer-to-peer computer networks designed by Petar Maymounkov and David Mazières in 2002. It specifies the structure of the network and the exchange of information through node (networking), no ...
that can still efficiently route in
small-world network
A small-world network is a graph characterized by a high clustering coefficient and low distances. In an example of the social network, high clustering implies the high probability that two friends of one person are friends themselves. The l ...
s. 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 uses
Uniform resource identifier
A Uniform Resource Identifier (URI), formerly Universal Resource Identifier, is a unique sequence of characters that identifies an abstract or physical resource, such as resources on a webpage, mail address, phone number, books, real-world obje ...
s (not approved by
IANA
The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Internet P ...
, although an application has been made). GNUnet URIs consist of two major parts: the module and the module specific identifier. A GNUnet URI is of form
gnunet://module/identifier
where ''module'' is the module name and ''identifier'' is a module specific string.
The primary codebase is written in
C, but there are
bindings in other languages to produce an API for developing extensions in those languages. GNUnet is part of the
GNU Project
The GNU Project ( ) is a free software, mass collaboration project announced by Richard Stallman on September 27, 1983. Its goal is to give computer users freedom and control in their use of their computers and Computer hardware, computing dev ...
. It has gained interest in the
hacker community after the
PRISM revelations.
GNUnet consists of several subsystems, of which essential ones are Transport and Core subsystems. Transport subsystem provides insecure link-layer communications, while Core provides peer discovery and encryption. 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 older
Gnutella
Gnutella is a peer-to-peer network protocol. Founded in 2000, it was the first decentralized peer-to-peer network of its kind, leading to other, later networks adopting the model.
In June 2005, Gnutella's population was 1.81 million computer ...
P2P protocol. Gnutella is not an official GNU project, while GNUnet is.
Transport
Originally, GNUnet used
UDP for underlying transport. Now GNUnet transport subsystem provides multiple options, such as TCP and SMTP.
The communication port, officially registered at
IANA
The Internet Assigned Numbers Authority (IANA) is a standards organization that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Internet P ...
, is 2086 (
tcp +
udp).
Trust system
GNUnet provides trust system based on an excess-based economic model. The idea of employing an economic system is taken from the
MojoNation network.
GNUnet network has no trusted entities so it is impossible to maintain a global ''reputation''. Instead, each peer maintains its own ''trust'' 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 drops requests from its neighbor nodes having lower internal trust value. However, when the peer has less resources than enough to fulfill everyone's requests, it denies requests of those neighbors that it trusts less and charges others by reducing their trust.
File sharing
The primary application at this point is
anonymous
Anonymous may refer to:
* Anonymity, the state of an individual's identity, or personally identifiable information, being publicly unknown
** Anonymous work, a work of art or literature that has an unnamed or unknown creator or author
* Anonym ...
,
censorship
Censorship is the suppression of speech, public communication, or other information. This may be done on the basis that such material is considered objectionable, harmful, sensitive, or "inconvenient". Censorship can be conducted by governmen ...
-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). GNUnet FS can additionally make use of
GNU libextractor to automatically annotate shared files with
metadata
Metadata (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including:
* Descriptive ...
.
File encoding
Files shared with GNUnet are ECRS (Encoding for Censorship-Resistant Sharing) coded.
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 its
RIPEMD-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 into
Merkle 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.
Queries and replies
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
. Peer that replies to query provides
to 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 to
Freenet
Hyphanet (until mid-2023: Freenet) is a peer-to-peer platform for censorship-resistant, Anonymity application, anonymous communication. It uses a decentralized distributed data store to keep and deliver information, and has a suite of free soft ...
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 or ''indirect'' it by replacing reply address with its own address. By indirecting queries peer provides
cover 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 of ''zero'' 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.
File sharing URIs
The ''fs'' module ''identifier'' consists of either ''chk'', ''sks'', ''ksk'' or ''loc'' followed by a slash and a category specific value. Most URIs contain hashes, which are encoded in
base32hex.
* ''chk'' identifies files, typically:
gnunet://fs/chk/ ile hash uery hash ile size in bytes/nowiki>
: File hash is the hash of the plaintext file, which allows decrypting it once it is downloaded. Query hash is the hash of topmost GBlock which allows downloading the whole tree of GBlocks that contain encrypted file. File size is required to determine the shape of the tree.
* ''sks'' identifies files within namespaces, typically:
gnunet://fs/sks/NAMESPACE/IDENTIFIER
* ''ksk'' identifies search queries, typically:
gnunet://fs/ksk/KEYWORD KEYWORD
* ''loc'' identifies a datum on a specific machine, typically:
gnunet://fs/loc/PEER/QUERY.TYPE.KEY.SIZE
Examples
A type of GNUnet filesharing URI pointing to a specific copy of
GNU GPL
The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...
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
GNU Name System
GNUnet includes an implementation of the GNU Name System (GNS), a decentralized and censorship-resistant replacement for
DNS. In GNS, each user manages their own
zones and can delegate subdomains to zones managed by other users. Lookups of records defined by other users are performed using GNUnet's DHT. GNS has been standardized in . The GANA registry manages the ".alt"
top-level domain
A top-level domain (TLD) is one of the domain name, domains at the highest level in the hierarchical Domain Name System of the Internet after the root domain. The top-level domain names are installed in the DNS root zone, root zone of the nam ...
in GNS.
Protocol translation
GNUnet can tunnel IP traffic over the peer-to-peer network. If necessary, GNUnet can perform IPv4-IPv6
protocol translation in the process. GNUnet provides a
DNS 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 facilitate
IPv6 transition IPv6 transition can refer to:
* IPv6 deployment, the process of transitioning the Internet to use the IPv6 protocol
* IPv6 transition mechanism
An IPv6 transition mechanism is a technology that facilitates the transitioning of the Internet from ...
. 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.
Social API
Gabor X Toth published in early September 2013 a thesis to present the design of a
social 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 using
PSYC (Protocol for SYnchronous Conferencing), which provides an extensible
RPC
RPC may refer to:
Science and technology
* Rational polynomial coefficient
* Reactive Plastic Curtain, a carbon-dioxide-absorbing device used in some rebreather breathing sets
* Regional Playback Control, a regional lockout technology for DVDs ...
(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 fully
peer-to-peer social networking platform.
Chat
A chat has been implemented in the CADET module, for which a
GTK
GTK (formerly GIMP ToolKit and GTK+) is a free software cross-platform widget toolkit for creating graphical user interfaces (GUIs). It is licensed under the terms of the GNU Lesser General Public License, allowing both Free software, free and ...
interface for
GNOME
A gnome () is a mythological creature and diminutive spirit in Renaissance magic and alchemy, introduced by Paracelsus in the 16th century and widely adopted by authors, including those of modern fantasy literature. They are typically depict ...
exists, specifically designed for the emerging Linux phones (such as the
Librem 5 or the
PinePhone
The PinePhone is a smartphone developed by Hong Kong–based computer manufacturer Pine64, designed to provide users with full control over the device. This is achieved through the utilization of mainline Linux-based mobile operating systems, ass ...
).
GNUnet CADET for mobile Linux – Reddit
/ref>
See also
* InterPlanetary File System
The InterPlanetary File System (IPFS) is a protocol, hypermedia and file sharing peer-to-peer network for sharing data using a distributed hash table to store provider information. By using content addressing, IPFS uniquely identifies each fi ...
* Comparison of file-sharing applications
* Synchronous conferencing
Online chat is any direct text-, audio- or video-based (webcams), one-on-one or one-to-many ( group) chat (formally also known as synchronous conferencing), using tools such as instant messengers, Internet Relay Chat (IRC), talkers and possib ...
Notes
References
Further references
*
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*
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*
*
External links
*
{{Cryptographic software
GNU Project software
Free file sharing software
Anonymity networks
Anonymous file sharing networks
Free software programmed in C
Cross-platform free software
Software using the GNU Affero General Public License
Key-based routing