A gateway is a piece of networking hardware or software used in

telecommunications network A telecommunications network is a group of Node (networking), nodes interconnected by telecommunications links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit ...

s that allows data to flow from one discrete network to another. Gateways are distinct from routers or switches in that they communicate using more than one protocol to connect multiple networks and can operate at any of the seven layers of the

OSI model The Open Systems Interconnection (OSI) model is a reference model developed by the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems inter ...

. The term ''gateway'' can also loosely refer to a computer or computer program configured to perform the tasks of a gateway, such as a

default gateway A default gateway is the node in a computer network using the Internet protocol suite that serves as the forwarding host ( router) to other networks when no other route specification matches the destination IP address of a packet. Role A gatew ...

or router, and in the case of

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 ...

, gateway is also often used as a synonym for reverse proxy. It can also refer to a device installed in homes that combines router and modem functionality into one device, used by ISPs, also called a residential gateway.

Network gateway

A network gateway provides a connection between networks and contains devices, such as protocol translators, impedance matchers, rate converters, fault isolators, or

signal A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...

translators. A network gateway requires the establishment of mutually acceptable administrative procedures between the networks using the gateway. Network gateways, known as protocol translation gateways or mapping gateways, can perform protocol conversions to connect networks with different network protocol technologies. For example, a network gateway connects an office or home

intranet An intranet is a computer network for sharing information, easier communication, collaboration tools, operational systems, and other computing services within an organization, usually to the exclusion of access by outsiders. The term is used in ...

to the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

. If an office or home computer user wants to load a

web page A web page (or webpage) is a World Wide Web, Web document that is accessed in a web browser. A website typically consists of many web pages hyperlink, linked together under a common domain name. The term "web page" is therefore a metaphor of pap ...

, at least two network gateways are accessed—one to get from the office or home network to the Internet and one to get from the Internet to the computer that serves the web page. On an

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP ...

(IP) network, IP packets with a destination outside a given

subnetwork A subnet, or subnetwork, is a logical subdivision of an IP network. Updated by RFC 6918. The practice of dividing a network into two or more networks is called subnetting. Computers that belong to the same subnet are addressed with an identic ...

are sent to the network gateway. For example, if a private network has a base

IPv4 Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. ...

address of 192.168.1.0 and has a subnet mask of 255.255.255.0, then any data addressed to an IP address outside of 192.168.1.0–192.168.1.255 is sent to the network gateway.

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

networks work in a similar way. While forwarding an IP packet to another network, the gateway may perform

network address translation Network address translation (NAT) is a method of mapping an IP address space into another by modifying network address information in the IP header of packets while they are in transit across a traffic Router (computing), routing device. The te ...

. In enterprise networks, a network gateway usually also acts as a proxy server and a firewall. On Microsoft Windows, the Internet Connection Sharing feature allows a computer to act as a gateway by offering a connection between the Internet and an internal network.

Internet-to-orbit gateway

An Internet-to-orbit gateway (I2O) connects computers or devices on the Internet to computer systems orbiting Earth, such as satellites or crewed spacecraft. Project HERMES, run by the Ecuadorian Civilian Space Agency, was first to implement this kind of gateway on June 6, 2009. Project HERMES has a maximum coverage of 22,000 km and can transmit voice and data. The Global Educational Network for Satellite Operations (GENSO) is another type of I2O gateway.

Cloud storage gateway

A cloud storage gateway is a network appliance or server which translates cloud storage APIs such as

SOAP Soap is a salt (chemistry), salt of a fatty acid (sometimes other carboxylic acids) used for cleaning and lubricating products as well as other applications. In a domestic setting, soaps, specifically "toilet soaps", are surfactants usually u ...

or REST to block-based storage protocols such as iSCSI, Fiber Channel or file-based interfaces such as NFS or CIFS. Cloud storage gateways enable companies to integrate private cloud storage into applications without moving the applications into a public cloud, thereby simplifying data protection.

IoT gateway

Internet of things Internet of things (IoT) describes devices with sensors, processing ability, software and other technologies that connect and exchange data with other devices and systems over the Internet or other communication networks. The IoT encompasse ...

(IoT) gateway provides the bridge (protocol converter) between IoT devices in the field, the cloud, and user equipment such as smartphones. The IoT gateway provides a communication link between the field and the cloud, and may provide offline services and real-time control of devices in the field. To achieve sustainable interoperability in the Internet of things ecosystem, two dominant architectures for data exchange protocols are used: bus-based ( DDS, REST,

XMPP Extensible Messaging and Presence Protocol (abbreviation XMPP, originally named Jabber) is an Open standard, open communication protocol designed for instant messaging (IM), presence information, and contact list maintenance. Based on XML (Ext ...

) and broker-based ( AMQP, CoAP, MQTT, JMI). Protocols that support information exchange between interoperable domains are classified as message-centric (AMQP, MQTT, JMS, REST) or data-centric (DDS, CoAP, XMPP).Bryon Moyer.
All About Messaging Protocols What Are the Differences?
. EE JOURNAL. April 20, 2015 Interconnected devices communicate using lightweight protocols that don't require extensive CPU resources. C, Java, Python and some scripting languages are the preferred choices of IoT application developers. IoT nodes use separate IoT gateways to handle protocol conversion, database storage or decision making (e.g. collision handling), in order to supplement the low intelligence of devices.

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