A gateway is a network security point that acts as an entrance to another network. On the Internet, a node or stopping point can be either a gateway node or a host (end-point) node. Both the computers of Internet users and the computers that serve pages to users are host nodes. The computers that control traffic within your company's network or at your local Internet service provider (ISP) are gateway nodes.
In the network for an enterprise, a computer server acting as a gateway node is often also acting as a proxy server and a firewall server. A gateway is often associated with both a router, which knows where to direct a given packet of data that arrives at the gateway, and a switch, which furnishes the actual path in and out of the gateway for a given packet.
The main job of a gateway is to convert protocols among communications networks. A router by itself transfers, accepts and relays packets only across networks using similar protocols. A gateway on the other hand can accept a packet formatted for one protocol (e.g. AppleTalk) and convert it to a packet formatted for another protocol (e.g. TCP/IP) before forwarding it. A gateway can be implemented in hardware, software or both, but they are usually implemented by software installed within a router. A gateway must understand the protocols used by each network linked into the router. Gateways are slower than bridges, switches and (non-gateway) routers.
Principles of a gateway are the same as a regular security guard standing, protecting, and stopping all traffic (cars) entering and exiting the street from your house. Also, he or she also checks your identification, and based on your identity they either allow you to pass through the "gate" or restrict you from entering the private street.
Question: What Is a Default Gateway?
You will sometimes see the term default gateway on network configuration screens in Microsoft Windows.
Answer: In computer networking, a default gateway is the device that passes traffic from the local subnet to devices on other subnets. The default gateway often connects a local network to the Internet, although internal gateways for local networks also exist.
Internet default gateways are typically one of two types:
- On home or small business networks with a broadband router to share the Internet connection, the home router serves as the default gateway.
- On home or small business networks without a router, such as for residences with dialup Internet access, a router at the Internet Service Provider location serves as the default gateway.
Default network gateways can also be configured using an ordinary computer instead of a router. These gateways use two network adapters, one connected to the local subnet and one to the outside network. Either routers or gateway computers can be used to network local subnets such as those in larger businesses.
In Microsoft Windows, the IP address of a computer's default gateway can be accessed in the 'ipconfig' or 'winipcfg' utilities (see sidebar).
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