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Gateway is also called inter network connector or protocol converter. Gateway can be used for both WAN interconnection and LAN interconnection. It is the most complex network interconnection equipment. The structure of gateway is similar to that of router, but the difference is that they are located at different interconnection levels.

1. Gateway working level and functions

The gateway works at the transport layer or above of the OSI reference model, and most of the gateways run at the application layer. Gateway is generally used for the interconnection of two networks with different high-level protocols.

Main function: The gateway is like a translator. It is necessary to use the gateway when networking with different communication protocols, different data formats, or even different network architectures. In addition, the gateway generally has filtering and security functions.

2. Gateway classification

Gateways are roughly divided into three categories according to their functions:

(1) Protocol gateway: As the name implies, this kind of gateway is mainly used for the interconnection of networks with different network communication protocols. As shown in Figure 3-14, an intranet communicates with a remote server through the Internet. In order to eliminate the differences in communication between different networks in the Internet (that is, the communication protocols may be different), so that users located in the LAN can smoothly access the resources of the remote server, At the front end of the LAN, we need a protocol conversion tool, namely protocol gateway, through which a network can interpret data information from other networks.

It can be said that today's Internet Website construction It depends on the protocol gateway to interconnect different networks and become a truly "open" interconnected system

(2) Application gateway: gateway set for some special applications. It is mainly used to convert the data format of a service into another data format of the service, so as to realize data exchange on the network. In practical application, if there are two types below.

Mail proxy gateway: It can support a variety of mail service systems, including Exchange/Outlook of MS, Domino/Notes of Lotus, and Group Wise of Novell. It enables the mails sent by different mail systems to be correctly received by various mail systems.

WAP proxy gateway: connect the wireless network with the Internet, so that WAP enabled mobile phones in the GSM network can access Internet resources, as shown in Figure 3-15.

(3) Security gateway: The most commonly used security gateway is the packet filter.

The packet filter is to authorize the source address, destination address, port number and network protocol of the packet. By filtering these information, the security gateway intercepts or even discards packets without permission. As shown in Figure 3-16, between the external network and the internal network, the security gateway equipment constructs a wall like network boundary, and any data must be filtered by the security gateway.

In a sense, security gateways and firewalls have something in common. Security gateways have great data processing capacity and fast processing speed, which can protect the local network well without forming a network bottleneck.

From the above summary, the gateway enables us to enjoy the rich network resources of the Internet, and because of the gateway, we can create a more secure and perfect network environment.

What is a gateway?

Date：2015-06-25 Source: Shangpin China Type: website encyclopedia
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