What is a Gateway?

A Gateway is a hardware device that acts as a 'gate' between 2 different networks. It can take the form of a router, switch, server, firewall or any other device/software that enables traffic flow in or out of a network. A gateway is commonly used to protect the nodes on a network, a node being any device connected to said network, even though the gateway is itself a node. A gateway device is often considered to be on the 'edge' of a network, this is based on the theory that all external data must pass through it before it can enter the network. It could be compared to a fence around a field, to get into the field you would have to enter via a gate, this also applies to data on a network that has a gateway device to the internet. Gateways may also perform additional functions like translating data from a format it was transmitted in to a format which the network or a specific device on the network can understand.

The most common type of gateway is a router, especially in home networks. Not only does it allow data to be sent and received by devices on the network with devices outside of the network, but it also has a firewall feature. A firewall is a software based gateway, it filters all data both in and out of the network, deciding what can enter and what is restricted based on a predetermined set of rules, usually defined by a network administrator. Its primary function is to analyse data in order to spot and block unauthorised or suspicious data from entering the network.

Furthermore, a Proxy Server is another form of firewall which acts like a gateway and utilises both hardware and software to filter data packets in and out of a network. They are the simplest form of firewall and operate between the network and an application. They also provide additional functionality in the form of content caching, this quarantines all data inbound to a network and scans its integrity before being allowed in. While this process is beneficial in the form of additional security, it does slow down the overall data throughput of the firewall and isn't fully compatible with some applications.