Proxy servers can help with everything from network security and privacy, to content filtering and efficiency, but what exactly are they? Discover more about proxy servers and how they operate below.

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What does a proxy server do?

A proxy server is a computer system that acts as a middleman between your computer and the server you're trying to access over the Internet. When your device is connected to a proxy, it will intercept the information you transmit from your computer, as well as the information being transmitted by the server of any website you access.

A proxy server can allow for anonymity as by randomly generating your computers IP address, your location can be unknown (our page explains more about IP addresses).

How does it work?

A proxy server works by intercepting connections between a sender and a receiver. All incoming data enters through one port and is forwarded to the rest of the network via another port, acting as a buffer between the data being transmitted by an Internet server to a computer, and vice versa.

This means that when a request is made over the Internet, such as downloading a file or accessing a web page, the information is passed first to the proxy, then to the computer that has made the request. This process removes any direct contact between the source and the computer that has made a request, allowing a proxy to do things like block certain websites or types of content, improve speed and performance, or prevent hackers or malicious programs from having direct access to your computer.

Why use one?

The main benefit of a proxy server is safety. As a proxy acts as a halfway house between your computer and the Internet and makes it significantly more difficult for hackers or malicious programs to access or attack your machine.

This is also true for businesses, as a proxy can use a technique called network address translation, making all the computers on a network anonymous, reducing the risk of an individual computer being targeted, or compromised, by hackers or viruses.

There are plenty of reasons why a proxy server might come in handy, with privacy, performance, and security among some of the chief reasons for using one. Some of the most common proxy types are explained below:

How does a content filtering proxy work?

A content filtering proxy server can be used within a workplace to implement filters on Internet usage and to block certain websites or types of content. This is especially useful in situations where inappropriate content must be censored, like schools or Internet cafés.

This works by analysing requests made by a computer, and then deciding whether this search term, website, or download, violates the content rules that have been set on the proxy server. If a computer makes a request for content that is inappropriate, it's intercepted by the proxy which determines if the request breaks any rules – then blocks the request so it never reaches the target server, preventing access. This can be a common practice in some offices, especially those where access to social media is prohibited.

In some cases, content filtering proxies can slow down your connection, as everything you input must be sent to a third party.

What is an open proxy?

An open proxy can be used via the Internet by anyone, instead of a closed proxy, which only allows users within a network group access, e.g. a content filtering proxy.

Open proxies are sometimes installed on devices by malware and viruses without the knowledge of the user, allowing hackers to hide their activity behind the location of the infected computer. Open proxies are also used to facilitate email spam using a similar method, using multiple networks of infected machines to avoid detection.

What is a caching server?

A caching server is used to improve performance by saving web pages in its memory (or "cache"), so it can serve web pages quicker without loading them from scratch. Caching proxies store a copy of a requested web page locally, so that when a user wants to see the same web page again, it loads the copy, which vastly improves performance speed.

These types of proxies are particularly useful in scientific fields, or any occasion where large amounts of data would put pressure on server performance if new requests were made often. One downside to cached websites is that the information will often be out of date, as the server will display the older version which has been saved to its cache. On this occasion, the cache must be emptied (or 'flushed') to remove the out of date version and make a copy of the newest one.

Want to know more about Internet safety?

Check out our page explaining the data behind malware, viruses, and more.

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