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What is a transparent proxy: an easy explanation

A proxy is a server that sits between your computer (the client) and the server of the website you are trying to visit (the internet). It can filter, authenticate, and cache your requests. A transparent proxy does exactly the same while being ‘invisible’. In other words, clients whose traffic is directed through a transparent proxy aren’t aware of its existence.

Emily Green

Emily Green

Mar 27, 2019 · 3 min read

What is a transparent proxy: an easy explanation

How does a transparent proxy work?

An ordinary proxy passes your requests to the internet on your behalf. Your request will first go to a proxy server, which will then change your private IP address to a public IP and pass that information on to your destination. The proxy remembers your private IP address so that once the answer is sent back, it will recognize that you requested this information and will send it back to you. Such proxies are usually accessed via specific software or a browser extension.

Transparent proxies, on the other hand, don’t require client-side configuration. They are set up on the whole network and are invisible to individual clients. You might not even know that your traffic is being routed through a transparent proxy. Contrary to ordinary proxies, it doesn’t modify your information, meaning that the request to the destination server will appear to have come directly from you.

What is a transparent proxy used for?

Setting up proxies on individual devices is laborious. Hence why transparent proxies are usually chosen by large organizations and some ISPs. However, there are more reasons why companies choose to use them:

  1. Censorship and monitoring
  2. Many companies use transparent proxies to censor the content accessed on their networks. With a proxy, they can create website whitelists and blacklists for their employees. For example, they might block social media websites so employees wouldn’t visit them during working hours. Public organizations such as schools and libraries use them, too. Some parents might use them so their kids couldn’t access disturbing content.

    Transparent content filtering proxies also help organizations monitor users’ activity. They record what websites were visited during working hours, and how much time was spent on them. They can even log attempts to access restricted content.

  3. Save bandwidth usage
  4. A transparent proxy can also be used for caching, which helps to save bandwidth. For example, if a company has a hundred computers that all need to download a specific software update, it’s enough for one computer to request a download. It will then be cached and stored on the proxy server. When other computers request the same software, it will be sent straight from the proxy. The request will no longer be sent out to the internet and back, reducing bandwidth load and improving loading times.

    Some ISPs in countries with limited bandwidth also use caching proxies. It helps them provide faster and uninterrupted service.

  5. Authenticate users
  6. Some companies that provide public WiFi will also use a transparent proxy to authenticate users. For example, if you are trying to log on to your favorite coffee shop’s WiFi, your traffic will first be directed to a sign-in page. You will only be connected to the internet after you agree to their terms and conditions. This way, the coffee shop can verify you as a user and track the websites you visit while on their network.

Do you need one?

Do you need a transparent proxy?

Transparent proxies were invented many years ago to solve a simple problem – to direct the traffic from devices connected on the same network to the internet. Nowadays, all routers have in-built NAT, which does the same thing. Unless you need to save your company’s data or protect your kids from sensitive content, you probably don’t need a transparent proxy server.

However, if you think that you might need a proxy, you should also consider the following:

  • A proxy may reduce your internet speed, especially when authentication is involved. Your device will think that it’s talking directly to the website’s server, but it will actually be connecting to a proxy, slowing down the service or even failing to connect. The same can happen for a VPN server, but you will be receiving powerful encryption in return. Also, there are ways to speed up your VPN.
  • Internet traffic going through a proxy usually isn’t encrypted and can be intercepted by hackers. A VPN, on the other hand, encrypts your traffic and gives you full control of your privacy. You can find out the differences between the two by reading VPN vs Proxy blog post.