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What is a Transparent Proxy?

Transparent Proxy Definition

What is a transparent proxy? A transparent proxy acts as a server position between a user’s device and the website they are trying to access. However, a transparent proxy server does not modify requests. That is what sets an HTTPS transparent proxy apart from a non-transparent one, which modifies a device’s requests to a website.

How Does a Transparent Proxy Work?

A transparent proxy can be installed without your knowledge and without any software or configurations on your part. It is also referred to as a "forced proxy" because it can be put in place by a webmaster or an internet service provider (ISP) without users knowing.

Transparent proxies serve as a conduit between clients and the internet, intercepting connections.

When a transparent proxy is used, a user’s actual IP address is made public in the HTTP header. Such a proxy only verifies and identifies your connection; it does not protect or modify your IP address.

Why Do Companies Use a Transparent Proxy?

Once a transparent proxy has been put into place, it is commonly used for content filtering. For example, a parent can use it to prevent their children from visiting inappropriate websites. It can be used similarly in an office setting if your company does not want users visiting certain websites, whether they contain dangerous or inappropriate material, or because they may waste employees' time. IT admins may be asked to put a transparent proxy in place.

You can also use a transparent proxy to prevent a distributed denial-of-service (DDoS) attack, which is used to overwhelm a website or web application with requests. This is because a transparent proxy can detect suspicious requests based on where they come from or the number being sent. It can then deny requests until the attack has been addressed by the security team.

Transparent Proxy for Secure Email

You could also use a transparent proxy to monitor email content and encrypt it so it cannot be read by intruders. It works by inspecting the content of emails as they get sent and received by the end user. If the transparent proxy detects malicious or suspicious content, it can discard the email, preventing it from going through.

Transparent Proxy vs. Non-Transparent Proxy

The most significant difference between a transparent and non-transparent proxy is that a non-transparent proxy modifies requests sent by the client. Also, a non-transparent proxy, unlike a transparent proxy, can hide its settings. This means that worms and spyware that need to know a proxy’s settings will not be able to get past a non-transparent proxy.

A non-transparent proxy can be used, for instance, to route all requests through a firewall, and the client, such as a web browser, knows that the requests are being sent to the firewall. On the other hand, with a transparent proxy, the client does not know its requests are getting routed through a firewall before being sent to their intended destination, such as a website.

Also, you have to configure a non-transparent proxy yourself, either using automated configuration scripts or doing it manually.

Use Cases for Transparent Proxy

A transparent proxy can be used in a variety of ways, and here are some of the most common:

1. Filtering or Censoring Content

The use of transparent proxies for censoring may be the most common. The government, businesses, and schools to block access to particular internet domains use transparent proxies. For instance, users will see an error message if they attempt to access any prohibited websites.

The error message can be configured by the organization that put the transparent proxy in place, so it can be hard to tell if it was the proxy that blocked the user from accessing the content they were after. This makes transparent proxies an effective method of preventing users from accessing potentially harmful sites—without the user knowing their traffic is being censored.

2. Authentication Gateway

Anytime you have been redirected to a web page other than the one you were trying to get to and asked for authentication information, you were interfacing with a transparent proxy. The proxy first intercepts your request and then, before allowing you to proceed, verifies your right to do so.

3. Web Caching

Web caching is another way transparent proxies are commonly used because they can reduce the amount of bandwidth your ISP has to provide as you try to access content on the internet. Web caching works by storing data that a user may want to access in the near future within the proxy's cache. When the user’s browser sends a request to access that content, the proxy intercepts the request and sends them the content the browser is looking for. This saves bandwidth because the data was saved locally on the proxy. Therefore, there was no need for it to be fetched from the original web server. As a result, the end user gets the content they want faster.

Pros and Cons of Transparent Proxies

As is the case with many technologies, transparent proxies have their pros and cons. Here are some of the most notable:


Content Filtering

You can block users from visiting certain websites and filter out harmful data by deploying and configuring a transparent proxy.

Data Compression

Due to its caching and data compression capabilities, a transparent proxy offers an effective way of presenting the same material to many users. As a result, it can be an effective option for businesses looking to boost network performance.

Functioning as a Gateway Proxy

A transparent proxy can be configured to block unwanted traffic based on a set of rules you set up. This makes it an effective way of preventing users from accessing dangerous or distracting sites.

Latency Reduction

A transparent proxy is popular among many providers because it provides latency reduction and high transmission bandwidth. This is possible because of the way a transparent proxy can cache web content and then provide it to end users faster.

DDoS Security

Additionally, a transparent proxy helps shield your server from DDoS attacks. It accomplishes this by serving as a buffer to protect your server from botnets sending unwanted requests to your websites or web applications.



Network Problems if Incorrectly Configured

A transparent proxy has the potential to drastically slow down the network if set up or configured incorrectly. Connection failures and slow speeds can be caused by improper caching and traffic redirection settings.

The Interception of Traffic and Eavesdropping

With a transparent proxy, all traffic is intercepted and subject to spying, particularly if someone has hacked your proxy. A single hack could provide access to massive volumes of sensitive data.

Data Leaks

If a hacker were to gain access to your transparency proxy, they could steal information from your organization.

How To Detect and Bypass a Transparent Proxy

When considering how to detect transparent proxy, it may be helpful to keep the following in mind: Some proxy servers can be quickly identified based on their setup, while others are more covert and challenging to detect.

One sign your traffic is being sent through a transparent proxy is when it gets rerouted to a different site before it is sent to your intended destination. For example, if you try to access a site while on a public Wi-Fi network, but you are first asked to provide login credentials, you are interacting with a transparent proxy.

To bypass a transparent proxy, you may have to use a different network. For example, suppose you want to access a site, one that your company thinks may hurt your productivity, for the sake of research. Your organization’s transparent proxy may prevent you from getting to it while connected to the network. But you can use a different network to get around the block.

For instance, you may want to check out a video that is on Facebook that can help you troubleshoot a problem that came across your desk. When you try to access the video, the transparent proxy blocks the content. To get around the proxy, you could just connect to your smartphones hotspot. Then your requests go straight to Facebook’s web server and you can watch the video.

How Fortinet Can Help

With FortiProxy, you get a secure web gateway that protects users in your organization from potentially harmful sites, dangerous malware, and DDoS attacks. In this way, you can prevent malicious actors who use the internet to launch attacks from taking advantage of employees in your company.


Is transparent proxy safe?

A transparent proxy is safe for people trying to access the internet as long as it has not been infiltrated by a hacker looking to steal sensitive information. Barring that situation, a transparent proxy simply sends web requests through to their destination, perhaps forcing the user to enter access credentials first.

What is the difference between transparent and non-transparent proxy?

The difference between a transparent and non-transparent proxy is that a non-transparent proxy alters requests and also lets the client, such as a web browser, know the request has been altered.