TRANSPARENT PROXY

What is Transparent Proxy?

Transparent proxies are intermediary systems that sit between a user and a content provider. When a user makes a request to a web server, the transparent proxy intercepts the request to perform various actions including caching, redirection and authentication. A proxy server that does modify the requests and responses id defined as a non-transparent proxy.

Transparent proxy means it is transparent. Also the original IP address available through a header. It can be easily detected. However, the use of a transparent proxy will get you around simple IP logs.

A transparent proxy can be used for various reasons, such as content filtering in schools and libraries, and as it does not need any configuration on the client side, it can be an easy-to-maintain alternative to other proxy types.

A software like Squid can make it easier to set up a free transparent proxy that you can control. Like any other proxy service or VPNs, you don't need to download any app or program to use the transparent proxy. Instead, it depends on how your network is configured.

How Transparent proxy works?

Transparent proxies act as intermediaries between a user and a web service. When a user connects to a service, the transparent proxy intercepts the request before passing it on to the provider. Transparent proxies are considered transparent because the user isn’t aware of them. On the other hand, the servers hosting the service recognize that the proxied traffic is coming from a proxy and not directly from the user.

Use of Transparent Proxies:

Transparent proxies are extremely versatile. The following list contains common examples of how transparent proxies are used

Proxy cache creates copies of the data stored on a server and serve the cached content to users. This reduces the strain on the web service by having the proxy provide the content instead of the service itself.

Filtering proxies prevent access to certain websites or web services. These are commonly implemented by organizations to prevent users from accessing resources that are unrelated or disruptive to the organization

Gateway proxies modify or block network traffic based on certain rules. Locations that offer public Wi-Fi often implement gateways that require users to register or accept an agreement before they can use the service.

Why use a Transparent Proxy?

There are several reasons why a transparent proxy may want to be implemented. As mentioned, they are used primarily at large organization but are also present in the infrastructure of certain Internet Service Providers (ISP’s) in order to reduce bandwidth usage by taking advantage of caching. Here are a few more scenarios that might arise within an organization that makes the transparent proxy a useful tool.

You want clients to use a proxy whether they want to or not.
You want to set up a proxy without having to configure each machine manually.
You don’t want clients to know their requests are running through a proxy.

Although the transparency factor can be an advantage in keeping it unknown to the client that they are being proxied, there are a few ways to detect that a proxy is being used. Detecting the transparent proxy can be done in a number of ways including:

Examining the traceroute for a proxied protocol (post 80) vs a non-proxied protocol (post 25)
Comparing results of online IP checkers using HTTP vs HTTPS
Examining the response when trying to connect to an IP where there is known to be no server
TCP Intercept is a traffic filtering security feature that protects TCP servers from TCP SYN flood attacks, which are a type of denial-of-service attack. TCP Intercept is available for IP traffic only.

In 2009 a security flaw in the way that transparent proxies operate was published by Robert Auger, and the Computer Emergency Response Team issued an advisory listing dozen of affected transparent and intercepting proxy servers.

How to detect if you are behind a proxy:

Depending on their configuration, detecting some proxy servers is easy, though others are more hidden and are difficult to spot.

A good way to check is to attempt a connection to a server that you know does not exist. Your browser will commonly throw a recognizable error when the connection fails. But if you are behind a proxy this error might be different, or instead, you might be redirected to a search pages