Why use proxy servers in companies?

Why use proxy servers in companies?

What is a proxy server ?

What is this image ?

He went crazy ?

No, not completely, you will understand below !

Here is what we are going to watch together:

Before you start, you should know that we often talk about a proxy server, but that this is a diminutive, indeed there are several types.
I’m going to start by explaining to you what the proxy server http (also called proxy web) corresponds because it’s the one we talk about the most and it’s also the one we talk about when we use the diminutive proxy. We will then see other types of proxy servers: proxy cache, transparent proxy, reverse proxy … .


To begin with, I think it is important to clarify that the term “proxy” can be translated by agent, proxy, intermediary

So a proxy server is a server that would act as an intermediary or a server that would be mandated to do something.

Let’s try to imagine the role of a proxy server outside of IT. We could explain this like this:

You have to collect a package or do your shopping, but you cannot or do not want to go there (for lack of time, because it is far away, or for any other reason …): You send someone to do it for you. This person (this agent) will pick up the package or shop for you and bring you back what he has recovered.

Here, the principle of the proxy server (agent).

But beware, if the agent has to pay for you, you will need to give him personal information such as your credit card code, and this is where we see that we must have all confidence in this agent (or entrust it only with tasks which do not require confidential information: that is to say recover a package which does not need payment).

Let’s see this in a little more detail:

Role of the proxy server http (or proxy web) :

When you surf the Internet, your computer is directly connected. He is the one who will look for the pages as in the diagram below:

The main disadvantage of this operation is that your computer is directly exposed on the Internet. But there are other drawbacks that I will explain to you later.

If now, we place a proxy server between your computer and the Internet, we obtain the following diagram:

  • your computer is connected to the proxy server,
  • and he’s the one connected to the Internet.
  • You are asking for pages from this server,
  • he will look for the requested pages on the Internet
  • and return the requested pages to you.

Your computer requests the pages from Proxy.
This one will pick up the pages and return them to your computer.

We can see very well on this diagram that your computer does not access the Internet directly.


For all of this to work, 2 important pieces of information must be given to the browser to tell them to use a proxy server. (except in the case of a transparent proxy see below).

  1. the server address
  2. the port used to exchange data (see What is service, port, protocol ?)

The browser only knows one address: that of the proxy server !

To find out how to change these parameters, go on how to modify my proxy parameters ?

The benefits.

The advantages are numerous :

  • anonymous surfing: It is not your address that is seen on the sites, but the address of the proxy. You are thus “almost anonymous” or “completely anonymous” (see a little lower).
  • protecting your computer: You are not the front line on the Internet, so you are better protected.
  • masking your connection location: The proxy can be in a country different from yours. When connecting to a site, the geolocation of the proxy is seen, not yours. This can be useful on some sites that filter the following connections to where they come from.
  • the cache (we will come back to this later)
  • filtering: as all requests and responses go through the proxy, it is possible to filter what is allowed to come out or enter, this is the case in many companies (we will come back to this later)

The disadvantages.

Who says advantages, also says disadvantages. As we have seen above, he is the intermediary between you and the web, so he sees and can record everything that runs between your computer and the web, it can be risky ! Just imagine that the person who manages this server is ill-intentioned. It has access to your entire browsing history.
If you are using a proxy, it must be impeccable because when you connect to your bank, your proxy may very well save your codes (even if these are issued in https flows) !
So you have to use a proxy so you are sure, or not to use it: that is, to put exceptions to the use of it
. Some people at certain sites absolutely recommend using proxys to be hidden, but these same people forget to talk about the security of confidential data that you send on the Internet.

Another disadvantage of proxy is the technology used on websites. Indeed, some sites may use direct connection technologies between your computer and the web server, in this case, it may be impossible to connect to these kinds of sites if you are hidden behind a proxy. Here again you will have to put the site concerned as an exception proxy.

If the proxy server is in high demand, it may take longer to respond, so it is possible that surfing through a proxy is a little slower than direct surfing on the Internet.

Proxy exceptions.

As I said above, for some sites, it is essential not to use the proxy: then exceptions must be used. (to protect your confidential data)

A proxy exception is an IP address or URL for which your browser will not use the proxy, but will connect directly to the Internet.

Here is an example of exceptions for 2 banks and an IP network :

You may have noticed above that it is possible (but not mandatory) to use a different server by protocol.

In the following articles :

We will address the following points:

  • The other types of proxy
    • Hide,
    • Transparent
    • Reverse
    • FTP .
  • How to use a proxy
  • Proxy list available

and finally, to prove that I’m not completely crazy, the image at the beginning of the article is the logo of “Squid”, one of the most famous proxy http software on Linux and Windows. (for your culture: squid means squid !)

As usual, all comments are welcome.
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