{"id":72180,"date":"2024-01-16T14:36:10","date_gmt":"2024-01-16T17:36:10","guid":{"rendered":"https:\/\/a3aengenharia.com\/en-us\/content\/technical-articles\/what-is-a-proxy-server\/"},"modified":"2026-04-29T16:49:33","modified_gmt":"2026-04-29T19:49:33","slug":"what-is-a-proxy-server","status":"publish","type":"articles","link":"https:\/\/a3aengenharia.com\/en-us\/content\/technical-articles\/what-is-a-proxy-server\/","title":{"rendered":"What Is a Proxy Server?"},"content":{"rendered":"

In computer networks, a Proxy Server<\/b> is a system or application that acts as an intermediary for client requests seeking resources from other servers. When a client connects to the proxy server and requests a service (such as a file, connection, web page, or other resources) from a different server, the proxy evaluates the request in order to simplify and control its complexity. Proxy servers were developed to add structure and encapsulation to distributed systems.<\/p>\n

Today, most proxies are web-based, making access to content on the World Wide Web easier and providing anonymity. They have a variety of uses, including content filtering and anonymity. In addition, a proxy server can modify the client request or the server response and, in some cases, can offer this feature even without connecting to the specified server.<\/p>\n

Proxy servers can also function as cache servers, temporarily storing data in computer networks. They are usually installed on machines with connections superior to those of the clients and with high storage capacity.<\/p>\n

A specific example is the HTTP cache proxy, which allows the client to request a document on the World Wide Web. The proxy looks for the document in its cache and, if found, handles the request and immediately returns the document. If it is not found, the proxy fetches the document from the remote server, delivers it to the client, and saves a copy in its cache. This results in reduced latency because it is the proxy server, rather than the original server, that is queried, while also reducing bandwidth usage.<\/p>\n

The Origin of Proxy Servers<\/h2>\n

The proxy server was conceived to meet the need to connect a Local Area Network (LAN)<\/a> to the Internet through a computer on the network that shares its connection with the other machines. In other words, if we consider the local network as an “internal” network and the Internet as an “external” network, the proxy server is the element that allows other machines to obtain external access.<\/p>\n

Normally, machines on the internal network do not have valid IP addresses on the Internet and therefore do not have a direct connection to it. Thus, any connection request from a machine on the local network to a machine on the Internet is directed to the proxy server. The proxy server, in turn, establishes contact with the desired machine and forwards the response back to the local network machine.<\/p>\n

Forward Proxy<\/h2>\n
\"A<\/figure>\n<\/p>\n

The Forward Proxy is an intermediary component that acts on the client side, representing it in communication with the server. There are three fundamental applications for a Forward Proxy:<\/p>\n

Shared Cache System<\/h2>\n

This system is intended to optimize performance when accessing static resources on a local network. The Forward Proxy caches resources that are frequently accessed, sharing them among all machines on the network. However, with the increase of encrypted traffic, this practice becomes less effective, because it prevents the Proxy from mediating encrypted traffic.<\/p>\n

Currently, the trend is toward increasingly encrypted traffic. When you access a website and see the padlock symbol next to the address bar, this means that the site and all its content are encrypted from the server to your web browser. This includes static resources, such as images. When traffic is encrypted, the Proxy server cannot cache that static resource.<\/p>\n

Therefore, the use of the Shared Cache System is increasingly falling out of use. Traffic encryption, which is a growing practice to ensure data security, makes Proxy mediation ineffective. As a result, the point of having this type of system is being lost. Organizations are seeking other solutions to optimize performance when accessing static resources on a local network.<\/p>\n

Privacy or Origin Masking<\/h2>\n

In this context, the Forward Proxy acts as an external intermediary with the objective of hiding the true origin of the traffic. When a client accesses the Proxy, it forwards the request to the destination server, causing the server to interpret that the traffic originates from the Proxy, thus hiding the client’s real identity.<\/p>\n

This method has several practical applications. For example, if a website in Europe is blocking access coming from a local network or from a specific country, such as Brazil, a Proxy server located in a country that is not being blocked (such as the United States) can be used to bypass that restriction. The client connects to the Proxy server in the United States, which then accesses the web server in Europe. To the server in Europe, it appears that the access is coming from the United States.<\/p>\n

However, there are some disadvantages to this method. The main one is the security issue. The Proxy server is an intermediary machine in network traffic and may not be trustworthy, especially if it is a public Proxy server available on the Internet. The owner of that Proxy server may be monitoring the traffic that passes through it. In addition, Proxy servers generally only serve web traffic, that is, access to Internet pages. This is because Proxy servers are protocol-specific. Even with SOCKS proxies, some protocols and applications cannot be configured to use a proxy server.<\/p>\n

For these reasons, the use of Proxy servers for origin masking is becoming less common. Instead, VPN Servers<\/a> are being used more and more often. VPN servers offer encryption and other advantages, making them a safer and more flexible option for origin masking.<\/p>\n

Access Control<\/h2>\n

In the context of the Forward Proxy, it assumes the role of implementing restrictive policies for Internet access on the local network. Configurable rules on the Proxy include time restrictions, blocking of websites based on keywords or specific policies. It works, essentially, like a firewall, controlling traffic from the client toward the Internet.<\/p>\n

A practical example of this can be found in many hotels around the world. When a guest connects to the hotel’s network and tries to browse the Internet, any site they attempt to access redirects them to a hotel authentication page. This page asks for information such as the room number and the guest’s surname. Once the guest is properly authenticated, Internet access is released. This is an example of access control implemented through a Forward Proxy.<\/p>\n

Reverse Proxy<\/h2>\n
\"A<\/figure>\n<\/p>\n

A Reverse Proxy acts as a representative of a server, serving as an intermediary in communication between the client and the server, but always representing the server side. There are three typical applications for a Reverse Proxy.<\/p>\n

Access Control<\/h2>\n

The first application is access control, also known as a firewall. As mentioned earlier, a firewall can function either as a Forward Proxy or as a Reverse Proxy, depending on its location and the direction of the traffic.<\/p>\n

A practical example of this can be seen when a web server located in Europe blocks traffic originating from Brazil. In this case, the rule configured in the firewall of the network connected to that server is “Block all traffic originating from Brazil.”<\/p>\n

There are many possible configurations in a firewall, ranging from blocking entire countries, blocking specific machines, to blocking based on access rules or patterns. Therefore, a firewall offers a wide range of filtering possibilities.<\/p>\n

CDN System (Content Delivery Network)<\/h2>\n
\"Two<\/figure>\n<\/p>\n

The second typical application of a Reverse Proxy is the CDN system (Content Delivery Network), also known as a content distribution network or content delivery network. A CDN is a specialized company that provides several servers at strategic points around the world. These servers act as intermediaries for Web servers.<\/p>\n

When you own a Web server and hire the services of a CDN, you gain access to a network of servers spread across the world. This network becomes available to you automatically. When a client tries to access your site, they are actually interacting with the CDN server geographically closest to them. This increases performance because the client never accesses your server directly, but rather the CDN server, which acts as a Reverse Proxy.<\/p>\n

The CDN server stores the static resources of your site in cache, such as images and style sheets. This allows the content to be delivered more quickly to the client. In addition, the CDN can function as a firewall, offering an extra layer of protection. You can configure traffic filtering parameters on the CDN servers. For example, you can filter access from clients in certain countries to your website.<\/p>\n

This configuration provides additional protection, and you do not necessarily need to have a firewall near your server, because the CDN, also being a Reverse Proxy, normally offers a control panel containing a firewall. Therefore, CDN servers can function as a filter, blocking or controlling access.<\/p>\n

In addition to access control, CDN servers may also have integrated optimization options to further improve performance. For example, they can optimize your site’s source code, delivering optimized code to the client, which will load the site and its resources more quickly.<\/p>\n

Another common optimization example is image optimization. Since the CDN stores static files, especially images, you can activate, if the platform offers this option, an image optimization feature. This means taking a large image and reducing its size, without quality loss, in order to deliver a smaller file to the client. Transferring a smaller file takes less time than transferring a larger one.<\/p>\n

Therefore, a CDN server can offer various optimization options, depending on the platform you hire. These are just some generic possibilities to help you understand what is meant by optimizations.<\/p>\n

Load Balancer<\/h2>\n

The third typical application of a Reverse Proxy is to act as a load balancer. Load balancing is a crucial process when a service is highly requested and a single machine may not be able to handle all the requests.<\/p>\n

For example, consider the Web server of a very popular site, such as Google. Google does not depend on a single server, but rather on a network of Web servers to handle the countless requests it receives per second.<\/p>\n

When you access Google’s website, you are not directly accessing a Web server. Instead, you are interacting with a load balancing system, which is a load balancer. This load balancer forwards your request to a Web server in Google’s network of Web servers.<\/p>\n

The load balancer can operate in two ways. It can simply perform a round-robin system, sending traffic to the first server, then to the second, and so on. Alternatively, it can be more intelligent and read the load level of each server, sending traffic to the server that is least busy.<\/p>\n

This is a common application in practice and is not restricted to Web servers. Load balancing can also be applied to e-mail services.<\/i><\/p>\n","protected":false},"excerpt":{"rendered":"

Understand what a proxy server is, how forward and reverse proxies work, and the main roles of caching, access control, privacy, CDN, and load balancing in computer networks.<\/p>\n","protected":false},"author":0,"featured_media":23407,"parent":0,"template":"","meta":{"_a3a_post_lang":"en-us","_a3a_translation_group_id":"aacf2c6c-b76f-4d7c-95a0-651d5674a14d","_a3a_i18n_canonical_slug":"what-is-a-proxy-server"},"categories":[307],"class_list":["post-72180","articles","type-articles","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles\/72180","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles"}],"about":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/types\/articles"}],"version-history":[{"count":1,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles\/72180\/revisions"}],"predecessor-version":[{"id":72181,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/articles\/72180\/revisions\/72181"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/media\/23407"}],"wp:attachment":[{"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/media?parent=72180"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/a3aengenharia.com\/en-us\/wp-json\/wp\/v2\/categories?post=72180"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}