Avast Academy Privacy VPN What is a Proxy Server and How Does it Work?

What Is a Proxy Server and
How Does It Work?

If you’ve ever been part of a school, company, or other similar organization, you’ve likely used a web proxy server. But what does “proxy” even mean? In this article, we define proxy servers, explain how web proxies work, and, most important, show you exactly what you can and cannot expect from proxies in terms of online privacy and security.

Written by Ivan Belcic
Published on March 11, 2020

What is a proxy server?

A proxy server is a bridge between you and the rest of the internet. Normally, when you use your browser to surf the internet, you connect directly to the website you’re visiting. Proxies communicate with websites on your behalf.

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    When you use an online proxy, your browser first connects to the proxy, and the proxy forwards your traffic to the website you’re visiting. That’s why proxy servers are also known as “forward proxies.” An internet proxy will also receive the website’s response and send it back to you.

    In everyday use, the word “proxy” refers to someone who is authorized to take an action on your behalf — such as voting in a meeting that you can’t attend. A proxy server fills the same role, but online. Instead of you communicating directly with the websites you visit, a proxy steps in to handle that relationship for you.

    Web proxies and HTTP proxies

    While some proxies are hosted within your internal network, a web proxy is publicly available over the internet. Anyone can visit a web proxy and use it to browse other websites through the proxy connection.

    An HTTP proxy focuses on the connection between a web server using HTTP and a client (your device). These proxies are frequently used as safety mechanisms, checking and filtering potentially harmful HTTP content from unsecured websites before the content reaches your computer or smartphone.

    HTTP proxies also protect web servers from some types of client-side cyberattacks, including DDoS attacks that exploit buffer overflows.

    What does a proxy server do, exactly?

    As your intermediary on the web, proxy servers have many useful roles. Here’s a few of the primary uses for a proxy server:

    • Firewalls: A firewall is a type of network security system that acts as a barrier between a network and the wider internet. Security professionals configure firewalls to block unwanted access to the networks they are trying to protect, often as an anti-malware or anti-hacking countermeasure. A proxy server between a trusted network and the internet is the perfect place to host a firewall designed to intercept and either approve or block incoming traffic before it reaches the network.

    • Content filters: Just as online proxies can regulate incoming connection requests with a firewall, they can also act as content filters by blocking undesired outgoing traffic. Companies may configure proxy servers as content filters to prevent employees from accessing the blocked websites while at work.

    • Bypassing content filters: That’s right — you can outsmart a web proxy with another proxy. If your company’s proxy has blocked your favorite website, but it hasn’t blocked access to your personal proxy server or favorite web proxy, you can access your proxy and use it to reach the websites you want.

    • Caching: Caching refers to the temporary storage of frequently accessed data, which makes it easier and faster to access it again in the future. Internet proxies can cache websites so that they’ll load faster than if you were to send your traffic all the way through the internet to the website’s server. This reduces latency — the time it takes for data to travel through the internet.

    • Security: In addition to hosting firewalls, proxy servers can also enhance security by serving as the singular public face of the network. From an outside point of view, all the network’s users are anonymous, hidden behind the internet proxy’s IP address. If a hacker wants to access a specific device on a network, it’ll be a lot harder for them to find it.

    • Sharing internet connections: Businesses or even homes with a single internet connection can use a proxy server to funnel all their devices through that one connection. Using a Wi-Fi router and wireless-capable devices is another solution to this issue.

    Wait — isn't that the same as a VPN?

    Proxies and VPNs both connect you to the internet via an intermediary server, but that’s where the similarities end. While an online proxy simply forwards your traffic to its destination, a VPN encrypts all traffic between your device and the VPN server.

    Proxies, VPNs, and Tor Browser are the three primary options for putting up some sort of boundary between you and the internet, and each has its advantages and potential drawbacks.

    How does a proxy server work?

    Any device or software on the internet typically falls into one of two roles: clients or servers. A client, such as your web browser, reaches out to servers with requests for data. When you visit a website with your browser, you’re sending a request to that site’s web server.

    Servers field requests and then reply with the requested data. Behind every website is a server or group of servers that work to deliver the website to your browser. These requests and replies are known as traffic.

    Without an online proxy, your computer communicates directly with web servers. All the websites that communicate with your browser can see your computer and speak with it directly. In other words, your IP address is public knowledge. But what if you want to get rid of all that public exposure?

    A web proxy or other proxy server sits in front of the client or a network of clients and handles this traffic on its behalf. This proxy server is another computer that’s connected to both the internet as well as your computer, and it has its own IP address. Your computer speaks only to the proxy, and the proxy forwards all communication onward to the internet at large.

    And when the internet replies, the proxy passes those replies to your computer. Many proxies — but not all types — can conceal your computer’s IP address, so that the websites you’re accessing don’t know who you really are. By connecting to a proxy with an IP address in a different part of the world, you can even “change” your geographical location on the internet.

    Types of proxy servers

    There’s not just one type of forward HTTP proxy: depending on your needs, there are different types of proxy server to choose from. The primary difference between these types is the degree of privacy they provide.

    Transparent proxies

    There’s no added privacy or security with a transparent proxy. When you use one, web servers receive your actual IP address, and they also can tell that you are connecting via a proxy.

    That’s why many people use transparent proxies for content filtering or caching purposes, rather than for security reasons. For example, any proxy on a corporate or school network is likely to be a transparent proxy.

    Anonymous proxies

    Anonymous proxies promise not to pass your IP address to the websites and services you use. Websites will receive a fake IP address instead of your actual one, which is why anonymous proxies are sometimes referred to as distorting proxies.

    However, like transparent proxies, anonymous proxies also don’t conceal the fact that you’re using a proxy. If some sites choose to deny service to proxy users, you won’t be able to visit them while using an anonymous proxy. 

    Because anonymous proxies do hide your IP address, they’re not a bad choice if you’re looking to gain a bit of control over your online privacy. But your protection isn’t likely to be as strong as it would be with a VPN like Avast SecureLine VPN, which hides your IP address while also shielding your traffic from would-be snoopers with encryption.

    High anonymity proxies

    Consider high anonymity proxies — also known as elite proxies — a step up from your regular anonymous proxy. The fundamentals are the same, except high anonymity proxies also disguise your use of the proxy itself. A website won’t be able to detect that you’re using a proxy if you use one of these.

    High anonymity proxies achieve this added protection by periodically altering your new IP address and also withholding any clues that they are serving as proxies on your behalf. They’re the most secure type of proxy.

    How to find your proxy server address and proxy settings

    If you’re on a network with an internet proxy, such as while at work, you can easily find the proxy server’s address from within your computer’s settings. You might need to do this while configuring other software or apps, for example, so those programs know to use the proxy’s IP address. While you won’t be able to deactivate a proxy set by the IT team at school or in your office, you’ll at least know exactly what’s going on.

    Here’s how to find your proxy server settings in Windows 10 and macOS:

    Finding your proxy server address in the Windows 10 proxy settings

    1. Open the Windows menu in the lower-left corner of the screen, then click the cog icon to open your Settings.


    2. In the Windows Settings menu, click Network & Internet.

      Network & Internet

    3. Select Proxy on the left-hand sidebar to display your computer’s proxy settings. If your connection is routed through a proxy, you’ll see that information here.


    Finding your proxy server address in the macOS proxy settings

    1. Open the Apple Menu by clicking the Apple icon in the top-left corner of your desktop. Then, select System Preferences.

      System Preferences

    2. Select Network.


    3. In the Network menu, select the type of network you’re using: Ethernet or Wi-Fi. Then, click Advanced.


    4. Open the Proxies tab to access your proxy settings.


    5. If your computer is connected to the internet via a proxy, you’ll see your proxy address here in your proxy settings. Just choose the type of proxy you’re using.


    Proxy servers vs. reverse proxies: what's the difference?

    Both proxy servers and reverse proxies act as buffers between the internet and the computers behind them, but in two different ways. Recall that a proxy server acts on behalf of a client or client network to process traffic to and from web servers. A reverse proxy, as you might imagine, is the opposite.

    A reverse proxy stands between a collection of web servers and the internet, and handles traffic on behalf of those servers. This way, an organization with lots of different servers — for example, a large website with many types of products and services — can house all its servers behind one public-facing internet presence. Just as a forward proxy ensures that no server can ever directly contact the clients behind it, a reverse proxy insulates its servers from client traffic.

    The difference between proxies and reverse proxies is subtle, but significant. In sum: proxies sit in front of clients, and reverse proxies sit in front of servers.

    The setup process

    You can set up a proxy from within your computer’s proxy settings, as seen earlier in this article. You can also set up a proxy directly inside your browser, though in many cases, you’ll only initiate the process there and complete it within your OS settings.

    In brief, you’ll need to input your proxy address and other information in your computer or browser proxy settings. For a detailed explanation, consult our step-by-step proxy setup guide to configure your proxy settings on Windows and macOS as well as in all of the leading browsers.

    If you don’t want to go through the trouble of setting up a proxy, you can connect to one of the many web proxies available online.

    What are the main benefits of using a proxy server?

    So, why use an HTTP proxy or other type of proxy server at all? Although they might not be the most airtight options for internet privacy, they’re still popular. Let’s explore why:

    • You want control: There’s a lot of wild stuff out there on the internet. If you’re a parent looking to shield your young children from some of it, a content filtering proxy server can help.

    • You want privacy: Both anonymous and high anonymity proxies hide your IP address from the websites you use. If you don’t want sites to know where your traffic is coming from, you might consider one of these proxy types.

    • You want your favorite sites to load faster: Cache your preferred websites on an internet proxy, and they’ll load faster next time you visit them.

    • You want to access blocked content: Any proxy that alters your IP address can do so in a way that shifts your geographical location online, allowing you to possibly circumvent content restrictions. You can also use a proxy to evade content blocks on your network.

    • You want to save money: Many web proxies are free, though we can’t vouch for their security or performance. Still, if you only need the above benefits from time to time, a free web proxy may prove sufficient.

    Are there any downsides?

    Proxies have their strengths, but they’re not without their limits and disadvantages:

    • Instability: Proxies, especially free ones, aren’t known for their rock-solid performance. Prepare to experience sudden disconnects or service disruptions.

    • Slow speed: Caching proxies improve the loading times for the websites cached there, but otherwise, a proxy may slow down your connection. This is a side effect of having to route your traffic through the proxy server.

    • Limited security: Though proxies can hide your IP address and host firewalls, some won’t encrypt your traffic like a VPN can. For example, if you’re connecting to your online proxy over a wireless network, another user on that network could potentially eavesdrop on your activity. This wouldn’t be possible with a VPN. There are some proxies that do cover your traffic with HTTPS encryption, and so if security is a concern, be sure to use one of these.

    • Restricted functionality: Proxies work on an app-by-app basis, and you can’t simply set one proxy to cover your entire device.

    Use a VPN to benefit from even better security

    For true control over your internet privacy and security, a proxy simply isn’t the right tool for the job. Avast SecureLine VPN will hide your IP address and internet activity and protect you on any network, including unsecured public Wi-Fi. And with fast servers located all around the world, you can access the content you want, no matter where you are.

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    Ivan Belcic