What Is a Web Proxy Server?

An organisation uses a web proxy server for cybersecurity and performance reasons including anonymising internal IP addresses and caching content for better data transfer speeds and less bandwidth usage. Businesses that use a web proxy server can also use it to filter out content that should not be downloaded on the corporate network. These servers work as an intermediate between the web and client devices. They are mainly used in corporate environments, but some cloud hosting services offer web proxy servers for individuals with smaller bandwidth limits who need access to faster online transfer speed.

Web proxy servers have two main purposes: cybersecurity and performance. Organisations that integrate a web proxy save money on bandwidth if the server caches large files such as images and media. The cost to build a web proxy is generally low, so it’s an inexpensive part of IT that has cost-saving benefits.

Anonymising Internal IP Addresses

Internet access for employees is a must in today’s corporate world, but providing open unfettered access to the internet leaves the company vulnerable to several threats. When employees connect to an attacker-controlled server, the outgoing IP address is logged on the server. Usually, this is a router IP address, but attackers can use this IP for a denial-of-service (DoS) attack. It can also tell the attacker that your employees are browsing the site, giving attackers the ability to create more targeted attacks such phishing.

With a web proxy server, the IP shown in web logs is the web proxy’s, which means an attacker would not have access to the corporate router outgoing IP address. The attacker could still launch a DoS attack against the proxy server, but this threat is much more manageable than the internal router being targeted.

Anonymising outgoing IP addresses is also important when carrying out sensitive actions online. For example, law enforcement performing an investigation on a site would not want to expose an internal IP address that leads back to investigators. A third-party web proxy would benefit in investigations and any other internet traffic that should be anonymous.

Caching and Performance Benefits

When a user accesses a website in their browser, the browser caches files on local storage. The next time the user opens the website, the browser first looks in cache to find files and uses them to display content. The website owner and the user can choose not to allow caching, but users typically have browsers configured to show cached data instead of downloading files with every site visit. Using cached content adds performance to web browsing.

Now imagine 1000 users on a corporate network who frequent the same website. Every user must use bandwidth to browse the site and download cached files, but what if the content could be downloaded just once and distributed across all 1000 user devices? If all 1000 employees connected to a web proxy server, the proxy server would download files, cache them locally, and then distribute the cached content to user devices when they browse a frequently viewed website.

The first benefit of cached content using a web proxy is performance. Users do not need to download files again, because cached content is sent from the proxy server to the device. The second benefit is cost savings. Most business internet connections charge based on the amount of bandwidth used every month. When users download cached content, they no longer use the bandwidth that would be used had they pulled files from the origin server.

Block Unwanted Content

Corporations must give employees internet access, but phishing and malware are a threat to data integrity. There are several ways to control content on user devices, and a web proxy server is one of them. A web proxy can be configured to block content from specific IP addresses or domains.

The organisation must download a list of reported domains or use a third-party provider to block content. When a user attempts to access a blocked domain, the web proxy server notifies the user that the content is blocked. A log of the access request is also made so that administrators can identify commonly blocked content.

A corporate web proxy server has few disadvantages, but public services open for anyone to use have risks. These risks are eliminated if organisations use network controls to force users to only use the approved proxy server. Network administrators can lock web browser configurations using domain controls such as Active Directory.

Free proxy servers are the biggest risk. Attackers host web proxy servers to trick users into connecting and disclosing sensitive data. All traffic that moves through a web proxy is available to the server administrator. If this traffic is unencrypted, it could lead to identity theft or account takeover. The user gets an anonymised IP address but at the cost of their data being logged on the web proxy server.

Privacy is a typical reason for using a web proxy, but none of the data that uses the server as an intermediate is private. Users should only use free proxy servers with non-sensitive traffic and understand that it’s possible an attacker is reading browsing habits. Browsing habits can be used to target users with other attacks such as phishing.

Most public free web proxy servers do not use encryption. This means that all traffic can be read in cleartext both on the server and as it passes across the internet. This issue is not a threat to simple browsing and traffic that is not sensitive, but users should never connect to a public free web proxy while authenticating into sites that contain sensitive data such as banking accounts or ecommerce accounts with stored payment methods.

A business can set up any type of server that protects internal users, but public proxy servers offer different privacy levels. It’s important to understand the different types of proxy servers so that you know what data will be accessible to the website host server and the web proxy owner. Not every proxy server offers anonymisation of IP addresses, so connecting to one of these proxy servers offers very little privacy.

Transparent Proxy

A transparent proxy server offers the least amount of privacy. With a transparent proxy connection, the user’s IP address is passed along to the target website. The only benefit to a transparent proxy is that it caches content and will speed up performance. They can also be used to block unwanted content. Public internet providers such as libraries and schools use transparent proxies.

Web proxies use several request headers to pass the original IP to a targeted web host. The two most common are “Forwarded” and “X-Forwarded-For”. Before browsing a website with a transparent proxy, test it to identify if your original IP is forwarded.

Anonymous Proxy

Many users want anonymity while browsing the internet, and an anonymous proxy is best for non-critical traffic. An anonymous proxy is identifiable by the targeted website administrator, but it will not pass the user’s original IP address to the host. This server makes web browsing completely anonymous for users.

Distorting Proxy

A distorting proxy takes an anonymous proxy a step further and sends a false IP address to the targeted website. This server will give the impression that the user is from another location, which hides the geolocation from the website administrator.

High Anonymity Proxy

The best of all web proxies for anonymity is a high anonymity proxy. The TOR network uses high anonymity web proxy servers. These web proxy servers offer encryption, shield the user’s IP from targeted website administrators, and changes the outgoing IP periodically. This means that users maintain complete privacy including geolocation protection.

• Apache
• HAProxy
• Internet Information Services (IIS) (included with Windows server operating systems)
• Nginx
• Privoxy
• Squid

• Varnish
• WinGate
• Ziproxy
• Tinyproxy
• RabbIT
• Polipo