TL;DR
Proxy servers sit between users and destination servers, routing requests and responses while offering benefits like load balancing, Internet Protocol (IP) shielding, content caching, and protection against certain cyberattacks. They come in several types — anonymous, distorting, reverse, transparent, and web proxies — each serving distinct purposes. While proxies are powerful tools for security and performance, they can also be exploited by malicious actors, making it essential to understand both their capabilities and their risks before deployment.
What is a proxy?
A proxy is an intermediary machine that sits between a user and a destination server, handling requests and responses on the user's behalf. Requests from users go to web proxies, which evaluate requests and forward them to the destination. Responses come back to the proxy, which dutifully passes them back to the user.
It might sound unusual to filter traffic this way. Wouldn't it be easier for a user to simply talk to a destination server without another machine getting in the way?
Proxy servers come with tangible benefits that make the installation more than worthwhile. While proxies can do many things, most offer a combination of load-balancing and enhanced security. They can keep your site from crashing, getting hacked, or both.
How do IP addresses relate to proxy servers?
Web proxies are machines connected to the internet. They have two Internet Protocol (IP) addresses (one public and one private), and they can intermediate between a user and a destination server.
How do IP addresses relate to proxy servers?
Let's begin with a quick overview of IP addresses. Every machine connected to the internet has one, and it looks like a random string of numbers and dots. There are 4.3 billion IPv4 addresses and 340 trillion in IPv6. IPv4 stands for Internet Protocol version 4, and IPv6 stands for Internet Protocol version 6. The Internet Protocol, which gives its name to the IP address, is the set of rules that governs the data you or others send. You don't need to remember IP addresses to use them, as your device does a bit of fancy footwork when you visit a site.
Your computer looks for the destination's IP address. A proxy server has what your computer believes is the destination address. Meanwhile, the destination server can keep the true IP address a secret.
There are multiple types of proxy servers, including:
- Anonymous. In 2013, close to 90 percent of internet users did something to preserve their online privacy. That number has likely climbed since then. If you've ever opened up a private browsing window, you've used a form of proxy server to protect yourself.
- Distorting. This proxy passes along a fake IP address for you, which could allow you to bypass filters. If you've ever tried to load a forbidden site from a locked-down machine, and you've used a proxy to do it, you know how valuable this tool can be.
- Reverse. This is a type of proxy to watch out for and protect against. Hackers' machines forward requests to servers with a hacker in the middle. The hacker then gains credentials to the destination site, at which point they can do anything the owner of the account can do, including viewing personal information or spending money.
- Transparent. Websites know they're dealing with a proxy, but even so, your IP address is passed along between servers during the communication process.
- Web proxies. Machines pass the full URL, not just a path, during communication.
A proxy server can do multiple things, such as:
- Alter. The server alters the data you send before it hits the destination server. You may not know this is happening, as you get back information you expected.
- Shield. The proxy server shields your IP address from the destination server, so no one knows about your visit. The server can also encrypt data.
- Block. The machine keeps some destination sites from loading based on your IP address.
How does a proxy server work?
Companies install proxy servers on individual computers, outside firewalls protecting servers, or between two devices on the network.
No matter where you install it, a proxy server is essentially a computer with a unique IP address that is reachable via the internet. Proxy servers accept requests, collect responses from destinations, and forward that data to the requester.
What can you use a proxy server for?
You define what a proxy server can do when you install it.
You can use a proxy server to:
- Monitor. Collect data on the URLs accessed by specific machines in your network. Collect virus information to better protect your network.
- Improve. Proxies can distribute loads to ensure that high traffic doesn't block access. Proxies can also work as content caches, so sites load quicker for repeat users.
- Translate. Proxies can deliver customized responses in the right language based on the location connected to your IP address.
- Hide. Proxies can block the specifics of your IP address from snoopy destination sites.
- Secure. Proxies can protect against some types of web server attacks.
- Steal. Proxies can be used by malicious actors as eavesdropping devices. Any content that flows between a user and a server (including passwords) could be seen by the hacker. This is why ensuring proxies are secure is important.
What are the pros and cons of using a proxy server?
If your company doesn't have a proxy server now, should you take the plunge? Let's examine the benefits and risks.
| Benefits | Risks |
|---|---|
| Protection. Proxies prevent some hackers from entering your private network. | Risks involve malignant uses of proxies. Hackers can manipulate the protections proxies provide. And hackers can set up their own proxies to steal information from unsuspecting parties. |
| Shielding. Proxies can protect your unique IP address, and shielding functions protect addresses connected to employee devices. | |
| Hiding. Reporters, security officers, and whistleblowers need to protect their sources, companies, and clients. Proxy servers can do this, and it's a core function, according to some bloggers. | |
| Performing. Proxy servers promise quick load times and fewer crashes. |
Proxies are used as part of secure firewall systems. If you don't have a firewall now, learn more about what they are and how they can help you.
Frequently asked questions
What is the difference between an anonymous proxy and a transparent proxy?
An anonymous proxy hides your IP address from the destination server, helping preserve your online privacy. A transparent proxy, on the other hand, still passes your IP address along during communication, even though the destination site knows it is dealing with a proxy.
Can a proxy server be used against me?
Yes. Malicious actors can set up reverse proxies to intercept communications between a user and a server, potentially stealing credentials and personal information. Proxies can also be used as eavesdropping devices to capture any content — including passwords — that flows between a user and a server.
Where can a proxy server be installed?
Proxy servers can be installed on individual computers, outside firewalls that protect servers, or between two devices on a network. Regardless of placement, the proxy acts as an intermediary that accepts requests and forwards responses.
How does a proxy server improve performance?
Proxy servers can distribute traffic loads to prevent high-volume requests from blocking access. They can also function as content caches, allowing frequently visited sites to load faster for repeat users.
What are the security risks of not securing a proxy server?
An unsecured proxy can be exploited by hackers who manipulate its protections or establish their own rogue proxies to steal information from unsuspecting users. This makes it critical to ensure that any proxy deployed in your network is properly secured.
What is a distorting proxy and when is it used?
A distorting proxy passes along a fake IP address on behalf of the user, which can allow them to bypass content filters or access restricted sites from locked-down machines.
References
The Internet Is Now Officially Too Big as IP Addresses Run Out. (July 2015). NBC News.
Anonymity, Privacy, and Security Online. (September 2013). Pew Research Center.
HTTP Request Smuggling: Abusing Reverse Proxies. (June 2020). SANS.
How Website Filtering Affects Workplace Productivity. (July 2018). ZD Net.
5 Reasons Your Company Should Use Proxy Servers. (June 2016). CMS Wire.
