A proxy server is a computer system or router that functions as a relay between client and server. It helps prevent an attacker from invading a private network and is one of several tools used to build a firewall. The word proxy means “to act on behalf of another,” and a proxy server acts on behalf of the user.
It is a server (a computer system or an application) that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or another resource available from a different server and the proxy server evaluates the request as a way to simplify and control its complexity. Proxies were invented to add structure and encapsulation to distributed systems. Today, most proxies are web proxies, facilitating access to content on the World Wide Web and providing anonymity.
Types
Types of proxy – A proxy server may reside on the user’s local computer, or at various points between the user’s computer and destination servers on the Internet.
- A proxy server that passes requests and responses unmodified is usually called a gateway or sometimes a tunneling proxy.
- A forward proxy is an Internet-facing proxy used to retrieve from a wide range of sources (in most cases anywhere on the Internet).
- A reverse proxy is usually an Internet-facing proxy used as a front-end to control and protect access to a server on a private network. A reverse proxy commonly also performs tasks such as load-balancing, authentication, decryption, or caching.
A proxy server may reside on the user’s local computer, or at any point between the user’s computer and destination servers on the Internet. A proxy server that passes unmodified requests and responses is usually called a gateway or sometimes a tunneling proxy. A forward proxy is an Internet-facing proxy used to retrieve data from a wide range of sources (in most cases anywhere on the Internet). A reverse proxy is usually an internal-facing proxy used as a front-end to control and protect access to a server on a private network. A reverse proxy commonly also performs tasks such as load-balancing, authentication, decryption, and caching.[rx]
Open proxies
An open proxy forwarding requests from and to anywhere on the Internet.
An open proxy is a forwarding proxy server that is accessible by any Internet user. In 2008, network security expert Gordon Lyon estimates that “hundreds of thousands” of open proxies are operated on the Internet.[rx]
- Anonymous proxy – This server reveals its identity as a proxy server but does not disclose the originating IP address of the client. Although this type of server can be discovered easily, it can be beneficial for some users as it hides the originating IP address.
- Transparent proxy – This server not only identifies itself as a proxy server but with the support of HTTP header fields such as, the originating IP address can be retrieved as well. The main benefit of using this type of server is its ability to cache a website for faster retrieval.
Reverse proxies
A reverse proxy takes requests from the Internet and forwards them to servers in an internal network. Those making requests connect to the proxy and may not be aware of the internal network.
A reverse proxy (or surrogate) is a proxy server that appears to clients to be an ordinary server. Reverse proxies forward request to one or more ordinary servers that handle the request. The response from the proxy server is returned as if it came directly from the original server, leaving the client with no knowledge of the original server.[rx] Reverse proxies are installed in the neighborhood of one or more web servers. All traffic coming from the Internet and with a destination of one of the neighborhood’s web servers goes through the proxy server. The use of reverse originates in its counterpart forward proxy since the reverse proxy sits closer to the web server and serves only a restricted set of websites. There are several reasons for installing reverse proxy servers:
- Encryption/SSL acceleration: when secure websites are created, the Secure Sockets Layer (SSL) encryption is often not done by the web server itself, but by a reverse proxy that is equipped with SSL acceleration hardware. Furthermore, a host can provide a single “SSL proxy” to provide SSL encryption for an arbitrary number of hosts, removing the need for a separate SSL server certificate for each host, with the downside that all hosts behind the SSL proxy have to share a common DNS name or IP address for SSL connections. This problem can partly be overcome by using the SubjectAltName feature of X.509 certificates.
- Load balancing: the reverse proxy can distribute the load to several web servers, each web server serving its own application area. In such a case, the reverse proxy may need to rewrite the URLs in each web page (translation from externally known URLs to the internal locations).
- Serve/cache static content: A reverse proxy can offload the web servers by caching static content like pictures and other static graphical content.
- Compression: the proxy server can optimize and compress the content to speed up the load time.
- Spoon feeding: reduces resource usage caused by slow clients on the web servers by caching the content the web server sent and slowly “spoon feeding” it to the client. This especially benefits dynamically generated pages.
- Security: the proxy server is an additional layer of defense and can protect against some OS and web-server-specific attacks. However, it does not provide any protection from attacks against the web application or service itself, which is generally considered the larger threat.
- Extranet Publishing: a reverse proxy server facing the Internet can be used to communicate to a firewall server internal to an organization, providing extranet access to some functions while keeping the servers behind the firewalls. If used in this way, security measures should be considered to protect the rest of your infrastructure in case this server is compromised, as its web application is exposed to attack from the Internet.
There are several reasons for installing reverse proxy servers
- Encryption / SSL acceleration: when secure websites are created, the SSL encryption is often not done by the web server itself, but by a reverse proxy that is equipped with SSL acceleration hardware. See Secure Sockets Layer. Furthermore, a host can provide a single “SSL proxy” to provide SSL encryption for an arbitrary number of hosts; removing the need for a separate SSL Server Certificate for each host, with the downside that all hosts behind the SSL proxy have to share a common DNS name or IP address for SSL connections. This problem can partly be overcome by using the SubjectAltName feature of X.509 certificates.
- Load balancing: the reverse proxy can distribute the load to several web servers, each web server serving its own application area. In such a case, the reverse proxy may need to rewrite the URLs in each web page (translation from externally known URLs to the internal locations).
- Serve/cache static content: A reverse proxy can offload the web servers by caching static content like pictures and other static graphical content.
- Compression: the proxy server can optimize and compress the content to speed up the load time.
- Spoon feeding: reduces resource usage caused by slow clients on the web servers by caching the content the web server sent and slowly “spoon feeding” it to the client. This especially benefits dynamically generated pages.
- Security: the proxy server is an additional layer of defense and can protect against some OS and Web Server-specific attacks. However, it does not provide any protection from attacks against the web application or service itself, which is generally considered the larger threat.
- Extranet Publishing: a reverse proxy server facing the Internet can be used to communicate to a firewall server internal to an organization, providing extranet access to some functions while keeping the servers behind the firewalls. If used in this way, security measures should be considered to protect the rest of your infrastructure in case this server is compromised, as its web application is exposed to attack from the Internet.
If the destination server filters content based on the origin of the request, the use of a proxy can circumvent this filter. For example, a server using IP-based geolocation to restrict its service to a certain country can be accessed using a proxy located in that country to access the service.
Web proxies are the most common means of bypassing government censorship, although no more than 3% of Internet users use any circumvention tools. In some cases, users can circumvent proxies that filter using blacklists using services designed to proxy information from a non-blacklisted location.
Proxies can be installed in order to eavesdrop upon the data flow between client machines and the web. All content sent or accessed – including passwords submitted and cookies used – can be captured and analyzed by the proxy operator. For this reason, passwords to online services (such as webmail and banking) should always be exchanged over a cryptographically secured connection, such as SSL. By chaining proxies which do not reveal data about the original requester, it is possible to obfuscate activities from the eyes of the user’s destination. However, more traces will be left on the intermediate hops, which could be used or offered up to trace the user’s activities. If the policies and administrators of these other proxies are unknown, the user may fall victim to a false sense of security just because those details are out of sight and mind. In what is more of an inconvenience than a risk, proxy users may find themselves being blocked from certain Web sites, as numerous forums and Web sites block IP addresses from proxies known to have spammed or trolled the site. Proxy bouncing can be used to maintain your privacy.
Anonymizer
An anonymizer or an anonymous proxy is a tool that attempts to make activity on the Internet untraceable. It is a proxy server computer that acts as an intermediary and privacy shield between a client computer and the rest of the Internet. It accesses the Internet on the user’s behalf, protecting personal information by hiding the client computer’s identifying information.
There are many reasons for using anonymizers. Anonymizers help minimize risk. They can be used to prevent identity theft or to protect search histories from public disclosure. Some countries apply heavy censorship on the internet. Anonymizers can help in allowing free access to all of the internet content, but cannot help against persecution for accessing the Anonymizer website itself. Furthermore, as the information itself about Anonymizer websites are banned in these countries, users are wary that they may be falling into a government-set trap.
Anonymizers are also used by people who wish to receive objective information with the growing target marketing on the internet and targeted information. For example, large news outlets such as CNN target the viewers according to the region and give different information to different populations. Websites such as YouTube obtain information about the last videos viewed on a computer and propose “recommended” videos accordingly, and most of the online targeted marketing is done by showing advertisements according to that region. Anonymizers are used for avoiding this kind of targeting and getting a more objective view of information.
Types
- Protocol specific anonymizers – Sometimes anonymizers are implemented to work only with one particular protocol. The advantage is that no extra software is needed. The operation occurs in this manner: A connection is made by the user to the anonymizer. Commands to the anonymizer are included inside a typical message. The anonymizer then makes a connection to the resource specified by the inbound command and relays the message with the command stripped out. An example of a protocol-specific anonymizer is an anonymous remailer for e-mail. Also of note are web proxies, and bouncers for FTP and IRC.
- Protocol independent anonymizers – Protocol independence can be achieved by creating a tunnel to an anonymizer. The technology to do so varies. Protocols used by anonymizer services may include SOCKS, PPTP, or OpenVPN. In this case either the desired application must support the tunneling protocol, or a piece of software must be installed to force all connections through the tunnel. Web browsers, FTP and IRC clients often support SOCKS for example, unlike telnet.
How a Proxy Works
Because a proxy server has its own IP address, it acts as a go-between for a computer and the internet. Your computer knows this address, and when you send a request on the internet, it is routed to the proxy, which then gets the response from the web server and forwards the data from the page to your computer’s browser, like Chrome, Safari, Firefox, or Microsoft Edge
How to Get a Proxy
There are hardware and software versions. Hardware connections sit between your network and the internet, where they get, send, and forward data from the web. Software proxies are typically hosted by a provider or reside in the cloud. You download and install an application on your computer that facilitates interaction with the proxy.
Often, a software proxy can be obtained for a monthly fee. Sometimes, they are free. The free versions tend to offer users fewer addresses and may only cover a few devices, while the paid proxies can meet the demands of a business with many devices.
How Is the Server Set Up?
To get started with a proxy server, you have to configure it in your computer, device, or network. Each operating system has its own setup procedures, so check the steps required for your computer or network.
In most cases, however, setup means using an automatic configuration script. If you want to do it manually, there will be options to enter the IP address and the appropriate port.
How Does the Proxy Protect Computer Privacy and Data?
A proxy server performs the function of a firewall and filter. The end-user or a network administrator can choose a proxy designed to protect data and privacy. This examines the data going in and out of your computer or network. It then applies rules to prevent you from having to expose your digital address to the world. Only the proxy’s IP address is seen by hackers or other bad actors. Without your personal IP address, people on the internet do not have direct access to your personal data, schedules, apps, or files.
With it in place, web requests go to the proxy, which then reaches out and gets what you want from the internet. If the server has encryption capabilities, passwords and other personal data get an extra tier of protection.
Benefits of a Proxy Server
Proxies come with several benefits that can give your business an advantage:
- Enhanced security: Can act like a firewall between your systems and the internet. Without them, hackers have easy access to your IP address, which they can use to infiltrate your computer or network.
- Private browsing, watching, listening, and shopping: Use different proxies to help you avoid getting inundated with unwanted ads or the collection of IP-specific data.
- Access to location-specific content: You can designate a proxy server with an address associated with another country. You can, in effect, make it look like you are in that country and gain full access to all the content computers in that country are allowed to interact with.
- Prevent employees from browsing inappropriate or distracting sites: You can use it to block access to websites that run contrary to your organization’s principles. Also, you can block sites that typically end up distracting employees from important tasks. Some organizations block social media sites like Facebook and others to remove time-wasting temptations.
Proxy Server vs. VPN
On the surface, proxy servers and virtual private networks (VPNs) may seem interchangeable because they both route requests and responses through an external server. Both also allow you to access websites that would otherwise block the country you’re physically located in. However, VPNs provide better protection against hackers because they encrypt all traffic.
Choosing VPN or Proxy
If you need to constantly access the internet to send and receive data that should be encrypted or if your company has to reveal data you must hide from hackers and corporate spies, a VPN would be a better choice.
If an organization merely needs to allow its users to browse the internet anonymously, a proxy server may do the trick. This is the better solution if you simply want to know which websites team members are using or you want to make sure they have access to sites that block users from your country.
A VPN is better suited for business use because users usually need secure data transmission in both directions. Company information and personnel data can be very valuable in the wrong hands, and a VPN provides the encryption you need to keep it protected. For personal use where a breach would only affect you, a single user, a proxy server may be an adequate choice. You can also use both technologies simultaneously, particularly if you want to limit the websites that users within your network visit while also encrypting their communications.