Also known as a Proxy or an Application-level Gateway, a proxy server is a server (either a computer system or an application) that serves as a hub for requests from clients seeking resources from other servers. In simpler terms, a server acts as an intermediary through which internet requests are processed. When a client connects to the proxy server in search of a service such as a web page, file, connection or any other resource available from a different server, the proxy server evaluates and processes the request, and then returns the requested service. The proxy basically simplifies and controls a service request’s complexity.
Principal Functions of Proxy Servers
Proxy servers serve various functions. In personal computing, proxies are used to enable user privacy as well as anonymous surfing. Regarding privacy, proxies can provide you with more privacy when connecting to the internet. All incoming data enters through one port and is forwarded to the rest of the network via another port. This basically blocks direct access between two networks. By blocking access, proxy servers make it a lot more difficult for hackers to obtain details of a private network and internal addresses.
If you ever want to surf the web anonymously, using a proxy server is the most secure way.
In an organization, a proxy server is used to enhance security, improve administrative control or caching services, among other purposes. Also, proxy services are used by organizations to filter requests. Filtering requests prevent employees from accessing a specific set of websites.
Proxy servers are also used to improve performance by caching web pages. This simply means that each time you request a URL from a certain web page, a copy is stored temporarily. The next time you request the same URL, the proxy server serves the stored copy instead of retrieving the original URL (which is often time-consuming) across the network, thereby improving performance.
Some proxy servers are a group of servers or applications whose function is to block common internet services. For example, the HTTP proxy intercepts web access. On the other hand, the SMTP proxy intercepts email.
In some cases, a proxy server can be one of the major components of a firewall.
Types of Proxy Servers
There are many different types of proxy servers. However, the commonly known proxies include;
• Regular Proxy listens on a separate port and browsers (clients) are configured to send requests for connectivity to that specific port.
• Transparent Proxy is configured in a way to eliminate the browser side (client side) configuration. It’s basically used due to its ability to cache websites but do not effectively provide anonymity to the users
• Anonymous Proxy identifies itself as a proxy but does not provide the original IP address. However, this proxy is detectable.
• Reverse Proxy is used to pass requests from the internet, through a firewall, directly to isolated, private networks. It prevents clients from obtaining direct, unmonitored access to sensitive data available on content servers on an isolated network. The proxy is also used to reduce network traffic if caching is enabled.
• Distorting Proxy identifies itself as a proxy but provides an incorrect original IP address through the HTTP headers.
• High Anonymity Proxy does not identify itself as a proxy and does not provide the original IP address. It’s basically undetectable.
Note that you should not confuse the Network Address Translation (NAT) device with a proxy server. A NAT device basically transparently changes the origination address of incoming traffic before passing it to the internet. On the other hand, a proxy server connects to, responds to, and receives traffic from the internet. It performs these actions by acting on behalf of the client computer.