What is a proxy?

A proxy is a system or server that sits between a client (end-user) and a server (such as a website server), intercepting requests from the client and forwarding them to the server, then returning the server’s response to the client. Proxy is a middleman in networking. 

Proxying

Proxying refers to the act of using a proxy server to act as an intermediary between a client (such as a web browser) and a server. When you connect to the internet through a proxy server, your computer first sends requests to the proxy server which then forwards those requests to the destination server. The response from the destination server is then sent back to the proxy server, which forwards it to your computer.

Key Functions of a Network Proxy

  1. Traffic Management: Proxies can manage network traffic by distributing requests across multiple servers, balancing the load, and preventing any single server from becoming overloaded.

  2. Security: Proxies can filter out malicious content, block access to certain websites, and protect the network from attacks by hiding the internal network structure.

  3. Privacy and Anonymity: By masking the client’s IP address, proxies help maintain user anonymity and privacy on the internet.

  4. Content Filtering and Control: Organizations use proxies to enforce policies by blocking access to inappropriate or non-work-related websites.

  5. Caching: Proxies can store copies of frequently accessed web resources, reducing the load on the network and speeding up access to these resources for users.

Types of Network Proxies

  1. Forward Proxy: Sits in front of clients and forwards client requests to the internet. Used by clients to access the internet through a firewall.

  2. Reverse Proxy: Sits in front of web servers and forwards requests from the internet to those servers. Used for load balancing, caching, and securing internal servers.

  3. Transparent Proxy: Intercepts requests without modifying them, and without requiring any configuration on the client side. Often used by ISPs and organizations for monitoring and filtering traffic.

  4. Anonymous Proxy: Hides the client’s IP address from the server, providing anonymity.

  5. High Anonymity Proxy (Elite Proxy): Hides the fact that it is a proxy and also hides the client’s IP address, making it difficult to detect.

How Network Proxies Work

When a client (e.g., a web browser) requests to access a resource (e.g., a webpage), the following steps occur:

  1. The request is sent to the proxy server instead of the target server.

  2. The proxy server evaluates the request, and applies any configured policies (e.g., content filtering, authentication).

  3. The proxy server forwards the request to the target server on behalf of the client.

  4. The target server processes the request and returns the response to the proxy server.

  5. The proxy server forwards the response to the client.

Use Cases

  • Enterprise Networks: Proxies are widely used in corporate networks to manage and secure internet access, enforce policies, and improve performance through caching.

  • Content Delivery Networks (CDNs): Proxies are used in CDNs to deliver content more efficiently by caching content closer to end-users.

  • Anonymity Services: Proxies are used in anonymity networks to hide users' identities and protect their privacy online.

Common proxy errors

  • A proxying loop, often referred to as a forwarding loop, is a situation where HTTP requests or responses keep being forwarded between two or more proxy servers, without reaching their intended destination. This creates an infinite loop of requests that can result in performance degradation, high server load, and potential service outages. Usually caused by: misconfiguration, circular proxy chains, Incorrect DNS settings or Load Balancer errors.

  • 502 Bad Gateway The proxy server received an invalid response from an inbound server it accessed while attempting to fulfill the request.