Why is network proxy technology so popular? Forward proxy | Reverse proxy

1. The concept of agency

I believe everyone has heard of the word proxy. Proxy plays an irreplaceable role in network architecture, such as accessing Internet websites through proxies in a local area network, accessing networks that cannot be directly connected through proxies, etc. In network architecture, proxy servers play an important role, and Nginx, as a high-performance Web server and reverse proxy server, is widely used in practical applications. Today, we will introduce forward proxy and reverse proxy, including basic concepts, principle analysis, and related configuration cases. (With the development of proxy technology, many websites have also made relevant anti-reverse proxy configurations. It is possible that you have configured relevant proxies, but they do not allow you to access.)

2. Forward Proxy

1. Basic Introduction

A forward proxy is a proxy server that sends requests to a server on behalf of a client. In a forward proxy scenario, the client does not directly access the target server, but accesses it through a forward proxy server. Typical application scenarios of a forward proxy include accessing restricted websites and protecting client privacy.

This type of proxy is actually quite common in life. For example, the technology used to access foreign websites is proxy technology. Sometimes, users want to visit a foreign website that cannot be directly accessed in China, but we can access a proxy server that can access this foreign website. In this way, the user's access to the foreign website needs to be forwarded through the proxy server, and the proxy server will also return the response to the request to the user. This process of surfing the Internet uses a forward proxy.

2. Principle

When a client initiates a request, the request is first sent to the forward proxy server, which then forwards the request to the target server and finally returns the target server's response to the client. The core of the forward proxy is that the proxy server acts as a representative of the client, hiding the client's true identity. A typical forward proxy technology: VPN network.

• The forward proxy requires relevant proxy configuration on the client, such as adding the proxy address in the browser.
• A forward proxy is a client proxy that acts as a proxy for the client. The server does not know the client that actually initiated the request.
• When accessing the target server through a forward proxy server, the target server does not know who the real client is, and does not even know that the one accessing it is a proxy (sometimes the agent directly pretends to be the tenant).

3. Usage scenarios

• Break through access restrictions: Through the proxy server, you can break through your own IP access restrictions and visit foreign websites, education networks, etc.
• Improve access speed: Proxy servers usually set up a large hard disk buffer, which will save the responses to some requests in the buffer. When other users access the same information again, the information is directly taken out of the buffer and transmitted to the user to improve access speed.
• Hide the client's real IP: Internet users can also use this method to hide their IP and avoid attacks.

4. Configuration Example

Assuming we need to use Nginx as a forward proxy to access www.baidu.com, we can achieve this through the following Nginx configuration:

 server { listen 80; server_name a.proxy.xyz; location / { resolver 8.8.8.8; proxy_pass http://www.baidu.com; } }

In this configuration, we define an Nginx service named a.proxy.xyz. When the client accesses this service, Nginx will proxy the request to www.baidu.com, thus realizing forward proxy access to the Baidu website.

3. Reverse Proxy

1. Basic Introduction

Reverse proxy means that the proxy server sends a response to the client on behalf of the server. In the reverse proxy scenario, the client directly accesses the proxy server, and the proxy server is responsible for forwarding the request to the backend target server and returning the target server's response to the client. Reverse proxy is often used in scenarios such as load balancing and security protection.

2. Principle

When a client sends a request, the request first reaches the reverse proxy server, which then forwards the request to the backend target server according to the configuration rules, and finally returns the target server's response to the client. The core of the reverse proxy is that the proxy server hides the true identity of the backend server. Common reverse proxy technology: Nginx load balancing.

A reverse proxy is a server-side proxy that acts as a proxy for the server, so that the client does not know the server that actually provides the service.

3. Usage scenarios

• Hide the real IP address of the server: Using a reverse proxy, you can hide the IP address of the server from the client.
• Load balancing: The reverse proxy server can perform load balancing and distribute client requests to different real servers based on the load conditions of all real servers.
• Improve access speed: The reverse proxy server can provide cache services for static content and dynamic content with a large number of access requests in a short period of time, thereby improving access speed.
• Provide security: The reverse proxy server can be used as an application layer firewall to protect websites from Web-based attacks (such as DoS/DDoS), making it easier to detect malware, etc. It can also provide encryption and SSL acceleration (such as SSL terminal proxy) for back-end servers, provide HTTP access authentication, etc.

4. Configuration Example

Assuming we need to use Nginx for load balancing configuration, we can achieve it through the following Nginx configuration:

 http { # 定义代理服务器地址upstream backend { server backend1.example.com; server backend2.example.com; } # 其他配置项... server { # 监听端口listen 80; # 代理到后端服务器location / { proxy_pass http://backend; } } }

This configuration uses Nginx's upstream module to define the address of the backend server, and uses the proxy_pass directive in location to proxy the request to the defined backend server group. This configuration makes Nginx a reverse proxy server, forwarding the client's request to the backend server, and then returning the backend server's response to the client.

Summarize

The proxy technology shared today has many uses in life. For example, you can build a proxy to access related websites or provide technical support to those in need. I will stop here and hope that everyone can understand it. For example, if you want to access openai related interfaces in China, you can use a proxy to solve it.