Regular expression-based access control configuration in Nginx reverse proxy

Nginx is a high-performance web server and reverse proxy server that is widely used in Internet services because of its efficiency and scalability. Nginx provides many mechanisms to control access and secure web applications, one of which is regular expression-based access control. This article will discuss how to use regular expression-based access control configuration in Nginx reverse proxy.

Nginx reverse proxy basics

Before we start to explain how to use regular expression-based access control, we need to understand some basic knowledge of Nginx reverse proxy.

The basic working principle of Nginx reverse proxy is to forward client requests to the back-end service. Typically, clients access web applications through HTTP requests, and the reverse proxy server receives these requests, forwards them to the backend web server, and returns the response to the client.

Unlike traditional load balancers, Nginx reverse proxies can perform other tasks besides simply forwarding requests to backend servers, such as controlling access, caching content, modifying request and response headers, etc. .

Regular expression-based access control

Nginx provides many mechanisms to control access and secure web applications, one of which is regular expression-based access control. Regular expressions can match request URLs exactly. Therefore, using regular expressions as matching rules allows us to control requested access more precisely.

A common way to use regular expressions for access control is to use location blocks. The role of the location block is to match the requested URI and execute a series of instructions when the match is successful. These instructions can include reverse proxying to backend servers, setting request headers, caching responses, controlling access, etc.

Using regular expression-based access control, you can usually use the following two methods:

1. Allow/forbid all requests, and then allow/forbid specified requests through regular expressions .
2. Reject all requests, and then allow specified requests through regular expressions.

Below we will introduce these two methods in detail.

Allow/forbid all requests, and then allow/forbid specified requests through regular expressions

This method is to use regular expressions to determine whether the request allows access. First, we need to add the following content to the Nginx configuration file:

location / {
  deny all;
  allow [ip_address];
}

The above configuration will block all requests and allow access to requests from the specified IP address. Next, we can use regular expressions to determine whether the requested access is allowed. For example, if we only want to allow specific URL requests, we can use the following configuration:

location / {
  deny all;
  allow [ip_address];
}

location ~ ^/allowed_path {
  allow all;
}

The above configuration will allow access from requests from the specified IP address and allow access to URLs starting with /allowed_path. All other requests will be denied.

Deny all requests, and then allow specified requests through regular expressions

This method is to deny all requests and use regular expressions to allow access to specific requests. We can use the following in the Nginx configuration file:

location / {
  deny all;
}

location ~ ^/(allowed_path|another_path) {
  allow all;
}

The above configuration will deny all requests and only allow access to requests starting with /allowed_path or /another_path.

Using regular expressions for access control allows us to control requested access more precisely. However, in order to ensure security and performance, we need to configure the Nginx reverse proxy server reasonably to avoid degrading user experience due to excessive restrictions on requests. At the same time, we also need to protect the reverse proxy server from malicious attacks, such as denial of service attacks, SQL injection attacks, and cross-site scripting attacks. Therefore, when using Nginx reverse proxy, we need to follow best practices to ensure the security and reliability of web applications.

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