Domain name retrieval blacklist strategy in Nginx reverse proxy

In Nginx's reverse proxy, it is often necessary to restrict accessed domain names to ensure the security and stability of the service. In response to this demand, Nginx provides a black and white list strategy to help administrators better complete domain name retrieval work.

First of all, we need to understand what a black and white list is. A blacklist or whitelist is a list that restricts or allows specific objects or behaviors. In Nginx's reverse proxy, the black and white list is a list of domain names that are allowed or prohibited to access. Domain names in the blacklist will be denied access, while domain names in the whitelist will be allowed access.

So, how to use Nginx’s black and white list strategy?

First, we need to define the black and white list rules in the Nginx configuration file. The following is a basic configuration example:

http {
    # 定义黑名单
    geo $blacklist {
        default 0;
        include /etc/nginx/blacklist;
    }
    
    # 定义白名单
    geo $whitelist {
        default 0;
        include /etc/nginx/whitelist;
    }
    
    server {
        listen       80;
        server_name  example.com;
        
        # 检查黑名单
        if ($blacklist = 1) {
            return 403;
        }
        
        # 检查白名单
        if ($whitelist = 0) {
            return 403;
        }
        
        location / {
            proxy_pass  http://backend;
        }
    }
}

In the above configuration, we define two geo variables: $blacklist and $whitelist. They are used to store domain names in the blacklist and whitelist respectively. Here, we store the blacklist and whitelist rules in two files, /etc/nginx/blacklist and /etc/nginx/whitelist. These two files can be set up according to actual needs.

Next, in the server section, we use the if statement to check the domain names in the blacklist and whitelist. If the check result is 1 (indicating that it is in the blacklist), return 403 (Forbidden). If the check result is 0 (indicating that it is not in the whitelist), 403 is also returned. This way you can restrict access to the domain name.

Of course, this is just a basic black and white list strategy. For different needs, we can configure Nginx's reverse proxy in more detail as needed to achieve more refined strategies.

It should be noted that although the black and white lists have a good restricting effect on some malicious attacks and access, they also have certain risks. For example, since black and white lists are restricted based on domain names, attackers can trick Nginx through DNS pollution and other means to bypass restrictions. Therefore, when using the black and white list strategy, careful consideration and decision-making need to be based on the actual situation.

In summary, the domain name retrieval blacklist and whitelist policies in Nginx reverse proxy can help administrators better control the access scope of services and achieve more secure and stable operations. We can define black and white list rules in the Nginx configuration file according to actual needs to achieve domain name restrictions.

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