Nginx security practice: preventing DDoS attacks

With the development of the Internet, network attack methods have become more and more diverse, including DDoS attacks. This attack method uses multiple attack sources to initiate a large number of requests to the target server at the same time, causing the server to be overwhelmed, thus can not work normally. Therefore, protecting the server is very important for some important websites. As a high-performance, cross-platform web server and reverse proxy server, Nginx can help us resist DDoS attacks. The following will summarize the actual security of Nginx, taking preventing DDoS attacks as an example.

1. Use Nginx's limit_conn_module module to limit the number of connections

The limit_conn_module module allows us to set the number of concurrent connections from the same source in the configuration file. This means that if an IP address sends a large number of requests, it will not be able to continue establishing new connections. This approach helps us prevent a single client or malicious program from using a large amount of connection resources and consuming server bandwidth.

The following is a simple configuration example:

http {
    ...
    limit_conn_zone $binary_remote_addr zone=one:10m;
    ...
    server {
        ...
        limit_conn one 10;
        ...
    }
}

In this configuration we create a conn_zone to store the client’s connection information, and set a limiter named one for Limit the number of concurrent connections from the same IP address to no more than 10. Under heavy traffic loads, a client may be temporarily throttled if it uses too many connections.

2. Increase server bandwidth

In the face of DDoS attacks, when our server cannot handle a large number of requests, we need to consider increasing server bandwidth to withstand higher traffic load . Consider increasing the bandwidth of your server's network interface or using load balancing to spread the traffic load.

3. Using Nginx’s HTTP reverse proxy

HTTP reverse proxy can effectively reduce the load on the server. Leveraging Nginx's reverse proxy feature to forward requests limits traffic to the proxy layer instead of being transmitted directly to the origin server. By setting up a reverse proxy server as our "frontend" we can spread the traffic load by routing traffic to multiple backend servers.

4. Use Nginx cache configuration

Nginx cache configuration can effectively reduce the load on the back-end server and shorten the response time. Cache content can be placed in the server's memory, and cache files can be cleaned as needed. In the event of a DDoS attack, caching can help us reduce server load, thereby preventing server crashes.

5. Using Nginx’s firewall configuration

Nginx’s firewall configuration can be used to restrict IP ranges, allowing or denying specific IP addresses to access the server. By configuring firewall rules, we can only allow specific IP addresses or IP address ranges to access the server, while prohibiting unauthorized access. This is an effective method that can help us prevent DDoS attacks against specific targets.

In short, "safety first" is a belief that each of us should adhere to. Through the above practical methods and means, we can better protect our servers, prevent DDoS attacks, and ensure the smooth operation of online services.

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