How to use PHP and Vue.js to develop applications that defend against Denial of Service (DOS) attacks

Title: How to use PHP and Vue.js to develop applications that defend against Denial of Service (DOS) attacks

Introduction:
With the increasing popularity and dependence on the Internet, network security issues have changed. becomes more and more important. One of the common network attacks is a denial of service (DOS) attack. The attacker sends a large number of requests to the server to exhaust its resources, making it inaccessible to normal users. This article will introduce how to use PHP and Vue.js to develop an application to defend against DOS attacks.

1. Back-end defense measures

1. Limit the number of concurrent connections
   In PHP, you can use the sem_acquire() and sem_release() functions to achieve access control of shared memory , used to limit the number of concurrent connections. The following is a sample code:

$maxConnections = 100; // 最大连接数
$semaphore = sem_get(1234); // 获取一个共享内存标识符

// 在请求处理之前，获取共享内存锁
if (sem_acquire($semaphore)) {
    // 根据实际情况进行处理

    // 释放共享内存锁
    sem_release($semaphore);
} else {
    // 返回服务器繁忙错误信息
    header("HTTP/1.1 503 Service Unavailable");
    exit("Server is busy, please try again later.");
}

2. Prevent malicious requests
   You can prevent malicious requests through the following steps:

• Limit requests Frequency: You can use current limiting algorithms, such as token bucket algorithm or leaky bucket algorithm, to control request frequency. The following is a simple leaky bucket algorithm example:

$rateLimit = 100; // 限制每秒请求数
$currentBucketSize = 0; // 当前桶中的请求数
$lastRequestTime = time(); // 上次请求时间

function handleRequest() {
    global $rateLimit, $currentBucketSize, $lastRequestTime;
    
    // 计算当前桶中请求数
    $elapsedTime = time() - $lastRequestTime;
    $currentBucketSize = max(0, $currentBucketSize - $elapsedTime * $rateLimit);
    
    // 判断桶中请求数是否超过限制
    if ($currentBucketSize >= $rateLimit) {
        // 返回请求过于频繁错误信息
        header("HTTP/1.1 429 Too Many Requests");
        exit("Too many requests, please slow down.");
    }
    
    // 处理请求
    
    // 更新桶中请求数和上次请求时间
    $currentBucketSize++;
    $lastRequestTime = time();
}

• Verify the legitimacy of the request: You can perform some simple legality verification on the request, such as checking the request header, request parameters, etc., to determine Whether it is a malicious request.

2. Front-end defense measures

1. Use verification code
   Adding verification code is a common method to identify whether it is a malicious request. You can require users to enter a verification code when they perform sensitive operations (such as logging in, registering, submitting a form, etc.) to ensure that the request comes from a real user.
2. Asynchronous loading and lazy loading
   By using the asynchronous loading and lazy loading functions provided by Vue.js, you can optimize page loading speed on the front end and reduce server pressure. For example, large images or scripts can be loaded lazily so that the page response speed will not be affected by the loading of too many resources when users browse the web.
3. HTTP request restrictions
   You can impose some restrictions on HTTP requests, such as the number of concurrent requests, request frequency, etc. These restrictions can be achieved using the axios library provided by Vue.js. The following is a sample code:

import axios from 'axios';

const maxConnections = 100; // 最大连接数
const semaphore = new Semaphore(maxConnections); // 一个信号量对象，实现可限制并发连接数

function sendRequest() {
    // 在请求发送之前，获取信号量
    semaphore.acquire()
        .then(() => {
            // 发送请求

            // 在请求完成后，释放信号量
            semaphore.release();
        })
        .catch(error => {
            // 返回服务器繁忙错误信息
            console.error("Server is busy, please try again later.", error);
        });
}

Conclusion:
By using the related functions of PHP and Vue.js, we can develop a An application that protects against Denial of Service (DOS) attacks. On the backend, server resources can be protected by limiting the number of concurrent connections and preventing malicious requests; on the frontend, measures such as verification codes, asynchronous loading, and HTTP request limits can be used to reduce server load and improve user experience. Of course, network security is an evolving field, and we need to continue to learn and update technology to deal with the ever-changing methods of network attacks.

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