Learn about common Linux server attack types: strategies and recommendations for prevention

Understand Common Linux Server Attack Types: Prevention Strategies and Recommendations

Introduction:

In today’s digital age, server attacks have become a Common security threats. Linux servers are widely used due to their stability and security, and have also become an important target in the eyes of attackers. This article will introduce some common types of Linux server attacks and provide some prevention strategies and suggestions. At the same time, we will also give some code examples to help readers better understand and practice.

1. Password attack types

1. Dictionary attack
   Dictionary attack is a common password attack method. The attacker tries to use a pre-built password dictionary to crack the user password. To protect against dictionary attacks, it is recommended to use strong passwords and limit the number of login attempts.
2. Brute-Force Attack
   Brute-Force attack is to crack a user's password by trying all possible password combinations. To protect against Brute-Force attacks, you can limit the number of login attempts and enable account lockout.

Sample code:

The following is a simple Python code example for limiting the number of login attempts:

import os

def verify_login(username, password):
    attempts = 0
    while attempts < 3:
        # 验证用户名和密码
        if username == "admin" and password == "password":
            return True
        else:
            attempts += 1
            print("登录失败，剩余尝试次数: {}".format(3 - attempts))
            password = input("请输入密码: ")
    return False

# 示例用法
username = input("请输入用户名: ")
password = input("请输入密码: ")

if verify_login(username, password):
    print("登录成功！")
else:
    print("登录失败，请稍后再试。")
    os.system("sleep 5")  # 延迟 5 秒

2. Network attack types

1. DDoS Attack
   DDoS (Distributed Denial of Service) attack refers to an attacker using a large number of computers at the same time to send a large number of forged requests, thereby preventing the server from serving normally. To protect against DDoS attacks, a combination of firewalls and traffic conditioners can be used, as well as limiting connection rates.
2. SYN attack
   SYN attack means that the attacker sends a large number of forged SYN requests, occupying server resources and causing normal users to be unable to access. In order to prevent SYN attacks, you can use SYN filters to filter requests and set a reasonable connection timeout.

Sample code:

The following is a simple Python code example for implementing a SYN filter:

import iptc

def add_syn_rule(ip_address):
    rule = iptc.Rule()
    rule.protocol = "tcp"
    rule.src = ip_address
    rule.create_target("DROP")

    chain = iptc.Chain(iptc.Table(iptc.Table.FILTER), "INPUT")
    chain.insert_rule(rule)

# 示例用法
ip_address = input("请输入需要过滤的 IP 地址: ")
add_syn_rule(ip_address)
print("SYN 过滤规则添加成功！")

3. Application security attack types

1. SQL injection attack
   SQL injection attack refers to an attacker inserting malicious SQL statements into input fields to obtain sensitive information, modify data, or execute arbitrary code. To protect against SQL injection attacks, you can use parameterized queries and input validation to filter user input.
2. XSS Attack
   XSS (cross-site scripting) attack refers to an attacker embedding malicious code into a web page to steal user data, tamper with page content, or provide malicious links. To prevent XSS attacks, all user input should be filtered and escaped to ensure that users cannot insert malicious scripts.

Sample code:

The following is a simple PHP code example to prevent SQL injection attacks:

<?php
function mysqli_safe_query($connection, $query, $params) {
    $_params = array();
    foreach ($params as $param) {
        $_params[] = mysqli_real_escape_string($connection, $param);
    }
    return mysqli_query($connection, vsprintf($query, $_params));
}

// 示例用法
$connection = mysqli_connect("localhost", "username", "password", "database");
$query = "SELECT * FROM users WHERE id = %d";
$id = $_GET["id"];
$result = mysqli_safe_query($connection, $query, array($id));
// ...
?>

Conclusion:

This article This article introduces some common types of Linux server attacks and provides corresponding prevention strategies and suggestions. It is hoped that readers can strengthen server security based on these suggestions and take appropriate measures to protect the server from attacks. Remember, security awareness and ongoing security updates are important parts of keeping your server secure.

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