Building secure remote access: Protect your Linux servers

Building Secure Remote Access: Protecting Your Linux Server

With the development of the Internet, remote access has become a common way to manage servers. However, remote access also exposes servers to a variety of potential security threats. To protect your Linux server from hackers, this article will cover some basic security measures and code examples.

1. Use SSH key authentication
   SSH (Secure Shell) is an encrypted remote login protocol that can securely connect to a server remotely. Compared with the traditional username/password login method, SSH key authentication is more secure. Here is sample code for generating and using SSH keys:

# 生成SSH密钥
ssh-keygen -t rsa -b 4096

# 将公钥复制到服务器
ssh-copy-id username@servername

# 禁用密码登录
sudo nano /etc/ssh/sshd_config
将 PasswordAuthentication 设置为 no

2. Using a firewall
   A firewall can help filter and block unauthorized connections. Access to specific ports and IP addresses can be restricted by setting appropriate rules. The following is sample code for setting up firewall rules using iptables:

# 允许所有本地连接
iptables -A INPUT -i lo -j ACCEPT

# 允许已建立的连接
iptables -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT

# 允许SSH连接
iptables -A INPUT -p tcp --dport 22 -j ACCEPT

# 其他所有连接均拒绝
iptables -A INPUT -j DROP

# 保存规则并启用防火墙
iptables-save > /etc/iptables.rules

3. Update your system and software regularly
   It is important to keep your system and software up to date, as updates often contain security patches. Regularly updating systems and software can reduce the risk of being exploited by known vulnerabilities. The following is sample code for using apt-get to update systems and software:

# 更新软件包列表
sudo apt-get update

# 执行系统更新
sudo apt-get upgrade

# 定期执行更新任务
sudo crontab -e
添加以下行，每周自动执行更新：
0 0 * * 0 apt-get update && apt-get upgrade -y

4. Using non-standard ports
   The default SSH port is 22, which is the port most commonly attempted by hackers one. By using a non-standard port (such as 2222) instead of the default port, the risk of being scanned and attacked can be reduced to a certain extent. The following is sample code to modify the SSH port:

# 编辑SSH配置文件
sudo nano /etc/ssh/sshd_config

# 将端口号修改为非默认端口
将 Port 22 改为 Port 2222

# 重启SSH服务
sudo service ssh restart

5. Configuring the Intrusion Detection System
   An intrusion detection system (IDS) can monitor network traffic and system activity on the server and warn you about Suspicious or malicious activity. The following is sample code for configuring an IDS using Snort:

# 安装Snort
sudo apt-get install snort

# 配置网络接口
sudo ifconfig eth0 promisc

# 启动Snort
sudo snort -i eth0 -c /etc/snort/snort.conf

When configuring remote access, keep the security of the server in mind. Properly setting access permissions, using strong passwords, regularly backing up data, and monitoring server health are all important security practices.

Summary:

This article introduces some basic measures and code examples to protect the security of remote access to Linux servers. Measures such as using SSH key authentication, setting firewall rules, regularly updating systems and software, using non-standard ports, and configuring intrusion detection systems can effectively reduce the risk of server attacks. In practical applications, it can be appropriately adjusted and improved according to specific needs. By building a secure remote access environment, you can better protect your Linux server from hackers.

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