5 Key Commands to Improve Linux Server Security

In today’s digital age, protecting the security of your server is crucial. Especially for servers using Linux operating systems, improving their security is an issue that cannot be ignored. This article will introduce 5 key commands that can help improve the security of your Linux server.

1. Using the firewall

The firewall can filter network traffic and restrict access to the server. In Linux, the iptables command is used to configure firewall rules. Here are some basic iptables commands:

• Allow a specific IP address or range of IP addresses to access the server: iptables -A INPUT -s <ip_address> -j ACCEPT</ip_address>
• Allow access to specific ports: iptables -A INPUT -p tcp --dport <port_number> -j ACCEPT</port_number>
• Block all inbound traffic: iptables -P INPUT DROP
• View current firewall rules:iptables -L

Configuring appropriate firewall rules can limit unnecessary access to the server and block potential s attack.

2. Use strong passwords

Weak passwords are a major entry point to hackers. On a Linux server, use the passwd command to change user passwords. Here are some suggestions for creating a strong password:

• Password length is at least 8 characters
• Use a combination of uppercase and lowercase letters, numbers, and special characters
• Avoid Common passwords, such as "password" or "123456"

At the same time, changing passwords regularly is also an important measure to maintain server security.

3. Update systems and software

Regularly updating systems and software is a critical step in keeping your server secure. Known vulnerabilities and security issues are fixed by updating the operating system and software. On Linux, you can update your system and software using the following commands:

• Ubuntu/Debian: sudo apt update && sudo apt upgrade
• CentOS/RHEL:sudo yum update
• Arch Linux: sudo pacman -Syu

Ensure that updates are performed regularly and security patches are installed in a timely manner to maintain Server security.

4. Disable Unnecessary Services

By default, Linux distributions may be installed with some unnecessary services turned on. These unwanted services may present security vulnerabilities or risks. By disabling unnecessary services, you can reduce your attack surface and improve your server's security. Here are some examples of commands to disable services:

• Ubuntu/Debian: sudo systemctl disable <service_name></service_name>
• CentOS/RHEL: sudo systemctl disable <service_name></service_name>
• Arch Linux: sudo systemctl disable <service_name></service_name>

5. Log in using SSH key

Using SSH keys to log in can improve the security of the server. Compared with the traditional username and password login method, SSH keys provide stronger security. Here are the steps to set up an SSH key login:

1. Generate an SSH key pair: ssh-keygen -t rsa
2. Copy the public key to the server: ssh-copy-id <username>@<server_ip></server_ip></username>
3. Modify the SSH server configuration file: sudo vi /etc/ssh/sshd_config
4. Disable password login: Change PasswordAuthentication yes to PasswordAuthentication no and save the file
5. Restart the SSH service: sudo systemctl restart sshd

Password-based Brute Force attacks can be effectively prevented by logging in using SSH keys.

Summary

Protecting the security of Linux servers is an ongoing effort. Server security can be significantly improved by using a firewall, strong passwords, updating systems and software, disabling unnecessary services, and logging in with SSH keys. In addition, regular backup of server data and setting up log monitoring are also necessary security measures.

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