Harden Linux servers: Use commands to configure security

With the development of the Internet, the security of Linux servers has become more and more important. As one of the widely used operating systems, Linux servers are often targeted by attackers. In order to strengthen the security of Linux servers, we can use some commands to configure security.

First, we should update the server’s operating system and software packages. Use the "apt-get update" command to update the package list, and then use the "apt-get upgrade" command to install the updated packages. This ensures that the server is using the latest security patches and fixes.

Secondly, we need to disable unnecessary services and ports. Use the "netstat -tuln" command to view the currently running services and listening ports. Then, use the "systemctl stop" and "systemctl disable" commands to stop and disable unnecessary services. For example, if we are not using an FTP server, we can use the "systemctl stop ftp" and "systemctl disable ftp" commands to stop and disable the FTP service.

Third, we should configure the firewall to restrict access to the server. Use the "ufw" command to configure firewall rules. For example, use the "ufw enable" command to enable the firewall, and then use the "ufw allow" command to allow specific IP addresses or ports to access the server. We can also use the "ufw deny" command to prohibit specific IP addresses or ports from accessing the server.

In addition, we can also use commands to increase the complexity of the account password. Use the "passwd" command to change the password, and then use the "pwquality.conf" file to configure password strength requirements. By modifying the parameters in this file, we can set the minimum number of characters, the number of uppercase letters, lowercase letters, numbers, and special characters that the password needs to contain.

In addition, we can use the "ssh-keygen" command to generate and manage SSH key pairs. This enables authentication by key instead of password. Using keys can greatly increase the security of your server.

Finally, we can also use commands to monitor the server’s log files. By checking server logs, we can detect potential security issues in time. Use the "tail" command to view the last few lines of the log file, and use the "grep" command to search for specific keywords to filter out relevant log information.

In short, by using commands for security configuration, we can strengthen the security of the Linux server. Updating the operating system and software packages, disabling unnecessary services and ports, configuring firewalls, increasing the complexity of account passwords, using SSH keys for authentication, and monitoring server logs are all important measures to protect server security. Please exercise caution during the configuration process to ensure the normal operation of the server and improve its security.

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