Linux Server security checklist

User Accounts and Authentication

Ensure all user accounts have strong, complex passwords.

Disable root login via SSH.

Implement two-factor authentication where possible.

Regularly review user accounts and remove inactive accounts.

Limit user privileges based on the principle of least privilege.

System Updates and Patch Management

Keep the operating system and installed packages up to date.

Regularly check for and apply security patches.

Use automated tools to manage updates when feasible.

Review and minimize installed applications to reduce vulnerabilities.

Firewall and Network Security

Configure a firewall to restrict incoming and outgoing traffic.

Use tools like iptables or firewalld to manage firewall rules.

Disable unused network services.

Implement Virtual Private Network (VPN) for remote access.

Regularly audit open ports and services.

File and Directory Permissions

Set appropriate permissions for files and directories.

Use the principle of least privilege for file access.

Regularly review and monitor file permissions.

Consider using access control lists (ACLs) for advanced permissions.

Logging and Monitoring

Enable and configure system logging (e.g., rsyslog).

Regularly review logs for unusual activity.

Implement log rotation to manage log file sizes.

Use monitoring tools to detect and alert on suspicious behavior.

Security Hardening

Disable unnecessary services and daemons.

Use security-enhanced Linux (SELinux) or AppArmor for additional security.

Configure SSH to use non-standard ports if possible.

Limit the use of sudo to specific users and commands.

Regularly audit system configurations for vulnerabilities.

Backup and Recovery

Implement regular backup procedures for critical data.

Store backups in a secure location (offsite or cloud).

Test backup and recovery processes periodically.

Ensure that backup files are encrypted and access-controlled.

Incident Response

Develop an incident response plan.

Train staff on incident detection and reporting.

Regularly test and update the incident response plan.

Maintain contact information for key personnel in case of an incident.

Compliance and Best Practices

Ensure compliance with relevant regulations and standards (e.g., GDPR, HIPAA).

Regularly review security policies and procedures.

Stay informed about the latest security vulnerabilities and trends.

Participate in security forums and communities for best practices.

This checklist serves as a guideline for securing a Linux server, helping administrators to systematically address various security aspects.