How To Secure or Hardening Linux OS 100+ Tips

Here are 100+ tips for hardening a Linux Server:

1. Keep your server updated with the latest security patches.

2. Use a firewall to block unnecessary incoming traffic.

3. Use SSH keys for authentication instead of passwords.

4. Disable root login via SSH.

5. Enable SELinux or AppArmor to enforce security policies.

6. Use a password manager to generate and securely store strong passwords.

7. Limit the number of users with administrative privileges.

8. Use two-factor authentication wherever possible.

9. Use encrypted protocols, such as HTTPS or SFTP, for data transfer.

10. Disable unnecessary services and daemons.

11. Use a centralized logging solution to monitor system activity.

12. Use a host-based intrusion detection system (HIDS) to detect suspicious activity.

13. Configure your server to send email notifications for critical events.

14. Disable any unused network ports.

15. Use a file integrity monitoring system (FIM) to detect unauthorized changes to system files.

16. Use a strong password policy and enforce regular password changes.

17. Use disk encryption to protect sensitive data.

18. Use a secure password policy for root and all other user accounts.

19. Limit user login attempts and lockout failed login attempts.

20. Disable unnecessary kernel modules.

21. Disable automatic login for users.

22. Use SSL/TLS certificates for web server encryption.

23. Use intrusion prevention systems (IPS) to detect and block suspicious activity.

24. Use a host-based firewall to block unnecessary incoming traffic.

25. Use secure DNS servers and DNSSEC to protect against DNS attacks.

26. Use intrusion detection systems (IDS) to detect and respond to security breaches.

27. Use secure protocols, such as SSH or HTTPS, for remote management.

28. Harden the network stack by disabling unused protocols.

29. Harden the file system by disabling any unnecessary file systems.

30. Use the least privilege principle for assigning user privileges.

31. Securely erase data from hard drives before disposal.

32. Use strong and unique passwords for all services.

33. Use a reverse proxy to protect web servers from direct access.

34. Use security tools to scan for vulnerabilities.

35. Disable unnecessary network services, such as telnet and FTP.

36. Use a host-based intrusion prevention system (HIPS) to block malicious activity.

37. Use secure DNS servers and DNSSEC to protect against DNS spoofing.

38. Disable or restrict access to dangerous commands, such as rm -rf.

39. Use secure protocols, such as HTTPS or FTPS, for file transfers.

40. Use network segmentation to limit the attack surface.

41. Use encrypted email services to protect sensitive email content.

42. Use intrusion detection tools to monitor for suspicious activity.

43. Harden the kernel by disabling any unnecessary features.

44. Use a host-based firewall to block outbound traffic from unauthorized programs.

45. Use network security tools, such as Wireshark or nmap, to detect security issues.

46. Use encryption to secure communication between servers.

47. Use a dedicated firewall appliance for additional security.

48. Use secure network protocols, such as SSH or SSL.

49. Use encryption to protect sensitive data in transit.

50. Use strong passwords for all user accounts.

51. Disable any unused software packages and services.

52. Use a virtual private network (VPN) for remote access to the server.

53. Use a host-based intrusion detection system (HIDS) to detect and respond to threats.

54. Use secure communication protocols for remote management, such as SSH or SSL.

55. Disable or limit access to dangerous commands and applications, such as ping or netcat.

56. Use intrusion prevention systems (IPS) to block known threats.

57. Use a network monitoring tool to detect and respond to network attacks.

58. Use secure network protocols, such as IPsec or SSL VPNs, for remote access to databases.

59. Use security-focused web application frameworks, such as Ruby on Rails or Django.

60. Use web application firewalls (WAFs) to protect against attacks on web applications.

61. Use security-focused database frameworks, such as PostgreSQL or MariaDB.

62. Limit access to sensitive data to authorized users only.

63. Use secure encryption algorithms, such as AES or RSA.

64. Disable any unused ports, such as UDP or TCP.

65. Use secure and encrypted communication protocols, such as TLS or SSL.

66. Implement least privilege policies for all user accounts.

67. Monitor network traffic for unusual activity.

68. Use secure configuration management tools, such as Ansible or Puppet.

69. Use intrusion detection tools to monitor for unauthorized access attempts.

70. Use intrusion prevention systems (IPS) to block known threats before they can cause damage.

71. Use anti-virus and anti-malware software to detect and remove threats.

72. Limit access to sensitive data by using virtual private networks (VPNs) and secure protocols.

73. Use disk encryption to protect against data theft.

74. Use strong passwords and multi-factor authentication for all accounts.

75. Use network access control (NAC) to limit access to sensitive data.

76. Use virtualization technology to isolate services and applications.

77. Use data loss prevention (DLP) tools to prevent data leakage.

78. Use secure configuration management to enforce security policies across multiple servers.

79. Use intrusion prevention tools to block suspicious traffic and activity.

80. Use encryption to secure sensitive data in transit and at rest.

81. Use access control mechanisms, such as RBAC, to limit user privileges.

82. Use secure network protocols, such as SSL or TLS, for all network traffic.

83. Use secure coding practices, such as input validation and output encoding, for web applications.

84. Use security-focused hosting providers that offer additional security measures.

85. Use secure password policies, such as length and complexity requirements.

86. Use intrusion detection tools to detect and respond to threats in real-time.

87. Use secure network topologies, such as DMZs, to isolate critical infrastructure.

88. Use intrusion prevention systems (IPS) to block known and unknown threats.

89. Use secure communication protocols, such as SSH or SSL, for all remote access.

90. Use secure configuration management to enforce security policies across multiple systems.

91. Use secure backup solutions to protect against data loss.

92. Use encryption to protect sensitive data in storage and transit.

93. Use secure protocols, such as SFTP or SCP, for file transfers.

94. Use secure network protocols, such as SSL or TLS, for all web traffic.

95. Use secure password policies, such as complexity requirements and regular changes.

96. Use secure network protocols, such as IPSec or SSL VPNs, for remote access.

97. Use secure coding practices, such as input validation and output encoding, for all applications.

98. Use intrusion prevention systems (IPS) to block malicious traffic and activity.

99. Use network segmentation to isolate sensitive data and services.

100. Use secure network topologies, such as VLANs or virtual private networks, to limit the attack surface.

101. Regularly patch and update all software and operating systems to fix known vulnerabilities.

102. Disable or remove unnecessary services and applications to reduce the attack surface.

103. Use firewalls to restrict incoming and outgoing network traffic.

104. Use secure file permissions to restrict access to sensitive files and directories.

105. Use intrusion detection systems (IDS) to monitor for suspicious activity.

106. Use secure remote access protocols, such as SSH or VPNs, for remote administration.

107. Implement secure data backup and recovery procedures.

108. Use host-based intrusion detection systems (HIDS) to monitor for suspicious activity on individual hosts.

109. Implement secure network architecture, such as segmentation and zoning, to limit the impact of an attack.

110. Use secure network protocols, such as IPSec or SSL VPNs, for all remote access.

111. Use secure software development practices, such as threat modeling and code reviews.

112. Use secure authentication protocols, such as Kerberos or LDAP.

113. Use secure network protocols, such as HTTPS or SSH, for all web traffic.

114. Use secure communication protocols, such as PGP or S/MIME, for email communication.

115. Use secure DNS protocols, such as DNSSEC or DNS-over-HTTPS.

116. Use secure time synchronization protocols, such as NTP or PTP.

117. Use secure network segmentation to isolate sensitive data and systems.

118. Implement secure software configuration management practices.

119. Use secure encryption protocols, such as AES or RSA, for all sensitive data.

120. Implement secure logging and monitoring practices to detect and respond to threats.

121. Use secure web application development practices, such as input validation and output encoding.

122. Use secure containerization technologies, such as Docker or Kubernetes, to isolate applications.

123. Use secure network protocols, such as RADIUS or TACACS+, for authentication and authorization.

124. Use secure network protocols, such as SNMPv3 or NetFlow, for network monitoring.

125. Use secure virtualization technologies, such as KVM or Xen, to isolate systems and applications.

126. Use secure operating system hardening practices, such as disabling unnecessary services and locking down file permissions.

127. Use secure web hosting practices, such as secure server configurations and SSL certificates.

128. Use secure email server configurations, such as DKIM or SPF.

129. Implement secure database administration practices, such as strong passwords and database backups.