Linux Server Hardening and Security Guide
Plan Linux server hardening across SSH, firewall, privileges, patching, AppArmor/SELinux, logging, MFA and attack-surface reduction.
What does this guide solve?
Linux security is not a single script; patching, identity, network controls, service minimization, MAC policies, logging and backup should be layered.
Patching and packages
Apply security updates regularly and reduce unnecessary packages/repositories.
Automatic updates still require reboot and maintenance-window policy.
SSH and privilege
Prefer named accounts with sudo and SSH keys/certificates instead of direct root login.
MFA, bastions and source-IP restrictions can be added according to risk.
Firewall and service surface
Expose only required ports and disable unused services.
Host firewalls complement rather than replace network firewalls.
AppArmor / SELinux
Mandatory Access Control can limit damage after application compromise.
Use audit logs to tune policy instead of simply disabling protection.
Logging
Centralize authentication, sudo, service and critical-change logs.
Time synchronization and retention matter for incident response.
Frequently Asked Questions
Is Linux secure without antivirus?
Not automatically. Need depends on workload and file flow; malware scanning may be appropriate on some servers.
Is changing the SSH port enough?
No. It may reduce scan noise but does not replace strong identity, firewalling and patching.
Should SELinux/AppArmor be disabled?
Generally no. Troubleshoot policy and logs instead of removing a security layer.
Sources and technical references
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