System Security

Hosting secure application code on an unprotected operating system leaves the infrastructure vulnerable to systemic compromise. Within DevSecOps frameworks, host-level operating system security represents the fundamental level of execution control. This chapter explores the security risks posed by misconfigured environments, such as disabling standard security frameworks or running processes with unrestricted administrative privileges. You’ll implement fine-grained access control using POSIX ACLs, secure filesystems with advanced mount parameters, and apply granular process privilege restrictions using Linux capabilities as an alternative to direct root access. Additionally, we’ll explore secure sudo policy mechanisms, clarify SELinux by customizing policies to meet operational requirements without compromising system security, and apply basic OpenSSL encryption to protect data in transit. Whether you’re a student eager to learn how to eliminate insecure configurations or an experienced administrator transitioning from broad permissions to strict, regulatory-compliant access models, this guide provides the technical blueprint you need to build resilient, enterprise-grade host environments.