LPIC-3 Security case studies
LPIC-3 Security · Put your knowledge to work in context.
LPIC-3 Security is one of the specialty certifications in the Linux Professional Institute (LPI) LPIC-3 program, which sits above LPIC-1 and LPIC-2 in LPI's Linux Professional track. The exam itself carries the code 303-300 and is built on objectives version 3.0.0. LPI describes itself as a vendor-neutral Linux and open source certification body with more than 350,000 certification holders in over 180 countries, and the LPIC-3 Security overview page is the entry point for the credential. The published objectives organize the exam into five topics: Cryptography (331), Host Security (332), Access Control (333), Network Security (334), and Threats and Vulnerability Assessment (335). The LPIC-3 Security case studies are 5 cases and about 3,578 words.
1Migrating an Internal CA from RSA to ECDSA Without Breaking Legacy Clients
You administer a two-tier internal PKI for 3,000 Linux hosts and 500 Java services. The root CA is offline; the issuing CA is an HSM-backed intermediate with a 10-year RSA-4096 key.
746 words, about 4 min2Secure Boot, an Unsigned Vendor Module, and a PCI DSS Audit
You run 400 Ubuntu 22.04 virtual machines and 40 physical database hosts under PCI DSS. Secure Boot is enabled, kernel lockdown is set to integrity, AIDE runs nightly, and auditd forwards to a central SIEM.
714 words, about 4 min3FreeIPA HBAC, sudo, and SELinux: Why a Service Account Cannot Restart the App
You manage 1,200 users and 60 RHEL 9 hosts with FreeIPA, SSSD, centralized HBAC and sudo rules, and SELinux enforcing. A monitoring service account, svc-mon , must SSH to application hosts and run systemctl restart app without a shell.
743 words, about 4 min4IPsec Tunnel Up but Only One Subnet Flows
Two sites run strongSwan 5.9 on Debian 12: HQ uses 10.10.0.0/16, and the branch uses 10.20.0.0/16. The branch is behind carrier-grade NAT (CGNAT).
699 words, about 3 min5Prioritizing a Critical CVE When the Vulnerable Service Is Not Exposed
You support 250 Kubernetes workloads and 80 VMs under PCI DSS. A monthly authenticated scan reports 1,200 findings, including 38 Critical.
676 words, about 3 min