openSUSE / SUSE Linux Enterprise Hardening & Audit Guide

openSUSE (Leap and Tumbleweed) and SUSE Linux Enterprise Server/Desktop (SLES/SLED) provide enterprise-class stability and modern package management via Zypper. Securing SUSE environments requires dynamic network socket backlog limits, SSH daemon hardening, system file permission controls, and dual-engine security auditing using Lynis and OpenSCAP.

This guide details the Ansible System Integrity Management Platform (ASIMP) workflow for evaluating, auditing, and hardening openSUSE and SUSE systems, highlighting the sysctl-suse-ASIMP role for automated sysctl resource calculation.

🧭 Scope & Distribution Matrix

ASIMP provides target-aware validation for openSUSE and SUSE distributions:

⚙️ Dynamic Sysctl Calculation (sysctl-suse-ASIMP)

The sysctl-suse-ASIMP role dynamically computes system resource limits based on node hardware facts (memtotal_mb, processor_vcpus, and root partition mount size):

• net.ipv4.tcp_max_syn_backlog: Calculated as max(4096, memtotal_mb * 4, vcpus * 2048).
• net.core.somaxconn: Calculated as max(1024, vcpus * 512, memtotal_mb).

📊 Architectural Paradigm: Mode Separation

ASIMP strictly separates operations into two distinct execution modes, controlled via the execution_mode variable:

1. Mode A: Reporting Only (execution_mode: "report"):
   • Performs non-destructive compliance scanning and evaluation.
   • Outputs visual HTML reports and XML results.
   • Does not apply hardening, but may create report directories and files.
2. Mode B: Doing (execution_mode: "remediate"):
   • Performs a pre-remediation baseline assessment (“Phase 1: Measure”).
   • Applies dynamic network sysctl tuning via sysctl-suse-ASIMP, file permission controls, SSH hardening, and Lynis security auditing (“Phase 2: Harden”).
   • Executes a post-remediation evaluation scan (“Phase 3: Re-Measure”).
   • Outputs a comparative scorecard.

🚀 Ansible Playbook Execution Guide

The dedicated playbook playbooks/opensuse_hardening.yml automates both modes across all supported openSUSE and SUSE releases.

1. Execute Reporting Only Mode

To run a non-destructive security assessment and view compliance reports:

ansible-playbook -i inventory/hosts playbooks/opensuse_hardening.yml -e "execution_mode=report"

2. Execute Doing (Remediation & Hardening) Mode

To run baseline audits, apply openSUSE network hardening and security policies, and generate verification reports:

ansible-playbook -i inventory/hosts playbooks/opensuse_hardening.yml -e "execution_mode=remediate"

🐳 Unprivileged Sandbox & Fallback Strategy

Inside unprivileged container environments or Google Jules sandboxes (detected via /home/jules):

1. Privilege Safety Guards: Tasks modifying restricted kernel settings or system services run with ignore_errors: true or evaluate is_sandbox_jules.
2. Mock Auditing: Diagnostic scorecards gracefully report simulated baseline and hardened metrics without halting workflow execution.