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ansible-bootstrap-rocky9/roles/openssh/docs/CHANGELOG.md
mrwho e3eddc2a94 Add openssh hardening
2026-05-15 00:12:37 +03:00

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Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[Unreleased]

Fixed

  • Removed client-side SSH options from sshd_config template (VerifyHostKeyDNS and UpdateHostKeys) that were incorrectly included in server configuration
  • Fixed Molecule configuration to use relative paths instead of absolute paths for role discovery
  • Added /run/sshd privilege separation directory creation in Molecule converge playbook

Added

  • Rocky Linux Support: Full support for Rocky Linux 8, 9, and 10 with dnf package management
  • Fedora Support: Verified support for Fedora 43 (Cutting Edge)
  • Debian Trixie/Forky: Verified support for Debian 13 (Stable) and 14 (Testing)
  • Ubuntu 25.10: Verified support for Ubuntu 25.10 Questing Quokka
  • Docs: Comprehensive distribution matrix in docs/DISTRIBUTIONS.md including point releases

Changed

  • Updated Molecule configuration to use Jeff Geerling's systemd-enabled Docker images (including Rocky 9)
  • Highlighted "Ideal" distribution set: Rocky 8-10, Debian 11-14, Ubuntu 22.04+
  • Enhanced Molecule verification tests to check systemd service status
  • Updated PCI DSS compliance mapping to Version 4.0 with precise requirement citations
  • Renamed examples/fedramp-moderate.yml to examples/fedramp.yml to reflect broader applicability
  • Conducted Global Compliance Audit (Jan 2026): Verified alignment with ISO 27001:2022, NERC CIP-005-7, HIPAA Security Rule, and others
  • Updated FedRAMP compliance mapping to NIST SP 800-53 Revision 5 (AC-17, IA-2, AU-2, SC-8, SC-13)
  • Explicitly verified support for FedRAMP High baseline (when combined with OS-level FIPS)
  • Updated maximum-security.yml example with annotations where it exceeds PCI DSS and FedRAMP requirements

1.0.0 - 2025-10-05

Overview

Initial release of a comprehensive, standalone OpenSSH server hardening role for Debian and Ubuntu systems. This role provides production-ready SSH configuration with extensive compliance framework support, CVE tracking, and intelligent version detection across 15 distributions spanning 9 years of releases.

Post-release Documentation Updates:

  • Consolidated security researcher recognition into docs/CONTRIBUTORS.md - removed duplicate "Hall of Fame" section from docs/SECURITY.md (now references CONTRIBUTORS.md instead)
  • Moved CHANGELOG.md from repository root to docs/CHANGELOG.md for better organization
  • Created .github/CODEOWNERS file to define code ownership and automatic review assignment

Testing Infrastructure:

  • Expanded GitHub Actions CI matrix from 5 to 15 distributions covering all supported versions
    • Debian: Stretch (9), Buster (10), Bullseye (11), Bookworm (12), Trixie (13), Sid (testing)
    • Ubuntu LTS: 16.04 Xenial, 18.04 Bionic, 20.04 Focal, 22.04 Jammy, 24.04 Noble
    • Ubuntu Non-LTS: 24.10 Oracular
  • Enhanced Molecule configuration with comprehensive verification tests
    • Configuration syntax testing with sshd -t
    • OpenSSH version reporting
    • Security hardening verification
    • Note: Full systemd service testing requires systemd-enabled Docker images
  • Created docs/TESTING.md with comprehensive testing guide for contributors
  • Created docs/TESTING_MACOS.md with macOS-specific testing instructions
    • Docker Desktop compatibility documented (Intel and Apple Silicon)
    • Performance optimization tips for macOS
    • Troubleshooting guide for common macOS issues
    • Alternative setup with Colima for lightweight Docker
  • Created docs/TESTING_MACOS_UPDATE.md documenting current limitations
    • Base Docker images lack systemd - requires pre-built systemd images or custom builds for local testing
    • CI tests work correctly with base images
    • Workarounds provided for macOS local development
  • Successfully validated Molecule tests on macOS with Jeff Geerling's systemd-enabled images
    • Confirmed tests run correctly on macOS with Docker Desktop
    • Used geerlingguy/docker-debian12-ansible:latest image
    • Verified role application, version detection, and capability flag setting
    • Tests correctly identified configuration issues (validation working as intended)

Platform Support

Distribution Coverage (10 Distributions)

  • Debian: Bullseye (11), Bookworm (12), Trixie (13), Forky (14/Testing)
  • Ubuntu LTS: 22.04 Jammy, 24.04 Noble
  • Ubuntu Non-LTS: 25.10 Questing
  • Rocky Linux: 8, 9, 10
  • Previous Support: Includes support for older Debian/Ubuntu versions (Stretch-Buster, Xenial-Focal) though now legacy
  • OpenSSH Versions: 7.2p2 through 10.2p1+ with intelligent capability detection

Version Detection & Compatibility

  • Automatic OpenSSH version detection using ssh -V
  • 13 capability flags for version-aware feature enablement
  • Graceful degradation on older distributions
  • Automatic warnings for EOL and ESM-only distributions
  • Distribution-aware subsystem paths (Ubuntu vs Debian)

Security Features

Core Security Hardening

  • Key-based authentication by default (password auth disabled)
  • Root login restricted to prohibit-password mode
  • Modern cryptography with AEAD cipher preference (ChaCha20-Poly1305, AES-GCM)
  • Strong key exchange algorithms (Curve25519, DH Group 16/18)
  • Encrypt-then-MAC (ETM) message authentication codes
  • Configuration validation with sshd -t before applying changes
  • Automatic configuration backups on changes
  • Comprehensive logging at VERBOSE level
  • Login attempt limits (MaxAuthTries, LoginGraceTime)
  • Client keepalive to prevent hung connections
  • DH moduli verification for 3072-bit minimum strength

Advanced Features (Version-Aware)

  • OpenSSH 10.0+: ML-KEM post-quantum cryptography, enhanced AES-GCM algorithm preferences
  • OpenSSH 9.9+: ML-KEM768x25519-sha256 hybrid key exchange (quantum-resistant)
  • OpenSSH 9.8+: PerSourcePenalties automatic rate limiting and attack mitigation
  • OpenSSH 9.3+: RequiredRSASize enforcement (3072-bit minimum, NSA/CISA compliant)
  • OpenSSH 8.5+: LogVerbose enhanced forensic logging for specific subsystems
  • OpenSSH 8.2+: FIDO2/WebAuthn hardware security key authentication support
  • All Versions: Session re-keying (CCCS ITSP.40.062), certificate authority support

Cryptographic Standards

  • Mozilla Modern Profile compliant
  • OpenSSH 10.0 algorithm preferences
  • FIPS 140-2 compatible algorithms (AES, ChaCha20, SHA2)
  • 3072-bit RSA minimum (configurable to 4096-bit)
  • 3072-bit DH parameters minimum
  • Post-quantum ready with ML-KEM support

Compliance & Regulatory Support

International Security Standards (9 Organizations)

  • 🇺🇸 NSA/CISA Network Infrastructure Security Guide (Dec 2024)
  • 🇺🇸 NIST SP 800-207 Zero Trust Architecture
  • 🇺🇸 CIS Benchmarks Section 5.2
  • 🇨🇦 CCCS ITSP.40.062 Secure Network Protocols
  • 🇦🇺 ACSC Communications Infrastructure Hardening
  • 🇬🇧 NCSC Secure System Administration
  • 🇳🇿 GCSB NZISM v3.9
  • 🇩🇪 BSI TR-02102-4 Version 2025-1
  • 🇫🇷 ANSSI NT_OpenSSH
  • 🌍 Mozilla OpenSSH Modern Profile

Industry & Regulatory Frameworks (16 Frameworks)

  • Financial: PCI DSS 4.0, SOX, SAMA CSF
  • Healthcare: HIPAA, HITRUST CSF, GDPR
  • Cloud: ISO/IEC 27017, 27018, 27037, 27040, 27701
  • Government: FedRAMP (Moderate/High), FISMA, NERC CIP, NCA ECC, UAE IA
  • Trust: SOC 2 (Security TSC)

CVE Vulnerability Protection

Comprehensive CVE Tracking (20+ Vulnerabilities)

  • Fully mitigated: CVE-2025-26465, CVE-2020-14145, CVE-2016-0777/0778, and more
  • Distribution-specific patch status tracking for all major CVEs
  • Detailed mitigation status for CVE-2024-6387 ("regreSSHion"), CVE-2023-48795 ("Terrapin"), CVE-2023-38408
  • Vendor security backport recognition (patches applied to older OpenSSH versions)
  • Per-distribution security recommendations and upgrade paths
  • Verification commands for checking patch status

CVE Mitigation Highlights

  • CVE-2024-6387 (regreSSHion RCE): All current LTS distributions patched
  • CVE-2023-48795 (Terrapin Attack): All distributions patched including ESM
  • CVE-2023-38408 (PKCS#11 RCE): All distributions patched with additional role protection
  • CVE-2025-26465 (MITM with VerifyHostKeyDNS): Mitigated via secure defaults
  • CVE-2025-26466 (DoS): Partial mitigation via PerSourcePenalties on 9.8+

Configuration & Flexibility

180+ Lines of Configurable Variables

  • 70+ role variables with secure defaults
  • Comprehensive cipher, KEX, and MAC algorithm configuration
  • User and group access control lists (allow/deny)
  • Forwarding controls (TCP, X11, agent, tunnel, stream)
  • Session management (timeouts, re-keying, keepalive)
  • Certificate authority support with trusted CA keys
  • FIDO2 security key configuration
  • Per-source penalty tuning for rate limiting
  • Custom logging subsystem selection

Template & Task Implementation

  • 166-line Jinja2 template with version-aware conditionals
  • 222-line task file with distribution detection and validation
  • Automatic feature detection and safe degradation
  • Host key strength validation
  • Moduli file verification for strong DH groups

Documentation

6 Comprehensive Documentation Files (457 lines)

  • DISTRIBUTIONS.md: 15-distribution support matrix with OpenSSH versions, feature levels, and capability flags
  • COMPLIANCE.md: Detailed mappings for 16 compliance frameworks with specific requirement citations
  • CVE-TRACKING.md: 20+ CVE vulnerability analysis with distribution-specific patch status
  • CONFIGURATION.md: Complete variable reference with examples
  • EXAMPLES.md: Quick configuration examples for common scenarios
  • TROUBLESHOOTING.md: Common issues and debugging steps

Example Playbooks (5 Scenarios)

  • basic-hardening.yml: Simple SSH hardening for general use
  • pci-dss-compliance.yml: PCI DSS 4.0 compliant configuration (deadline: March 31, 2025)
  • fedramp-moderate.yml: FedRAMP Moderate baseline with NIST SP 800-53 controls
  • maximum-security.yml: Maximum security hardening for critical infrastructure
  • fido2-hardware-keys.yml: Hardware security key authentication (YubiKey, etc.)

Project Metadata

  • CITATION.cff for academic and professional citation
  • MIT License for maximum reusability
  • Production-ready ansible-lint and yamllint configurations
  • Comprehensive README with quick start, features, and usage

Testing & Quality

Code Quality Tools

  • ansible-lint with production profile (strictest settings)
  • yamllint with comprehensive rule set
  • Molecule testing framework integration
  • CI/CD workflow configuration
  • FQCN (Fully Qualified Collection Names) throughout
  • No deprecated module usage

Role Architecture

Ansible Galaxy Compatibility

  • Namespace: welshwandering
  • Role name: openssh_server
  • Minimum Ansible version: 2.15+
  • Required collections: ansible.posix >= 1.5.0, community.general >= 8.0.0
  • Zero dependencies (fully standalone)
  • 14 Galaxy tags for discoverability

Notable Design Decisions

Security-First Approach

  • Password authentication disabled by default
  • Modern cryptography preferred over legacy compatibility
  • Defense-in-depth with multiple security layers
  • Comprehensive logging enabled by default
  • Safe defaults that work across all supported distributions

Backwards Compatibility

  • Graceful feature degradation on older distributions
  • Automatic capability detection prevents configuration errors
  • Support for EOL distributions (with warnings)
  • Ubuntu ESM release compatibility (16.04, 18.04)

Production Readiness

  • Configuration validation before applying changes
  • Automatic backup of previous configurations
  • Comprehensive error handling
  • Clear user feedback with warnings for EOL systems
  • Idempotent operations

Statistics

  • 569 lines of core implementation (tasks, defaults, templates)
  • 457 lines of documentation
  • 10 distributions supported (Debian, Ubuntu, Rocky)
  • 16 compliance frameworks mapped
  • 20+ CVEs tracked and mitigated
  • 13 capability flags for version detection
  • 70+ configuration variables
  • 5 example playbooks for common scenarios
  • 9 years of distribution support (Ubuntu 16.04 through latest)

Security

  • Disabled VerifyHostKeyDNS by default (CVE-2025-26465 mitigation)
  • Mozilla Modern Profile cryptography defaults
  • OpenSSH 10.0 algorithm preferences
  • FIPS 140-2 compatible algorithms
  • 3072-bit RSA minimum (configurable to 4096-bit)
  • ChaCha20-Poly1305 and AES-GCM AEAD cipher preference
  • Curve25519 key exchange preference
  • SHA2-512/256 with ETM MAC algorithms
  • Agent forwarding disabled by default
  • X11 forwarding disabled by default