Sr. Linux Systems Administrator

Astrion; Columbia (MD); On-site; USD 145,000 - 165,000; Full time

Job summary

Astrion is seeking a Senior Linux Systems Administrator to build, secure, and sustain Linux servers, HPC clusters, and enterprise storage across multiple isolated networks in Columbia, MD. This on-site role requires an active TS/SCI clearance and DoD RMF/STIG compliance expertise.

The candidate will patch, harden, and operate RHEL systems, manage an HPC workload and NetApp storage, and automate with Bash, Python, and Ansible while maintaining security documentation and ATO readiness.

Qualifications

• Active TS/SCI clearance is required.
• Bachelor's degree in CS/IT or equivalent experience.
• 8+ years of Linux systems administration in DoD/classified environments.
• Deep RHEL expertise, scripting, and automation experience.
• DoD STIG compliance on Linux and HPC cluster administration.
• Experience with DoD RMF, discov ery and accreditation processes.
• Experience with enterprise storage (NetApp ONTAP) and offline patching.

Responsibilities

• Administer, patch, and sustain RHEL servers/workstations across multiple isolated networks.
• Hardening to STIGs, remediate findings, control configuration drift.
• Administer HPC cluster, compute nodes, PBS Professional, storage, and interconnect.
• Manage NetApp ONTAP storage, NFS/CIFS exports, backups, and capacity planning.
• Automate provisioning with Bash/Python/Ansible, including air-gapped systems.
• Patch air-gapped networks via offline repositories and trusted media.
• Enforce identity/access controls (LDAP/SSSD, Kerberos, FreeIPA/AD).
• Integrate Linux endpoints with CI/security tools and RMF monitoring.
• Contribute to ATO processes, STIG checklists, and risk assessments.
• Develop security artifacts and system documentation.

Skills

RHEL admin

Bash

Python

Ansible

LDAP/SSSD

Kerberos

STIG compliance

HPC cluster

NetApp ONTAP

RMF compliance

ACAS/SCAP

Air-gapped patching

Education

Bachelor's degree in Computer Science/IT or related field

Tools

PBS Professional

NetApp ONTAP

Kubernetes/ Podman

Red Hat Satellite

Nessus/SCAP

LDAP integration

Job description

Overview

Senior Linux Systems Administrator

LOCATION: Columbia, MD (Onsite)

JOB STATUS: Full-time

CLEARANCE: Active Top Secret / TS/SCI (Required)

TRAVEL: Less than 10%

SALARY RANGE: $145k - $165k

Astrion has an exciting opportunity for a highly experienced Senior Linux Systems Administrator to build, secure, and sustain the Linux server and workstation estate, the high-performance computing (HPC) cluster, and the enterprise storage that run across three or more isolated classified networks supporting Department of Defense/Department of War (DoD/DoW) environments in Columbia, MD. The ideal candidate brings deep Red Hat Enterprise Linux (RHEL) expertise, extensive experience operating inside closed and air-gapped classified enclaves, and a proven record of building and maintaining systems in compliance with Risk Management Framework (RMF), DoD STIG, and Comply-to-Connect (C2C) requirements. This position requires Monday through Friday on-site work at our facility in Columbia, MD.

REQUIRED QUALIFICATIONS / SKILLS

• Active TS/SCI security clearance (required)
• Bachelor's degree in Computer Science, Information Technology, or related field (or equivalent experience)
• 8+ years of Linux systems administration experience within DoD/DoW or classified environments
• Deep expertise in:
  • RHEL administration (installation, patching, performance tuning, kernel and systemd, storage, and networking)
  • Scripting and automation (Bash, Python, Ansible)
  • Linux identity and authentication (LDAP/SSSD, Kerberos, FreeIPA or AD integration)
• Demonstrated experience implementing and maintaining DoD STIG compliance on Linux
• Hands-on experience administering an HPC cluster (workload scheduler such as PBS Professional or similar)
• Experience administering enterprise storage (NetApp ONTAP, NFS)
• Strong understanding of:
  • RMF (Risk Management Framework)
  • DISA security requirements and accreditation processes
  • DCSA accreditation standards
• Active DoD 8140 (formerly DoD 8570) compliant baseline certification (e.g., Security+ CE, CISSP)
• Active DoD 8140 compliant computing environment certification (e.g., minimum Red Hat Certified System Administrator (RHCSA))
• Experience with:
  • Offline and air-gapped patching (Red Hat Satellite or internal repositories)
  • ACAS or Nessus and SCAP scanning
  • SIEM integration and log analysis
  • Continuous monitoring under RMF

KEY COMPETENCIES

• Advanced Linux systems administration and troubleshooting
• Security hardening and compliance enforcement
• Automation and scripting
• Strong analytical and problem-solving abilities
• Excellent communication and documentation skills
• Ability to operate in high-security, mission-critical environments

PREFERRED QUALIFICATIONS / SKILLS

• Red Hat Certified Engineer (RHCE) or Red Hat Certified Architect (RHCA)
• HPC experience with PBS Professional
• NetApp Certified Data Administrator (NCDA)
• Automation at scale (Ansible Automation Platform, Git-based configuration management)
• Zero Trust architectures and containerization (Podman, Kubernetes) in classified environments
• Prior experience supporting Cross Domain Solutions (CDS) programs
• Experience with cloud-based DoD environments (e.g., Azure Government, Azure Secret)
• Project management experience and experience briefing executive leadership

RESPONSIBILITIES

• Administer, patch, and sustain RHEL servers and workstations across three or more isolated classified networks, each operated as its own authorization boundary
• Build, harden, and baseline Linux systems to DoD Security Technical Implementation Guides (STIGs); remediate findings and control configuration drift
• Administer and tune the HPC cluster, including compute nodes, the workload scheduler (e.g., PBS Professional), the shared or parallel filesystem, and the low-latency interconnect
• Administer NetApp storage (ONTAP), including volumes, NFS and CIFS exports, snapshots, capacity planning, and backup and recovery
• Automate provisioning, configuration, and remediation with Bash, Python, and Ansible, including on disconnected systems
• Perform patching and updates on air-gapped networks through approved offline processes (e.g., Red Hat Satellite or internal repositories and trusted media transfer)
• Administer Linux identity and access (LDAP/SSSD, Kerberos, FreeIPA or Active Directory integration, sudo, PAM), enforcing least privilege
• Implement and maintain C2C and 802.1x posture for Linux endpoints and integrate with the security tool stack
• Perform vulnerability remediation and continuous monitoring in accordance with RMF controls; run and interpret ACAS and SCAP scans and review audit logs
• Support the Authority to Operate (ATO) process, including STIG checklists, POA&Ms, and risk assessments
• Develop and maintain system documentation, diagrams, SOPs, and security artifacts
• Troubleshoot complex issues across multi-network, multi-vendor environments
• Collaborate with cybersecurity, network, systems engineering, and mission stakeholders to ensure secure, reliable operations
• Support audits, inspections, and compliance validation activities