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 idóneo 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

📌 Sr. Linux Systems Administrator (Colombia)
🏢 Astrion
📍 Colombia