Sr. Linux Systems Administrator

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 environmentsDeep 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 LinuxHands-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 processesDCSA accreditation standardsActive 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 scanningSIEM integration and log analysisContinuous monitoring under RMF KEY COMPETENCIES Advanced Linux systems administration and troubleshootingSecurity hardening and compliance enforcementAutomation and scriptingStrong analytical and problem-solving abilitiesExcellent communication and documentation skillsAbility 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 ProfessionalNetApp Certified Data Administrator (NCDA)Automation at scale (Ansible Automation Platform, Git-based configuration management)Zero Trust architectures and containerization (Podman, Kubernetes) in classified environmentsPrior experience supporting Cross Domain Solutions (CDS) programsExperience 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 boundaryBuild, harden, and baseline Linux systems to DoD Security Technical Implementation Guides (STIGs); remediate findings and control configuration driftAdminister and tune the HPC cluster, including compute nodes, the workload scheduler (e.g., PBS Professional), the shared or parallel filesystem, and the low-latency interconnectAdminister NetApp storage (ONTAP), including volumes, NFS and CIFS exports, snapshots, capacity planning, and backup and recoveryAutomate provisioning, configuration, and remediation with Bash, Python, and Ansible, including on disconnected systemsPerform 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 privilegeImplement and maintain C2C and 802.1x posture for Linux endpoints and integrate with the security tool stackPerform vulnerability remediation and continuous monitoring in accordance with RMF controls; run and interpret ACAS and SCAP scans and review audit logsSupport the Authority to Operate (ATO) process, including STIG checklists, POA&Ms, and risk assessmentsDevelop and maintain system documentation, diagrams, SOPs, and security artifactsTroubleshoot complex issues across multi-network, multi-vendor environmentsCollaborate with cybersecurity, network, systems engineering, and mission stakeholders to ensure secure, reliable operationsSupport audits, inspections, and compliance validation activities