Linux and Windows Systems Administrator

Leidos Corporate Information Security Office (CISO), reporting through the Digital sector, is seeking a Linux and Windows System Administrator to support and maintain complex classified environments. The selected candidate will be responsible for administering, securing, troubleshooting, and maintaining Windows and Linux systems across physical and virtual infrastructures. This role supports mission-critical operations by ensuring system availability, compliance with security requirements, and reliable day-to-day operations within a secure enterprise environment.Location: All work will be performed onsite in our Beavercreek, OH office.Clearance: You must currently carry an active DoD Secret clearance to qualify for consideration.Primary ResponsibilitiesAdminister and maintain Windows Workstations, Windows Server, and Linux systems (RHEL, Rocky Linux, Ubuntu) across physical, virtual, and air-gapped environments.Perform Tier 2 incident resolution, troubleshoot technical issues, conduct root-cause analysis, and collaborate with engineering, cybersecurity, and stakeholders to resolve complex problems.Execute system patching, vulnerability remediation, configuration management, and compliance activities.Implement and maintain monitoring, logging, backup and recovery solutions, and operational documentation/runbooks.Support account and access administration in accordance with least-privilege principles and organizational security policies.Automate repetitive administrative tasks using PowerShell, Bash, Ansible, or similar automation tools.Deploy and maintain operating system images using PXE/network boot, Kickstart, disk imaging, answer files, and automated installation methods.Perform system hardening and security compliance using DISA STIGs, SCAP, and NIST 800-53 security controls.Administer and troubleshoot Active Directory, DNS, DHCP, file servers, virtualization platforms, and Layer 2 network switching, including VLAN configuration, TCP/IP connectivity, and switch port administration in an air-gapped environment.Support dual-boot bare-metal systems and virtualized environments.Participate in after-hours support and on-call rotations as required.Research, analyze, and resolve Windows, Linux, and networking issues to maintain system availability, reliability, and performance.Basic QualificationsCurrent Active DoD Secret security clearance.Current CompTIA Security+ certification.Bachelor's degree in a technical field with 4-8 years of relevant experience. Additional years of relevant experience may be considered in lieu of a degree.Experience administering Windows Server and Linux systems in secure or air-gapped environments.Experience implementing DISA STIGs, SCAP, NIST 800-53 security controls, and system hardening practices.Experience administering:Active DirectoryDNSDHCPFile ServersExperience building, integrating, maintaining, troubleshooting, and remediating Windows and Linux systems.Experience deploying operating systems using PXE, Kickstart, ISO/disk imaging, and automated installation methods.Experience configuring and troubleshooting Layer 2 switching, VLANs, TCP/IP, and network connectivity.Experience managing Windows and Linux updates, patching, and vulnerability remediation.Ability to develop automation scripts using PowerShell and Bash.Familiarity with Linux software repository management.Ability to work independently and collaboratively with minimal supervision.Strong analytical, communication, and problem-solving skills.Preferred QualificationsRed Hat Certified System Administrator (RHCSA) certification.Experience administering VMware, Hyper-V, or other virtualized environments.Experience with automation and configuration management tools, including Ansible.Experience supporting secure or classified DoD environments.Knowledge of backup, recovery, logging, and monitoring solutions.Experience performing DISA STIG remediation, SCAP compliance validation, and vulnerability scanning using Tenable NessusIf you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo — because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 — and moving faster than anyone else dares.Original Posting:September 30, 2026For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above.Pay Range:Pay Range $87,100.00 - $157,450.00The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.SummaryLocation: Beavercreek, OHType: Full time