System Administrator

Leidos' Corporate Information Security Office, reporting through the Digital sector, is seeking a System Administrator to support various classified environments. The successful candidate will be responsible for maintaining, securing, and supporting a complex classified information system, as well as ensuring compliance with security protocols and regulations.

Location: All work will be performed on site in our San Diego, CA office.

Clearance: You must hold a current, active DoD Top Secret Clearance to qualify for consideration.

Primary Responsibilities

This role includes a combination of duties to protect information, and maintain security controls, for an entire system, site, or program to reduce risk.

• Administer, maintain, and troubleshoot Windows and Linux-based workstations and servers within a mixed operating system environment.
• Manage Active Directory services, including user and computer accounts, Group Policy Objects (GPOs), DNS, and system authentication.
• Perform routine system maintenance, software installations, patching, configuration updates, and hardware troubleshooting to ensure system availability and reliability.
• Configure and maintain network infrastructure, including switches, VLANs, IP addressing, firewall rules, and network connectivity.
• Administer enterprise storage and file-sharing services, including SMB, NFS, iSCSI, and applicable file system permissions and access controls.
• Implement and maintain system security configurations in accordance with DISA STIGs, JSIG, RMF, and organizational cybersecurity requirements.
• Execute vulnerability assessments and compliance scans using tools such as DISA SCC, Evaluate-STIG, and Tenable Nessus; remediate identified findings and document corrective actions.
• Develop and maintain automation scripts using PowerShell, Bash, or Ansible to improve system administration efficiency, configuration consistency, and repeatability.
• Monitor system health, performance, storage utilization, backup operations, and security logs to proactively identify and resolve operational issues.
• Support system backup, recovery, and data protection activities to ensure operational continuity and data integrity.
• Follow established change management processes, including documenting, coordinating, and implementing approved system modifications.
• Develop and maintain technical documentation, system configurations, network diagrams, and standard operating procedures (SOPs).
• Collaborate with Information System Security Officers (ISSOs), Information System Security Managers (ISSMs), and engineering personnel to support continuous monitoring, security assessments, and authorization activities.
• Provide technical support to end users, troubleshoot reported issues, and coordinate with program stakeholders to minimize operational disruptions.
• Assist with hardware refreshes, system deployments, technology upgrades, and infrastructure modernization initiatives.
• Other duties as assigned.

Basic Qualifications

• Bachelor’s degree coupled with 4-8 years of experience or equivalent relevant industry-standard experience and certifications may be considered in lieu of a degree.
• Must be a U.S. Citizen.
• Must currently hold an Active Top Secret security clearance to be considered along with sustained ability to be cleared to Special Access Programs (SAP) and ability to obtain a Polygraph.
• Must have a current DoD 8570 IAT level II or higher certification such as CompTIA Security+.
• Windows and Linux Administration: Experience administering, configuring, troubleshooting, and maintaining both Windows and Linux operating systems in an enterprise environment to include workstations, Active Directory, DNS, and Group Policy.
• Classified Systems and Compliance: Experience supporting Special Access Program (SAP) environments, including familiarity with the Joint Special Access Program Implementation Guide, Risk Management Framework (RMF), and system authorization lifecycle requirements.
• Networking and Security Technologies: Working knowledge of enterprise networking concepts and switching technologies including TCP/IP, VLANs, subnetting, RADIUS, firewall rules, and networking troubleshooting.
• Security Compliance and Vulnerability Management: Experience utilizing common compliance tools including DISA SCAP, Evaluate STIG, Tenable Nessus, and Trellix. Ability to interpret scan results, identify security efficiencies, implement corrective actions, and maintain compliance documentation.
• Enterprise Storage and File Services: Experience configuring, managing, and troubleshooting enterprise storage and file-sharing technologies including iSCSI, SMB, and NFS. Understanding of Windows NTFS permissions, Linux file permissions, access control lists, and secure storage provisioning.
• Change and Configuration Management: Knowledge of established change management processes, configuration baselines, documentation standards, and system lifecycle procedures. Ability to plan, document, and execute system changes while minimizing operational impact and maintaining security compliance.
• Technical Troubleshooting and Operational Support: Strong demonstrated ability to independently diagnose and resolve moderately complex hardware, software, operating system, and network issues. Experience performing software installation, system updates, remote administration, and routing maintenance within controlled environments.
• Technical Documentation and Collaboration: Ability to develop and maintain technical documentation, standard operating procedures, work instructions, and system configuration records. Experience collaborating with engineering, cybersecurity, and program stakeholders to support operational requirements.

Preferred Qualifications

• RedHat Certified System Administrator (RHCSA) certification.
• Automation and Scripting: Experience developing, modifying, and executing automation scripts or playbooks using PowerShell, Bash, or Ansible to improve system deployment, configuration management, patching, security, compliance, and operational repeatability.
• Advanced Infrastructure Experience: Experience administering virtualized environments, working with High Performance Computing (HPC), and managing enterprise backup and recovery solutions.

If 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.

The 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.