On-Site Mission-Critical Systems Admin | TS/SCI Polygraph

Leidos; St. Louis (MO); On-site; USD 92,300 - 166,850; Full time

Job summary

Leidos in St. Louis, MO is seeking a Senior Systems Administrator to join the Chinook Program supporting the Intelligence Community.

You will maintain and enhance Windows and Linux server environments, ensuring reliability, security, and performance of mission-critical systems used across development, test, and production environments. This role requires US citizenship, active Top Secret/SCI with poly, and hands-on experience with RMF/STIG, AD, VMware, and scripting.

Qualifications

• US citizenship is required per contract.
• Bachelor's degree in IT/CS/Engineering with 8–12 years of relevant experience or a Master's with 6–10 years of relevant experience.
• 8+ years of enterprise systems administration experience.
• Experience supporting mission-critical DoD or Intelligence Community environments.
• Strong administration experience with Windows Server, RHEL, VMware vSphere, Active Directory, DNS/DHCP, and Group Policy.
• Experience with scripting and automation using PowerShell, Bash, or Python.
• Experience implementing and maintaining STIG compliance.
• Knowledge of RMF security controls and vulnerability remediation.
• Strong troubleshooting and analytical skills.
• Security+ CE or higher DoD 8570/8140 certification.

Responsibilities

• Administer, maintain, and support the customer enterprise.
• Install, configure, patch, upgrade, and lifecycle manage Windows and Linux servers.
• Monitor system health, performance, and availability using enterprise tools.
• Troubleshoot hardware, software, OS, and application issues.
• Support deployment across development, test, staging, and production.
• Coordinate maintenance windows and orchestrate upgrades with minimal disruption.
• Develop automation scripts using PowerShell, Bash, or Python.
• Perform backup, recovery, and disaster recovery operations.
• Support accreditation activities and ensure RMF/STIG compliance.
• Manage user accounts, permissions, and AD integrations.
• Collaborate with security to remediate vulnerabilities and maintain compliance.
• Assist incident response, root cause analysis, and corrective actions.
• Document configurations and SOPs; maintain technical docs.
• Participate in on-call rotation and after-hours support.
• Interface with customer to address operational tasking.

Skills

US citizenship

Windows Server

RHEL

VMware vSphere

Active Directory

DNS/DHCP

Group Policy

PowerShell

Bash

Python

Scripting

STIG compliance

RMF security controls

Security+ CE

Education

Bachelor's degree in Information Technology, Computer Science, Engineering, or related field

Master's degree (optional) with 6-10 years of relevant experience

Tools

Windows Server

RHEL

VMware vSphere

Active Directory

DNS/DHCP

Group Policy

Job description

Leidos in St. Louis, MO is seeking a Senior Systems Administrator to join the Chinook Program supporting the Intelligence Community.

You will maintain and enhance Windows and Linux server environments, ensuring reliability, security, and performance of mission-critical systems used across development, test, and production environments. This role requires US citizenship, active Top Secret/SCI with poly, and hands-on experience with RMF/STIG, AD, VMware, and scripting.