Systems Administrator Sr Principal; TS​/SCI Poly Security Clearance

Position: Systems Administrator Sr Principal (TS/SCI with Poly Required) with Security Clearance
Job Category: IT Infrastructure and Operations

Requisition Number: SYSTE
002170 Posting Details
* Posted:
June 18, 2026

* Full-Time

* On-site

* Salary Range: $ USD to $ USD Job Details Description GCI embodies excellence, integrity and professionalism. The employees supporting our customers deliver unique, high-value mission solutions while effectively leveraging the technological expertise of our valued workforce to meet critical mission requirements in the areas of Data Analytics and Software Development, Engineering, Targeting and Analysis, Operations, Training, and Cyber Operations. We maximize opportunities for success by building and maintaining trusted and reliable partnerships with our customers and industry.

At GCI, we solve the hard problems. As a Sr. Systems Administrator, a typical day will include the following duties:
The candidate will be accountable for Windows system administration, application-based system services and developer-based applications that support the infrastructure. Responsibilities on these systems include SA engineering, operations and maintenance, troubleshooting, configurations, installation, and research and development to ensure continual and optimal operation. The position requires general technical knowledge of systems, networks, and application security as well as an understanding of operational-level security frameworks, policies, processes, and standards.

The candidate must have strong analytical skills for troubleshooting complex issues, attention to detail, and the ability to multitask in a fast-paced environment.

KEY RESPONSIBILITIES
* Maintain Windows operating systems, application support, integration, design, and assistance as needed with additional duties to support the team

* Schedule and install Windows security patching, file and server backups, maintain group policies, troubleshoot server issues, and manage server installs (rack, configure, security harden, maintain)

* Schedule, plan and perform system upgrades

* Maintain, plan and monitor the back-end infrastructure

* Support cyber security engineer performing security analysis of audit logs and other artifacts of a networked computer system REQUIRED QUALIFICATIONS
* Demonstrated experience with Microsoft Windows 11 & Windows Server 22, Active Directory, Group Policy and Certificate Authority administration

* Demonstrated experience with Hypervisor technologies (Hyper-V virtual machines, virtual networking and failover clustering, KVM, VMware, ESXi and vCenter virtual machines, virtual networking and failover capabilities, etc.)

* Remote server access and management (RDP and KVM)

* Demonstrated experience installing and configuring systems which support infrastructure and/or R&D activities

* Demonstrated experience with installing and updating patches on the operational and development systems, and documenting compliance

* Demonstrated experience collaborating with other systems administrators, security analysts, and network engineers to solve complex problems

* Experience in leveraging scripting and system automation tools (Power Shell, BASH, etc.)

* Demonstrated experience in performing and maintaining system backups

* Experience performing with minimal guidance under pressure and tight deadlines

* Excellent communication skills (written, verbal and face-to-face)

* Securing and maintaining standalone environments DESIRED SKILLS
* Experience with PKI and Windows Certificate Authority administration

* Experience with Linux distributions (Rocky, Ubuntu, etc.) and CLI capabilities

* Experience in applying cyber security practices in real-world environments

* Experience working with log analytic tools such as Splunk, Rapid 7 (regular scanning and reporting requirements)

* Powershell use and scripting capabilities

* Nakivo active backup utility

* Whats Up Gold network change management

* Inter Mapper network monitoring

* Smarter Mail internal SMTP mail

* IT and security certifications

* Familiar with Atlassian suite of tools

* Knowledge of cloud technologies, provisioning and security
* A candidate must be a US Citizen and requires an active/current TS/SCI with Polygraph clearance. Equal Opportunity Employer / Individuals with Disabilities / Protected Veterans Qualifications Skills Behaviors :
Motivations :
Education Preferred BA/BS or better. Experience Required 8 years:
Demonstrated work related experience. Licenses & Certifications Equal Opportunity Employer