Senior Linux System Administrator

Overview i3 is looking for an experienced Senior Linux System Administrator to join our team. In this role, you’ll be the go-to person for keeping our mission‑critical Linux systems secure, stable, and running smoothly. We work in a dynamic environment supporting multiple organizations, so we need someone who communicates well, adapts quickly, and knows how to operate effectively. You’ll be working closely with our engineering and security teams to troubleshoot complex issues across both Linux and Windows platforms. Because of the nature of the mission, you might occasionally need to jump in during off‑hours to provide support, but your primary focus will be day‑to‑day administration, security, and infrastructure stability. Responsibilities System Administration & Security: Build and maintain our Linux configurations, locking them down according to DISA STIGs and JSIG requirements. You'll also manage user accounts, permissions, and daily monitoring to make sure our hardware and key processes are highly available. Vulnerability Management: A big part of this job is keeping us secure. You’ll run regular ACAS scans, handle system patching, and remediate vulnerabilities. DevOps & Infrastructure: You will own and administer our GitLab environment. This includes managing users, configuring repositories, and supporting CI/CD pipelines, as well as handling containerization and Kubernetes. Operations: You'll take care of routine backups to ensure all our system data is recoverable, and you'll write and maintain the documentation for how our systems are installed and secured. Qualifications Associate’s or Bachelor’s degree in Computer Science, IT, or a related field (or equivalent hands‑on work experience). 10+ years of Linux systems administrator experience, specifically working inside classified environments. Active Top Secret clearance (including SAP Eligibility). U.S. Citizenship is required. Technical Skills: Deep experience working in a mixed OS environment (Red Hat Enterprise Linux and Windows Server). Strong scripting skills—you should be comfortable writing in Bash, Python, or PowerShell. Real‑world experience with GitLab, CI/CD configurations, Kubernetes, and containerization. You need to be heavily familiar with DoD security practices, ACAS, and applying STIGs. Certifications: You must meet industry baseline requirements, which means you need at least a CompTIA Security+ and a Red Hat certification (RHCSA or higher). Network+ and containerization certs are bonus. Security Practices: You need to know the ins and outs of OPSEC and PHYSEC measures and how to conduct yourself professionally in a classified environment. Preferred A Red Hat Certified Engineer (RHCE) certification. A Cisco certification (CCNA or above). Hands‑on experience with virtualization, specifically VMware (and related certifications). Experience using log centralizing tech like Splunk or the ELK Stack. Knowledge/Skills Knowledge of office administration and procedures. Exceptional judgment capabilities and relationship management skills. Excellent communication, teamwork, and client service skills; ability to clearly communicate in discussions and written documents, and to deliver feedback clearly and tactfully. Interact with a diverse array of customers and staff in a professional and courteous manner. Work independently with accountability for accurate and complete results. Be extremely organized and exceptionally detail oriented. Work well both independently and in a team environment. Be energized by a fast-paced work environment. Must be able to communicate with others effectively. Analyze information and respond appropriately. Manage time wisely and prioritize tasks. Provide superior customer service. Multi-task in a pleasant manner. Work well under pressure. PHYSICAL DEMANDS The physical demands described here are representative of those that must be met by an employee to successfully perform the essential functions of this job. While performing the duties of this job, the employee is regularly required to talk or hear. The employee frequently is required to stand; walk; handle or feel; and reach with hands and arms. The employee is occasionally required to sit; climb or balance; and stoop, kneel, crouch or crawl. The employee must be able to lift and/or move up to 10 pounds and occasionally lift and/or move up to 25 pounds. Specific vision abilities required by this job include close vision, distance vision, peripheral vision, depth perception and ability to adjust focus. Regular i3 hours are 8:00 a.m. - 5:00 p.m. Monday-Friday, however, additional hours may be required on occasion. Regular and punctual attendance is required. #J-18808-Ljbffr