Senior IT Systems Administrator

Castelion Corporation
Torrance, CA
Category Security
Job Description
Castelion is seeking a highly skilled and security-focused Senior IT Systems Administrator to join its team. The ideal candidate will have experience in systems administration in a secure, enterprise IT environment and strong experience with Linux and Windows Servers.

Requirements

  • Administer, maintain, and secure Linux and Windows based server environments.
  • Manage cloud IaaS and virtualization platforms including Microsoft Azure, AWS, and on-premises platforms.
  • Implement and maintain system hardening in compliance with DoD STIGs, NIST frameworks, CMMC, and more.
  • Monitor system performance, conduct root cause analysis, and resolve complex infrastructure issues.
  • Ensure system availability and disaster recovery through backups, patch management, and redundancy planning.
  • Manage user and group lifecycles in Microsoft 365.
  • Collaborate with cybersecurity teams during audits, incident response, and vulnerability remediation.
  • Lead IT infrastructure projects including upgrades, migrations, and system deployments.
  • Document system configurations, procedures, and changes to maintain accurate and secure records.
  • Train and mentor junior IT staff, promoting a culture of compliance and technical excellence.

Benefits

  • Comprehensive medical, vision, and dental insurance
  • Four weeks of paid time off per year
  • Long-term stock incentives
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