SimVentions, Inc. seeks a System Administrator to support Defense & Aerospace IT and cybersecurity operations. You'll manage Windows/Linux servers, networks, and virtualized environments; harden and patch systems; implement STIGs; and monitor performance, availability, and security. Partner with cybersecurity teams on RMF/DoD compliance and incident response. You'll script automation, manage backups, and support end users. Join a collaborative, mission-focused culture where your work directly supports national defense and offers meaningful growth in a values-driven environment.