Caleb Sims

About Caleb Sims

RHCSA and Security+ CE certified Linux Systems Administrator at L3Harris Technologies, supporting defense and national security infrastructure.Core skills: RHEL 7/8/9, CentOS, Ubuntu Server, Windows Server, Active Directory, Group Policy, Ansible, Bash, Python, Docker, Kubernetes, VMware vSphere, SELinux, iptables, firewalld, DNS, DHCP, Apache, Nginx, NFS, Samba, LVM, ZFS, RAID. Security and compliance: DISA STIG hardening (96% compliance), SIEM deployment with Graylog, Zero Trust architecture, vulnerability management, incident response workflows, SCAP/OpenSCAP scanning, FIPS 140-2 alignment, PKI with HashiCorp Vault. Monitoring and operations: Nagios Core, CheckMK, centralized logging, fleet management, PXE boot provisioning, disaster recovery planning, storage encryption. Automation and DevOps: Ansible playbooks across fleet nodes (40% reduction in manual admin time), CI/CD pipelines, Infrastructure as Code, containerized workloads with Docker and Podman. My GitHub (rhellyroll) hosts 24 production grade lab projects spanning core Linux foundations, enterprise operations, and mission systems architecture, including F-35 ALIS simulations, coalition ops infrastructure, and Kubernetes mission stacks. Career transition from insurance adjusting brought me strong incident management, multi stakeholder coordination, SLA discipline, and audit ready documentation skills. Security+ CE satisfies DoD 8570/8140 IAT Level II. Pursuing RHCE, VCP, LPIC. Clearance eligible. Targeting: Systems Administrator, Cybersecurity Analyst, Network Engineer, IT Support Specialist roles at defense contractors and federal technology companies. Email: c••••••••@gmail.com

Experience

1. Sr Associate Software Engineer

   L3Harris Technologies

   Mar 2026 — Present

   Administered RHEL-based Linux systems (RHEL 7/8/9, Rocky 8) across unclassified and DCSA-accredited secure DoD environments, supporting full lifecycle operations including provisioning, patching, configuration management, and break/fix troubleshooting.Installed, configured, and hardened enterprise infrastructure services including LDAP/DS389, DNS, DHCP, NTP, SMB, and PXE Boot across multi-OS environments spanning Linux and Windows.Enforced DoD cybersecurity compliance standards including RMF, DISA STIG, CMMC, DFARS, and NIST 800-53/171, leveraging tools such as Nessus and OpenSCAP to validate system hardening posture.Managed user access controls, security policies, and backup and recovery operations across mission-critical systems in secure, accredited environments.Authored technical documentation including build manuals, work instructions, and configuration diagrams supporting security operations, management, and software integration teams.Collaborated with a multidisciplinary team of Linux, Windows, and network administrators to integrate mission software and resolve complex distributed system issues.