Edgar Arellano

Linux System Administrator | AWS Cloud Engineer | Technical Support Engineer

Work Experience

Linux System Administrator

Maintained a medical Electronic Health Record system (EHR) by applying weekly patches and managing user accounts with least privilege access.
Assisted in migrating the EHR from RHEL 7 to RHEL 8 and patched RHEL servers hosted on Azure to enhance system security and performance.
Authored detailed documentation for patching procedures and routine system maintenance tasks.
Automated the detection of inactive Linux user accounts with a Bash script, streamlining account deactivation processes.
Implemented security measures, system audits, and backups to ensure data integrity and compliance with security protocols.

Linux System Administrator

Managed on-premise Linux infrastructure for Oncor's Information Systems, overseeing 1000+ diverse Linux servers (bare metal and VMs) running on RHEL 6, 7 & 8.
Leveraged Ansible to write playbooks that automate server inventory management, enabling efficient monitoring of diskspace utilization on critical directories such as /tmp, /var, and /root.
Developed custom Bash scripts to streamline server administration, automating SSH key distribution to hundreds of servers, enhancing security and simplifying remote access management.
Contributed to vulnerability management efforts by creating a Bash script to assess Linux systems for the presence of the IPVLAN kernel module, ensuring timely identification and mitigation of security risks across the infrastructure.

AWS System Administrator

Administered AWS cloud infrastructure for Informed DNA's genetic management systems and designed AWS VPC networks with public/private subnets, NAT Gateway, and VPN tunnel for secure communication with an external customer's on-premise network.
Managed Windows Server (2016, 2019) and Linux (CentOS/RedHat) EC2 instances in AWS, automating patching with AWS Systems Manager and monitoring performance with CloudWatch alarms, resulting in improved system reliability and a 20% reduction in infrastructure costs.
Configured AWS security services, including Web Application Firewalls (WAF), AWS Shield (DDoS mitigation), and IAM Identity Center for user management, SSO/MFA access, and enhanced system security for public-facing applications.
Implemented RDS storage autoscaling, cross-region/multi-AZ backups, and EC2 backup strategies using EBS Data Lifecycle Manager and AWS Backup for disaster recovery across 50 Linux EC2 servers, 5 RDS instances, and 2 Redis instances.
Managed SSL certificates for 40 web servers using Digicert, AWS ACM, and Route 53, while configuring CloudWatch Dashboards to monitor critical system metrics for EC2, RDS, ELB, and EBS volumes.

AWS System Administrator

Oversee and administer AWS GovCloud SaaS infrastructure for Perspecta's Veteran Affair's (VA) MVP project.
Scheduled a monthly automated patching maintenance window using AWS Patch Manager that patched 100+ Linux servers.
Deployed custom AWS CloudWatch alarms for 80 Ubuntu EC2 servers and 30 DB instances, alerting when server CPU, Memory, and Disk Utilization thresholds are crossed.
Configured Linux server backups by utilizing tagging/AWS backup and disaster recovery tests to ensure business continuity.
Administered 40 IAM user accounts, enforcing least privilege access policies through tags. Governed access to resources like AWS Session Manager, CodeDeploy, CodeCommit, and more.

IT Support

Supported 10 on-prem Microsoft Windows servers and provided technical assistance to 700 end users, handling server administration, PC troubleshooting, Active Directory management, and cybersecurity compliance, while offering direct user support and maintaining clear communication throughout the process.
Led the successful onboarding and mentorship of six new support engineers, ensuring their seamless integration into the team. Additionally, I served as a quality control point, upholding standards for work and documentation to enhance overall team performance.

Bachelor Of Science in Information Systems
The University Of Texas, Arlington • Arlington, TX (07/2014)

Introduction to Programming Using Python — The University of Leeds (12/2024 - Present)
Terraform Associate — Hashi Corp (05/2023)
AWS Certified SysOps Administrator - Associate — AWS (12/2020)
AWS Certified Solutions Architect - Associate — AWS (02/2019)