John Leisner
Odenton,Maryland
Summary
Certified CompTIA Security+ and A+ Windows and Linux System Administrator working in the cleared industry for 10+ years looking for work in any areas of Sys Admin, DevOps, AWS and primarily looking for telework/hybrid work.
Overview
12
12
years of professional experience
1
1
Certification
Work History
Senior System Administrator
Freedom Technology Solutions
02.2025 - Current
- Manages almost a dozen SSPs to maintain security posture and compliance for the mission.
- Administer and maintain enterprise Windows and/or Linux servers in virtualized and bare-metal environments.
- Plan and execute system upgrades, migrations, and disaster recovery procedures.
- Provides Tier 3 escalation support and lead root cause analysis for complex incidents.
- Implement and manage Active Directory, DNS, DHCP, Group Policy, and file/print services.
- Configure, patch, and secure systems in accordance with STIGs and government standards through (LA)
VMware Cloud Administrator
Jacobs
06.2024 - Current
- WAN Installation and management of network components and VMware appropriate for classroom network infrastructures across several sites across the United States.
- Experience installing, maintaining, and updating VMware vCenter and ESXi Hosts and VMs
- Experience with networking technologies such as routers, switches, encryption, and firewalls.
SCIF OPS System Administrator
SCD information Technology
01.2024 - 06.2024
- Work on a fast-paced small team of system administrators providing support for implementation, troubleshooting and maintenance of Information Technology (IT) systems for critical enterprise applications Manages IT system infrastructure and any processes related to these systems.
- Provides support to IT systems including day-to-day operations, monitoring and problem resolution for all the client, server, storage, network devices, etc. Provides Tier 1 (Help Desk) and Tier 2 (Escalation) problem identification, diagnosis, and resolution of problems
- Configures and manages UNIX and Windows operating systems, installs and loads operating system software, troubleshoots, maintains integrity and configures network components along with implementing operating systems enhancements to improve reliability and performance.
AWS Cloud Support Engineer
Applied Insight
03.2020 - 12.2023
- Interact with various UNIX and Linux operating systems, applications, environments, and cloud computing platforms to create IT automation and orchestration activities.
- Perform incremental testing actions on code, processes, and deployments using various methods such as putty to identify ways to streamline execution and minimize errors encountered.
- Experience in Commercial Cloud Environments such as AWS and Azure with a firm knowledge of the Amazon Management Console to troubleshoot issues within EC2 instances, S3 buckets, IAM roles, Workspaces and several other cloud tools.
- Firm knowledge and experience working within Jira & Confluence products as well as junior level experience with scripting in BASH & Python.
- Worked within Tenable and Trellix ePolicy Orchestrator (EPO) to address Critical and High Vulnerabilities within the environment as well as install Trellix onto systems.
Windows System Administrator
Eagle Alliance/AT&T
03.2014 - 02.2020
- Installed, operated, maintained, repaired and modified enterprise equipment such as Windows 10 computers and virtual environments.
- Performed a variety of maintenance and technical support on products such as equipment, integrated systems and subsystems, and software at customer locations.
- Effective at deploying critical security updates/patches to enterprise equipment on a crucial time schedule.
- Monitor system performance, ensure seamless network connectivity, and implement security measures to protect against cybersecurity threats
Software License Asset Manager
Inovex
01.2013 - 03.2014
- Provided excellent support for customers via remote assistance and/or telephone to quickly and correctly resolve software/license tickets.
- One of a handful System Admin Technicians tasked with providing Free Open Source Software (FOSS) and licensed software to thousands of customers on a daily basis.
Education
Studying - Cybersecurity
AACC
Arnold, MarylandHigh School Diploma -
Glen Burnie High School
06-2010
Skills
- Active Directory Management
- Windows and Linux Administration
- AWS console configuration and EC2 management
- CISCO Networking
- Tier 1 & Tier 2 Problem Solving Expertise
- Jira and Confluence Management
- 3-4 years of linux patching and admin experience
- VMware Vcenter and ESxi host management
Certification
CompTIA A+ June 2022
CompTIA Security+ February 2024
Timeline
Senior System Administrator
Freedom Technology Solutions
02.2025 - Current
VMware Cloud Administrator
Jacobs
06.2024 - Current
SCIF OPS System Administrator
SCD information Technology
01.2024 - 06.2024
AWS Cloud Support Engineer
Applied Insight
03.2020 - 12.2023
Windows System Administrator
Eagle Alliance/AT&T
03.2014 - 02.2020
Software License Asset Manager
Inovex
01.2013 - 03.2014
Studying - Cybersecurity
AACC
High School Diploma -
Glen Burnie High School
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