Marathon is seekeing Windows / Linux System Administrator
to manage and support internal-use telephony systems for our Homeland Security customer. This role provides technical leadership for the configuration, maintenance, and troubleshooting of enterprise telephony infrastructure, with responsibilities spanning operating systems, networking, security, and application support.

This position is on-site and requires a Secret Clearance.

Job-Specific Essential Duties and Responsibilities:
- Manage and support enterprise telephony systems across these programs, including hardware, software, peripherals, and call applications such as WFO/WFM, CMS, and call recording platforms.
- Install, configure, operate, monitor, and maintain enterprise infrastructure, including web servers (e.g., IIS), application servers, and telecom hardware (e.g., Dell PowerEdge servers, Anaya J Series phones).
- Install, configure, troubleshoot, and resolve issues related to telephony systems, Windows / Linux servers, network connectivity, and system integrations with Active Directory, DNS, DHCP, and LDAP.
- Collaborate with cross-functional teams to implement telephony solutions that ensure high availability, call quality, and compliance with security and performance standards.
- Apply regular and emergency patches to Windows / Linux Server environments to maintain security and compliance.
- Perform system upgrades and migrations, including planning, testing, and execution.
- Conduct regular system health checks and preventive maintenance.
- Coordinate with security teams to address audit findings and implement appropriate remediations.
- Other tasks as assigned.

Job-Specific Minimum Requirements:
- Active Secret security clearance.
- Due to contract requirements, only US Citizens can be considered. Candidates with dual citizenship cannot be considered.
- 7+ years of relevant experience in systems administrator or systems engineering.
- Experience with Windows / Linux Server environments, including installation, patching, and troubleshooting.
- Experience with telephony platforms, including Avaya and call recording/workforce management applications.
- Experience with VMware environments, including ESXi and vCenter, for installation, upgrades, troubleshooting, and ESXi certificate management.
- Networking experience includes IPv4 / IPv6, ports/protocols, and monitoring.
- Familiarity with remediation and validation of security vulnerabilities in a Windows / Linux Server environment.
- Proficiency with managing and monitoring infrastructure, including telephony peripherals and server systems.
- Knowledge of client/server certificate management.
- Experience with Active Directory and Group Policy Administration.
- Candidates must reside within a commutable distance for daily onsite work and on-call requirements.
- This contract supports systems that require 24x7x365 uptime. Candidates must be willing and able to meet recall requirements, including participation in a rotational on-call schedule.

Preferred/Desirable Skills:
- Prior Client suitability
- Scripting experience (PowerShell, Shell scripting)
- Experience with virtualization technologies (VMWare)
- Experience with Microsoft SQL Server and PostgreSQL databases
- Demonstrated experience with Active Directory and Group Policy administration
- Experience with security vulnerability remediation and validation