Senior Systems Administrator (Open Source)

Location: Remote Employment in Vietnam

Type: Full-time

Schedule: Flexible time

Compensation: 55,000,000 - 65,000,000 VND/month

Company: Twin Signal

About Twin Signal

Twin Signal, a ZenitechCS company, is dedicated to launching new products and expanding into new markets, building on our proven foundation of excellence. For more than 15 years, ZenitechCS has delivered reliable IT solutions to clients across California, USA. Through Twin Signal, we’re extending that legacy with focused AI-first innovation and market expansion.

Our capabilities span end-to-end technology services, including IT Service Management, Software Development, Database Administration, Information Security, Offensive Security, Physical Security Management, Business Intelligence, Computer Networking, and Systems Administration.

Work Policy

This position is 100% remote. The Senior Systems Administrator (Open Source) is expected to be available and responsive during the established working hours, with some flexibility based on operational requirements. Team members must maintain a secure working environment and prevent data exposure through cameras, bystanders, insecure networks, or other risks.

This position includes opportunities for equity compensation, allowing employees to participate in the company’s long-term growth and success.

Position Overview

We are seeking an experienced Senior Systems Administrator to lead the administration, reliability, and security of our hybrid IT environment. This advanced role combines hands-on Linux and Windows engineering, cloud administration, security operations, vulnerability management, and technical leadership.

The successful candidate will take ownership of complex infrastructure and security issues, improve operational maturity, establish standards and procedures, mentor team members, and partner with leadership to reduce risk and improve service reliability.

Key Responsibilities

- Own the administration, maintenance, availability, and security of Linux and Windows systems

- Deploy and configure open source software systems

- Lead execution and continuous improvement of the vulnerability management program

- Monitor infrastructure and security systems, investigate alerts, and coordinate incident response

- Design and implement secure, scalable solutions across on-premises and cloud environments

- Serve as the escalation point for complex systems, network, access, and security issues

- Develop technical standards, operating procedures, runbooks, and incident documentation

- Identify recurring operational risks and lead corrective and preventive initiatives

Primary Responsibilities

- Administer and optimize Azure, Xen, OpenStack environments

- Manage identity, user accounts, privileged access, and role-based access controls

- Lead system hardening, configuration management, patching, and remediation activities

- Administer Microsoft 365 and Google Workspace environments

- Manage endpoint, server, backup, logging, monitoring, and security tooling

- Conduct root-cause analysis for incidents and recurring service issues

- Coordinate technical work with internal stakeholders, vendors, and service providers

- Provide advanced technical support and escalation assistance to staff members

Secondary Responsibilities

- Monitor networks, systems, applications, and security events for anomalies

- Investigate and respond to security incidents in accordance with established procedures

- Troubleshoot complex network, connectivity, performance, and availability issues

- Support disaster recovery, business continuity, and backup restoration testing

- Participate in capacity planning and infrastructure lifecycle management

- Contribute to automation initiatives using scripting and infrastructure management tools

Required Qualifications

- Strong professional English communication skills, both written and verbal

- 8+ years of progressive experience in systems administration, infrastructure engineering, NOC operations, or a closely related role

- Advanced Linux administration and command-line expertise in production environments

- Strong Windows Server administration experience

- Hands-on experience administering Azure and/or AWS environments

- Strong knowledge of TCP/IP, DNS, DHCP, VPNs, firewalls, routing, switching, and network troubleshooting

- Demonstrated experience with vulnerability management, system hardening, patch management, and remediation

- Experience with security monitoring, logging, SIEM, endpoint protection, and incident response tools

- Experience administering Microsoft 365 and Google Workspace

- Strong knowledge of identity and access management, least privilege, MFA, and privileged access controls

- Experience writing technical documentation, runbooks, incident reports, and root-cause analyses

- Proven ability to independently lead complex troubleshooting and security investigations

- Excellent analytical, organizational, prioritization, and stakeholder communication skills

Preferred Qualifications

- Relevant certifications such as RHCSA/RHCE, Microsoft Azure Administrator, AWS SysOps Administrator, CompTIA Security+, CySA+, CCNA, or equivalent

- Experience with scripting or automation using Bash, Python, or PowerShell

- Experience with infrastructure-as-code or configuration management tools

- Familiarity with security frameworks and controls such as CIS, NIST, ISO 27001, or SOC 2

- Experience in an MSP, multi-client, or highly regulated environment

- Prior experience mentoring technical staff or leading infrastructure and security initiatives

Open Source Technologies List

- EuroOffice / OCIS

- Stalwart Mail Server

- Jitsi

- Rocket Chat

- HarfangLab

- OpenZiti

- deSEC

- SFTPGo

- STACKIT

- Brevo

- Selfhosted Drupal

- CryptPad

- SurveyJS

- Keycloak

- Matrix / Element / Signal Bridge

- OpenStack

- Xen Hypervisor

- RustFS

- RustFS

- Kopia | Duplicati

- Chatwoot

- OpenSense

- OpenWRT Router / MikroTik

- OpenWRT Banana Pi / MikroTik

- PiHole

- Headscale

- Vikunja

- Passbolt

- OpenBao

- Mesh Central

- Forgejo

- Harbor

- 3CX

- OpenVAS

- Documenso

- SnipeIT

- Check Stock or Bank ACH/Wire

Schedule

The hours are flexible, but the candidate must be able to respond to issues during the following time: Monday to Friday: 8:00 - 17:00 (Vietnam Time).

Compensation

Senior Systems Administrator (Open Source): 55,000,000 - 65,000,000 per month

The salary offered to each candidate will be determined through an assessment of the candidate’s overall qualifications, experience, and fit for the role.

Important Note: We will not hire a candidate who receives a “low” assessment in English proficiency.

Perks & Benefits

- End of Year Bonus: Standard bonus is valued at least 1 month salary. If the company is successful, and staff have performed well, then highly performing staff may receive larger bonuses. USA, Spain, Mexico, and Argentina will receive bonuses around January 1rst. Vietnamese staff will receive bonuses before Tết.

- Health Insurance: Health insurance will be provided to all staff.

- Dental Insurance: Dental insurance will be provided to all staff.

- Vision Insurance: Vision insurance will be provided to all staff.

- Remote Work: The position is 100% remote.

- Paid Time Off (PTO): We offer a base of 15 days of paid time off in addition to 12 days for national holidays (total of 27 paid days off). Additional time off can be requested as needed.

- Mentorship: We will offer on the job training, continuing education, code review, and technical assistance when required.