Network Engineer – Operational Technology (OT)

SECURA SINGAPORE PTE. LTD.; Singapore; On-site; SGD 70,000 - 110,000; Full time

Job summary

SECURA SINGAPORE PTE. LTD. is seeking an experienced Network Engineer to design, implement, maintain, and secure network infrastructure for an OT/industrial environment.

The role focuses on a segmented, air-gapped network to ensure reliable and secure communication among industrial systems and supporting IT. You will manage site-to-site VPNs, DMZ services, Microsoft Entra ID (Azure AD), and firewall configurations while upholding cybersecurity and change-management practices in a critical

Qualifications

• 3+ years of experience in network engineering in OT/industrial environments.
• Strong knowledge of TCP/IP, VLANs, routing, DNS, DHCP, and troubleshooting.
• Experience with enterprise firewalls and site-to-site VPNs.
• Proficient in network segmentation and DMZ architecture.
• Familiar with Microsoft Entra ID / Azure AD and Windows servers.
• Understanding of cybersecurity for OT and secure network design.

Responsibilities

• Configure, maintain, and troubleshoot network infrastructure within an air-gapped OT environment.
• Manage switches, routers, firewalls, VLANs, routing, and segmentation.
• Implement secure segmentation between OT, IT, DMZ and other zones.
• Maintain network diagrams, IP schemes, documentation, and inventories.
• Perform changes with minimal disruption to critical operations.
• Configure and troubleshoot site-to-site VPN connections.
• Manage a DMZ hosting services used by clients to upload files.
• Support network authentication with Microsoft Entra ID/Azure AD.
• Assist with OT device connectivity and network access issues.

Skills

3+ years of experience in network工程

TCP/IP

VLANs

Subnetting

Routing

DNS

DHCP

Network troubleshooting

Enterprise firewalls

Site-to-site VPNs

Network segmentation

DMZ architecture

Microsoft Entra ID / Azure AD

Windows-based servers

Network monitoring tools

Cybersecurity principles

Job description

Job Summary

We are seeking an experienced Network Engineer to design, implement, maintain, and secure network infrastructure supporting an Operational Technology (OT) / industrial environment.

The role will primarily focus on managing a segmented and air-gapped network environment, ensuring reliable and secure communication between industrial systems, servers, network devices, and supporting infrastructure. The successful candidate will also be responsible for firewall management, site-to-site VPN connectivity, DMZ services, Microsoft Entra ID (Azure AD), and network security.

This role requires a strong understanding of both network infrastructure and cybersecurity principles, with particular emphasis on maintaining the availability, integrity, and security of OT environments.

Key Responsibilities

Network Infrastructure & OT Environment

• Configure, maintain, and troubleshoot network infrastructure within an air-gapped OT environment.
• Manage network switches, routers, firewalls, VLANs, routing, and network segmentation.
• Implement and maintain secure network segmentation between OT, IT, DMZ, and other network zones.
• Maintain accurate network diagrams, IP addressing schemes, configuration documentation, and network inventories.
• Perform network configuration changes while minimizing disruption to critical operational systems.
• Configure and troubleshoot site-to-site VPN connections between approved locations or network environments.
• Manage and maintain a DMZ environment hosting web-based services used by clients to upload files.
• Support network and authentication requirements associated with Microsoft Entra ID (formerly Azure Active Directory).
• Assist with identity-related network access, authentication, and connectivity issues.

Industrial Devices & OT Support

• Provide network support for industrial equipment, including industrial printers and other OT-connected devices.
• Troubleshoot communication issues between industrial devices, servers, and network infrastructure.
• Work with OT engineers, vendors, and equipment manufacturers to resolve network-related issues.
• Ensure industrial devices are appropriately segmented and protected from unauthorized network access.
• Understand the operational constraints of industrial environments, including the importance of availability and controlled change management.
• Setting up / troubleshoot SFTP connection.

Network Security & Compliance

• Apply cybersecurity best practices to OT and network infrastructure.
• Maintain strict access controls within the air-gapped environment.
• Identify and mitigate network security risks and vulnerabilities.
• Participate in security assessments, audits, and incident investigations where required; such as ISO 27001
• Maintain network security documentation and configuration baselines.
• Follow formal change management, backup, and disaster recovery procedures.
• Ensure changes to OT networks are properly assessed, tested, documented, and approved before implementation.

Requirements

Technical Skills

• 3+ years of experience in network engineering, preferably within industrial, manufacturing, critical infrastructure, or OT environments.
• Strong understanding of TCP/IP, VLANs, subnetting, routing, DNS, DHCP, and network troubleshooting.
• Hands-on experience with enterprise firewalls.
• Experience configuring and troubleshooting site-to-site VPNs.
• Experience with network segmentation and DMZ architecture.
• Working knowledge of Microsoft Entra ID / Azure AD.
• Experience supporting Windows-based servers and network-connected devices.
• Familiarity with network monitoring and diagnostic tools.
• Understanding of cybersecurity principles and secure network design.

OT / Industrial Experience

Experience working in an Operational Technology (OT), industrial, manufacturing, or air-gapped environment will be highly advantageous.

Candidates should understand the differences between traditional IT and OT environments, particularly:

• Availability and operational continuity are critical.
• Network changes must be carefully controlled and tested.
• Legacy systems and industrial equipment may have strict compatibility requirements.
• Security controls must be implemented without disrupting industrial operations.
• Network segmentation and controlled access are essential to protecting OT systems.

Key Competencies

• Strong analytical and troubleshooting skills.
• Good understanding of network security.
• Ability to work independently in a controlled and security-sensitive environment.
• Strong documentation and communication skills.
• Ability to work with OT engineers, vendors, and external clients.
• Strong attention to detail.
• Good understanding of change management and risk assessment.
• Ability to respond effectively to network incidents and service disruptions.
• Willingness to work outside normal business hours for planned maintenance or critical incidents when required.