Senior Infrastructure & Network Engineer (L3)

About this role

Senior Infrastructure & Network Engineer (L3) (Part-time)
Architecture, Security & Compliance
Position Summary
We are seeking a highly experienced Senior Infrastructure & Network Engineer (Level 3) to provide senior-level technical oversight, architecture review, configuration validation, project assurance, and infrastructure compliance support across our enterprise technology environment.
This is not a traditional network administration or deployment-focused position.
The primary purpose of this role is to serve as a senior technical reviewer and trusted second set of eyes for infrastructure and network projects. The engineer will review proposed architectures and implementations, identify technical or security weaknesses, recommend improvements, assist with complex configuration adjustments when necessary, and independently verify that systems have been implemented correctly.
The engineer will work closely with IT leadership, infrastructure teams, vendors, MSPs, and the cybersecurity team to ensure that technology implementations are reliable, scalable, secure, properly documented, and aligned with established cybersecurity and compliance requirements.
The role will also participate in the development of automation and AI-assisted compliance validation, including an AI CISO platform designed to continuously review technical controls, configurations, asset coverage, and compliance evidence.
Core Responsibilities

• Review network and infrastructure architectures before implementation.

• Review configurations implemented by internal teams, vendors, MSPs, and other technical resources.

• Validate that infrastructure projects follow technical, security, and vendor best practices.

• Identify design weaknesses, configuration problems, unnecessary exposure, and operational risks.

• Provide recommendations for improving architecture, reliability, performance, security, and maintainability.

• Perform post-implementation reviews to verify systems were configured as designed.

• Assist engineers with complex configuration changes and troubleshooting when senior-level expertise is required.

• Independently validate remediation after identified issues have been corrected.

• Participate in technical design and architecture discussions for new projects.

• Review implementation plans, change plans, testing procedures, and rollback strategies.

• Maintain and improve technical standards, configuration baselines, and review checklists.

Advanced Network Engineering Skills
The successful candidate should possess advanced Level 3 knowledge of:

• TCP/IP and advanced network troubleshooting.

• IPv4 addressing and subnetting.

• Layer 2 and Layer 3 switching.

• VLANs and network segmentation.

• STP/RSTP.

• LACP and link aggregation.

• ACLs.

• NAT.

• DHCP and DNS.

• OSPF and BGP.

• VPN technologies.

• Firewall concepts and policy design.

• Multi-site networking.

• Network redundancy and high availability.

• Enterprise Wi-Fi.

• Network performance analysis.

• Packet-level troubleshooting using Wireshark or equivalent tools.

The engineer should be capable of reviewing an unfamiliar network environment and identifying architectural, configuration, performance, reliability, and security concerns.
Infrastructure Architecture & Technical Assurance
Strong experience reviewing:

• Network diagrams and architecture.

• Switch and router configurations.

• Firewall rules and ACLs.

• VLAN and segmentation strategies.

• Management networks.

• Wireless architecture.

• VPN and remote-access configurations.

• High-availability designs.

• Internet and WAN connectivity.

• Authentication and administrative access.

• Logging and monitoring configurations.

• Infrastructure firmware and software standards.

• Backup and recovery architecture.

• Vendor-proposed technical solutions.

Security & Compliance Engineering
This position is not part of the cybersecurity/SOC function, but the engineer must have a strong understanding of cybersecurity architecture and compliance requirements.
Required knowledge includes:

• Network segmentation.

• Zero Trust principles.

• Least privilege.

• Secure administrative access.

• MFA and SSO.

• Privileged-access concepts.

• Endpoint protection architecture.

• EDR/XDR architecture.

• Secure Internet access.

• Encryption requirements.

• Logging and telemetry.

• Vulnerability-remediation requirements.

• Infrastructure hardening.

• Secure configuration baselines.

• Defense-in-depth principles.

The engineer should have working knowledge of frameworks such as:

• NIST Cybersecurity Framework.

• CIS Critical Security Controls.

• Cyber-insurance technical requirements.

• Common enterprise security-control requirements.

Configuration & Compliance Validation
A major responsibility of this position is independently validating technical controls.
Examples include reviewing whether:

• Management interfaces are properly isolated.

• Administrative access is appropriately restricted.

• Network segmentation is implemented correctly.

• Firewall and ACL rules match the intended design.

• Required MFA controls are properly configured.

• Endpoint-management platforms cover the intended systems.

• Security agents are correctly deployed and communicating.

• Required logs are being generated and forwarded.

• Network equipment is running approved configurations and firmware.

• Encryption requirements are implemented.

• Infrastructure configurations follow approved security baselines.

Identity & Endpoint Architecture
Strong understanding of:

• Microsoft Entra ID.

• Duo MFA and SSO.

• SAML.

• OAuth/OIDC concepts.

• Conditional Access concepts.

• RBAC.

• Privileged-access concepts.

• Service accounts.

• Windows enterprise management.

• macOS enterprise management concepts.

• RMM and endpoint-management architecture.

• Patch-management architecture.

• Endpoint security architecture.

Preferred Technology Experience
Experience with the following…