Senior IT Systems Engineer

Horizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find and fix and verify exploitable attack vectors before criminals exploit them. Our flagship product, the NodeZeroTM platform, delivers production-safe autonomous pentests and other key assessment operations that scale across the largest internal, external, cloud, and hybrid cloud environments. Node Zero has been adopted by organizations of all sizes, from small educational institutions to government agencies and Global 100 enterprises.

It is used by ITOps/Sec Ops teams, consulting pentesters, and MSSPs and MSPs.

We are a fusion of former U.S. Special Operations cyber operators, startup engineers, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools, false positives resulting in alert fatigue, blind spots, "checkbox" security culture, cybersecurity skills shortage, and the long lead time and expense of hiring outside consultants. Collectively, we are a team of learn it alls, committed to a culture of respect, collaboration, ownership, and results.

We are seeking a security-minded IT Systems Engineer with a genuine passion for networking — someone equally comfortable hardening identity and email infrastructure as they are managing routing and firewall policy. This role is roughly 60% security, identity, and email systems and 40% network engineering.

You will own the controls that protect how our distributed workforce authenticates, communicates, and connects, while keeping the underlying network reliable and well-documented. This role partners closely with Security and the Help Desk team to resolve escalated issues and to keep network, identity, and email infrastructure aligned with company security standards.

This role will be responsible for.....

• Administer and secure Okta (or equivalent IdP/SSO), managing authentication policies, access provisioning, and integration with downstream applications

• Architecting, Administering and secure the company email/collaboration platform, including mail flow rules, spam/phishing filtering, DKIM/DMARC/SPF configuration, and data loss prevention policies

• Own operations, monitoring, and incident response for network, email and identity security controls including firewall policy, and threat detection

• Triage incidents and remediate or elevate per incident response procedures

• Collaborate across teams (Security and Help Desk) to resolve escalated connectivity issues, support onboarding/offboarding, and ensure infrastructure remains aligned with security standards.

• Evaluate and recommend improvements to identity architecture, email security posture, and related tooling

• Administer and maintain network infrastructure: switches, routers, firewalls, and wireless access points while also supporting a distributed workforce, including capacity planning and performance monitoring

• Design and implement network changes (VLANs, routing, firewall rule changes) with minimal disruption to business operations

• Maintain accurate documentation of network topology, configurations, and email/identity security architecture

• Manage vendor relationships and support contracts for network, firewall, identity, and email security tooling

• Demonstrate a commitment to integrity, process improvement, and customer satisfaction

• Must have hands-on experience administering an identity/SSO platform (e.g., Okta) in a production environment, including access policies and app integrations

• Must have experience configuring and maintaining email security controls, including SPF, DKIM, DMARC, and anti-phishing/anti-spam tooling

• Must have experience…