Senior Software Engineer, Networking

SimSpace serves as an AI Proving Ground where organizations can confidently train, test, and outmaneuver adversaries in any environment. Trusted by allied governments, militaries, enterprises, and research institutions worldwide, SimSpace enables adaptive, AI-ready defenses that stay ahead of evolving threats. Founded in 2015 by experts from U.S. Cyber Command and MIT Lincoln Laboratory, the platform unifies training, testing, and validation in a realistic, live-fire simulation—helping teams evaluate security investments, optimize performance, and compress cyber readiness cycles from months to days.

Why join SimSpace? We are an organization that is focused on building our culture and mindfully enhancing our atmosphere every day which is why we have collaborated on an integral value system. Our governing philosophy of being Human Centered is deeply embedded within our value system. We apply this philosophy to every one of our internal team members, external clients, and their customers.

How Do We Work? We believe that people are at the center of everything we do. SimSpace fosters a culture of continuous learning, curiosity, and professional growth. That belief shows up in action: in-house training, internal and external learning platforms, cyber conferences, industry events, and dedicated time for skill development. Our people are empowered to shape their careers - and it shows. Year over year, SimSpace consistently outperforms industry benchmarks in internal mobility, promotions, and total rewards growth.

Who Thrives Here? We are a team of innovators, protectors, and problem-solvers. We believe diversity of thought and experience fuels better solutions, and we’re committed to building teams that reflect the communities we serve. Whether you’re remote or office-based, you’ll collaborate with talented colleagues across departments and time zones, united by the mission to create a safer digital world.

We invite you to apply today!

We are looking for a Senior Software Engineer to serve as the technical lead for SimSpace's internet simulation platform — the system that makes cyber range environments behave like the real internet at the network layer. This is foundational, novel work: you will be designing and building a kernel-level simulation layer that reproduces the observable behavior of worldwide internet routing — correct ASN topology, realistic inter-AS latency, accurate traceroute and MTR output — without instantiating a single virtual router. The approach is grounded in a patent pending eBPF-based architecture developed at SimSpace, and this role will take that proof of concept into a production-grade system. As the technical lead on a newly formed team, you will set architectural direction, mentor peer engineers, and partner closely with a Principal Engineer and your Engineering Manager to build something that does not yet exist at this fidelity in the industry.

The team is responsible for:

• A persistent, control-plane internet simulation service that serves multiple concurrent cyber ranges without per-range instantiation

• An eBPF-based network simulation layer providing geographically accurate ASN routing, inter-AS latency enforcement, and traceroute and MTR fidelity entirely in kernel space

• Lightweight in-range proxy agents that receive topology configuration from the control plane and handle local packet interception without requiring a full simulation stack in every range

• A topology database encoding real-world ASN-to-CIDR mappings, inter-AS latency models, and geographic placement data that drives the simulation

• Dynamic reconfiguration of the simulated internet topology at runtime without disrupting in-flight traffic

What will you be doing as a Senior Software Engineer, Network Simulation at SimSpace?

• Own the end-to-end architecture of the eBPF-based routing simulation layer, including XDP and TC hook point design, BPF map structure, and synthetic ICMP TTL-exceeded generation that makes traceroute and MTR behave correctly against the simulated topology

• Design and build the control-plane topology database and the pipeline that compiles real-world internet topology data into a form that in-range agents can consume and apply

• Architect the in-range proxy agent: the lightweight component that bridges the persistent control plane to individual cyber ranges, applying topology configuration locally and handling DNS delegation and traffic forwarding

• Define the interface contract between the control plane and in-range agents, including topology update propagation, graceful degradation when control plane connectivity is interrupted, and agent lifecycle management

• Serve as technical lead for the team — making daily architectural decisions across the full service scope, conducting design reviews, and maintaining engineering quality across all four engineering roles on the team

• Partner with other Engineers on novel simulation challenges, bring independent judgment to architectural tradeoffs, and shape the technical roadmap

• Mentor engineers on the team, raising the bar on systems design, kernel-level debugging, and engineering rigor

• Collaborate with adjacent platform teams on the operational model for a long-lived, multi-tenant service serving active cyber range deployments

Who you are:

• Experience building SDN controllers or control planes with OpenFlow, OVS, or equivalent interfaces

• Deep expertise in Linux kernel networking and eBPF program development, including XDP, TC hooks, BPF map types, and the tradeoffs involved in kernel-space packet processing

• Strong systems programming skills — C or Rust for eBPF program development, and Go or Python for the control-plane agent and tooling layer

• Solid understanding of real-world internet routing — BGP, ASN topology, CIDR allocation, inter-AS peering — sufficient to model it faithfully without running routing software

• Experience designing systems with well-defined control plane and data plane separation, particularly where distributed components may have intermittent connectivity to a central controller

• Demonstrated technical leadership: you have set architectural direction and driven engineering quality across a team, whether as a tech lead, principal, or senior-plus individual contributor

• Comfort at the intersection of research and production engineering — this role involves taking a proof of concept and building it into something that runs reliably at scale

• Familiarity with Kubernetes as the deployment environment for both control plane services and distributed agent components

• Experience with network simulation, traffic shaping, or cyber range infrastructure is a strong plus

• Prior work in cybersecurity, defense, or government-adjacent environments is a plus given SimSpace's customer base

We’re proud to offer a competitive and comprehensive package designed to support your well-being, growth, and success:

• Compensation. Base salary range: $160,000 - $225,000, reflecting our confidence in your expertise and impact, with the opportunity for annual bonuses tied to company performance and individual contributions.

• Health & Wellness. Comprehensive medical, dental, and vision benefits, plus savings plans—coverage starts on day one!

• Mental Health Support. Access to company-paid counseling, coaching, and resources for you and your family through Spring Health.

• Financial Well-Being. Plan for your future with a 401(k)-retirement savings plan featuring a company match.

• Flexible Time Off. Take the time you need with unlimited vacation and dedicated health & wellness days. SimSpace provides flexible solutions to meet the diverse work-life needs of team members.

• Parental Leave. Paid leave plans to support you and your loved ones during life’s most important moments.

• Ownership Opportunities: Equity stock options at hire, with annual performance-based grants—become an invested stakeholder in our shared success.

• Referral Rewards: Earn $1,500–$3,500 for every qualified hire through our employee referral program.

• Peloton Interactive Wellness Program: Full- and partial- subsidized membership plans and equipment discounts to help you reach your personalized fitness goals.

• Continuous Learning: Access a LinkedIn Learning membership to prioritize your personal and professional development.

• Social Connections: Monthly reimbursements for meaningful connections with teammates through our SocialSpace Community.

• Extra Perks: Legal plan coverage, pet insurance, wellness reimbursements, and more to simplify life’s details.

SimSpace is an Equal Opportunity Employer:

In compliance with federal law, all persons hired will be required to verify identity and eligibility to work in the United States and to complete the required employment eligibility verification document form upon hire.

SimSpace is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, pregnancy, genetic information, disability, status as a protected veteran, or any other protected category under applicable federal, state, and local laws. We are committed to providing an inclusive and welcoming environment for all members of our staff, clients, volunteers, subcontractors, vendors, and clients.

Research shows that women and people from underrepresented groups only apply to jobs if they meet all of the qualifications. However, no one ever meets 100% of the qualifications. SimSpace encourages you to break that statistic and to apply. We look forward to your application!

We also consider qualified applicants regardless of criminal histories, in accordance with applicable law. We are committed to providing reasonable accommodations for qualified individuals with disabilities in our job application procedures. If you need assistance or accommodation due to a disability, please contact careers@simspace.com.

SimSpace does not accept unsolicited resumes from employment agencies.

Actual compensation for the position is based on a variety of factors, including, but not limited to affordability, skills, qualifications and experience, and may vary from the range.