The Network Software Engineer will support DARPA's QuANET program. The role focuses on building and testing software that integrates network emulation, routing, telemetry, and cyber-response logic. The developer will work hands-on with Python and C++, create reproducible test environments, debug Linux and container networking issues, and collaborate with senior engineers across hardware, cyber, and networking teams. Strong systems and distributed-networking skills are essential; quantum-domain experience is not required. Candidates with deep implementation ability and broad networking expertise are preferred. Primary Responsibilities: • Design, implement, and test network systems software in Python and C++. • Build and debug Linux-based network topologies using namespaces, veth pairs, bridges, iproute2, iptables/nftables, and traffic-control tooling. • Develop and maintain containerized network emulation environments using Docker and related container networking patterns. • Integrate inter-process messaging such as ZeroMQ, gRPC, protobuf, or similar mechanisms. • Support reproducible CI/CD and regression testing for network and systems code. • Use network simulation or emulation tools such as Containerlab, Kathara, Mininet, ns-3, GNS3, or equivalents. • Troubleshoot distributed behavior such as convergence, message ordering, failure detection, and eventual consistency. • Write clear design notes, implementation plans, and technical status updates for mixed technical and non-technical audiences. • Participate in code review and collaborate with cross-functional research teams. Basic Qualifications: • Bachelor's degree in computer science, computer engineering, electrical engineering, networking, or a related technical field and 4-8 years of relevant experience, or a master's degree with 2-6 years of relevant experience; additional relevant experience may be considered in lieu of degree. • Hands-on programming experience in Python and C++, with strength in at least one and working competence in both. • Experience building, operating, or debugging a distributed system at non-trivial scale, such as consensus systems, message brokers, service meshes, distributed databases, routing systems, or comparable systems. • Practical Linux networking experience, including namespaces, veth pairs, bridges, iproute2, iptables/nftables, and tc. • Docker or container networking experience beyond basic container usage, including bridge, macvlan, host networking, CNI, or multi-container interconnect patterns. • Familiarity with inter-process messaging frameworks such as ZeroMQ, gRPC, protobuf, or similar. • Experience with C++ build and debug tooling such as CMake, gdb, valgrind, perf, or equivalents. • Experience with standard Python development, testing, and packaging workflows. • Experience contributing to CI/CD or reproducible test environments for systems, networking, or software projects. • Git fluency and experience participating in code review. • Must be a US citizenship with ability to obtain and maintain a US government security clearance. Preferred Qualifications: • Working knowledge of routing protocols such as BGP, OSPF, IS-IS, or similar, including ability to read and interpret RFCs. • Experience with FRR, Bird, Quagga, GoBGP, or other open-source routing stacks. • Prior contribution to open-source routing daemon or network-stack projects. • Experience with network operating systems such as SONiC, Cumulus, VyOS, or comparable systems. • Experience with streaming telemetry or observability stacks such as gNMI, OpenConfig, Prometheus, or Grafana. • Experience with Containerlab, Kathara, Mininet, ns-3, GNS3, or comparable network emulation/simulation tooling in production-grade use. • Prior experience on government-funded R&D programs such as DARPA, IARPA, ONR, AFRL, ARL, DOE, or NSF. • Experience with tactical, contested, or resilient networking • TS/SCI Security Clearance Original Posting: June 24, 2026 For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above. Pay Range: Pay Range $87,100.00 - $157,450.00 The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.