Systems Engineer, Spectrum

Cloudflare • San Francisco, CA

14h • Onsite

About The Position

Cloudflare's Packet Processing team builds and operates the L3/L4 dataplane services that sit at the front door of our global network. We own the systems that receive, inspect, route, and forward every packet entering Cloudflare — from DDoS-scrubbed IP transit to TCP/UDP application traffic — across every colo in the world. Our work spans Unimog (Cloudflare's L4 load balancer that steers traffic to the right machine in every datacenter), Magic Transit and Cloudflare WAN (our IP-layer DDoS protection and private connectivity products), and Spectrum (our L4 reverse proxy for arbitrary TCP and UDP applications). Together, these systems form the packet-processing foundation of the Traffic Management organization. We are a team of engineers who obsess over performance, correctness, and reliability at massive scale. We work close to the metal, we own what we build in production, and we take pride in shipping systems that "just work" for a very large fraction of the internet.

Spectrum is Cloudflare's Layer 4 reverse proxy — the front door for arbitrary TCP and UDP traffic. It gives customers Cloudflare's DDoS mitigation, anycast performance, TLS termination, and global footprint for any TCP or UDP application: gaming servers, SSH, MQTT, custom protocols, and TLS-terminated services of every shape. Spectrum's edge dataplane runs across every Cloudflare colo, terminating and forwarding a very large volume of concurrent connections per second, and its control plane manages configuration, provisioning, and integration with adjacent Cloudflare systems.

As a member of Spectrum in the Packet Processing team, we're looking for a Systems Engineer who wants to take shared ownership of a critical, high-scale L4 proxy and help evolve it into the next generation of Cloudflare's non-HTTP traffic platform. This is a rare opportunity to work on a product with massive existing scale while helping shape where it goes next as a first-class part of our L3/L4 dataplane story.

Requirements

• Experience building and shipping large-scale, reliable, highly distributed systems
• Strong programming experience in Go ; familiarity with or willingness to work in Rust is a plus
• Solid understanding of L3 and L4 networking : TCP, UDP, IP, connection state, NAT, anycast, and packet flows
• Experience with Linux networking primitives — sockets, eBPF, network namespaces, netfilter/nftables, tc
• Experience designing and integrating RESTful APIs and backend systems
• Comfort with operating what you build in production — on-call rotations, incident response, and root-cause analysis
• Ability to reason about existing systems at scale : reading unfamiliar code, understanding hidden dependencies, and safely evolving software that has been in production for years
• Excellent debugging and optimization skills, particularly around performance and connection lifecycle issues
• Focus on clarity in written and verbal communication; ability to work across teams to land shared solutions

Nice To Haves

• Experience with TLS termination , PROXY protocol, or L4/L7 proxies (Envoy, HAProxy, nginx stream, etc.)
• Experience with ClickHouse , Kafka, or large-scale connection/flow analytics pipelines
• Experience with globally-distributed KV or config-push systems
• Prior work on DDoS mitigation, anycast routing, L4 load balancing, or high-throughput edge network daemons
• Contributions to open-source networking or proxy projects

Responsibilities

• The Spectrum edge dataplane (Go): TCP/UDP connection acceptance and forwarding, TLS termination, PROXY protocol, connection accounting, and eBPF integrations
• The Spectrum control plane (Go): application configuration APIs, provisioning, and the systems that push config globally to every edge machine
• Cross-dataplane integrations : how Spectrum fits together with Unimog for L4 load balancing, with Magic Transit for IP transit, with Argo Smart Routing for accelerated origin paths, etc
• Operational excellence : analytics pipelines, observability, on-call, incident response, and paying down technical debt in a product with a long production history
• Roadmap evolution : help shape where Spectrum goes next as the L4 counterpart to our HTTP proxy stack
• You'll partner closely with the rest of Packet Processing, other Traffic Management teams, DDoS, DNS, Core SRE, and Edge SRE to solve problems that span the entire Cloudflare stack.

Benefits

• We’re not just a highly ambitious, large-scale technology company. We’re a highly ambitious, large-scale technology company with a soul.
• Fundamental to our mission to help build a better Internet is protecting the free and open Internet.
• Project Galileo : Since 2014, we've equipped more than 2,400 journalism and civil society organizations in 111 countries with powerful tools to defend themselves against attacks that would otherwise censor their work, technology already used by Cloudflare’s enterprise customers--at no cost.
• Athenian Project : In 2017, we created the Athenian Project to ensure that state and local governments have the highest level of protection and reliability for free, so that their constituents have access to election information and voter registration. Since the project, we've provided services to more than 425 local government election websites in 33 states.
• 1.1.1.1 : We released 1.1.1.1 to help fix the foundation of the Internet by building a faster, more secure and privacy-centric public DNS resolver. This is available publicly for everyone to use - it is the first consumer-focused service Cloudflare has ever released.
• Here’s the deal - we don’t store client IP addresses never, ever. We will continue to abide by our privacy commitment and ensure that no user data is sold to advertisers or used to target consumers.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed