Role: Embedded C Developer – OpenSync/OpenWrt WiFi Router with Cellular
Location: Denver, CO (4 days onsite/week)
Interview: R2 F2F
Required Skills
• 5+ years of embedded C development on Linux-based platforms
• Strong proficiency in C programming — pointers, memory management, IPC, event-driven architectures
• Experience with OpenWrt build system, package management, UCI configuration, and JFFS2/SquashFS overlay filesystems
• Familiarity with OpenSync or similar cloud-managed CPE frameworks (OVSDB, protobuf, MQTT telemetry)
• Experience with cellular modem integration — AT commands, QMI, network interface management (rmnet/wwan)
• Strong understanding of Linux networking — routing tables, metrics, netfilter, bridge interfaces, IPv4 and IPv6 dual-stack, neighbor discovery, DHCPv4/DHCPv6, SLAAC, and prefix delegation
• Understanding of TLS handshake with mutual authentication using X.509 certificates, certificate chain validation, and secure provisioning
• Knowledge of security and tunneling protocols — GRE tunneling, IPsec, VPN overlays, and secure encapsulation for cloud-managed traffic
• Experience with event loop frameworks (libev, libuv, or similar)
• Proficiency with debugging tools — GDB, strace, tcpdump, kernel logs, serial console
• Familiarity with Git, GitLab CI/CD, cross-compilation toolchains
• Understanding of WiFi standards (802.11ax/be) and wireless driver configuration
Top Skills:
1. Embedded C Development on Linux/OpenWrt
o C programming, Linux internals, debugging, IPC, event-driven design
2. OpenSync/OpenWrt Platform Development
o OpenSync Managers, OVSDB, UCI, MQTT, OpenWrt build system
3. Linux Networking & LTE/5G Cellular Integration
o Routing, IPv4/IPv6, failover, QMI/MBIM, modem management, GRE/IPsec
