Embedded C Developer – OpenSync/OpenWrt WiFi Router with Cellular

Location: Denver, CO – 4 days onsite per week
Interview: 2 Rounds – Round 2 is Face-to-Face

Job Summary

We are seeking an experienced Embedded C Developer with strong expertise in Linux, OpenWrt, OpenSync, WiFi routers, Linux networking, and cellular modem integration.

Required Skills & Experience

• 5+ years of hands-on Embedded C development on Linux-based platforms.
• Strong proficiency in C programming, including:
  • Pointers and memory management
  • IPC mechanisms
  • Event-driven architectures
  • Linux system programming
• Hands-on experience with OpenWrt, including:
  • OpenWrt build system
  • Package management
  • UCI configuration
  • JFFS2/SquashFS overlay filesystems
• Experience with OpenSync or similar cloud-managed CPE frameworks.
• Knowledge of:
  • OVSDB
  • Protobuf
  • MQTT telemetry
  • OpenSync Managers
• Strong experience with cellular modem integration, including:
  • AT commands
  • QMI/MBIM
  • rmnet/wwan interfaces
  • Network interface management
  • LTE/5G connectivity and failover
• Strong understanding of Linux networking, including:
  • Routing tables and metrics
  • Netfilter
  • Bridge interfaces
  • IPv4/IPv6 dual-stack
  • Neighbor Discovery
  • DHCPv4/DHCPv6
  • SLAAC
  • IPv6 Prefix Delegation
• Understanding of TLS and secure provisioning, including:
  • TLS handshake
  • Mutual authentication
  • X.509 certificates
  • Certificate chain validation
• Knowledge of networking security and tunneling technologies:
  • GRE
  • IPsec
  • VPN overlays
  • Secure encapsulation for cloud-managed traffic
• Experience with event-loop frameworks such as libev, libuv, or similar.
• Proficiency with embedded/Linux debugging tools:
  • GDB
  • strace
  • tcpdump
  • Kernel logs
  • Serial console
• Experience with Git, GitLab CI/CD, and cross-compilation toolchains.
• Understanding of WiFi standards, including 802.11ax/802.11be and wireless driver configuration.

Top Skills

1. Embedded C Development on Linux/OpenWrt
   • C programming
   • Linux internals
   • Debugging
   • IPC
   • Event-driven software design

2. OpenSync/OpenWrt Platform Development
   • OpenSync Managers
   • OVSDB
   • UCI
   • MQTT
   • OpenWrt build system

3. Linux Networking & LTE/5G Cellular Integration
   • Routing
   • IPv4/IPv6
   • Network failover
   • QMI/MBIM
   • Cellular modem management
   • GRE/IPsec