Cilium is open source software for providing and transparently securing network connectivity and loadbalancing between application workloads such as application containers or processes. Cilium operates at Layer 3/4 to provide traditional networking and security services as well as Layer 7 to protect and secure use of modern application protocols such as HTTP, gRPC and Kafka. Cilium is integrated into common orchestration frameworks such as Kubernetes and Mesos. A new Linux kernel technology called BPF is at the foundation of Cilium. It supports dynamic insertion of BPF bytecode into the Linux kernel at various integration points such as: network IO, application sockets, and tracepoints to implement security, networking and visibility logic. BPF is highly efficient and flexible. To learn more about BPF, read more in our extensive BPF and XDP Reference Guide.