For decades, adding new networking or security features to Linux required either submitting a patch to the core kernel (a multi-year process) or compiling fragile out-of-tree kernel modules that risked crashing the entire operating system upon null-pointer dereferences.
eBPF (Extended Berkeley Packet Filter) fundamentally rewrote this paradigm. It acts as a sandboxed virtual machine inside the Linux kernel, allowing engineers to run verified, safe bytecode in response to system calls, socket operations, or kprobes with zero context-switching overhead.
