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Dec 3, 2020 · Fundamentals

What Really Happens Inside Linux When recvfrom Receives a Packet?

This article walks through the complete Linux kernel path a network packet follows—from the NIC’s DMA and hardware interrupt, through soft‑interrupt handling, NAPI polling, protocol‑stack registration, IP and UDP processing, all the way to the user‑space recvfrom system call—revealing the many hidden steps that make packet reception possible.