Writing a scanner in C forces careful thinking about packet construction, timeout behavior, and how target systems actually respond.
Important design choices
- Blocking versus non-blocking sockets
- Sequential probing versus concurrency
- Timeout calibration
- Interpreting service banners safely
connect(socket_fd, (struct sockaddr *)&server_addr, sizeof(server_addr));
The goal is not to replace established tools. It is to learn the underlying protocol mechanics well enough to reason about their output with confidence.