Check if a specific TCP or UDP port is open

This article will show you how to scan in c++ a TCP or UDP port to see if it’s open.

The TCP (Transmission Control Protocol ) is intended to provide a reliable process-to-process communication service in a multinetwork environment. The TCP is intended to be a host-to-host protocol in common use in multiple networks.

User Datagram Protocol (UDP) is one of the core protocols of the Internet Protocol Suite. Using UDP, programs on networked computers can send short messages sometimes known as datagrams (using Datagram Sockets) to one another.

UDP does not guarantee reliability or ordering in the way that TCP does. Datagrams may arrive out of order, appear duplicated, or go missing without notice. Avoiding the overhead of checking whether every packet actually arrived makes UDP faster and more efficient, for applications that do not need guaranteed delivery.