Concepts / Ports, sockets and UDP

Ports, sockets and UDP

Port

Also called port number, well-known port

A 16-bit number that picks the program on a device: web 80 and 443, DNS 53, SSH 22.

IP gets a packet to the device; the destination port in the TCP or UDP header gets it to a program. Servers listen on known ports; clients use ephemeral ports picked by their kernel.

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