17. TCP Keepalive
17.1. Introduction
Many newcomers to TCP/IP are surprised to learn that no data whatsoever flows across an idle TCP connection. That is, if neither process at the ends of a TCP connection is sending data to the other, nothing is exchanged between the two TCP endpoints. There is no polling, for example, as you might find with other networking protocols. This means that we can start a client process that establishes a TCP connection with a server and walk away for hours, days, weeks, or months, and the connection should remain up. In theory, intermediate routers can crash and reboot, data lines may go down and back up, but as long as neither host at the ends of the connection reboots (or changes its IP address), the connection ...
Get TCP/IP Illustrated, Volume 1: The Protocols, 2nd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
