Flows in the Real World

"A flow is a series of packets that all share the same source and destination IP addresses, source and destination ports, and IP protocol." What the heck does that mean, really? Let's pull this description apart and see what it really means in a few places in the real world. I'll start with the simplest network traffic, a ping request and response, and then proceed to more complicated examples of DNS and HTTP requests.

ICMP Flows

Although ICMP is most commonly associated with ping requests, it also carries the most basic instructions for Internet routing and management. Certain individual flows, such as ICMP redirects, can carry useful information, but to keep things simple, I'll cover the common ping.

ICMP has no TCP-style ...

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