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Can someone demystify computer Ports for me? Please? Blocking, unblocking, opening, allowing, VPNs and their effect, what ports are and what they do, step by step, when you have to interact with them? (lemmy.dbzer0.com)

submitted 7 months ago by [email protected] to c/[email protected]

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It's the one thing when I'm configuring things that makes me wince because I know it will give me the business, and I know it shouldn't, but it does, every time. I have no real idea what I'm doing, what it is, how it works, so of course I'm blindly following instructions like a monkey at a typewriter.

Please guide me into enlightenment.

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[–] [email protected] 1 points 7 months ago

You have servers that provide some kind of resource or service, and clients that use those resources or services (will just say resource from now on).

Servers provide that resource using a port so clients will come ask for it using that port.

Sometimes servers can do multiple things, so they will provide multiple resources...maybe a web server hosting a web page is also an email server that can receive and send email too. They do those things using different ports to distinguish the kind of request it's getting.

On the client side, clients use source ports to distinguish which app asked for a resource. Think of your browser having 20 tabs open, each has it's own source port so your computer never gets confused which page goes to which tab.

I'm skipping a lot of things (ports flipping for replies, well known, etc), but that's the basics.