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.
I love your analogy for ports, but I’m not sure about the VPN one.
If you imagine network traffic as mail going through the postal system, then a VPN is like a private mail tunnel between two locations, that nobody else can enter or look into. Mail sent via the tunnel is private and nobody else can read it. The person at the other end of the tunnel can either open the mail themselves (ie a VPN from your laptop to your home server to access it when you’re away), or forward the mail somewhere else (ie if you’re routing Internet-bound traffic through it) and nobody will know it came from you originally.
I’m not sure that’s a completely accurate analogy either. When you’re using a VPN people can still see that you are sending traffic through your tunnel, they just can’t tell what it is that you’re sending. It’s like looking through frosted glass; there’s definitely something moving in there but you can’t tell what.
I suppose the best way to describe it is you send a locked box to a trusted friend; everyone handling it can see the box but can’t tell what’s inside. Inside the box is a letter, your friend posts it so it looks like it came from them. Your friend then gets a reply, puts it in a locked box, and send it back to you. Nobody between you and your friend can snoop on your mail but anyone between your friend and the final destination can.