An illustrated guide to Amazon VPCs

Summary

Back to indexIn this section, I talk about why VPCs were invented and how they work. This is critical to understand because almost everything you do in AWS will happen inside of VPC. If you don't understand VPCs, it will be difficult to understand any of the other networking concepts.If you're reading this, maybe you have one of theseand you just found out that to put your app on AWS, you need all of this:And you have no idea what VPCs, subnets and so on are.I'll help you learn about all those pieces. A little about me, I’m a long-tailed duck, and I run a business selling phones to hackers, called Blackhatberry. Now let's get started.This is the story of VPCs (Virtual Private Cloud)s, our first big topic. Many moons (and suns) ago, some AWS engineers were sitting in a room. They had a serious issue."Guys, lets talk business. Why aren't more companies moving to AWS?" they said."Maybe because all instances run in a single shared network, which means users can access each other's instances, and see each other's data," someone said."Maybe because it's hard for them to move their existing servers to AWS, because of IP address conflicts," someone else said."Wait… what are IP address conflicts?”“And existing servers? Shouldn’t they be moving to our servers?”This is the first reason people weren’t switching to AWS. Here's what I mean by IP address conflicts. I own a bunch of servers for Blackhatberry. One of them has the IP address `172.98.0.1`. Now, my neighbor also has a server for her business. She loves my ip address. “Ah, 172.98.0.1, what a beautiful destination,” she says. So she copies my address! Now we both have servers with the same IP address!Sidebar: You can find your local IP address using `ipconfig getifaddr en1` (works for Macs for wireless internet connections).Now you're thinking "so what?". And actually... you're totally right. Even though our servers have the same IP address, they are in different networks, so it's not an issue.But here comes trouble. Bec...