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  • EC2 Instance Connect Endpoint Adventure

    EC2 Instance Connect Endpoint Adventure

    Li Pi on July 24, 2023

    Exciting (Or not?) news from AWS again. I’m here to guide you through the murky waters of EC2 Instance Connect Endpoints, those shiny new toys from Amazon Web Services. Yes, I know, another AWS feature, just when you thought you were starting to get the hang of it all!

    Before we dive in, I want you to picture this: you’re sitting there, hunched over your terminal, SSHing into yet another EC2 instance. You probably already have a bastion station, or even better, a VPN that can connect you to your VPC. you probably also have MFA enabled on this bastion/VPN, and probably also have a MFA for your AWS account so using awscli requires you to have another prompt. so in order to ssh to a machine you just created with Terraform you probably had to answer 2 MFA prompts…

    You’re so used to the routine by now you could do it in your sleep. But then, you pause. “Wait a minute,” you think to yourself. there must be a better way with less MFA prompts.

    Enter the EC2 Instance Connect Endpoint, AWS’s answer to your security concerns…or so they’d have you believe.

    Tunnel Vision

    First off, what is an EC2 Instance Connect Endpoint? Well, it’s basically a private tunnel to your EC2 instance. Sounds fancy, right? You create one in a subnet in your VPC (you have been using VPCs, haven’t you?), and then when you want to connect to your instance, you simply specify the ID. No more public IPv4 address required! Simple, right? Well, not so fast.

    But What About Security?

    “But wait!” I hear you cry. “Does this mean I can just throw my EC2 instances out there without a care in the world, safe in the knowledge that my EC2 Instance Connect Endpoint will protect me from all harm?”

    If only it were that simple.

    You see, using an EC2 Instance Connect Endpoint doesn’t inherently make an EC2 instance safe if it’s not nestled snugly inside a private VPC. That’s because Security group misconfiguration and Application with exposed ports are still going to be there. The EC2 Instance Connect Endpoint is a lovely tool for connecting to your instances without a public IPv4 address, without having to open ports for SSH trafic, or using solutions like Teleport, Bastions or VPNs,

    but it’s not a magical security bubble.

    Be Prepared (Yes, That’s a Lion King Reference)

    IAM permissions still control access to create and connect to these endpoints. And you can – and should – configure additional security group rules to restrict inbound traffic. For instance, you can only allow traffic on management ports from the EC2 Instance Connect Endpoint.

    And remember, all attempts to connect to instances, successful or not, are logged to CloudTrail. So, if you see something, say something. Or rather, if CloudTrail logs something, do something.

    The Moral of the Story

    So, what’s the moral of our story? EC2 Instance Connect Endpoint is a fantastic tool, but it doesn’t replace good old-fashioned security best practices. Don’t get me wrong, it’s a great step forward and it simplifies a lot of processes, but it’s not a panacea for all your security concerns.

    Remember, AWS is like a Swiss Army knife: it’s full of tools, some of which you might never use, and some of which are incredibly useful. But none of them are going to be much help if you don’t know how to use them, or worse, if you use them incorrectly.

    So, dear reader, stay vigilant, keep learning, and above all, keep those EC2 instances safe. After all, they’re counting on you.

    Until next time, keep those command lines humming and remember: there’s no place like