1. Introduction

Ever locked yourself out of your own S3 bucket? That’s like asking a golfer if he’s ever landed in a bunker. We’ve all been there.

Scenario:

A sudden power outage knocks out your internet. When service resumes, your ISP has assigned you a new IP address. Suddenly, the S3 bucket you so carefully protected with that fancy bucket policy that restricts access by IP… is protecting itself from you. Nice work.

And here’s the kicker, you can’t change the policy because…you can’t access the bucket! Time to panic? Read on…

This post will cover:

• Why this happens
• How to recover
• How to prevent it next time with a “safe room” approach to bucket policies

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2. The Problem: Locking Yourself Out

S3 bucket policies are powerful and absolute. A common security pattern is to restrict access to a trusted IP range, often your home or office IP. That’s fine, but what happens when those IPs change without prior notice?

That’s the power outage scenario in a nutshell.

Suddenly (and without warning), I couldn’t access my own bucket. Worse, there was no easy way back in because the bucket policy itself was blocking my attempts to update it. Whether you go to the console or drop to a command line, you’re still hitting that same brick wall—your IP isn’t in the allow list.

At that point, you have two options, neither of which you want to rely on in a pinch:

1. Use the AWS root account to override the policy.
2. Open a support ticket with AWS and wait.

The root account is a last resort (as it should be), and AWS support can take time you don’t have.

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3. The Safe Room Approach

Once you regain access to the bucket again, it’s time to build a policy that includes an emergency backdoor from a trusted environment. We’ll call that the “safe room”. Your safe room is your AWS VPC.

While your home IP might change with the weather, your VPC is rock solid. If you allow access from within your VPC, you always have a way to manage your bucket policy.

Even if you rarely touch an EC2 instance, having that backdoor in your pocket can be the difference between a quick fix and a day-long support ticket.

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4. The Recovery & Prevention Script

A script to implement our safe room approach must at least:

• Allow S3 bucket listing from your home IP and your VPC.
• Grant bucket policy update permissions from your VPC.
• Block all other access.

Options & Nice-To-Haves

• Automatically detect the VPC ID (from the instance metadata).
  • …because you don’t want to fumble for it in an emergency
• Accept your home IP as input.
  • …because it’s likely changed and you need to specify it
• Support AWS CLI profiles.
  • …because you should test this stuff in a sandbox
• Include a dry-run mode to preview the policy.
  • …because policies are dangerous to test live

This script helps you recover from lockouts and prevents future ones by ensuring your VPC is always a reliable access point.

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5. Using the Script

Our script is light on dependencies but you will need to have curl and the aws script installed on your EC2.

A typical use of the command requires only your new IP address and the bucket name. The aws CLI will try credentials from the environment, your ~/.aws config, or an instance profile - so you only need -p if you want to specify a different profile. Here’s the minimum you’d need to run the command if you are executing the script in your VPC:

./s3-bucket-unlock.sh -i <your-home-ip> -b <bucket-name>

Options:

• -i Your current public IP address (e.g., your home IP).
• -b The S3 bucket name.
• -v (Optional) VPC ID; auto-detected if not provided.
• -p (Optional) AWS CLI profile (defaults to $AWS_PROFILE or default).
• -n Dry run (show policy, do not apply).

Example with dry run:

./s3-bucket-unlock.sh -i 203.0.113.25 -b my-bucket -n

The dry run option lets you preview the generated policy before making any changes—a good habit when working with S3 policies.

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6. Lessons Learned

Someone once said that we learn more from our failures than from our successes. At this rate I should be on the AWS support team soon…lol. Well, I probably need a lot more mistakes under my belt before they hand me a badge. In any event, ahem, we learned something from our power outage. Stuff happens - best be prepared. Here’s what this experience reinforced:

• IP-based policies are brittle.
  • Your home IP will change. Assume it.
• We should combine IP AND VPC-based controls.
  • VPC access is more stable and gives you a predictable backdoor. VPC access is often overlooked when setting up non-production projects.
• Automation saves future you under pressure.
  • This script is simple, but it turns a frustrating lockout into a 60-second fix.
• Root accounts are a last resort, but make sure you have your password ready!
  • Avoid the need to escalate by designing resilient access patterns upfront.

Sometimes it’s not a mistake - it’s a failure to realize how fragile access is. My home IP was fine…until it wasn’t.

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7. Final Thoughts

Our script will help us apply a quick fix. The process of writing it was a reminder that security balances restrictions with practical escape hatches.

Next time you set an IP-based bucket policy, ask yourself:

• What happens when my IP changes?
• Can I still get in without root or AWS support?

Disclaimer

Thanks to ChatGPT for being an invaluable backseat driver on this journey. Real AWS battle scars + AI assistance = better results.