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Asked: 2024-09-27T09:14:32+05:30 In: ,

I am experiencing an issue with connecting to my AWS EC2 instance using Ubuntu 18. When I attempt to access it, I receive an error indicating that there is a problem with the public key permissions. Can anyone provide guidance on how to resolve this connection error?

I’ve run into a bit of a snag while trying to connect to my AWS EC2 instance that’s running Ubuntu 18. It’s been super frustrating because I followed all the usual steps to set it up, but now I’m stuck. Every time I try to SSH into it, I get this error message about public key permissions. Has anyone else dealt with this?

Here’s the situation: I launched the EC2 instance a few days ago and created a new key pair for access. I downloaded the private key (.pem file), and I made sure to set the right permissions on it by running the `chmod 400` command. But when I try to SSH with it using `ssh -i /path/to/key.pem ubuntu@`, I keep getting this error related to the public key permissions. It’s like the instance isn’t recognizing my key or something, and it’s so confusing!

I’ve double-checked that I’m using the correct username (it’s definitely ubuntu since it’s an official Ubuntu instance), and the public IP address is right too. I even made sure the security group attached to the instance allows incoming traffic on port 22 from my IP. I thought about the network ACLs, but I can’t see anything off there either.

I’ve also tried connecting from different terminals and machines, just in case it was something local on my end, but no luck. I checked the instance’s status on the AWS console, and it’s running just fine. The only thing I can think of is maybe there’s an issue with the way I set up the key pair or something funky going on with the instance itself.

If anyone has run into this kind of issue before or knows where I might have gone wrong, I’d really appreciate any tips or tricks to help me troubleshoot this connection problem. Are there specific logs I should check, or some other permissions I might have missed? Thanks!

Amazon EC2
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    1. AWS EC2 SSH Connection Issues

      Stuck Connecting to EC2 Instance via SSH

      Sounds like you’re having a rough time! I’ve been there, so let’s see if we can figure this out together.

      First off, it’s great that you checked the key permissions with `chmod 400`. That’s usually one of the common hiccups. Just make sure the path to your `.pem` file is correct when you’re trying to connect.

      One thing you might wanna double-check is if you’re on the right user. You mentioned using ubuntu for the username, which is correct for Ubuntu AMIs, but make sure there are no typos when you type it in the SSH command.

      Another idea is to look at the security group settings again. You mentioned allowing incoming traffic on port 22—perfect! Just ensure that it’s set up to allow traffic from your IP (or 0.0.0.0/0 for testing, but be cautious with that).

      If you’ve verified everything and it still doesn’t work, try checking the instance’s Instance Settings or looking at the console logs in the AWS EC2 management section. Sometimes the boot logs can give hints if there’s any issue with key authentication.

      Have you considered if the private key was downloaded correctly or was corrupted in some way? If you suspect the key is the issue, you could try creating a new key pair and attaching it to your instance (you’ll need to access it through the AWS console or use a different instance). Just remember, you can’t change a key pair for a running instance; you’ll need to make a new one.

      Finally, if you’re still hitting walls, the community is your best friend! Check out forums like Stack Overflow or the AWS forums with your specific error message. There’s a chance someone has had the exact same problem.

      Hope this helps a bit! Good luck, and don’t get discouraged—these things can be tricky!


    2. It sounds like you’re facing a common issue related to SSH key authentication, which can be quite frustrating. Since you’ve checked that you are using the correct username and public IP address, along with the appropriate permissions on your private key file (`chmod 400`), the next area to investigate would be the configuration of the key pair itself. First, ensure that the public key associated with your key pair was correctly added to the `~/.ssh/authorized_keys` file on the EC2 instance. If you have access to the console (via the EC2 Instance Connect, for instance), you can verify the contents of the `authorized_keys` file to ensure that your public key is present and correctly formatted. Another possibility is that the key may not have been properly registered upon instance creation; in such cases, you might need to create a new key pair and add the corresponding public key into the `authorized_keys` file manually.

      Another factor to consider is the security group settings. You’ve mentioned that port 22 is open, which is essential, but ensure that it also allows connections from the right source IP range. Pay attention to the restrictions, as sometimes a misplaced CIDR notation (like using `0.0.0.0/0` instead of your specific IP) can lead to unexpected issues. Additionally, check your network ACLs, as these could also inadvertently block your SSH connections. If everything seems to be in order and the issue persists, consider checking the EC2 instance’s system logs from the AWS Management Console to look for any boot-time errors or issues that might affect connectivity. If none of these solutions work, it may be worthwhile to launch a new instance with a fresh key pair while ensuring to backtrack on the steps taken to avoid similar issues in the future.

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