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Fixing ‘Server Refused Our Key’ Error When Logging into New AWS Ubuntu Instance

Ubuntu 2

In this article, we will explore the ‘Server Refused Our Key’ error that you may encounter when logging into a new AWS Ubuntu instance. We’ll delve into the potential causes of this issue and provide a step-by-step guide to resolving it.

Quick Answer

To fix the ‘Server Refused Our Key’ error when logging into a new AWS Ubuntu instance, you can start by updating your SSH client to the latest version. If that doesn’t resolve the issue, verify that your SSH key pair is correctly associated with your instance. Additionally, check and correct the permissions and ownership of the .ssh directory and authorized_keys file.

Understanding the ‘Server Refused Our Key’ Error

The ‘Server Refused Our Key’ error typically arises when there’s an issue with the SSH key pair you’re using to connect to your AWS instance. It can also occur due to incorrect permissions or ownership of the .ssh directory or authorized_keys file.

Updating Your SSH Client

The first step in troubleshooting this issue is to ensure that your SSH client is up-to-date. If you’re using PuTTY, you can download the latest version from the official PuTTY website. For WinSCP users, you can find the latest version on the official WinSCP website.

Checking SSH Key Pair

If updating your SSH client doesn’t resolve the issue, the next step is to verify your SSH key pair.

  1. Log in to your AWS Management Console.
  2. Navigate to the EC2 Dashboard.
  3. Click on ‘Key Pairs’ under ‘Network & Security’.
  4. Check if the key pair you’re using to connect to your instance is listed there.

If your key pair isn’t listed, you’ll need to create a new one and associate it with your instance.

Verifying Permissions and Ownership

Incorrect permissions or ownership of the .ssh directory or authorized_keys file can also cause the ‘Server Refused Our Key’ error.

To check and correct permissions:

  1. Log into your instance using the EC2 Instance Connect feature in the AWS Management Console.
  2. Run the following command to set the correct permissions for the .ssh directory:
    chmod 700 ~/.ssh
    This command sets the permissions of the .ssh directory such that only the owner can read, write, and execute files in the directory.
  3. Run the following command to set the correct permissions for the authorized_keys file:
    chmod 600 ~/.ssh/authorized_keys
    This command sets the permissions of the authorized_keys file such that only the owner can read and write the file.

To check and correct ownership:

  1. Run the following command to ensure the .ssh directory is owned by the correct user:
    chown $USER:$USER ~/.ssh
    This command changes the owner of the .ssh directory to the current user.
  2. Run the following command to ensure the authorized_keys file is owned by the correct user:
    chown $USER:$USER ~/.ssh/authorized_keys
    This command changes the owner of the authorized_keys file to the current user.

Conclusion

The ‘Server Refused Our Key’ error when logging into a new AWS Ubuntu instance can be caused by several factors, including an outdated SSH client, an incorrect SSH key pair, or incorrect permissions or ownership of the .ssh directory or authorized_keys file. By following the steps outlined in this article, you should be able to troubleshoot and resolve this issue. If the problem persists, consider reaching out to Amazon AWS Support for further assistance.

What is an SSH key pair?

An SSH key pair consists of a private key and a public key. The private key is securely stored on your local machine, while the public key is added to the authorized_keys file on the server you want to connect to. When you try to log in to the server, the server uses the public key to verify your identity and grants you access.

How can I generate a new SSH key pair?

To generate a new SSH key pair, you can use the ssh-keygen command on your local machine. Open a terminal and run the command ssh-keygen -t rsa -b 4096 -C "your_email@example.com". This will generate a new RSA key pair with a 4096-bit key size. You can specify your own email address or leave it blank. The command will prompt you to choose a location to save the key pair and set a passphrase for the private key if desired.

What should I do if the ‘Server Refused Our Key’ error persists after following the troubleshooting steps?

If the ‘Server Refused Our Key’ error persists after following the troubleshooting steps, you may need to double-check the SSH key pair and ensure it is correctly associated with your AWS instance. Additionally, you can try restarting the instance or reaching out to Amazon AWS Support for further assistance.

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