SSH Copy ID Fail: Manually Adding Key to EC2 Instance

SSH Copy ID Fail: Manually Adding Key to EC2 Instance

When working with two created EC2 instances, SSH access from one instance to another may fail, even with a PEM key. This article will guide you through the process of manually adding the key to the EC2 instance.

Prerequisites

• Two created EC2 instances
• SSH access to the first EC2 instance
• PEM key for the EC2 instances

Background

When creating two EC2 instances, the standard process for SSH access from one instance to another involves using the PEM key. However, sometimes the SSH copy ID command fails, and manual intervention is required. This issue can occur due to various reasons, such as a misconfigured security group or incorrect permissions on the PEM key.

Manually Adding Key to EC2 Instance

To manually add the PEM key to the EC2 instance, follow these steps:

1. Log in to the first EC2 instance using SSH.
2. Create a new directory for the PEM key.

mkdir ~/.ssh

3. Copy the PEM key to the newly created directory.

cp /path/to/pem/key ~/.ssh/id_rsa

4. Change the permissions on the PEM key.

chmod 600 ~/.ssh/id_rsa

5. Create a new file named authorized_keys in the .ssh directory.

touch ~/.ssh/authorized_keys

6. Append the contents of the PEM key to the authorized_keys file.

cat ~/.ssh/id_rsa >> ~/.ssh/authorized_keys

7. Change the permissions on the authorized_keys file.

chmod 600 ~/.ssh/authorized_keys

8. Change the ownership of the .ssh directory and the authorized_keys file.

chown -R ec2-user:ec2-user ~/.ssh

Testing SSH Access

After manually adding the PEM key to the EC2 instance, test SSH access to the second EC2 instance. If the SSH access is successful, the manual key addition process is complete.

References

• Amazon Web Services. (2022). Amazon EC2 Key Pairs
• Amazon Web Services. (2022). Prerequisites for Connecting to Your Instance

This article covered the topic of manually adding a PEM key to an EC2 instance when the SSH copy ID command fails. By following the steps outlined in this article, you can establish SSH access between two EC2 instances.