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How To Fix “No such file or directory” Error when Moving SSH Key to Authorized Keys

Ubuntu 15

In this article, we will address a common issue encountered by system administrators and developers when dealing with SSH keys – the “No such file or directory” error. This error typically occurs when you’re trying to move your SSH key to the authorized_keys file. Before we delve into the solution, let’s understand the context and the cause of this error.

Quick Answer

To fix the "No such file or directory" error when moving your SSH key to the authorized_keys file, you need to create the .ssh directory and the authorized_keys file, and set the correct permissions for them. Then, add your public key to the authorized_keys file.

Understanding SSH Keys and Authorized Keys

SSH keys are a secure way of logging into a server without needing a password. The SSH key pair consists of a public key, which can be shared freely, and a private key, which should never be shared.

The authorized_keys file, located in the .ssh directory in your home directory, is a file that contains all the public keys of the users that are allowed to log into the server.

The Cause of the Error

The “No such file or directory” error usually arises when either the .ssh directory or the authorized_keys file does not exist in your home directory. This could happen if you have never used SSH keys on that server before.

Fixing the Error

To fix this error, you need to create the .ssh directory and the authorized_keys file, and set the correct permissions for them. Here’s how you can do this:

Step 1: Create the .ssh directory

First, you need to create the .ssh directory if it doesn’t exist. You can do this using the mkdir command:

mkdir ~/.ssh

In this command, mkdir stands for “make directory”, ~ is a shortcut for your home directory, and .ssh is the name of the directory you’re creating.

Step 2: Set the Correct Permissions for the .ssh Directory

Next, you need to set the correct permissions for the .ssh directory. This is important for security reasons. You can do this using the chmod command:

chmod 700 ~/.ssh

In this command, chmod stands for “change mode”, 700 sets the permissions so that only the owner can read, write, and execute, and ~/.ssh is the directory you’re changing permissions for.

Step 3: Create the authorized_keys File

Now, you need to create the authorized_keys file if it doesn’t exist. You can do this using the touch command:

touch ~/.ssh/authorized_keys

In this command, touch is used to create a new file, and ~/.ssh/authorized_keys is the path to the file you’re creating.

Step 4: Set the Correct Permissions for the authorized_keys File

Finally, you need to set the correct permissions for the authorized_keys file. This is also important for security reasons. You can do this using the chmod command:

chmod 600 ~/.ssh/authorized_keys

In this command, chmod stands for “change mode”, 600 sets the permissions so that only the owner can read and write, and ~/.ssh/authorized_keys is the file you’re changing permissions for.

Adding the Public Key to the authorized_keys File

Now that you have created the .ssh directory and the authorized_keys file and set the correct permissions for them, you can add your public key to the authorized_keys file. You can do this using the cat command:

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

In this command, cat is used to display the contents of a file, ~/.ssh/id_rsa.pub is the path to your public key file, >> is used to append output to a file, and ~/.ssh/authorized_keys is the file you’re appending to.

Conclusion

By following these steps, you should be able to fix the “No such file or directory” error when moving your SSH key to the authorized_keys file. This will enable you to use SSH keys for authentication, which is a more secure method than using passwords.

Remember to always keep your private key secure and never share it with anyone. If you believe your private key has been compromised, generate a new SSH key pair immediately.

What is the purpose of SSH keys?

SSH keys are used for secure authentication when logging into a server without needing a password. They consist of a public key and a private key, with the public key being shared with the server to verify the user’s identity.

Where can I find the authorized_keys file?

The authorized_keys file is located in the .ssh directory within your home directory. The full path to the file is usually ~/.ssh/authorized_keys.

How do I create the .ssh directory?

You can create the .ssh directory by using the mkdir command followed by the path to the directory. For example, mkdir ~/.ssh will create the .ssh directory in your home directory.

What permissions should I set for the .ssh directory?

The recommended permissions for the .ssh directory are 700, which means only the owner can read, write, and execute. You can set the permissions using the chmod command, like this: chmod 700 ~/.ssh.

How do I create the authorized_keys file?

You can create the authorized_keys file by using the touch command followed by the path to the file. For example, touch ~/.ssh/authorized_keys will create the authorized_keys file in the .ssh directory.

What permissions should I set for the authorized_keys file?

The recommended permissions for the authorized_keys file are 600, which means only the owner can read and write. You can set the permissions using the chmod command, like this: chmod 600 ~/.ssh/authorized_keys.

How do I add my public key to the authorized_keys file?

You can add your public key to the authorized_keys file by using the cat command to append the contents of your public key file to the authorized_keys file. For example, cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys will append your public key to the authorized_keys file.

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