How to fix Permissions 0644 for '/home/user/.ssh/id_rsa' are too open. in SSH

Use ls -la to view the current permissions:

ls -la ~/.ssh/id_rsa

Look for the permission string at the start of the output. Permissions like -rw-r--r-- (0644) or -rwxr-xr-x (0755) are too open.

Use chmod to set permissions to 600 (read and write for owner only):

chmod 600 ~/.ssh/id_rsa

Or for a more restrictive read-only access:

chmod 400 ~/.ssh/id_rsa

Mode 600 allows you to read and modify the key (sometimes needed for key management), while 400 restricts it to read-only.

The .ssh directory itself must have permissions 700 (read, write, execute for owner only):

chmod 700 ~/.ssh

Check the result:

ls -ld ~/.ssh

You should see drwx------ (700 permissions).

To ensure all files in your .ssh directory have correct permissions:

chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys ~/.ssh/known_hosts ~/.ssh/config 2>/dev/null
chmod 600 ~/.ssh/id_rsa ~/.ssh/id_ed25519 2>/dev/null
chmod 644 ~/.ssh/*.pub

This sets:
- 700 for the directory
- 600 for private keys (id_rsa, id_ed25519, etc.)
- 644 for public keys (*.pub files)
- 600 for other sensitive files (authorized_keys, known_hosts, config)

After fixing permissions, retry your SSH command:

ssh user@hostname

Or if using a specific key:

ssh -i ~/.ssh/id_rsa user@hostname

The connection should now succeed. If it still fails, check that you're connecting with the correct username and that the public key is in the remote system's authorized_keys file.