The warning you're seeing occurs because the permissions set on the private key file are too permissive, allowing users other than the owner to read or potentially modify the file. SSH keys need to be kept secure to prevent unauthorized access to your servers.
To resolve this warning, you should set the permissions of your private key file to be readable only by your user. This can be done with the following command:
chmod 600 /home/user/key
Here's what the permissions do:
- `600` permission means that only the file owner has read and write permissions. No other user can read, write, or execute the key.
- 'chmod' is the command used to change the file mode bits.
Execute the command in your terminal. After you've made the change, SSH will no longer complain about the permissions as the key is now properly secured.
Do note that if you're using a different user or if your key is in a different path, you should change `/home/user/key` to reflect the correct user and path to your private key.
For future reference and for anyone stumbling upon this issue, it's crucial to maintain strict permissions on private keys, as they are the equivalent of passwords for SSH authentication. A best practice is to generate the key with secure permissions from the start, which you can usually do with the `ssh-keygen` utility. When it prompts for a save path, you can just hit enter to use the default (`~/.ssh/id_rsa` for RSA keys), with correct permissions already set.