So you created SSH keypair, installed public key on the server you want to connect to but, probably, made this not as described in this article: How To Set Up SSH Keys and now the server refuses your key and in /var/log/secure we can see message like this:
Authentication refused: bad ownership or modes for file /home/user/.ssh/authorized_keys
or
Authentication refused: bad ownership or modes for directory /home/user/.ssh
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