Linux Administration Cookbook

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SSH is sensitive about the permissions that its files have.

You don't want your private key to be readable by any random user who might be on your system, so as a result, plain SSH won't work if it thinks you have bad permissions set.

Generally, this won't be an issue if you've just generated your keys, but if you later move them between computers, you might find that you've spoiled the permissions slightly.

A good rule of thumb is to assume locked-down settings:

[vagrant@centos1 ~]$ ls -lha .ssh/total 28Kdrwx------. 2 vagrant vagrant  134 Aug  8 14:05 .drwx------. 3 vagrant vagrant   95 Aug  8 10:29 ..-rw-------. 1 vagrant vagrant  389 Aug  7 16:40 authorized_keys-rw-------. 1 vagrant vagrant  464 Aug  8 10:04 id_ed25519-rw-r--r--. ...