[linux]ssh passwordless login authorized_keys permission

root@am1[~]{18:23}# ssh-copy-id -i ~/.ssh/id_rsa.pub am3
root@am3's password:
Now try logging into the machine, with "ssh 'am3'", and check in:

.ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

因為之前有更改，am3上的 /root 的權限，
所以只要改回把 .ssh 與 .ssh/authorized_keys 改回正確的權限，
就可以使用key 登入了。