Recently, when using SSH to connect to GitHub, suddenly prompted "Permissions 0644 for '/root/.ssh/id_rsa ' is too open" and disconnected.
Carefully read the SSH document and this hint, probably the meaning of SSH private key permissions Open scale is too large, can be freely appreciated, SSH's own policy closed ssh.
Solution: Reduce permissions from 0644 to 0600
chmod 0600 ~/.ssh/id_rsa
Ssh:permissions 0644 for '/root/.ssh/id_rsa ' is too open