I'm configuring Hadoop environment.I have use $ ssh-keygen -t rsa -P  to generate id_rsa.pub and id_rsa.And use cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys to set password-free login.Now, I enter ssh localhost command and get this error: The authenticity of host 'localhost (::1)' can't be established.How can I solve this problem?
CentOS7 SSH can't connect localhost?
centos;ssh;hadoop
The authenticity of the host can't be established just means that the host key is not present in ~/.ssh/known_hosts and it needs to register it before allowing SSH to connect to it. Just type yes and it should work.Also, don't forget to change the permissions of ~/.ssh/authorized_keys to 0600 or the key won't be authorized due to wrong file permissions.