ssh login appears Are you sure you want to continue connecting (yes/no)?

1. You can use the parameters of ssh -o to set.
For example: ssh -o StrictHostKeyChecking=no [email protected]
2. Modify /etc/ssh/ssh_config and
change the # StrictHostKeyChecking ask to StrictHostKeyChecking no

The solution for slow login:
First use ssh [email protected] -vvv to see which step appears to be slow.
For example: debug1: Unspecified GSS failure. Minor code may provide more information
No credentials cache found

The above problems can be set through the ssh -o parameter. Use: -o GSSAPIAuthentication=no
For example: ssh -o GSSAPIAuthentication=no [email protected]