root@spectre:~# ssh-keygen 
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:bIcQJwbB5RqKcXGJWha9qfJpGm3YyLxkBmLlb9Hdue0 root@k8s2-master
The key's randomart image is: +---[RSA 2048]----+ | o=+== . | | +o+o + | |.+...oo | |.+o.oo.o... . | |+..o.. .S..o | |B=. . .. . o | |+O+. o . . | |+o= . . | |.+ E | +----[SHA256]-----+ '
root@spectre:~# sshpass -p 12345mtr. ssh-copy-id -f root@192.168.211.51
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'root@192.168.211.51'"
and check to make sure that only the key(s) you wanted were added.