[root@hadoop2 ~]# ssh-copy-id hadoop1
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
The authenticity of host ‘hadoop1 (192.168.52.101)‘ can‘t be established.
ECDSA key fingerprint is SHA256:tmlEUTX/zC4HLJENTTO6X2Kx0ELMHn95iT9c8foctvI.
ECDSA key fingerprint is MD5:1a:04:b6:95:d7:2e:ec:a0:50:04:46:9d:2a:73:77:0e.
Are you sure you want to continue connecting (yes/no)? yes
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
root@hadoop1‘s password: 

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh ‘hadoop1‘"
and check to make sure that only the key(s) you wanted were added.

[root@hadoop1 ~]# cd /root/.ssh
[root@hadoop1 .ssh]# scp authorized_keys hadoop1:$PWD
root@hadoop1‘s password: 
authorized_keys