Linux - SSH - Password-less login - generate public key - migrate data without password between two VM servers

SUMMARY:
two server : A , B
source server : A
destination server : B
the steps of migrate data from A to B without password.
(1) generate A public key.
(2) copy A's public key to B.
(3) login A remote B without password to copy file. // NOTES : if want to login B to remote A , need to install B's public key to A.

DETAIL:
1、login source server 'A' with root create usergroup and user which user have not password.

//create usergroup
# groupadd goodmood
//create user
# useradd -d /home/goodmooduser -m -g goodmood goodmooduser
//give user and usergroup to directory and recursive.
# chown -R goodmooduser:goodmood /home/goodmooduser

2、login destination server 'B', do same step as step1.

3、login source server 'A', generate public key.

# cd /opt/SSHtectia/util/
# ls
# ./generate_keys goodmooduser
# cd /etc/opt/SSHtectia/keys/goodmooduse
# cat id_rsa_2048_a.pub

4、login destination server 'B', do same step as step3.

5、install the public key of source server 'A' to destination server 'B'

# cd /etc/opt/SSHtectia/keys
# ls
# cd goodmooduser
# vi goodmooduser@A.pub // parse 'A' public key
# vi authorization //add below script to this file.
Key goodmooduser@A.pub
Options command="eval $SSH_ORIGINAL_COMMAND",allow-from="A.nam.nsroot.net"

6、login source server 'A' with root, then execute below steps without password, copy file or directory from source server /Adirectory to destination server /Bdirectory

su - goodmooduser
sftp goodmooduser@B.nam.nsroot.net
put /Adirectory /Bdirectory
exit