SCP Command Without Prompt Password

Dear all, when use scp command, we are asked the password on remote server right ? In some cases, i need scp command without password. For example, when executed script backup database, backup automatically transfered to another server.

Okay, here some steps :

Server 1, hostname : sitea IP : 192.168.112.163
Server 2, hostname : siteb IP : 192.168.112.166

1. Try to ssh to target server
[root@sitea ~]# ssh 192.168.112.166 date

it creates directory /root/.ssh/ automatically

2. Create public and private key on server 1
[root@sitea ~]# ssh-keygen -t rsa

it creates private key and public key
[root@sitea ~]# ls -1 /root/.ssh/id_rsa*
/root/.ssh/id_rsa
/root/.ssh/id_rsa.pub

3. Copy public key to server 2
 [root@sitea ~]# scp /root/.ssh/id_rsa.pub root@192.168.112.166:/home

4. Copy the contents of id_rsa.pub to ~/.ssh/authorized_keys
 [root@siteb ~]# cat /home/id_rsa.pub >> ~/.ssh/authorized_keys
 [root@siteb ~]#chmod 700 ~/.ssh/authorized_keys

5. Edit /etc/hosts
192.168.112.163     sitea
192.168.112.166     siteb

Now, we can do command scp without password