Usually when ssh session is performed for the first time to destination host, the prompt message will be appeared to confirm whether connection should be continued or not. It is due to the destination host has not defined yet inside known_hosts file.
The authenticity of host 'xxx.xxx.xxx.xxx (xxx.xxx.xxx.xxx)' can't be established. RSA key fingerprint is 90:e8:5f:59:7e:87:e4:33:35:60:77:10:a1:af:62:b0. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added 'xxx.xxx.xxx.xxx' (RSA) to the list of known hosts. Password: Last login: Tue Jan 19 21:47:16 2016 from xx.xx.xx.xx
To avoid this message, parameters StrictHostKeyChecking and CheckHostIP can be put and set value as “no” in ssh connection as below example:
usersource@sourcehost> ssh -oStrictHostKeyChecking=no -oCheckHostIP=no userdest@destinationIP