After Jailbreaking and installing OpensSSH do the following

meathenterpr

Install mobileterminal and use the following commands
su root
enter root password usually the default alpine
use the following command to change the default password
passwd <new_password>
and confirm it.
Do the same for the user mobile.

more instructions here.

If you do not do this the following may occur
Worm rickrolls unsecured jailbroken iPhones via SSH

Will someone please think of the kids