I think We have to find another way to solve this proble.Hello,
you cannot execute remote commands through ssh from router, you can do that
from any other linux host that is available to you.
also access to router without password is not advised to, as a better practice
use key to log in remotely through ssh and in your script point to a key file,
so your router is protected.
user ssh-keys import file="your pub key "
ssh 192.168.250.250 -l admin -i .ssh/id_dsa /ppp active print