SSH error when launching nodes on another machine

edit

We added this line to our launch file in order to run a node on another machine:

<machine name="robot" address="robot.dynamic.edu" env-loader="/opt/ros/groovy/env.sh" user="turtlebot"/>

The problem is we get this error:

<a href="http://robot.dynamic.edu">robot.dynamic.edu</a> is not in your SSH known_hosts file.

Please manually:
   ssh <a href="mailto:turtlebot@robot.dynamic.edu">turtlebot@robot.dynamic.edu</a>

then try roslaunching again.

If you wish to configure roslaunch to automatically recognize unknown hosts, please set the environment variable ROSLAUNCH_SSH_UNKNOWN=1

Our environment variable is set to:

#!/usr/bin/env sh
# generated from catkin/cmake/templates/env.sh.in

if [ $# -eq 0 ] ; then
   /bin/echo "Usage: env.sh COMMANDS"
   /bin/echo "Calling env.sh without arguments is not supported anymore. Instead spawn a subshell and source a setup file manually."
   exit 1
else
  . "/opt/ros/groovy/setup.sh"
  exec "$@"
fi