[Answered ]-How to relay user actions from the server to an external device

Search ROS mult machine will help with this case.

http://wiki.ros.org/ROS/Tutorials/MultipleMachines

In short, you set other devices IP in the local devices /etc/hosts
In this file, you can assign correct IP to each other

Do it for all devices.

Then at one machine runs roscore

In this roscore, you will have a rosip see the message coming out from roscore usually you core IP address + 11311

Then at second machine, set ROS_MASTER_URI to the ros IP + port that you find.

THen two machines can share topics and services.

Ps. if you encounter port 22 issues when trying to ssh when following the tutorial. reinstall open-ssh-server and open-ssh-client