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Security Across Two Machines

Goal: Make two different machines communicate securely

Tutorial level: Intermediate

Time: 7 minutes

Background

The previous tutorials have used two ROS nodes on the same machine sending all network communications over the localhost interface. Let’s extend that scenario to involve multiple machines, since the benefits of authentication and encryption then become more obvious.

Suppose that the machine with the keystore created in the previous demo has a hostname Alice, and that we want to also use another machine with hostname Bob for our multi-machine talker/listener demo. We need to move some keys from Alice to Bob to allow SROS 2 to authenticate and encrypt the transmissions.

Create the second keystore

Begin by creating an empty keystore on Bob; the keystore is actually just an empty directory:

ssh Bob
mkdir ~/sros2_demo
exit

Copy files

Next copy the keys and certificates for the talker program from Alice to Bob. Since the keys are just text files, we can use scp to copy them.

cd ~/sros2_demo/demo_keystore
scp -r talker USERNAME@Bob:~/sros2_demo/demo_keystore

That will be very quick, since it’s just copying some very small text files. Now, we’re ready to run a multi-machine talker/listener demo!

Launch the nodes

Once the environment is set up, run the talker on Bob:

ros2 run demo_nodes_cpp talker --ros-args --enclave /talker_listener/talker

and launch the listener on Alice:

ros2 run demo_nodes_py listener --ros-args --enclave /talker_listener/listener

Alice will now be receiving encrypted messages from Bob.

With two machines successfully communicating using both encryption and authentication, you can use the same procedure to add more machines to your ROS graph.