virtual machine master to robotic armv7 node communication issues

edit

running a virtual machine as the master and having trouble getting rostopic to get data.

always asks if my messages are built.

Is there a way to confirm that they are built?

Edit: I noted my question was vague without details...

I attempt

rostopic ech /turtle1/cmd_vel

Response:

ERROR: Cannot load message class for [geometry_msgs/Twist]. Are your messages built?

Some googling says I should be able to run sudo netcat from both directions, but I can only do it one way..... still working on it.....

if I run (on virtual Machine MASTER (lvbuser001-VirtualBox)): sudo netcat -l 1234

and run (on ARMv7 (chip)): sudo netcat lvbuser001-VirtualBox 1234

it works!

if I run (on ARMv7 (chip)): sudo netcat -l 1234

and run (on virtual Machine MASTER): sudo netcat chip 1234

it fails!