We learned that generation of the necessary SSL certificates failed when you attempt to configure a Nimsoft tunnel during installation on Linux using the nimldr utility. The installation returns an error regarind authentication failure. You must instead simply install the hub using nimlr and then use the tunnelsetup utility to generate the CA and client SSL certs and configure the connection.
Answer 'no' when nimldr asks 'Are you setting up a NimBUS Tunnel between this Hub and another Hub?'. After the installer completes navigate to NIMSOFT_HOME\hub and execute the tunnelsetup script.
I hope this saves you the time it cost us.