That's not good. That's your MITM protection.
You can use certutil on the master to make a cert for the slave, using the above command on the master. Then, use pk12util to export the slave cert/key, then take that pk12 file to the slave and use pk12util to import it (and use certutil to import the CA cert).
Thanks for this, it worked. I had to disable: check hostname against name in cerfificate for outbound SSL connections,
but its actually working now.