bulmanp - The private_key parameter should be the contents of the private key file (in your case, the 2nd option should have worked).  Here is the working code I use :   f = open("/root/.ssh/id_rsa", "r") id_rsa = f.read() #print id_rsa f.close() #passwordless certificate login apicommand = cm.host_install(user_name="root", private_key=id_rsa, host_names=hostIds, cm_repo_url=cm_repo_url, java_install_strategy="NONE", unlimited_jce=True).wait()    ... View more