You seem to use the latest SUM version (SP16) which is completely integrated into Host Agent.
You have to start it as root in the SUM directory:
./STARTUP confighostagent <Your SID>
The output of above command will give you an URL to connect to.
Make sure to configure SAP Host Agent to use SSL because above process will connect to the SSL port (1129) of the Host Agent.
An update of your Host Agent binaries might also be required.