On Mac OS X, applications cannot listen on ports below 1024 without root access. For security reasons, running MassTransit as root is not recommended. In order to listen on privileged ports, you will need to redirect the traffic to a high-numbered port that MassTransit can listen on. Most commonly, this configuration is necessary to allow MassTransit to listen on the standard FTP ports (20 and 21) or the standard TCP/IP Secure port (443) without running as root.
For Mac OS X 10.4 and 10.5 Workstation, please follow the instructions in this document.
For Mac OS 10.5 Server, please follow the instructions in this document.
For Mac OS 10.4 Server, please follow the instructions to use Xinetd to listen on privileged ports in Configuring MassTransit Server to listen on ports less than 1024 on Mac OS X using xinetd.