Netscape ENTREPRISE SERVER 6.1 - INSTALLATION AND MIGRATION GUIDE Installation And Migration Manual page 17

Make sure the port you choose isn't already in use. On UNIX and Linux systems,
you can check the file
don't assign a port number that is reserved for another service. If you choose a port
that is currently being used by another service, the installation program prompts
you for another port.
NOTE If you use UNIX or Linux, and you choose a server port number lower than
1024, you must be logged in as root to start the server. After the server
binds to the port, the server changes from the root user account to the user
account you specify. If you choose a port number higher than 1024, you
don't have to be the root user to start the server.
on the server machine to make sure you
/etc/services
Chapter 1
Other Technical Requirements
Before You Install Netscape Enterprise Server 17