tobypage, Welcome to McAfee community.
port 80 for update.nai.com/Products/CommonUpdater
port 21 for ftp.nai.com/CommonUpdater
these are already default and already defined in Server Settings \ Source Sites
you will also find Proxy Settings under Server Settings.
ePO will need access to these either directly or via proxy. the other way you can check in DAT or products is by downloading them using your grant numbers on a different system, going to "Master Repository" and checking them in.