I have a MacBook Air running OSX 10.10.5 with Norton Security 7.1 Build 94 and Norton Online Backup 2.1.10. I have been getting the following message “An unknown service (port 13000) is starting on your Mac ” with the attributed application Norton Online Backup. Despite choosing “Allow all connections to this service” and checking “Always take this action” and saving, I keep getting it. Does anyone have any ideas? I suspect Norton will need to take a look at this and see if it is a bug they need to work out between their products...