Q: what is port 8770

iMacs with retina displays don't run Classic.

Norton is unnecessary for Macs.

They have a built-in Firewall in Apple menu -> System Preferences -> Sharing.

Uninstall Norton.  It slows down Macs, and is totally unnecessary bloatware.

The only software a Mac needs that is a utility that is not built-in, is probably a backup software, although you could use Time Machine or Disk Utility*:

http://www.macmaps.com/backup.html

As for port 8770, that is likely a Norton only port, since it is not listed here:

TCP and UDP ports used by Apple software products - Apple Support

* Links to my pages may give me compensation.

I've seen Macs hit by viruses and a Mac lab hit by a virus... That was many years ago, to be honest, but I run Norton to safeguard against future viruses although I have good friends I trust who do not run anti-virus software on their Macs... I value my data so I do.

Time Machine is a built in backup utility and a good one.

Port 8770 is not a Norton only port. It is used for sharing iPhoto photos and for Airdrop.

I have to admit that the firewall portion of Norton is driving me up the wall, so the point about the Mac having it's own firewall is relevant. Although Norton also provides DeepSight which is a database of IPs used by hackers/attackers that have been detected by those running Norton software and shared to the whole community of Norton users.

There are no links to any of my pages in my post so there's no compensation to be had in what I write here... ;-)

-Scott