What visual front end are you referring to? There are a few of them to choose from.

‎They usually just call the yum python libraries and or command. No additional ports required.

In general yum only requires ports 80, and 443 for 90% of public repos; however yum supports using other methods like rsync too‎. Also port numbers my vary. For example I've seen publicly posted yum repos hosted on odd ports like HTTPS on port 8443 so you need to look at the repos you are using to determine if any of them are using odd port numbers and or protocols 


Sent from my BlackBerry 10 smartphone.
  Original Message  
From: hansel
Sent: Monday, February 9, 2015 09:57
To: [log in to unmask]
Subject: what port does theyum visual frontend use?

From the command line, "yum info <any valid search>" produces output, 
while the visual frontend always reports "no results were found" (annoying 
passive voice). The visual tool does provide repository listings.

It appears the reason is that yesterday (Sun 2/8) I closed a port at the 
router used by this tool. 80, 8080, and 443 (as well as 992) are open and 
I thought that was sufficient. Yum docs claim 443 and 80 are sufficient, 
at least as I read them.

This is a Motorola router integrated with a cable modem (SBG6580) -- that 
has worked mostly flawlessly for about a year.

FWIW, this change reduced root breakin attempts from thousands to 1 in 24 
hours, so it may be a reasonable trade-off.

Thank you,
Mark Hansel