Open ports in Tor Browser vs other browsers

Question

I checked for open ports using GRC Shields Up website, obtaining a perfect stealth score on the following platforms and browsers (latest version of each one up to 06/06/2016):

• Windows 7: IE, Chrome, Firefox, Firefox Dev Edition, Opera, Opera Beta, Comodo Dragon, Ice Dragon, Chromodo, Vivaldi, Pale Moon, Torch. They all also passed the Reverse DNS test. Also the DNS leak test always worked properly with fine results.
• iOs 7.1.2: Safari and Chrome. No port responded but Reverse DNS failed.
• Android 4.4.2: Firefox. Same as iOs.

Then I tried to use GRC tests on Tor Browser on Windows 7 with active and configured Windows Firewall and Comodo Firewall. As a result I got a failed Reverse DNS test (which of course did not point to my ISP) and for the ports test it says that port 80 and port 443 are open. Also DNS leak test did not work.

My question is: why on every browser and system i checked, my ports are always stealth and non responsive but when i check Tor, 2 of them are plain open? Is it normal? Is it some kind of vulnerability? Does it vary depending on the exit node configuration and can i do or should do something about that?

Answer 1

First thing's first, GRC is a well-known charlatan and snake-oil salesman with a documented history of being outstandingly wrong. You shouldn't listen to what he has to say about "security" or believe that any of his products live up to his grandiose claims.

The second thing is that this isn't scanning you, it's scanning the relay you are exiting from, which will have at least one open port: it's ORPort where it listens for incoming Tor connections and possibly a DirPort, some kind of http port with a page page explaining that it's an exit relay, and maybe a remote administration method (e.g. ssh). It is orthogonal to "security" that these ports are "open".

N.B. I am not going to troubleshoot every aspect of Steven Gibson's (expectedly) malfunctioning snake-oil software.