Hi forum,
I have used comodo firewall for years and it has always passed the shields up test.
However i have just ran a test with CIS latest version and shields up reports that port 0 is now in a closed state and subsequently fails the test.???
Comodo firewall has NEVER failed this test before and im a little stunned to be honest.
I have always used mobile broadband.
Could anybody please explain what is happening here please?
Thanks. :o
Hey Mrarnold, I dont think I would lose any sleep over it. A closed port is equally secure as a “stealthed” port.
If you run Tcpview does it show port 0 in a listening state ? If so use Tcpview to figure out the PID and use Process Explorer to figure out which services are running under it.
Also on the odd chance do you have any software running that requires a Python interpreter. Look under programs and features and see if anything Python related is installed.
Hi sayer,
Thank you for your response.
I have just checked with process hacker and there is nothing listening on port 0.
No i dont have anything python related installed.
I just found it odd that it has just suddenly occured.
Not sure if the shields up site has changed in any way?
Thanks again. :-TU
Also note, if you are using a router, unless you’ve set up a DMZ, ShieldsUp is probing your router, not your software firewall.
With mobile broadband you may be using an IP address in a public range effectively putting you behind a router of your ISP. Is your IP address in a public private range (192.168.x.y, 172.16.x.y or 10.x.y.z)?
Those listed are private IP addresses…
Thx Sanya. I edited my post accordingly.
Hi eric and thank you.
My private addressess are in the 192 range. 
I bet they are…
Back on topic. Is the IP address your phone gets from you provider in a private or public range?
Okay i reverted back to a image with comodo firewall 5.12 installed and it passes the shields up perfectly so its definitely an issue with version 6 firewall. 88)
I just ran Shields Up when I came across this thread, and port 0 is stealthed on my machine. I’m using CIS 6.2 and all my ports are stealthed, along with me passing the whole test.
Thats weird.!
must be just my computer then…even though this has never occured before. ???
As has already been pointed out, it’s likely nothing to do with your software firewall.
Not to mention that there is nothing insecure in having a port reporting that it’s closed instead of “stealth”. Contrary to what Steve Gibson would like you to believe, having your ports stealthed does not make you invisible on the internet.
“Stealth” is not a valid TCP/IP protocol. The way networking was designed, when a computer makes a request of another computer, it expects a response. Even if your computer is turned off, an upstream router will report that your machine is unreachable. So if someone pings your address and gets no reply, they know that there is a machine at that address that is actively dropping requests. So much for stealth! >:-D
A closed port is a secure port. If ShieldsUp reports that all of your ports are closed, you have nothing to worry about. A hacker would need to work to get into your machine, and more often than not they’ll just target somebody with open ports.
So don’t be concerned if your machine doesn’t pass this bogus test… Open ports? Yes, you need to figure out what’s going on and close them if possible. Non-stealthed ports? Absolutely not a concern. 
Thank you kindly Heffed,puts my mind at rest. :-TU
Comodo Firewall can only stealth your computer’s ports, not your router’s ports. Gibson Research’s SHIELDS UP! says it scans your computer’s ports but it actually scans your router’s ports. Port 0 is a non-existent port invented by Gibson Research for testing potential vulnerabilities (see GRC | Port Authority, for Internet Port 0 . They do not say how to stealth it.
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