Need help opening ports

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Charles L. Cotton
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Need help opening ports

#1

Post by Charles L. Cotton » Wed Mar 18, 2020 12:14 pm

I need to open five ports but I'm having trouble. I'm on Comcast/Xfinity using my own modem (Netgear CM700) and a Tenda AC15 (AC1900) router. I'm running Windows 10 and Norton Internet Security. I'm not sure if Windows Defender Firewall or Norton is causing the problem. I've tried the following to no avail:
  • 1. Added the ports (port forwarding) in the Tenda router;
    2. Opened the ports on Windows Defender Firewall
    3. Added a "rule" to Norton allowing traffic through the ports.
When this didn't work, I turned Norton off and tested again. The ports are still closed. This leads me to think Norton is not the problem.

I searched Norton and YouTube for a fix, but I've found nothing. Any suggestions?

It's my understanding that ports are opened or blocked by either the router, Windows, or Norton, or any combination, rather than the modem. Is this correct?

Thanks,
Chas.


Grayling813
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Re: Need help opening ports

#2

Post by Grayling813 » Wed Mar 18, 2020 12:33 pm

Charles - it's also possible, depending upon which ports that your ISP is blocking them on their network.

Have you tried running netstat.exe on your computer to see which ports are open?

Here's a website with netstat and other tools to check ports.
https://techtalk.gfi.com/scan-open-port ... ick-guide/
“Is there nothing to sing about to-day? Then borrow a song from tomorrow; sing of what is yet to be. Is this world dreary? Then think of the next.” - Charles Spurgeon


jerry_r60
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Re: Need help opening ports

#3

Post by jerry_r60 » Wed Mar 18, 2020 12:36 pm

Not the modem however there is another possibility. Some ISP's block particular ports, discouraging people from running a server at home. I googled comcast / xfinity and came up with this list they say they are blocking. Good luck.

https://business.comcast.com/help-and-s ... t-network/
or
https://www.xfinity.com/support/article ... cked-ports

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Syntyr
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Re: Need help opening ports

#4

Post by Syntyr » Wed Mar 18, 2020 12:40 pm

https://www.grc.com/shieldsup

This is the shields up Port scanning website if you'll direct it to the IP address of your computer behind your modem and firewall it will scan all of the ports and I'll tell you what's open what's stealth and everything else so that might at least tell you where it's failing
Syntyr
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Charles L. Cotton
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Re: Need help opening ports

#5

Post by Charles L. Cotton » Wed Mar 18, 2020 2:29 pm

Well, the problem is solved, but this is interesting. If I run a port check from one of the many websites, the ports I opened in the Tenda router show to be blocked. However, when I run a "port check" in the software I need to use, the check shows all five ports to be "ok" meaning they are open. :headscratch

Thanks folks.
Chas.


RottenApple
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Re: Need help opening ports

#6

Post by RottenApple » Wed Mar 18, 2020 6:17 pm

Charles L. Cotton wrote:
Wed Mar 18, 2020 2:29 pm
Well, the problem is solved, but this is interesting. If I run a port check from one of the many websites, the ports I opened in the Tenda router show to be blocked. However, when I run a "port check" in the software I need to use, the check shows all five ports to be "ok" meaning they are open. :headscratch

Thanks folks.
Chas.
Charles,

Ports work both ways: Inbound and Outbound. Port 80 (standard HTTP port) is open for outbound traffic by default. But that same port (80), will also be closed to inbound traffic by default. When you checked from "one of the many websites", they were testing the inbound access of the ports. But when you "run a "port check" in the software", it's only looking at outbound access. In effect, each port has 2 settings (one of each):

Inbound (outside your network to inside your network):
In-Allow (WAN-LAN Allow)
In-Deny (WAN-LAN Deny)
In-Drop (WAN-LAN Drop)

Outbound (inside your network to outside your network):
Out-Allow (LAN-WAN Allow)
Out-Deny (LAN-WAN Deny)
Out-Drop (LAN-WAN Drop)

If a site outside your network shows a port is blocked, then that would be In-Deny. If the software (which is inside your network) shows that the same port is open, then that would be Out-Allow.

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Re: Need help opening ports

#7

Post by Charles L. Cotton » Wed Mar 18, 2020 10:03 pm

RottenApple wrote:
Wed Mar 18, 2020 6:17 pm
Charles L. Cotton wrote:
Wed Mar 18, 2020 2:29 pm
Well, the problem is solved, but this is interesting. If I run a port check from one of the many websites, the ports I opened in the Tenda router show to be blocked. However, when I run a "port check" in the software I need to use, the check shows all five ports to be "ok" meaning they are open. :headscratch

Thanks folks.
Chas.
Charles,

Ports work both ways: Inbound and Outbound. Port 80 (standard HTTP port) is open for outbound traffic by default. But that same port (80), will also be closed to inbound traffic by default. When you checked from "one of the many websites", they were testing the inbound access of the ports. But when you "run a "port check" in the software", it's only looking at outbound access. In effect, each port has 2 settings (one of each):

Inbound (outside your network to inside your network):
In-Allow (WAN-LAN Allow)
In-Deny (WAN-LAN Deny)
In-Drop (WAN-LAN Drop)

Outbound (inside your network to outside your network):
Out-Allow (LAN-WAN Allow)
Out-Deny (LAN-WAN Deny)
Out-Drop (LAN-WAN Drop)

If a site outside your network shows a port is blocked, then that would be In-Deny. If the software (which is inside your network) shows that the same port is open, then that would be Out-Allow.
Then I need to make sure the inbound port is open too.

Thanks,
Chas.


RottenApple
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Re: Need help opening ports

#8

Post by RottenApple » Thu Mar 19, 2020 5:20 pm

Charles L. Cotton wrote:
Wed Mar 18, 2020 10:03 pm
Then I need to make sure the inbound port is open too.

Thanks,
Chas.
Only if the software actually requires it. Make sure to check with the vendor beforehand.


uthornsfan
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Re: Need help opening ports

#9

Post by uthornsfan » Thu Mar 19, 2020 6:10 pm

You may need your modem to put your router in a DMZ, then do your port forwarding on the Netgear router.

What is the Wan IP on the Netgear, if it is a 192.168.x.x address then you are trying to do double NAT and that won't work.

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