Ook so weird situation.

I'm trying to run a server socket in a python program (bit of code don't worry about it). For it to work I need to forward a port for the server to run on. I've forwarded the port I'm using for my code according to the instructions detailed on this site for my router: http://portforward.com/

When I use the PFPortChecker (part of PFNetworkUtilites, also from that site) it says the port I have forwarded is indeed open on both TCP and UDP protocols. However if I use any online port checking sites I get a negative result. Additionaly I'm not able to connect from external devices to the program I've made despite it working in the past when i did not have this port forwarding problem.

I have a Technicolor TG582n FTTC router and I've portforwarded by creating a custom application and assigning it to my network device using the toolbox utility.

One site did say my port was filtered possibly by my firewall when I tested on it, however when I completely disabled my firewall and re-ran the test on that site it still says my port was filtered and other sites still came back negative.

  • Your ISP may be blocking that port. For example, customer.xfinity.com/help-and-support/internet/…
    – Steven
    Commented Sep 28, 2015 at 21:25
  • With NAT, you can’t disable the firewall. Compare your router’s apparent external IP address with results from IP checking websites.
    – Daniel B
    Commented Sep 28, 2015 at 21:30
  • You write "I have a Technicolor TG582n FTTC router and I've portforwarded by creating a custom application and assigning it to my network device using the toolbox utility." <-- I can't believe you think anybody is supposed to know what you are talking about re "the toolbox utility" not everybody has a technicolour dreamcoat blah blah model XYZ router. You should elaborate on that if you're going to say it.
    – barlop
    Commented Sep 28, 2015 at 22:36

1 Answer 1


this is really easy to troubleshoot.

first make sure the program is running on the port. So do the command

C:\>netstat -aon <ENTER>


C:\>netstat -aon | find "1234"<ENTER> <--- if your port is port 1234

See that it shows

You could always start a server on the port e.g. nc in cygwin, nc -l 1234 or you could try any server.. BRS Webweaver, BPFTP, Apache, ssh VNC, whatever your server is. Your server program is fine.

Now try to connect to your server. You could use telnet. Telnet ip port e.g. telnet 1234 Telnet client in Win7 needs to be enabled. Or you could with cygwin use the nc command to connect to a server. so nc 1234 See if it connects.

See if you can connect from the machine itself, do nc 1234

Once you have tested that you can connect from your LAN.

Only, Once you can connect from your LAN, then you do the port forwarding.

Looking at the description of the program you mention http://portforward.com/help/portcheck.htm It says it makes its own program on the port you are testing. So if you find that one gives you a green light, but online port scanners don't, then maybe your program isn't listening on a port.

You need to test

A)Is your server rujnning.  shown in netstat with port.
B)Can you connect to your server locally 
C)Can you connect from LAN (if not then an OS firewall is stopping you
D)THEN, look at port forwarding

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