Billion UK Forum

I'm probably being a bit dim here but can someone explain to me why port 1723 would be showing as "closed" on my 7800N (latest firmware).

Basically I was looking to check my home security on the router so i started with "nmap -sT myhostname" from an external host - I wanted to see if the open ports I had corresponded with the ports I forwarded on the 7800N. They broadly did but I cannot understand why port 1723 shows as "closed", I have no requirement for it and don't know why it shows at all in the scan.

Be grateful if someone can scan there own router and confirm it shows for them and/or explain it ?

thanks

bt

Hi billyt

This might be becuase the router has on board PPTP server which uses port 1723.

When not is use this will be closed.

OK, that makes sense - nothing to be concerned about then by the sounds of it. thanks.

Sorry for bumping an old post but I've had no response to my query.

I'm having the same issue on my 7800NX. The port forwarding is disabled for port 1723 and external checks show this as closed. It's odd, because if you try and map another reserved router port, say for FTP, then the router is happy to change it's default mapping.

I get no warning that the port is in use or that it won't be forwarded, yet port scanners show 1723 is always closed. You're right, this must be to do with the onboard VPN but there must be a way to disable it and force the port to open... I've been trawling though the net and the router firmware but I can't open it... I guess it's possible that the router doesn't allow VPN passthru but Billion tech support won't comment either way.

There must be someone else using PPTP? Can anyone shed light on this issue?

Thanks in advance...

ffiren wrote:Sorry for bumping an old post but I've had no response to my query.

I'm having the same issue on my 7800NX. The port forwarding is disabled for port 1723 and external checks show this as closed. It's odd, because if you try and map another reserved router port, say for FTP, then the router is happy to change it's default mapping.

I get no warning that the port is in use or that it won't be forwarded, yet port scanners show 1723 is always closed. You're right, this must be to do with the onboard VPN but there must be a way to disable it and force the port to open... I've been trawling though the net and the router firmware but I can't open it... I guess it's possible that the router doesn't allow VPN passthru but Billion tech support won't comment either way.

There must be someone else using PPTP? Can anyone shed light on this issue?

Thanks in advance...

I'm not sure if Netalyzr would have anything on this as it tends to have a suggestion as to why a particular port is closed that wouldn't normally be as well as any other Networking abnormalities http://netalyzr.icsi.berkeley.edu/ (requires Java).

ffiren wrote:Sorry for bumping an old post but I've had no response to my query.

I'm having the same issue on my 7800NX. The port forwarding is disabled for port 1723 and external checks show this as closed. It's odd, because if you try and map another reserved router port, say for FTP, then the router is happy to change it's default mapping.

I get no warning that the port is in use or that it won't be forwarded, yet port scanners show 1723 is always closed. You're right, this must be to do with the onboard VPN but there must be a way to disable it and force the port to open... I've been trawling though the net and the router firmware but I can't open it... I guess it's possible that the router doesn't allow VPN passthru but Billion tech support won't comment either way.

There must be someone else using PPTP? Can anyone shed light on this issue?

Thanks in advance...

I can't really comment as we don't carry the Bipac 7800NX within the UK (I don't have a unit to run tests with ), have you tried to contact your local vendor for support (I assume you have not purchased the unit within the UK)

No it's not a uk model but it's the same chipset.

Billion tech support say the port is always open yet external probing refutes this. They have asked me to simply return the unit which must be a last resort. I must say, they were pretty hopeless!

If I forward any port I can prove and confirm that it's open. Forwarding port 1723 for pptp does nothinging. Enabling the VPN server on the router opens the port but won't allow pass through as the router wants to intercept traffic.

Ignoring my specific router. Does anyone with a 7800 have VPN pass through working. If so, how?

Thanks guys, but this site has been more helpful than the Australian counterpart.

ffiren wrote:No it's not a uk model but it's the same chipset.

Billion tech support say the port is always open yet external probing refutes this. They have asked me to simply return the unit which must be a last resort. I must say, they were pretty hopeless!

If I forward any port I can prove and confirm that it's open. Forwarding port 1723 for pptp does nothinging. Enabling the VPN server on the router opens the port but won't allow pass through as the router wants to intercept traffic.

Ignoring my specific router. Does anyone with a 7800 have VPN pass through working. If so, how?

Thanks guys, but this site has been more helpful than the Australian counterpart.

Ok so I have run some tests off the Bipac 7800DX with firmware 2.32d (The onboard PPTP server has not been enabled)

The first screen shot is with the no port forwarding rule added, the port 1723 shown as stealthed (a device with PPTP enabled is connected to the router, but UPNP has not opened the port)

The second screen shot is when I have added a port forwarding rule, port 1723, to IP address 192.168.1.100, which is hosting our PPTP server the port now showing as open

The third screen shot is when I have deleted the PPTP incoming connection on our XP machine, the port now shows as closed, (as the port forwarding rule is pointing to a device which does not have port 1723 running)

Thank you so very much for taking the time to troubleshoot this for me.

I'll reproduce your steps with the specified firmware.

I'm in your debt.

Ok.

I reproduced your steps but the port remain closed unless VPN server was enabled in the router.

I re-flashed the current firmware and performed a factory reset to no avail. I used the previous firmware revision and it all works fine.

must be a bug in the software!

Firmware PCRange7800NX_2.32c.afw dated 16/10/13 works fine.
I wouldn't recommend anyone update to PCRange7800NX_2.32d.afw

Thanks for the help

http://au.billion.com/products/wireless ... 800nx.html