Help needed setting up Netcomm NFV18ACV port forwarding

Forums › LAN (ethernet/Wifi/routers/Bluetooth) › Help needed setting up Netcomm NFV18ACV port forwarding

1 | 2

ageorge

626 posts

Ultimate Geek

#2560324 8-Sep-2020 14:20

djtOtago:

192.168.20.100 will work, But there has to be something on your internal network with that IP address. Otherwise you are just forwarding to nothing.

Please check out my first 2 images. The default gateway is 192.168.20.1 so Im assuming that any IP in that range as a port forward should allow the Port checker to respond as open, or not?

Pluralsight

Learn cloud, mobile, security, data and web technologies with Pluralsight (affiliate link).

djtOtago

982 posts

Ultimate Geek

#2560336 8-Sep-2020 14:46

A port checker will only know the port is open if the destination responds.

yitz

1874 posts

Uber Geek

#2560341 8-Sep-2020 14:55

Sometimes 443 is unable to be forwarded as it is reserved for a service on the router itself and this may be hard coded into the firmware.

If you can log in to the router using telnet you can issue iptables --list you might find without any port forwards an entry in one of the chains for port 443 TCP/UDP preset by the firmware.

You may wish to choose to use an alternative port. Under port forwarding change External port start/end to something else say 8443 leaving the Internal port start/end at 443 and check. When you access from the outside you will need to use the alternative port which may or may not be suitable depending on your application.

ageorge

626 posts

Ultimate Geek

#2560350 8-Sep-2020 15:08

yitz:

Sometimes 443 is unable to be forwarded as it is reserved for a service on the router itself and this may be hard coded into the firmware.

No ports forwarded work. Only if I switch off the firewall then all are open.

yitz

1874 posts

Uber Geek

#2560357 8-Sep-2020 15:25

ageorge:

No ports forwarded work. Only if I switch off the firewall then all are open.

That's quite unusual then as such a firewall setting typically only applies to services running on the router itself and whether or not they should be exposed on the WAN side. You would not expect the firewall setting to apply to port forwards as that's not very intuitive. You should be able to port forward with the firewall on (as is recommended).

Make sure you are not checking the status of common ports such as 53, 80, 443 etc. as those may not reflect your port forwards but services running on the router itself.

1101

3086 posts

Uber Geek

#2560360 8-Sep-2020 15:28

If this is an ISP supplied router , it might never port forward properly .
Ive seen plenty of ISP's routers with various weird port forward/DMZ issues

First , make sure the router isnt using 443 itself for https , so change that to 444 in the routers settings (if thats possible on that router)

The best option is often to buy another router (from the recommended list here) , everything suddenly works as it should then . You will need to change the routers https port either way .

ageorge

626 posts

Ultimate Geek

#2560418 8-Sep-2020 16:34

1101:

If this is an ISP supplied router , it might never port forward properly .
Ive seen plenty of ISP's routers with various weird port forward/DMZ issues

Hi I think Im going to have to hard reset the modem/router and try again.

I just tried to set up a DDNS service, and thats not working either so it would appear the setup is flakey.

yitz

1874 posts

Uber Geek

#2560432 8-Sep-2020 16:52

Your Netcomm router is the only one you have and is directly connected to your ONT on the wall ?

ageorge

626 posts

Ultimate Geek

#2560433 8-Sep-2020 16:56

yitz:

Your Netcomm router is the only one you have and is directly connected to your ONT on the wall ?

I do have other routers eg a tenda and nfv14 but configuration is as you say above.

Tried the NFV14 but same, yet to try the Tenda.

yitz

1874 posts

Uber Geek

#2561789 10-Sep-2020 15:45

https://help.slingshot.co.nz/hc/en-us/articles/360005168434-Port-Filtering

I have just come across this help desk article (seemingly updated today 🤨) which explains Slingshot block a range of ports on their broadband service and that this is able to be turned off through their customer self-service portal.

Anyway it seems the OP has changed ISPs but thought I might leave it here in case anyone has the same issue.

ageorge

626 posts

Ultimate Geek

#2561801 10-Sep-2020 15:59

yitz:

https://help.slingshot.co.nz/hc/en-us/articles/360005168434-Port-Filtering

I have just come across this help desk article (seemingly updated today 🤨) which explains Slingshot block a range of ports on their broadband service and that this is able to be turned off through their customer self-service portal.

Anyway it seems the OP has changed ISPs but thought I might leave it here in case anyone has the same issue.

Thanks for the suggestion, but after Econofibre came online, I also assumed this, but hasn't made an iota of difference.

What gets me is using the Netcomm modem I can open up the services, and they will port through to my LAN/PC (the destination IP) but I cant do the same with port forwarding.

Having used the NFV18 and NFV14 modems with same results, I think the next step is to bring the Tenda AC10 into the mix. I never had this problem under ADSL with a Dlink modem, where I could port forward no problem.

I think the key is that if services can get through, which are ports without destination IP address, then Port Forwarding with an IP address should behave in exactly the same way except with more security. There is no question that Im using the correct IPv4 LAN address. Clearly, the destination PC is not blocking the port range, if its working with services.

Regards and thanks, Al.

ageorge

626 posts

Ultimate Geek

#2561834 10-Sep-2020 16:53

Also, checking out other threads I find some say you must have a server or similar running for the port to show as open.

So I did this alistair@alsmain:~$ nc -l 5632 &

for a port 5632 in port forwarding, still no joy.

1 | 2