Cannot forward a port on a UPC modem

moon2

I have a little service running on a raspberry pi which I want to be reachable over the internet. If I ssh into the raspberry pi i can telnet (and get a valid response) when using either `127.0.0.1`or the raspberry pi's local ip `192.168.192.62`. If I swap to my laptop, I can telnet to `192.168.192.62` and get a valid response too. That means within my own local network everything seems to be working just fine.

However if I telnet using my public IP i always get this:

Trying $PUBLIC_IP...
telnet: connect to address $PUBLIC_IP: Connection refused
telnet: Unable to connect to remote host

I've gone into the settings for the UPC horizon box and tried setting up a port forward to the raspberry pi's IP (using the correct port) and i've also tried setting the raspberry pi's IP as the DMZ. Neither of which result in telnet being able to connect successfully.

Finally, just for completeness, if I use the regular application to try and connect to the service, that application fails to connect as well.

Is the UPC box just failing to forward ports correctly or am I doing something wrong? I just don't understand what's going on here.

ED E

1. Theres a mistake in your config
2. You're on DSLite and regular nat is not possible.

Is your modem reporting an IPv6 WAN address?

Wabbit Ears

Its a horizon Box so not using DSlite.

The problem is common enough due to the fact that the Horizon box does not support WAN (external Internet address, or the address that shows when you goto www.whatismyip.com) port mirroring.


So, LAN addresses (192.x.x.x) will work from inside your LAN but your WAN address wont.

Does this mean that the port forwarding doesnt work? No, not at all, It just means y you cant access the WAN address from your internal LAN.

To test this you need to actually be on the internet from a device not on your own internal network. more often than not you can do this on your phone if you temporarily disconnect wifi. you can also tether your phone to your laptop and connect via that if you need a PC specific app to test it.

ED E

What you're saying is Hairpin NAT doesnt work. OP test this with your phones data plan if you have one.

Are you sure Horizon precludes DSLite? It seemed for a while all new customers were being pushed onto DSLite.

moon2

I brought the raspberry pi over to a friends house yesterday just because I was so sure something was wrong with this UPC setup, and as I hoped it did work when i forwarded the ports on his box. My phone could connect to the raspberry pi via 3G and wifi.

However it still refuses to work from my own UPC box. The inexplicable part is that if i do not run the server part of the application on my macbook and I do a port check using yougetsignal dot com it says the port is closed. If i then start the server part of the app, it says that the port is open. However nothing is actually able to connect successfully via the public ip

On this horizon box (an smt-g7400 or something like that?) it does report a regular 89.100.x.x ipv4 address as it's WAN ip.

Madness :P

Wabbit Ears

ED E wrote: »

What you're saying is Hairpin NAT doesnt work. OP test this with your phones data plan if you have one.

Are you sure Horizon precludes DSLite? It seemed for a while all new customers were being pushed onto DSLite.

nope, its not hairpin NAT which is slightly different but the point is still the same, it can only be tested from another separate internet connection.

My understanding is Certain types of UPC modem have moved to DSlite, but not all of them and not horizon yet