I am trying to send data through MQTT between two Raspberry Pi's over LTE. Raspberry Pi's are connected to internet via Huawei USB surfstick. when i checked on port open utilities online, it seems port1883 is open. Yet I am not able to publish data. I think I am behind carrier grad NAT so not able to send data to ports or my ISP is blocking incoming traffic at ports. How can i achieve this ? Any other alternatives?
1 Answer
To work out if you are behind CGNAT, check your machine's IP address with ifconfig. If it's an RFC 1918 number, then you are. If it is not an RFC 1918 number, you might still be. Check your public IP address via whatismyip, if it doesn't match the output of ifconfig, then you are.
If one or both devices are behind a CGNAT implementation, the only way to connect into an open port would be to have an intermediate device sitting between them negotiating connections. For example, a VPN server that both Pis can connect into, thus creating an end-to-end VPN tunnel between them.
-
yes i thought this as an option. How can i find from ifconfig result if I am behind CGNAT or not ?– SparkCommented Sep 29, 2017 at 15:39
-
-
Under ppp0 interface in ifconfig result, I get a public IP address and when I cross checked using whatismyip website it gives me back the same IP address. so does that mean I am not behind CGNAT?– SparkCommented Sep 29, 2017 at 15:52
-
-
But still I am not able to send data to 1883 port. what might be the reason ?– SparkCommented Sep 29, 2017 at 15:55