I'm trying to use UPnP to open a port, so I'm experimenting with miniupnpc. I've observed a handful of people use and suggest upnpc -a <internal ip> <internal port> <external port> <protocol> to open the specified external port and point it to the application running on the specified internal port.
Before I continue, I will note that UPnP is on in my router's settings, and that it lists a few connections, though when I check them with a port checker I find that none of them are actually working? Or at least none of them seem to be open.
When I try to map the internal port 5000 to the external port 7777 with the following command:
upnpc -a 192.168.1.10 5000 7777 tcp
What I find is that it "works" without any explicit errors, but the external ip it maps to isn't really an external ip at all. Here's the output following the command given above:
upnpc : miniupnpc library test client, version 2.1.
(c) 2005-2019 Thomas Bernard.
Go to http://miniupnp.free.fr/ or https://miniupnp.tuxfamily.org/
for more information.
List of UPNP devices found on the network :
desc: http://192.168.1.1:5000/Public_UPNP_gatedesc.xml
st: urn:schemas-upnp-org:device:InternetGatewayDevice:1
Found a (not connected?) IGD : http://192.168.1.1:5000/Public_UPNP_C3
Trying to continue anyway
Local LAN ip address : 192.168.1.10
ExternalIPAddress = 192.168.0.153
InternalIP:Port = 192.168.1.10:5000
external 192.168.0.153:7777 TCP is redirected to internal 192.168.1.10:5000 (duration=0)
Obviously, 192.168.0.153 is not an external IP Address, and yet it seems to be treating it as though it is. Why might this be?
EDIT: Upon further inspection, it seems like since I have a multi-router set up, the "external ip" here is actually the internal ip of the secondary router. I wonder why this is, though, and whether it can be circumvented.
