External ports without proxy

1

I have a few apps that want to accept TCP connections, and receive UDP packets from external sources. The separate instances of the app are supposed to have different IPs. I don’t think exposing them via [[services.ports]] achieves what I want, that will route all traffic to my app’s public IP to an app instance selected by the Fly proxy. My app also makes outbound connections, I assume those will look like they are coming from IPs that do not much the public IP. How do I achieve this? As far as I can tell, my app is achieving some connectivity, it looks like outbound connections and packets work as expected, but it’s possibly NAT-like, but inbound packets from arbitrary locations don’t seem to be arriving at the app instances.

2

Fly VMs can’t be addressed directly from the internet with IPV4, though you may be able to do this with the IpV6 address in FLY_PUBLIC_IP.

And you’re right - outgoing connections will not use a predictable IP address.

If the issue you’re having is with incoming UDP traffic, check out the instructions in this guide: Running Fly.io Apps On UDP and TCP

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3

Thanks, the article clarifies how to do UDP through the proxy. However it doesn’t cover how to expose ports directly without using the proxy.

4

Hi @eruanno

You can open a port on the vm directly using the experimental allowed_public_ports config but this only works over IPv6.

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Thanks @charsleysa that helped a lot.