I found an old post saying UDP support is coming in Feb, do we have full UDP support now?

I am testing some UDP application but it seems still not fully working right now.

We have not shipped IPv6 UDP yet, it is more difficult than we expected and seems less important in general.

Is IPv4 bad for your purposes?

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Some clients are preferring V6-only, I will stay with V4 UDP for now.

Thanks for the update.

Hi: Any timelines for IPv6 UDP?

(I haven’t checked if it works, but asking just in case).

It doesn’t, right now. It’s on our agenda but it’s a couple features down the list.

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The usecase I have for IPv6 UDP (not solvable with IPv4) is transparently proxying TCP/UDP connections.

For ex, our DNS resolver always answers with our app’s fly IPs for all DNS requests from our clients. That is, say example.com from client-A gets 2a09:8080:1::abcd, while example.com from client-B gets 2a09:8080:1::1234 (assuming both of those IPv6 are assigned to our fly app).

Then, when a UDP/TCP request from client-A hits 2a09:8280:1::abcd, the fly app (reading from the mapping set by the DNS server) proxies those packets to example.com. Think of it like a fragile NAT-PT (which in itself is fragile).

This is only possible with IPv6 because of its abundance. Say, I vend 100K IPv6 addresses (assuming fly considers it fair-use), I can assign one IPv6 address per client-IP per DNS query and still not exhaust my supply, while persisting a route mapping for (client-IP, proxy-IP, dest-IP) tuple for 10 days to a month.