3 ms·

The app data only need to go via a server if you don't have IPv6 and your IPv4 NAT is in the minority of NAT boxes that breaks the usual P2P NAT workarounds[1]

• drdaeman 3y ago
  I haven't bothered to learn why, but if both broadcaster and viewer are behind a symmetric NAT, usual STUN tricks don't always seem to work in practice. At least they haven't worked for me. I have a DIY WebRTC forwarder for a RTSP stream, that lives on a home server behind a NAT. It has NAT because it lives in a cgroup that's isolated to IoT VLAN, and I haven't originally planned on WebRTC there, hoping I could make it work with restreaming over HTTP or Websockets. The NAT there is of the most common type: nftables' masquerade statement for the appropriate output interface, the usual conntrack allow established,related rule, and rule that allows outbound connections. For whatever reason, WebRTC only worked for me when my viewing device wasn't behind any other NATs. Now, this is not a proper argument. Being a very lazy ass I haven't bothered with diagnostics so I don't know why it hadn't worked. I was already quite frustrated with various cross-browser JS shenanigans and after checking that STUN was indeed configured but had not worked, I've just punched a couple of port forwards and called it a day. For whatever reason P2P streaming seem to work somewhat worse in practice than it should've been in theory. Usual computer leprechauns, I guess.