server: listening on two ports at the same time

I have long wanted to listen on two ports, one UDP and one (different)
TCP, so that clients could have a better chance of connecting

I find that many wifi networks block lots of things, including 1194/udp.
Apparently the people who configure firewalls think people using
facebook etc. is ok, and nerd protocols like openvpn, xmpp and matrix
are harmful, so it seems best to blend in :-(


I saw in the 2.7.0 release notes one could do this, but couldn't figure
it out.   Finally I found this blog post:

  https://www.willifix.net/blog/openvpn-2-7-multisocket-howto

which says that instead of "udp" and "port 1194" in the config, one
should instead have (with my changing the tcp port to be different):

  local 0.0.0.0 1200 udp
  local 0.0.0.0 1300 tcp

I have a configuration with a specific listen address, and different
ports on udp and tcp, and it seems to work.


(It would be great if someone could do a blog post or docs change to
explain how to configure nginx to function as a proxy to reach an
openvpn server on the same host, so that the connection from the client
to the server would just be on 443/tcp.   Critically, this should work
without interfering with the web server, so no remapping /.)