On Sun, Aug 4, 2019 at 8:31 AM DL Neil <PythonList at danceswithmice.info> wrote:
> On 3/08/19 5:20 PM, Cameron Simpson wrote:
> > On 03Aug2019 08:52, DL Neil <PythonList at DancesWithMice.info> wrote:
> >> On 3/08/19 8:32 AM, Terry Reedy wrote:
> >>> 2. Do two systems connect directly peer-to-peer or through a server?
> >> Exclusively the latter (thus far in the investigation).
> > If one party is remote and both are behind a NAT (_very_ common in
> > Australia, for example) then you always need an external intermediary.
> > Even if that intermediary does no more than connect some sockets from
> > each end together and blindly pass traffic.
> As is the case with many of the A/V comms packages, if the software is,
> or appears to be, a web-browser (IP port 80); then there should be no
> particular problem with either NAT or firewalls.
That covers one end only - the "active" or "connecting" end. The other
end has to be "passive" or "listening", and that is a lot harder to
handle. Hence the need for the broker - one server has the listening
ends for everyone, and all the actual Idle processes connect to that.