Bidirectional Networking

[Emanuele D'Arrigo]

Hey Bryan, thank you for your reply!

On Dec 13, 3:51 am, Bryan Olson <fakeaddr... at nowhere.org> wrote:
> > Is it possible then to establish both a server and a client in the
> > same application?
>
> Possible, and not all that hard to program, but there's a gotcha.
> Firewalls, including home routers and software firewalls, typically
> default to disallowing connections in the 'wrong' direction. If the
> client initiates all connections, you avoid a world of hassles.

Ah yes, I can see that. Uhm. I have absolutely no idea right now how a
firewall works from a programming point of view and what happens in
normal "residential" circumstances. I.e. it's clear that firewalls are
configured to allow http traffic because I can browse the internet. Is
that done leaving a specific port open? Or does the browser request
the firewall to open a specific port for it and the firewall trust the
browser to handle safely anything that comes through?

I.e. in the case of the code in this thread, would it be the
responsibility of the application to tunnel through the firewall and
listen for connections or would it be the responsibility of the user
to configure the firewall so that the application can receive a
connection?

Thanks for your help!

Manu