I would like to discuss a situation when Messenger operates behind a
firewall (primarily audio and video communication). So, lets presume that we
have two parties one party is directly connected to the Internet (no NAT)
without a firewall (or an UPnP firewall - WinXP ICF, for example), and the
other party is behind a NAT and a "hard rock" stateful firewall (doesn't
allow any incoming connections). My question is - why audio/video (camera)
communication doesn't work in this scenario? I don't see the reason for
this, except a flaw in the protocol. I mean, it surely is possible that
firewalled party can enter some kind of "passive" mode (like FTP) and
establish a connection with another party that is not behind a NAT/firewall.

Hi Dinko,

Assuming both clients are using either MSN Messenger 7 and Windows Live Messenger 8 it should
actually. Failing that, it should use a relay server (which to be fair, is overloaded a lot
of the time and doesn't work).

If you're using Windows Messenger however, both sides need to have a direct connection (via
UPnP or no NAT) or it won't work.

--
Jonathan Kay
Microsoft MVP - Windows Messenger/MSN Messenger/Windows Live Messenger
Associate Expert
http://www.microsoft.com/windowsxp/expertzone/
Messenger Resources - http://messenger.jonathankay.com
All posts unless otherwise specified are (c) 2006 Jonathan Kay.
You *must* contact me for redistribution rights.
--

"Dinko Deranja" <(E-Mail Removed)> wrote in message news:(E-Mail Removed)...
>I would like to discuss a situation when Messenger operates behind a firewall (primarily
>audio and video communication). So, lets presume that we have two parties one party is
>directly connected to the Internet (no NAT) without a firewall (or an UPnP firewall - WinXP
>ICF, for example), and the other party is behind a NAT and a "hard rock" stateful firewall
>(doesn't allow any incoming connections). My question is - why audio/video (camera)
>communication doesn't work in this scenario? I don't see the reason for this, except a flaw
>in the protocol. I mean, it surely is possible that firewalled party can enter some kind of
>"passive" mode (like FTP) and establish a connection with another party that is not behind a
>NAT/firewall.
>
>

"Jonathan Kay [MVP]" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Assuming both clients are using either MSN Messenger 7 and Windows Live
> Messenger 8 it should actually.

We are using MSN Messenger 7.5 (party without NAT upgraded to Live 8.0
yesterday).

> Failing that, it should use a relay server (which to be fair, is
> overloaded a lot of the time and doesn't work).

Which relay server? Is it something that I can install?

I mean, if a proxy or relay server could be installed somewhere on the
Internet, than it should work in case both parties are behind a NAT/firewall
too, because no inbound connections are necessary in this case..