OKay Måns,

As you wrote, "If both machines can make outgoing connections to a
third machine,
it's possible for them to communicate."

So what I understood is, If both the host A and B are behind different
firewalls, then they can only commnunicate if they initiate a
connection with a third machine(server). So in this case both A and B
has to initiate a connection with Server.

Now say host B is behind the firewall then, A and B can only
communicate if and only if B initiate the outbound connection to A or
server(which will in turn be connected with A). Right??

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myself_rajat@yahoo.com (Rajat) writes:

> OKay Måns,
>
> As you wrote, "If both machines can make outgoing connections to a
> third machine, it's possible for them to communicate."
>
> So what I understood is, If both the host A and B are behind different
> firewalls, then they can only commnunicate if they initiate a
> connection with a third machine(server). So in this case both A and B
> has to initiate a connection with Server.

That's what was trying to say.

> Now say host B is behind the firewall then, A and B can only
> communicate if and only if B initiate the outbound connection to A or
> server(which will in turn be connected with A). Right??

If A is not behind any firewall, it can obviously be connected to by
B, provided its firewall allows outgoing connections to A.  If you
want outside hosts to be able to initiate connections to B, B will
have to first make a connection to a proxy on the outside, which will
forward incoming connections to B over some kind of tunnel.  Of
course, doing this will probably violate every security policy set by
the administrator of B.

--
Måns Rullgård
mru@inprovide.com

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