UDP packets to PC behind NAT

[Grant Edwards]

On 2006-09-15, Janto Dreijer <jantod at gmail.com> wrote:

> I have a server with a static "public" IP and a client behind a NAT. I
> would like to send UDP packets from the server to the client. So what I
> need to do is open up a "hole" in the NAT and let the server know the
> target IP and port of the client where it can send its packets.
>
> Now I have read somewhere that you can have TCP and UDP running on the
> same port.

True.

> Not sure if this is true.

It is.

> Would it be a reasonable solution to initiate a TCP connection
> from the client to the server and somehow (?) let the server
> figure out how the client is connecting? And then send UDP to
> client over the same (IP, port)?

I doubt that will work unless the firewall has been
specifically designed to recognize that pattern of activity and
allow the incoming UDP packets.  I don't think most firewall
have default rules that allow UDP packets to tunnel back along
a TCP connection.

-- 
Grant Edwards                   grante             Yow!  Clear the
                                  at               laundromat!! This
                               visi.com            whirl-o-matic just had a
                                                   nuclear meltdown!!