[OT] Handling multiple UDP clients through NAT

Bryan Sant bryan.sant at gmail.com
Tue Feb 6 13:43:03 MST 2007

On 2/6/07, Steve <smorrey at gmail.com> wrote:
> Specifically, I currently keep track of clients in a hashmap, with the
> hash being comprised of their IP address and port.

When you say, "their IP and port", you're meaning source IP address
and source port (not the destination port) right?  Using a source IP
and destination port would not be unique for NATed clients.  Using
source IP and source port is ALWAYS unique from the server's

> That kind of works, except that some NAT Gateways and routers
> (specifically my own ActionTec Gateway POS from Qwest), block
> unsolicited incoming UDP packets on all ports regardless of if the
> same IP address is responding, as was used in the initial request, if
> the response packet is coming in on a port different than the one the
> original discovery packet was sent from.

I've very, very, glad that firewalls block this traffic.  Could you
imagine all of the garbage packets that people would send to you all
the time if firewalls didn't block non-solicited packets?


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