> to TALK TO DEVICE A
> 
>   FUDPSockettoSend := TUDPBlockSocket.Create();
>   FUDPSockettoSend.Connect('192.168.0.200','4000');
> 
> to LISTEN FROM DEVICE A
> 
>   FUDPSockettoListen := TUDPBlockSocket.Create();
>   FUDPSockettoListen.Bind('192.168.0.45','4001');
> 
> 192.168.0.45 is one of the IPS on my PC.
> 
> The result is, i dont get ANYMORE packages.

It's looks like Device A sending datas by a broadcast instead of 
unicast to your IP address.

If device send unicast to a one IP address, then it cannot be readed 
by other local IP addresses! Only destination IP interface can see 
this UDP packet. 

It is possible only when you are reading broadcast. Broadcast can be 
readed by all interfaces who see broadcast message. (If it is network 
broadcast, then it can see by all interfaces within same IP network.) 
And broadcasts are readable only when you is binded to 0.0.0.0.

When you bind to some specific local IP, then you cannot read 
broadcasts. You can read only unicast packets what is delivered to 
your binded IP adddress. But you see no packet.

So, I think, Device A not using unicast to your IP, but sending datas 
by a broadcast. Or some crappy software hooks your winsock interface 
(firewall, antivirus,...)


-- 
Lukas Gebauer.

http://synapse.ararat.cz/ - Ararat Synapse - TCP/IP Lib.
http://geoget.ararat.cz/ - Geocaching solution


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