[Synalist] How does BIND work?

[Sergei R. <sro...@gm...>]

Hi guys,

Have the following PC config:
NIC1: 192.168.81.15 / 255.255.255.0
NIC2: 10.0.0.1 / 255.255.255.0

Want to do:
Want to send UDP broadcast packet to dest. addr. 255.255.255.255 from
specified IP address on the PC (for example from 192.168.81.15 to
255.255.255.255)

Problem:
UDP broadcast packet doubles to:
1. source 192.168.81.15, dest. 255.255.255.255 sent via NIC1
2. source 192.168.81.15, dest. 255.255.255.255 sent via NIC2
So, recipients in 10.0.0.0 network receive broadcast packets with from
FROM Ip address is 192.168.81.15 !
10.0.0.0 network's machines get IP using: ip:= sock.GetRemoteSinIP;

How I use sockets:
TUDPClient = class(TThread)
.......
CSock: TUDPBlockSocket;
.................

constructor TUDPClient.Create;
begin
..................
CSock:= TUDPBlockSocket.Create;
CSock.Bind(192.168.81.15,'0');
CSock.EnableBroadcast(true);
......
end;

procedure TUDPClient.Execute;
begin
...................
        CSock.Connect ('255.255.255.255', '11111');
        CSock.SendBuffer(PChar(LocData),Length(LocData));
......
//LocData is a string that I want to send.

end;

Why UDP packet been bound to specified IP, sends both to 192.168.81.0
and 10.0.0.0 networks with the SAME SOURCE IP address (192.168.81.15)
?

I need to send the UDP broadcast packets bounded to each IP on the PC
to 255.255.255.255

I imagine it should be like this:
CSockBind: array of TUDPBlockSocket;

constructor TUDPClient.Create;
begin

//getting all IPs of current PC to IPsToBind stringlist

LocalIPsCount:= IPsToBind.Count;
SetLength(CSockBind,LocalIPsCount);

for i:= 0 to LocalIPsCount-1 do
    begin
    CSockBind[i]:= TUDPBlockSocket.Create;
    CSockBind[i].Bind(IPsToBind[i],'0');
    CSockBind[i].EnableBroadcast(true);
    end;

end;

procedure TUDPClient.Execute;
begin
.............
//send packets
    for i:= 0 to LocalIPsCount-1 do
        begin
        if terminated then break;
        CSockBind[i].Connect('255.255.255.255', '11111');
        CSockBind[i].SendBuffer(PChar(LocData),Length(LocData));
        sleep(1);
        end;

.............
end;

I.e I thought that
- CSockBind[1] sends packet to 255.255.255.255 from source
192.168.81.15 via NIC1 to 192.168.81.0 network
- CSockBind[2] sends packet to 255.255.255.255 from source 10.0.0.1
via NIC2 to 10.0.0.0 network

But I does not work....every packet doubles on each NIC and sent to
bott (192... and 10...) networks with source IP 192.168.81.15  (!!!!)

Where I'm wrong?

Thanks alot.

-- 
Sergei