Upd broadcast on all adapters using sockets

[Gunnar_Frenzel]

Hello,
this might be an easy question, but I don't have any handy solution at
hand. I have an application that is supposed to send UDP broadcast. So
far so easy, I did:

Socket sockSendBroadca st = null;
IPEndPoint ipeSendBroadcas t = null;

ipeSendBroadcas t = new IPEndPoint(IPAd dress.Broadcast , iSomePort);

sockSendBroadca st = new Socket(ipeSendB roadcast.Addres sFamily,
SocketType.Dgra m, ProtocolType.Ud p);

sockSendBroadca st.SetSocketOpt ion(SocketOptio nLevel.Socket,
SocketOptionNam e.Broadcast, 1);

sockSendBroadca st.SendTo(Encod ing.ASCII.GetBy tes("blah"),
ipeSendBroadcas t);
That works fine so far, but when I have two in the system (e.g. LAN and
WLAN NIC in different subnets) then it sends the broadcast to the LAN
broadcast address on the LAN adapter only. So I didn't reach any WLAN
devices. What I want to do is send a broadcast the the LAN subnet
broadcast address as well as the WLAN subnet broadcast address. I could
get all local IPs using IPHostEntry of the local machine but how can I
create the corresponding broadcast sockets without binding them to a
specific Port? It is supposed to use the next free port as source port,
just like it does using the code above for one network adapter. For
example is there a way to get the corresponding Subnetbroadcast address
when I have all local IPs retreived from the IPHostEntry to create two
IPEndPoints with instead of using IPAddress.Broad cast? Then the
broadcast to subnet's 2 broadcast address would probably send using
adapter 2...
Thanks in advance and sorry if it's totally easy and I'm to confused to
see the easy way... ;)
Gunnar

[Markus Stoeger]

Gu************@ web.de wrote:

That works fine so far, but when I have two in the system (e.g. LAN and
WLAN NIC in different subnets) then it sends the broadcast to the LAN
broadcast address on the LAN adapter only. So I didn't reach any WLAN
devices. <snip>

You are on the right track already. You have to bind one socket to each
network interfaces IP address. If you bind to port 0 it will allocate
the next free port. And use SetSocketOption to enable broadcasting.

hth,
Max

[Gunnar_Frenzel]

Ah right, binding to port 0. I'll try this. Thanks a lot.