I'm a beginner with Socket programming in c# and I wonder how to send packet data for specific NIC.
I knew there was a way to set specific network device using setsockopt in python3 like that
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, 25, str(str(netinterface) + '\0').encode('UTF-8')) // netinterface => 'eth1'
except OSError :
print("Failed set eth1")
there were eth0 and eth1 and I did send packet successfully to eth1.
I found a way set option to socket like this, but I dont know how to resolve NIC using this APIs.
UdpClient udpclient = new UdpClient(new IPEndPoint(IPAddress.IPv6Any, 15118));
IPAddress multicateAddress = IPAddress.Parse("FF02::1");
udpclient.JoinMulticastGroup(multicateAddress);
Socket uSocket = udpclient.Client;
uSocket.SetSocketOption() // <- How... to?
If there is tutorials or any documents, it will help me.
Please comment thx.
Whether bind your socket to a specific IP address of an interface on the NIC you're looking for or modify your OS routing table to send packets to a specific network through a specified interface.
UdpClient isn't just a socket, but anyway I don't see an issue in binding it to a specific IP. See the docs for details.
Related
I am trying to use PCap.NET to send a SYN packet to a destination. When using the WinSock API I can see the TCP Options in Wireshark.... But when I use PCap.NET to build and send the packet, the options are not included. Here is the TCP layer I use to build the packet :
TcpLayer tcpLayer = new TcpLayer
{
SourcePort = _sourcePort,
DestinationPort = _destinationPort,
SequenceNumber = _seqNumber,
ControlBits = TcpControlBits.Synchronize,
Window = _windowSize,
};
This is the a WireShark ScreenGrab for sending a SYN using WinSock, where the TCP options are visible.
And this is the Wireshark ScreenGrab sending a SYN using PCap.NET, where the TCP options are not visible.
I understand that when building a Pcap TCP layer you can set the options property to None.... I haven't done that, thinking that by leaving it as its default that the options would send the same way it does for WinSock. Can anybody provide any explanation or advice for this problem. Thanks in advance for the help!
If you create a new TcpLayer, you need to set the Options property in order to have options in the TCP layer.
If you don't set the Options property, it will, by default, set to None.
I'm attempting to send and receive UDP packets from the same machine using two separate programs but so far I've not been able to receive anything. I've attempted completely turning off my firewall and that still hasn't worked.
Sending program
var sender = new UdpClient(Dns.GetHostName(), 2055);
var data = new byte[] { 0, 1, 2, 3, 4, 5 };
sender.Send(data, data.Length);
Receiving program
var receiver = new UdpClient(2055);
var endPoint = new IPEndPoint(IPAddress.Any, 2055);
var data = receiver.Receive(ref endPoint);
System.Console.WriteLine("Data received");
I've even copy and pasted code from this tutorial http://www.codeproject.com/Articles/10649/An-Introduction-to-Socket-Programming-in-NET-using and still had no success.
The problem is in var sender = new UdpClient(Dns.GetHostName(), 2055);
You need to specify your local host IP which is 127.0.0.1 since you are on the same machine. This should work:
var sender = new UdpClient("127.0.0.1", 2055);
From About multicast IP addresses and ports (TechNet):
Multicast IP addresses are class-D addresses that fall within two ranges: 224.0.0.0 through 239.255.255.255 and FF00:0000:0000:0000:0000:0000:0000:0000 through FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF. The addresses in the first range are Internet Protocol version 4 (IPv4) addresses. The addresses in the second range are Internet Protocol version 6 (IPv6) addresses.
For intranet use, it is recommended that you use IPv4 addresses in the range 239...*. Port numbers can range between 1 and 65535. The routers on the network over which you are transmitting your content must be multicast-enabled, meaning that they must be able to interpret class-D addresses or they will not be able to forward your multicast information to clients.
You have to use an IP address in this range because of network-level filtering. There's a table of commonly-used multicast addresses on Wikipedia.
Actually, the tutorial you're using notes this too:
UDP also supports multicasting i.e. sending a single datagram to multiple receivers. To do so, the sender sends a packet to an IP address in the range 224.0.0.1 – 239.255.255.255 (Class D address group).
I have a query about the behaviour of UdpClient.
Consider I create a UdpClient and bind it to a specific remote IP address and port using the Connect method:
controlClient1 = new UDPClient();
controlClient1.Connect(TargetIP1, ControlPort);
I then create a second UdpClient and bind it to a different remote IP address but the same port:
controlClient2 = new UDPClient();
controlClient2.Connect(TargetIP2, ControlPort);
Will controlClient1.Availble return the number of messages received from TargetIP1 only?
Many Thanks.
Yes it will report only the number of bytes available to read in that client object. Refer UDPClient
I'm trying to send a broadcast message from a C# app on one machine to a Python script on another. If I specify the Python machine's IP as my endpoint, I can send a message just fine. Here's how I'm sending my message:
const int PORT = 12345;
using (var sock = new UdpClient())
{
var endpoint = new IPEndPoint(IPAddress.Parse(remoteIP), PORT);
//var endpoint = new IPEndPoint(IPAddress.Broadcast, PORT);
byte[] bytes = Encoding.UTF8.GetBytes("hello, world!");
sock.Send(bytes, bytes.Length, endpoint);
}
On the Python side, I'm receiving as follows:
import socket
PORT = 12345
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('', PORT))
#sock.bind(('<broadcast>', PORT))
while 1:
data,addr = sock.recvfrom(1024)
if not data: break
print(data)
I can send my message from one machine to another successfully. However, I have multiple machines to which I want my message to go (UDP broadcast), but when I use IPAddress.Broadcast as my endpoint, Python doesn't receive my message. I've also tried binding my Python socket to <broadcast>, but that doesn't help, and binding to my C# machine's IP gives me the error socket.gaierror: [Errno -3] Temporary failure in name resolution.
I don't know if this is an issue of C# not sending the broadcast or of Python not receiving it.
You can use a network analyzer such as Wireshark to verify the operation of your networking code. I suspect that if you do, you will find that no broadcast datagram is actually set.
Lacking a good, complete code example it's hard to say for sure what the reason would be. But the cause of this would most likely be because you have not set the Socket.EnableBroadcast property for your socket. It defaults to false and if not set to true, broadcast datagrams won't be sent even if you send to a broadcast address.
I'm trying to send a broadcast UDP message to a C# application. I have tried the following code to send the message. Which I found on the php.net website as a comment to the socket_sendto manual page.
<?php
$sock = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
socket_set_option($sock, SOL_SOCKET, SO_BROADCAST, 1);
socket_sendto($sock, $broadcast_string, strlen($broadcast_string), 0, '255.255.255.255', $port);
?>
This doesn't work for me, maybe it's my network.
But it does work if I replace the broadcast IP '255.255.255.255' to my specific IP e.g. '192.168.1.128'. I can see this message coming in with Wireshark, while I can't see this using the above code. This leads me to believe there is something wrong with the PHP side of the code. I really want to use broadcasting or some kind of multicasting for my program, so I'm a bit stuck at the moment ;)
I use the following on the (C#) receiving end (for testing):
UdpClient subscriber = new UdpClient(15000);
IPEndPoint ep = new IPEndPoint(IPAddress.Any, 15000); ;
byte[] pdata = subscriber.Receive(ref ep);
string data = Encoding.ASCII.GetString(pdata);
MessageBox.Show(data);
subscriber.Close();
Any idea what could be the cause of this?
Try specifying the MSG_DONTROUTE flag in your script. Taking inspiration from this CodeGuru post, if this isn't specified the routers make the decision on whether or not to broadcast your message.
socket_sendto($sock, $broadcast_string, strlen($broadcast_string), MSG_DONTROUTE, '255.255.255.255', $port);
255.255.255.255 is a "limited" broadcast whereas your 192.168.1.255 is a "directed" broadcast.
Limited in simple terms means that it is only send within the LAN. LAN as defined by directly connected hosts, i.e. with no router in between. Routers--with a few exceptions--do not pass a limited broadcast but a directed broadcast.
Now, with your initial problem and question, I can only guess that you are sending your broadcast across a router.