private static IPv4Packet BuildDhcpDiscoverMessage(NetworkInterface inter, ushort packetId, uint dhcpTransactionId)
{
var hardwareAddress = new HardwareAddress(HardwareAddressType.Ethernet,
inter.GetPhysicalAddress().GetAddressBytes());
var dhcpPacket = new DhcpPacket();
dhcpPacket.Operation = DhcpOperation.Request;
dhcpPacket.MessageType = DhcpMessageType.Discover;
dhcpPacket.TransactionId = dhcpTransactionId;
dhcpPacket.HardwareAddress = hardwareAddress;
var dhcpUdpPacket = new UdpPacket();
dhcpUdpPacket.SourcePort = 68;
dhcpUdpPacket.DestinationPort = 67;
dhcpUdpPacket.Payload = dhcpPacket;
var dhcpIpPacket = new IPv4Packet();
dhcpIpPacket.Source = IPAddress.Any;
dhcpIpPacket.Destination = IPAddress.Broadcast;
dhcpIpPacket.Identifiation = packetId;
dhcpIpPacket.Payload = dhcpUdpPacket;
return(dhcpIpPacket);
}
private static IPv4Packet BuildDhcpRebindMessage(DhcpOffer offer, NetworkInterface inter, ushort packetId, uint dhcpTransactionId)
{
var hardwareAddress = new HardwareAddress(HardwareAddressType.Ethernet,
inter.GetPhysicalAddress().GetAddressBytes());
var dhcpPacket = new DhcpPacket();
dhcpPacket.Operation = DhcpOperation.Request;
dhcpPacket.MessageType = DhcpMessageType.Request;
dhcpPacket.TransactionId = dhcpTransactionId;
dhcpPacket.HardwareAddress = hardwareAddress;
dhcpPacket.ClientAddress = offer.ClientAddress;
dhcpPacket.Options.Add(new DhcpClientIdentifier(hardwareAddress));
var dhcpUdpPacket = new UdpPacket();
dhcpUdpPacket.SourcePort = 68;
dhcpUdpPacket.DestinationPort = 67;
dhcpUdpPacket.Payload = dhcpPacket;
var dhcpIpPacket = new IPv4Packet();
dhcpIpPacket.Source = offer.ClientAddress;
dhcpIpPacket.Destination = offer.DhcpServer;
dhcpIpPacket.Identifiation = packetId;
dhcpIpPacket.Payload = dhcpUdpPacket;
return(dhcpIpPacket);
}
static void Main(string[] args)
{
var interfaces = NetworkInterface.GetAllNetworkInterfaces();
foreach (var item in interfaces.Select((i, idx) => new { nr = idx + 1, inter = i }))
{
Console.WriteLine($"-{item.nr}- {item.inter.Name}");
}
Console.Write("> Choose a interface: ");
int selection = int.Parse(Console.ReadLine());
var mainInterface = interfaces[selection - 1];
var random = new Random();
ushort packetId = (ushort)random.Next();
uint dhcpTransactionId = (uint)random.Next();
ITransportPacketFactory transportPacketFactory = new TransportPacketFactoryImpl();
IApplicationPacketFactory applicationPacketFactory = new ApplicationPacketFactoryImpl();
var dhcpDiscover = BuildDhcpDiscoverMessage(mainInterface, packetId, dhcpTransactionId);
bool running = true;
bool rcvAck = false;
ManualResetEvent rcvAckEvent = new ManualResetEvent(false);
DhcpOffer selectedOffer = null;
var socket = SetupPromiscousSocket(mainInterface);
Console.WriteLine("Send DHCP Discover...");
dhcpDiscover.Send(socket);
ISet <DhcpOffer> offers = new HashSet <DhcpOffer>();
var recieverThread = new Thread(() =>
{
while (running)
{
IPv4Packet rcvPacket = IPv4Packet.Recieve(socket, transportPacketFactory, applicationPacketFactory);
if (rcvPacket != null && rcvPacket.Payload is UdpPacket udpPacket)
{
if (udpPacket.Payload is DhcpPacket responseDhcpPacket)
{
switch (responseDhcpPacket.MessageType)
{
case DhcpMessageType.Offer:
DhcpOffer offer = DhcpOffer.FromDhcpPacket(responseDhcpPacket);
offers.Remove(offer); // remove old offer from server if necassary
offers.Add(offer);
Console.WriteLine($"New Offer from {rcvPacket.Source}");
break;
case DhcpMessageType.Ack:
if (!rcvAck)
{
Console.WriteLine("OK from server - ready to launch!");
int exitCodeInter = ExecuteNetshCommand(
$"interface ipv4 set address name=\"{mainInterface.Name}\" static" +
$" {selectedOffer.ClientAddress} {selectedOffer.SubnetMask} {selectedOffer.Gateway} 1"
);
Console.WriteLine($"netsh Interface exit code - {exitCodeInter}");
int exitCodeDns = ExecuteNetshCommand(
$"interface ipv4 set dnsservers \"{mainInterface.Name}\" static {selectedOffer.DnsServer} primary no"
);
Console.WriteLine($"netsh DNS exit code - {exitCodeDns}");
rcvAckEvent.Set();
}
rcvAck = true;
break;
}
}
}
}
});
recieverThread.Start();
Thread.Sleep(500);
if (offers.Count == 0)
{
Console.WriteLine("Resending DHCP Discover...");
dhcpDiscover.Send(socket);
}
Console.WriteLine("> Press any key to stop adding new offers\n");
Console.ReadKey();
Console.WriteLine();
Console.WriteLine("-- Select DHCP server offer --");
DhcpOffer[] finalOffers = offers.ToArray();
foreach (var item in finalOffers.Select((o, idx) => new { nr = idx + 1, offer = o }))
{
Console.WriteLine($"-{item.nr}- Offer from {item.offer.DhcpServer}");
Console.WriteLine($" Client address: {item.offer.ClientAddress}");
Console.WriteLine($" Gateway address: {item.offer.Gateway}");
Console.WriteLine($" DNS server: {item.offer.DnsServer}");
Console.WriteLine($" Domain: {item.offer.Domain}");
}
Console.Write("> Choose a offer: ");
selection = int.Parse(Console.ReadLine());
selectedOffer = finalOffers[selection - 1];
Console.WriteLine("Send DHCP Request");
IPv4Packet dhcpRequest = BuildDhcpRequestMessage(selectedOffer, mainInterface, ++packetId, dhcpTransactionId);
dhcpRequest.Send(socket);
Console.WriteLine("Waiting for DHCP Ack and netsh...");
rcvAckEvent.WaitOne();
running = false;
socket.Close();
Console.WriteLine("> Press any key to close");
Console.ReadKey();
}
