public static void SendTcpSyn(NetworkDevice dev)
{
byte[] bytes = new byte[54];
TCPPacket tcp = new TCPPacket(lLen, bytes, true);
//Ethernet fields
tcp.SourceHwAddress = dev.MacAddress; //Set the source mac of the local device
tcp.DestinationHwAddress = destMAC; //Set the dest MAC of the gateway
tcp.EthernetProtocol = EthernetProtocols_Fields.IP;
//IP fields
tcp.DestinationAddress = destIP; //The IP of the destination host
tcp.SourceAddress = dev.IpAddress; //The IP of the local device
tcp.IPProtocol = IPProtocols_Fields.TCP;
tcp.TimeToLive = 20;
tcp.Id = 100;
tcp.Version = 4;
tcp.IPTotalLength = bytes.Length - lLen; //Set the correct IP length
tcp.IPHeaderLength = IPFields_Fields.IP_HEADER_LEN;
//TCP fields
tcp.SourcePort = sourcePort; //The TCP source port
tcp.DestinationPort = destPort; //The TCP dest port
tcp.Syn = true; //Set the SYN flag on
tcp.WindowSize = 555;
tcp.AcknowledgementNumber = 1000;
tcp.SequenceNumber = 1000;
tcp.TCPHeaderLength = TCPFields_Fields.TCP_HEADER_LEN; //Set the correct TCP header length
//tcp.SetData( System.Text.Encoding.ASCII.GetBytes("HELLO") );
//Calculate checksums
tcp.ComputeIPChecksum();
tcp.ComputeTCPChecksum();
dev.PcapOpen(true, 20);
//Set a filter to capture only replies
dev.PcapSetFilter("ip src " + destIP + " and ip dst " +
dev.IpAddress + " and tcp src port " + destPort + " and tcp dst port " + sourcePort);
//Send the packet
Console.Write("Sending packet: " + tcp + "...");
dev.PcapSendPacket(tcp);
Console.WriteLine("Packet sent.");
//Holds the reply
Packet reply;
//Wait till you get a reply
while ((reply = dev.PcapGetNextPacket()) == null)
{
;
}
//print the reply
Console.WriteLine("Reply received: " + reply);
dev.PcapClose();
}
/// <summary>
/// Resolves the MAC address of the specified IP address
/// </summary>
/// <param name="destIP">The IP address to resolve</param>
/// <param name="deviceName">The local network device name on which to send the ARP request</param>
/// <returns>The MAC address that matches to the given IP address</returns>
public string Resolve(String destIP, string deviceName)
{
string localMAC = LocalMAC;
string localIP = LocalIP;
NetworkDevice device = new NetworkDevice(DeviceName);
//if no local IP and MAC addresses specified, use the ones
//configured on the local device
if (localIP == null)
{
localIP = device.IpAddress;
}
if (LocalMAC == null)
{
localMAC = device.MacAddress;
}
//Build a new ARP request packet
ARPPacket request = BuildRequest(destIP, localMAC, localIP);
//create a "tcpdump" filter for allowing only arp replies to be read
String arpFilter = "arp and ether dst " + IPUtil.MacFormat(localMAC);
//open the device with 20ms timeout
device.PcapOpen(true, 20);
//set the filter
device.PcapSetFilter(arpFilter);
//inject the packet to the wire
device.PcapSendPacket(request);
ARPPacket reply;
while (true)
{
//read the next packet from the network
reply = (ARPPacket)device.PcapGetNextPacket();
if (reply == null)
{
continue;
}
//if this is the reply we're looking for, stop
if (reply.ARPSenderProtoAddress.Equals(destIP))
{
break;
}
}
//free the device
device.PcapClose();
//return the resolved MAC address
return(reply.ARPSenderHwAddress);
}
