public IPv4Packet CreateIPv4Packet(EthernetPacket ethernetHeader)
{
int ipv4PacketTotalLength = Int32.Parse(textBoxTotalLength.Text);
byte[] bytes = new byte[EthernetFields_Fields.ETH_HEADER_LEN + ipv4PacketTotalLength];
IPv4Packet ipv4Packet = new IPv4Packet(
EthernetFields_Fields.ETH_HEADER_LEN,
bytes);
// Ethernet fields
ipv4Packet.EthernetHeader = ethernetHeader.Bytes;
// IP fields
ipv4Packet.Version = 4;
ipv4Packet.IPHeaderLength = IPv4Fields_Fields.IP_HEADER_LEN;
ipv4Packet.TypeOfService = Int32.Parse(textBoxDS.Text);
ipv4Packet.IPTotalLength = ipv4PacketTotalLength;
ipv4Packet.Id = 0;
ipv4Packet.FragmentFlags = Int32.Parse(textBoxFlags.Text);
ipv4Packet.FragmentOffset = 0;
ipv4Packet.TimeToLive = Int32.Parse(textBoxTTL.Text);
ipv4Packet.IPProtocol = (IPProtocol.IPProtocolType)((DictionaryEntry)comboBoxIPProtocols.SelectedItem).Key;
ipv4Packet.SourceAddress = IPAddress.Parse(textBoxSourceAddress.Text);
ipv4Packet.DestinationAddress = IPAddress.Parse(textBoxDestinationAddress.Text);
ipv4Packet.ComputeIPChecksum(true);
ipv4Packet.IPData = GetRandomPacketData(ipv4Packet.IPPayloadLength);
return ipv4Packet;
}
/// <summary> Computes the IP checksum, optionally updating the IP checksum header.
///
/// </summary>
/// <param name="update">Specifies whether or not to update the IP checksum
/// header after computing the checksum. A value of true indicates
/// the header should be updated, a value of false indicates it
/// should not be updated.
/// </param>
/// <returns> The computed IP checksum.
/// </returns>
public int ComputeIPChecksum(bool update)
{
if (ipv4 != null)
{
return(ipv4.ComputeIPChecksum(update));
}
else if (ipv6 != null)
{
return(0); // ipv6 packets don't contain a checksum
}
else
{
throw new System.InvalidOperationException("ipv4 and ipv6 are both null");
}
}
public ScanMessage Connect(IPEndPoint ipEndPoint)
{
// SYN packet creation
//MAC address of gateway is provided by arp protocol
ARP arper = new ARP(device.Name);
arper.LocalIP = device.Interface.Addresses[0].Addr.ipAddress;
arper.LocalMAC = device.Interface.MacAddress;
PhysicalAddress gatewayHwAddress = arper.Resolve(gatewayAddress);
EthernetPacket ethernetHeader = new EthernetPacket(
device.Interface.MacAddress,
gatewayHwAddress,
EthernetPacketType.IPv4,
null);
byte[] content = new byte[
EthernetFields_Fields.ETH_HEADER_LEN +
IPv4Fields_Fields.IP_HEADER_LEN +
TCPFields_Fields.TCP_HEADER_LEN];
IPv4Packet ipv4Packet = new IPv4Packet(
EthernetFields_Fields.ETH_HEADER_LEN,
content);
// Ethernet header
ipv4Packet.EthernetHeader = ethernetHeader.Bytes;
// IP fields
ipv4Packet.Version = 4;
ipv4Packet.IPHeaderLength = IPv4Fields_Fields.IP_HEADER_LEN;
ipv4Packet.IPTotalLength = content.Length - EthernetFields_Fields.ETH_HEADER_LEN;
ipv4Packet.Id = 100;
ipv4Packet.TimeToLive = 20;
ipv4Packet.IPProtocol = IPProtocol.IPProtocolType.TCP;
ipv4Packet.SourceAddress = device.Interface.Addresses[0].Addr.ipAddress;
ipv4Packet.DestinationAddress = ipEndPoint.Address;
ipv4Packet.ComputeIPChecksum(true);
TCPPacket tcpPacket = new TCPPacket(
EthernetFields_Fields.ETH_HEADER_LEN,
content);
// TCP fields
tcpPacket.SourcePort = 2222;
tcpPacket.DestinationPort = ipEndPoint.Port;
tcpPacket.SequenceNumber = 1000;
tcpPacket.AcknowledgmentNumber = 1000;
tcpPacket.Syn = true;
tcpPacket.TCPHeaderLength = TCPFields_Fields.TCP_HEADER_LEN;
tcpPacket.WindowSize = 555;
// Calculate checksum
tcpPacket.ComputeTCPChecksum(true);
try
{
device.Open(false, 20);
device.SetFilter(String.Format("ip src {0} and tcp src port {1} and tcp dst port {2}",
tcpPacket.DestinationAddress,
tcpPacket.DestinationPort,
tcpPacket.SourcePort));
// Send the packet
device.SendPacket(tcpPacket);
TCPPacket replyPacket = null;
bool replyReceived = false;
Stopwatch watch = new Stopwatch();
watch.Start();
// Condition including timeout check.
while (watch.ElapsedMilliseconds < timeout && replyReceived != true)
{
if ((replyPacket = (TCPPacket)device.GetNextPacket()) != null)
{
replyReceived = true;
}
}
if (!replyReceived) // A reply hasn't been received
{
return ScanMessage.Timeout;
}
else if (replyPacket.Rst) // Remote host reset the connection
{
return ScanMessage.PortClosed;
}
else if (replyPacket.Ack) // Remote host replied with a TCP packet
{
tcpPacket.Syn = false;
tcpPacket.Rst = true;
tcpPacket.WindowSize = 0;
tcpPacket.ComputeTCPChecksum(true);
device.SendPacket(tcpPacket);
return ScanMessage.PortOpened;
}
else
{
return ScanMessage.Unknown;
}
}
catch (Exception)
{
return ScanMessage.Unknown;
}
finally
{
device.Close();
}
}