public ushort GetChecksum(ref byte[] Packet, int start, int end, ref System.Net.IPAddress SourceAddress, ref System.Net.IPAddress DestinationAddress)
{
byte[] PseudoPacket;
PseudoPacket = new byte[12 + Packet.Length];
System.Buffer.BlockCopy(SourceAddress.GetAddressBytes(), 0, PseudoPacket, 0, 4);
System.Buffer.BlockCopy(DestinationAddress.GetAddressBytes(), 0, PseudoPacket, 4, 4);
PseudoPacket[8] = 0;
PseudoPacket[9] = 17;
System.Buffer.BlockCopy(System.BitConverter.GetBytes(System.Net.IPAddress.HostToNetworkOrder((short)Packet.Length)), 0, PseudoPacket, 10, 2);
System.Buffer.BlockCopy(Packet, 0, PseudoPacket, 12, Packet.Length);
return(IPPacket.GetChecksum(ref PseudoPacket, 0, PseudoPacket.Length - 1));
}