i am working on a school project. i am trying to make a sniffer.
in school the project works but in my house there is a problem.
this is the exception it throws me:"An attempt was made to access a socket in a way forbidden by its access permissions"
this is my code:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Net;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Net;
namespace MJsniffer
{
public enum Protocol
{
TCP = 6,
UDP = 17,
Unknown = -1
};
public partial class MJsnifferForm : Form
{
private Socket mainSocket; //The socket which captures all incoming packets
private byte[] byteData = new byte[4096];
private bool bContinueCapturing = false; //A flag to check if packets are to be captured or not
private delegate void AddTreeNode(TreeNode node);
public MJsnifferForm()
{
InitializeComponent();
}
private void btnStart_Click(object sender, EventArgs e)
{
if (cmbInterfaces.Text == "")
{
MessageBox.Show("Select an Interface to capture the packets.", "MJsniffer",
MessageBoxButtons.OK, MessageBoxIcon.Error); //THIS IS WHERE THE PROBLEM IS.
return;
}
try
{
if (!bContinueCapturing)
{
//Start capturing the packets...
btnStart.Text = "&Stop";enter code here
bContinueCapturing = true;
//For sniffing the socket to capture the packets has to be a raw socket, with the
//address family being of type internetwork, and protocol being IP
mainSocket = new Socket(AddressFamily.InterNetwork,
SocketType.Raw, ProtocolType.IP);
//Bind the socket to the selected IP address
mainSocket.Bind(new IPEndPoint(IPAddress.Parse(cmbInterfaces.Text), 0));
//Set the socket options
mainSocket.SetSocketOption(SocketOptionLevel.IP, //Applies only to IP packets
SocketOptionName.HeaderIncluded, //Set the include the header
true); //option to true
byte[] byTrue = new byte[4] {1, 0, 0, 0};
byte[] byOut = new byte[4]{1, 0, 0, 0}; //Capture outgoing packets
//Socket.IOControl is analogous to the WSAIoctl method of Winsock 2
mainSocket.IOControl(IOControlCode.ReceiveAll, //Equivalent to SIO_RCVALL constant
//of Winsock 2
byTrue,
byOut);
//Start receiving the packets asynchronously
mainSocket.BeginReceive(byteData, 0, byteData.Length, SocketFlags.None,
new AsyncCallback(OnReceive), null);
}
else
{
btnStart.Text = "&Start";
bContinueCapturing = false;
//To stop capturing the packets close the socket
mainSocket.Close ();
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "MJsniffer", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void OnReceive(IAsyncResult ar)
{
try
{
int nReceived = mainSocket.EndReceive(ar);
//Analyze the bytes received...
ParseData (byteData, nReceived);
if (bContinueCapturing)
{
byteData = new byte[4096];
//Another call to BeginReceive so that we continue to receive the incoming
//packets
mainSocket.BeginReceive(byteData, 0, byteData.Length, SocketFlags.None,
new AsyncCallback(OnReceive), null);
}
}
catch (ObjectDisposedException)
{
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "MJsniffer", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
private void ParseData(byte[] byteData, int nReceived)
{
TreeNode rootNode = new TreeNode();
//Since all protocol packets are encapsulated in the IP datagram
//so we start by parsing the IP header and see what protocol data
//is being carried by it
IPHeader ipHeader = new IPHeader(byteData, nReceived);
TreeNode ipNode = MakeIPTreeNode(ipHeader);
rootNode.Nodes.Add(ipNode);
//Now according to the protocol being carried by the IP datagram we parse
//the data field of the datagram
switch (ipHeader.ProtocolType)
{
case Protocol.TCP:
TCPHeader tcpHeader = new TCPHeader(ipHeader.Data, //IPHeader.Data stores the data being
//carried by the IP datagram
ipHeader.MessageLength);//Length of the data field
TreeNode tcpNode = MakeTCPTreeNode(tcpHeader);
rootNode.Nodes.Add(tcpNode);
//If the port is equal to 53 then the underlying protocol is DNS
//Note: DNS can use either TCP or UDP thats why the check is done twice
if (tcpHeader.DestinationPort == "53" || tcpHeader.SourcePort == "53")
{
TreeNode dnsNode = MakeDNSTreeNode(tcpHeader.Data, (int)tcpHeader.MessageLength);
rootNode.Nodes.Add(dnsNode);
}
break;
case Protocol.UDP:
UDPHeader udpHeader = new UDPHeader(ipHeader.Data, //IPHeader.Data stores the data being
//carried by the IP datagram
(int)ipHeader.MessageLength);//Length of the data field
TreeNode udpNode = MakeUDPTreeNode(udpHeader);
rootNode.Nodes.Add(udpNode);
//If the port is equal to 53 then the underlying protocol is DNS
//Note: DNS can use either TCP or UDP thats why the check is done twice
if (udpHeader.DestinationPort == "53" || udpHeader.SourcePort == "53")
{
TreeNode dnsNode = MakeDNSTreeNode(udpHeader.Data,
//Length of UDP header is always eight bytes so we subtract that out of the total
//length to find the length of the data
Convert.ToInt32(udpHeader.Length) - 8);
rootNode.Nodes.Add(dnsNode);
}
break;
case Protocol.Unknown:
break;
}
AddTreeNode addTreeNode = new AddTreeNode(OnAddTreeNode);
rootNode.Text = ipHeader.SourceAddress.ToString() + "-" +
ipHeader.DestinationAddress.ToString();
//Thread safe adding of the nodes
treeView.Invoke(addTreeNode, new object[] {rootNode});
}
//Helper function which returns the information contained in the IP header as a
//tree node
private TreeNode MakeIPTreeNode(IPHeader ipHeader)
{
TreeNode ipNode = new TreeNode();
ipNode.Text = "IP";
ipNode.Nodes.Add ("Ver: " + ipHeader.Version);
ipNode.Nodes.Add ("Header Length: " + ipHeader.HeaderLength);
ipNode.Nodes.Add ("Differntiated Services: " + ipHeader.DifferentiatedServices);
ipNode.Nodes.Add("Total Length: " + ipHeader.TotalLength);
ipNode.Nodes.Add("Identification: " + ipHeader.Identification);
ipNode.Nodes.Add("Flags: " + ipHeader.Flags);
ipNode.Nodes.Add("Fragmentation Offset: " + ipHeader.FragmentationOffset);
ipNode.Nodes.Add("Time to live: " + ipHeader.TTL);
switch (ipHeader.ProtocolType)
{
case Protocol.TCP:
ipNode.Nodes.Add ("Protocol: " + "TCP");
break;
case Protocol.UDP:
ipNode.Nodes.Add ("Protocol: " + "UDP");
break;
case Protocol.Unknown:
ipNode.Nodes.Add ("Protocol: " + "Unknown");
break;
}
ipNode.Nodes.Add("Checksum: " + ipHeader.Checksum);
ipNode.Nodes.Add("Source: " + ipHeader.SourceAddress.ToString());
ipNode.Nodes.Add("Destination: " + ipHeader.DestinationAddress.ToString());
return ipNode;
}
//Helper function which returns the information contained in the TCP header as a
//tree node
private TreeNode MakeTCPTreeNode(TCPHeader tcpHeader)
{
TreeNode tcpNode = new TreeNode();
tcpNode.Text = "TCP";
tcpNode.Nodes.Add("Source Port: " + tcpHeader.SourcePort);
tcpNode.Nodes.Add("Destination Port: " + tcpHeader.DestinationPort);
tcpNode.Nodes.Add("Sequence Number: " + tcpHeader.SequenceNumber);
if (tcpHeader.AcknowledgementNumber != "")
tcpNode.Nodes.Add("Acknowledgement Number: " + tcpHeader.AcknowledgementNumber);
tcpNode.Nodes.Add("Header Length: " + tcpHeader.HeaderLength);
tcpNode.Nodes.Add("Flags: " + tcpHeader.Flags);
tcpNode.Nodes.Add("Window Size: " + tcpHeader.WindowSize);
tcpNode.Nodes.Add("Checksum: " + tcpHeader.Checksum);
if (tcpHeader.UrgentPointer != "")
tcpNode.Nodes.Add("Urgent Pointer: " + tcpHeader.UrgentPointer);
return tcpNode;
}
//Helper function which returns the information contained in the UDP header as a
//tree node
private TreeNode MakeUDPTreeNode(UDPHeader udpHeader)
{
TreeNode udpNode = new TreeNode();
udpNode.Text = "UDP";
udpNode.Nodes.Add("Source Port: " + udpHeader.SourcePort);
udpNode.Nodes.Add("Destination Port: " + udpHeader.DestinationPort);
udpNode.Nodes.Add("Length: " + udpHeader.Length);
udpNode.Nodes.Add("Checksum: " + udpHeader.Checksum);
return udpNode;
}
//Helper function which returns the information contained in the DNS header as a
//tree node
private TreeNode MakeDNSTreeNode(byte[] byteData, int nLength)
{
DNSHeader dnsHeader = new DNSHeader(byteData, nLength);
TreeNode dnsNode = new TreeNode();
dnsNode.Text = "DNS";
dnsNode.Nodes.Add("Identification: " + dnsHeader.Identification);
dnsNode.Nodes.Add("Flags: " + dnsHeader.Flags);
dnsNode.Nodes.Add("Questions: " + dnsHeader.TotalQuestions);
dnsNode.Nodes.Add("Answer RRs: " + dnsHeader.TotalAnswerRRs);
dnsNode.Nodes.Add("Authority RRs: " + dnsHeader.TotalAuthorityRRs);
dnsNode.Nodes.Add("Additional RRs: " + dnsHeader.TotalAdditionalRRs);
return dnsNode;
}
private void OnAddTreeNode(TreeNode node)
{
treeView.Nodes.Add(node);
}
private void SnifferForm_Load(object sender, EventArgs e)
{
string strIP = null;
IPHostEntry HosyEntry = Dns.GetHostEntry((Dns.GetHostName()));
if (HosyEntry.AddressList.Length > 0)
{
foreach (IPAddress ip in HosyEntry.AddressList)
{
strIP = ip.ToString();
cmbInterfaces.Items.Add(strIP);
}
}
}
private void SnifferForm_FormClosing(object sender, FormClosingEventArgs e)
{
if (bContinueCapturing)
{
mainSocket.Close();
}
}
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
//MessageBox.Show(comboBox1.SelectedItem.ToString());
}
private void treeView_AfterSelect(object sender, TreeViewEventArgs e)
{
}
private void treeView2_AfterSelect(object sender, TreeViewEventArgs e)
{
}
}
}
