C# TCP protocol. Convert IP to URL

Question

How I can convert ip to url? I want to create sniffer where user can see at the end of day list of sites and total time that he spend on the each site

static void Sniff(IPAddress ip)
{
    Socket sck = new Socket(AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.IP);
    //sck.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Broadcast, 1);
    sck.Bind(new IPEndPoint(ip, 0));
    sck.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.HeaderIncluded, true);
    sck.IOControl(IOControlCode.ReceiveAll, new byte[4] { 1, 0, 0, 0 }, null);
    byte[] buffer = new byte[24];
    Action<IAsyncResult> OnReceive = null;
    OnReceive = (ar) =>
    {
        Console.WriteLine(
            "{0}\t{1}:{2}\t===>\t{3}:{4}"
            , buffer.Skip(9).First().ToProtocolString()
            , new IPAddress(BitConverter.ToUInt32(buffer, 12)).ToString()
            , ((ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(buffer, 20))).ToString()
            , new IPAddress(BitConverter.ToUInt32(buffer, 16)).ToString()
            , ((ushort)IPAddress.NetworkToHostOrder(BitConverter.ToInt16(buffer, 22))).ToString());
        buffer = new byte[24];
        sck.BeginReceive(buffer, 0, 24, SocketFlags.None,
            new AsyncCallback(OnReceive), null);
    };

    sck.BeginReceive(buffer, 0, buffer.Length, SocketFlags.None,
            new AsyncCallback(OnReceive), null);
}

public static string ToProtocolString(this byte b)
{
    switch (b)
    {
        case 1: return "ICMP";
        case 6: return "TCP";
        case 17: return "UDP";
        default: return "#" + b.ToString();
    }
}

Answer 1

As BugFinder mentioned below your question: It is not as simple as finding the IP address to know what website a user is visiting. A single IP address can host multiple websites and there is no telling what website it is the one the user of the computer is visiting (unless you use a proxy, monitor the web requests or something like that).

In case knowing the host name is enough: You could use the DNS object in C#. For example:

static void Main(string[] args) { string ip = "8.8.8.8"; Console.WriteLine(Dns.GetHostEntry(ip).HostName); //prints the host name Console.ReadKey(); }

Will give the following output in the console:

google-public-dns-a.google.com