C# 3.0 Cookbook, 3rd Edition

16.8. Use Sockets to Scan the Ports on a Machine

Problem

You want to determine the open ports on a machine to see where the security risks are.

Solution

Use the CheapoPortScanner class constructed for your use; its code is shown in Example 16-5. CheapoPortScanner uses the Socket class to attempt to open a socket and connect to an address on a given port. The OpenPortFound event is available for a callback when an open port is found in the range supplied to the CheapoPortScanner constructor or in the default range (1 to 65535). By default, CheapoPortScanner will scan the local machine.

Example 16-5. CheapoPortScanner class

class CheapoPortScanner
{
    #region Private consts and members
    const int PORT_MIN_VALUE = 1;
    const int PORT_MAX_VALUE = 65535;

    private int _minPort = PORT_MIN_VALUE;
    private int _maxPort = PORT_MAX_VALUE;
    private List<int> _openPorts = null;
    private List<int> _closedPorts = null;
    private string _host = "127.0.0.1"; // localhost
    #endregion

    #region Event
    public class OpenPortEventArgs : EventArgs
    {
    int _portNum;
    public OpenPortEventArgs(int portNum) : base( )
    {
        _portNum = portNum;
    }

    public int PortNum
    {
    get { return _portNum; }
    }
}

public delegate void OpenPortFoundEventHandler(object sender, OpenPortEventArgs args);
public event OpenPortFoundEventHandler OpenPortFound;
#endregion // Event

#region CTORs & Init code
public Cheapo PortScanner( )
{
    // Defaults are already set for ports and localhost SetupLists( ); } public CheapoPortScanner(string host, int minPort, int maxPort) ...