关于如何获取网吧IP的问题。

我写了个小东东，帮助捕获指定网卡的数据传输。我在家里和公司的机子上装了都能用。可是有朋友拿到网吧用，就不能用了。是不是网吧的机子有什么特殊的设置？
如果是动态分配，但也应该可以检测出来嘛。有一家网吧显示IP为：0.0.0.61 ，但一点开始绑定，就弹出 "在其上下文中，请求的地址无效"的错误提示。
哪位大侠能帮助解释一下。如何解决这个问题。谢谢。
代码如下：
获取IP列表：
                IPHostEntry HosyEntry = Dns.GetHostEntry((Dns.GetHostName()));
                if (HosyEntry.AddressList.Length > 0)
                {
                    int i = 1;
                    foreach (IPAddress ip in HosyEntry.AddressList)
                    {
                        sIPList.Add(ip.ToString());
                        
                        this.cbox_IP.Items.Add(ip.ToString());
                        i++;
                    }
                }绑定IP：
               if (!bContinueCapturing)
                {
                    //Start capturing the packets...
                    //btnStart.Text = "&Stop";                    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(CaptureIPAddress), 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);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "小工具", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }