使用System.Net命名空间对网络进行操作

利用IPHostEntry类的GetHostByName方法，可以根据机器名来找到该机器的IP地址。

using System.Net;

    protected void mybutton_Click(object sender, EventArgs e)
    {
        IPHostEntry hostInfo = Dns.GetHostByName(txtDomain.Text);
        showmsg.Text = hostInfo.HostName;
    }

    <form id="form1" runat="server">
    <div>
        <asp:Label ID="showmsg" runat="server" Width="229px"></asp:Label><br />
        请输入机器名：<asp:TextBox ID="txtDomain" runat="server"></asp:TextBox>
        <asp:Button ID="mybutton" runat="server" OnClick="mybutton_Click" Text="确定" /></div>
    </form>

利用IPHostEntry类的GetHostByAddress方法，可以根据IP地址来找到该机器名。

using System.Net;

        protected void mybutton_Click(object sender, EventArgs e)
    {
        IPHostEntry hostInfo = Dns.GetHostByAddress(txtDomain.Text);
        showmsg.Text = hostInfo.HostName;
    }

    <form id="form1" runat="server">
    <div>
        <asp:Label ID="showmsg" runat="server" Width="229px"></asp:Label><br />
        请输入机器名：<asp:TextBox ID="txtDomain" runat="server"></asp:TextBox>
        <asp:Button ID="mybutton" runat="server" OnClick="mybutton_Click" Text="确定" /></div>
    </form>

检测服务器开放的端口信息

using System.Net.Sockets;
using System.IO;

protected void Page_Load(object sender, EventArgs e)
    {
        int[] arrPort = new int[5] { 21, 23, 25, 110, 1433 };
        string strServer = "localhost";
        string strService, strResponse, strShow;
        int intport;
        for (int i = 0; i < arrPort.Length; i++)
        {
            intport = arrPort[i];
            switch (intport)
            {
                case 21:
                    strService = "FTP服务";
                    break;
                case 23:
                    strService = "Telnet服务";
                    break;
                case 25:
                    strService = "SMTP服务";
                    break;
                case 110:
                    strService = "POP3服务";
                    break;
                default:
                    strService = "无法知道";
                    break;
            }
            if ((strResponse = TcpConnect(strServer, intport)) != "没有开放")
            {
                strShow = "<b>" + intport.ToString() + "</b>端口: " +
                    strResponse + "(<font color=red>" + strService + "</font>)";
            }
            else
            {
                strShow = "<b>" + intport.ToString() + "</b>端口没有开放: " 
                    + "(<font color=red>" + strService + "</font>)";
            }
            pnlServer.Controls.Add(new LiteralControl(strShow + "<p>"));
        }
    }

    public string TcpConnect(string strServer, int intPort)
    {
        string strResult;
        TcpClient tcpc = new TcpClient();
        try
        {
            tcpc.Connect(strServer, intPort);
            Stream s = tcpc.GetStream();
            StreamReader sr = new StreamReader(s, System.Text.Encoding.Default);
            strResult = sr.ReadLine();
        }
        catch (Exception ee)
        {
            strResult = "没有开放";
        }
        finally
        {
            tcpc.Close();
        }
        return strResult;            
    }

    <form id="form1" runat="server">
    <div>
        使用Socket探测主机信息<br />
        <asp:Panel ID="pnlServer" runat="server" Height="254px" Width="400px">
        </asp:Panel>
    </div>
    </form>