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Resolving Host Names:

For various security reasons, there are going to be times when you need to find the Host Name for a specific IP Address. The following is a an ASP script that you can use to print out a DNS. This script will create a temporary .TXT file and then print out the report onto the client's web page.

If you are doing your own access logs for your web site, you should make modifications to this script and add it to your logging routines, in the SESSION_ONSTART event of your global.asa file.

This code must be run on a Windows 2000 or Windows NT Server to work properly. It creates an object from the Windows Scripting Host object model. You can download the latest version of Windows Scripting from Microsoft.com:

<%@ Language="VBScript" %> <% Option Explicit %> <% '******** 'Here's the Function you'll be using to find the Host Name-***** 'Function ResolveIP(strFindIP), call with an IP address****** 'Returns a Host Name *************** '***************************************** Function ResolveIP(strFindIP) 'First create your Shell, so you can run lookup from the command line of the server Set objScriptShell = Server.CreateObject("Wscript.Shell") 'Now call ResolveIP --> only works for Win2K and NT 'then the results will be put in a temp file -- change the .txt file name to whatever you want 'I have it looking in a dResolveIP folder, but you can change that objScriptShell.Run "%ComSpec% /c nslookup" & strFindIP _ & "> " & Server.MapPath("dResolveIP") & "\temp.txt", 0, True 'Open the temp Text File and Read out the strTemp2 set objFSO = Server.Createobject("Scripting.FileSystemObject") Set objTS = objFSO.OpenTextFile(Server.MapPath("dResolveIP") & "\temp.txt") strTemp = Null strTemp2 = Null i = 0 Do While Not objTS.AtEndofStream strTemp2 = Trim(objTS.Readline) If i > 2 Then ' DNS Info shouldn't be shown strTemp = strTemp & strTemp2 & "<BR/>" End If i = (i + 1) Loop 'now clean up your memory and get rid of the temp file objTS.Close objFSO.DeleteFile Server.MapPath("dResolveIP") & "\temp.txt" Set objFSO = Nothing ResolveIP = strTemp End Function '***************************************** 'End of ResolveIP function***************************************** '***************************************** '***************************************** 'Now get the IP Address you're going to be lookin up***************************************** '***************************************** dim strLookup, strPostGet,objScriptShell,objFSO, strReturn If Request.Form("frmLookup") = "" Then 'REMOTE_ADDR gets the client's IP strLookup = Request.ServerVariables("REMOTE_ADDR") Else 'if a new IP has been entered, look that one up strLookup = Request.Form("frmLookup") End If %> <html> <body> <form Method="POST" Name="frmInterface"> IP Address: <input type="text" name="frmLookup" ID="frmLookup" value="<%=strLookup%>"> <input type="button" name="bSub" ID="bSub" value="Resolve IP Address" onClick="document.frmInterface.submit()"> </form> <% '***************************************** 'Now write out the information '***************************************** '***************************************** strPostGet = uCase(Request.ServerVariables("REQUEST_METHOD")) If strPostGet = "POST" Then 'use the submitted IP address strReturn = ResolveIP(strLookup) If strReturn <> "" Then Response.Write strReturn Else 'else the function call failed/timed out/etc. Response.Write "Could Not Resolve DNS For " & strLookup & "<BR/>" End If End If %> </body> </html>

Related Links: Run a Command Line in ASP | Get IP Addresses in ASP

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