DNS NsLookup in an ASP page

The Domain Name System (DNS) is the method by which Internet addresses in mnemonic form - such as www.activexperts.com - are converted into the equivalent numeric IP address such as 212.97.55.136. To the user and application process this translation is a service provided either by the local host or from a remote host via the Internet. The DNS server (or resolver) may communicate with other Internet DNS servers if it cannot translate the address itself.
DNS names are constructed hierarchically. The highest level of the hierarchy is the last component or label of the DNS address. Labels can be up to 63 characters long and are not case sensitive. A maximum length of 255 characters is allowed. Labels must start with a letter and can only consist of letters, digits and hyphens.

Nslookup is a popular program for UNIX, LINUX and Windows to query Internet domain name servers. It allows the user to query name servers for information about various hosts and domains or to print a list of hosts in a domain.

ActiveSocket provides an easy-to-use development/scripting interface to use the same operations as NsLookup, through the DnsServer class. By using ActiveSocket, you can very easily create or enhance Windows applications/scripts with DNS lookup features.

ActiveSocket features the following: ICMP, HTTP and HTTPs (supporting for proxy servers, secure web sites), FTP, DNS, Telnet, NTP time protocol, RSH remote shell script interface, SNMP (Simple Network Management Protcol), SNMP Traps, Sockets, WOL (Wake-On-LAN), and more.

Step 1: Download and install ActiveSocket

Download ActiveSocket from the ActiveXperts Download Site and start the installation. The installation guides you through the installation process.

Step 2: Create a new Web Site

First, create a new directory on the IIS Server's file system. This directory will hold the ASP later on.

From the 'Start menu', click on 'Administrative Tools' and click on 'Internet Information Services (IIS) Manager'. Right-click on the 'Web Sites' container and choose 'New->Web Site':

(Click on the picture to enlarge)

The 'Web Site Creation Wizard' is shown, guiding you thorugh the process of creating a new web site. Provide all necessary information:

Description - a friendly description of the new site;
IP / Port / Host Header - choose your preferred way to distinguish between other web sites on the server;
Path - select the directory that will store the ASP file(s);
Web Site Access Permissions - in the Web Site Access Permissions dialog, enable 'Read' and 'Run scripts (such as ASP)';

You're now able to write an ASP script to use IP protocols with ActiveSocket.

Step 3: Create the from

First of all we need to create a form in HTML to get the login information for the ftp server. All we actually need is:

The log-in name.
The password.
The server we want to connect to.
And the directory we're going to list.

In this sample all we're going to do is create a ASP file that is able to list files and directories in a directory. Using ActiveSocket it is easy to create a page that makes you able to upload and to download files.

You can create a form that looks like this:

(Click on the picture to enlarge)

Step 4: Making it happen

You can list files using ActiveSocket ftp in 3 steps.

Creating an object to use ActiveSocket
Connect to the server
List the files

Creating the object
Now that we have all the information we need, we need to create an object witch supports communicating through ActiveSocket. To do this we only need one line of code:

   Set objFtp = Server.CreateObject( "ActiveXperts.FtpServer" )

Connecting to the server
To connect to the server we're using the ActiveSocket method "Connect".

 objFtp.connect request("server"), request("username"), request("password")

This makes a code look like this:

if request("submitbutton") <> "" then

  dim objFiles

  ' create the object
  Set objFtp = Server.CreateObject( "ActiveXperts.FtpServer" )
	
  objFtp.clear
	
  ' set the logfile
  objFtp.logfile = request("logfile")
  
  ' connect
  objFtp.connect request("server"), request("username"), request("password")
  objFtp.ChangeDir request("directory")
	
else
  ' do nothing
end if

Listing the files
If the previous actions have been succesfully executed, we can list the files. To list these files we're using two ActiveSocket methods:

We're using "FindFirstFile" to find the first file.
We're using "FindNextFile" to move on to the next.

When we know what the first file is we're starting a loop. If one file is listed, FindNextFile is used to move on to the next. If there is no more file, the software will return an error. Thats why we created the following code:


  ' find the first file
  if objFtp.LastError <> 0 then
    response.write("Connection failed..<br>")
  else
    set objFiles = objFtp.FindFirstFile()
  end if
	
  ' list the files
  if objFtp.LastError <> 0 then
    response.write("<tr><td>Sorry.. Failed to list the files..</td></tr>")
  else
    getfiles
  end if	


sub getfiles

  'show the contents in a table
  response.write ("Files in directory " & request("directory") & " :")	
  response.write ("<table>")
	
  'the software will return an error if there is no more file to display, so:
  do while objFtp.LastError = 0
     response.write("<tr>")
     response.write("<td>")
		 
     'display folders
     if objFiles.IsDirectory = 0 then
       response.write "File:"
     else
       response.write "Directory:"
     end if
	   
     response.write("</td>")
     response.write("<td class=files>")		 		 		 		 
	   
     'display the names
     response.write(objFiles.name)
		 
     response.write("</td>")
     response.write("</tr>")
		 
     'find the next file; continue the loop
     set objFiles = objFtp.FindNextFile 
  loop

  response.write "</table>"
	
end sub

The ActiveSocket tool is a Network Communications ActiveX software component (SDK). This control supports SNMP, SMTP, POP3, Telnet, TCP, NTP, RSH, HTTP, HTTPs, FTP, DNS, ICMP and more, and can be used by any Windows development platform, including Visual Basic .NET, Visual CSharp .NET, ASP .NET (VB,CS), ASP, Visual Basic, Visual Studio/Visual C++, Delphi, PHP, ColdFusion, HTML, VBScript and any other ActiveX/COM compliant platform. The ActiveSocket Toolkit is an ActiveXperts Software B.V. Product.