Reconfiguring a network from static IP addressing to DHCP is a chore no system administrator wants to do, but now there's help.
Companies grow over time, and their networks have to grow along with them. This means that the static IP addressing that was used when the network was small will no longer practical once the systems number more than a few dozen. Unfortunately, changing machines from static to dynamic addressing usually means visiting each machine, logging on as a local administrator, and clicking through numerous properties sheets to reconfigure TCP/IP settings for network adapters.
However, there's an easier way. The VBScript in this hack uses Registry writes to change the TCP/IP settings on a machine from static IP to DHCP.
Type the script into Notepad (with Word Wrap disabled) and save it with a .vbs extension as Static2DHCP.vbs:
'All variables declared
Option Explicit
Dim oWSHShell
Dim sNIC, sMan
Dim iCount
Set oWSHShell = WScript.CreateObject("WScript.Shell")
' Set the DCHP service to autostart
oWSHShell.RegWrite "HKLM\SYSTEM\CurrentControlSet\Services\DHCP\Start", 2
' Get Network card
On Error Resume Next
iCount = 1
Do
sNIC = oWSHShell.RegRead("HKLM\SOFTWARE\Microsoft\Windows NT\ " & _
"CurrentVersion\NetworkCards\" & iCount & "\ServiceName")
sMan = oWSHShell.RegRead("HKLM\SOFTWARE\Microsoft\Windows NT\ " & _
"CurrentVersion\NetworkCards\" & iCount & "\Manufacturer")
' Skip the Async and NDIS services
If sMan <> "Microsoft" And Err.Number = 0 Then
Call SetNIC
End If
iCount = iCount + 1
Loop Until Err.Number <> 0
' Clear the error
Err.Clear
' End of Script
Sub SetNIC
Dim iTest
' Set the NIC service to use DHCP
sNIC = "HKLM\SYSTEM\CurrentControlSet\Services\" & sNIC &"\Parameters\TCPIP\"
iTest = oWSHShell.RegRead(sNIC & "EnableDHCP")
If iTest = 0 Then
oWSHShell.RegWrite sNIC & "EnableDHCP", 1, "REG_DWORD"
oWSHShell.RegWrite sNIC & "IPAddress", "0.0.0.0", "REG_MULTI_SZ"
oWSHShell.RegWrite sNIC & "SubnetMask", "0.0.0.0", "REG_MULTI_SZ"
End If
End Sub
To run this hack, call the Static2DHCP.vbs script from a logon script and use Group Policy to assign this logon script to users' machines. When a user next logs on to his machine, the machine's TCP/IP settings will be changed from static to dynamic addressing. To lease an address from the DHCP server, the user's machine needs to be rebooted, so you could also send out a message asking all users to reboot their machines using the method in [Hack #35] or some other approach. If you like, the logon script could also be combined with the SU utility from the Windows 2000 Server Resource Kit to perform a hands-off migration from static to dynamic addressing.
?Rod Trent
 | Windows Server Hack |
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