Month: May 2011

Windows : Uninstalling a hotfix from the Recovery Console

Use the following steps to remove a hotfix from a Windows Operating system whilst running from the recovery console:
1) Ensure you have a record of installed hotfixes/patches (the KB numbers are the important bit!) that you wish to remove.
2) Boot to the recovery console
3) Check for installed patches/hotfixes; dir $*
4) Change to the directory of the hotfix/patch you wish to remove, change text in red to match the KB number: CHDIR $NTUninstallKBXXXXXXXXX
5) To uninstall execute the spunist.txt file; BATCH spuninst.txt

DNS Scavenging : Existing Environment

Many peopple are wary of the impact of enabling DNS scavenging on an existing environment. Th following command/script will allow you to identify all of the records that will be deleted if you were to enable scavenging.

First execute the command: dnscmd SRV /enumrecords zone @ /continue > DNS_Records.txt

Save the text below into a file names DNSScavenge.vbs, then execute the command: cscript.exe /nologo DNSScavengeTest.vbs DNS_Records.txt >> DNS.csv

‘———————————————————————————————-

Const ForReading = 1
Const ForWriting = 2
Const ForAppending = 8
Const AGING_TOKEN = “[Aging:”

Const DDNS_NO_REFRESH = 7        ‘ The dynamic DNS no refresh period, where an update classified as a refresh will not be accepted for the record
Const DDNS_REFRESH = 7            ‘ The dynamic DNS refresh period, during which an update will be accepted for the record
Const GMT_OFFSET = +10            ‘ Offset in hours to adjust the resultant times based on the current GMT timezone

Set objFSO = CreateObject(“Scripting.FileSystemObject”)

If WScript.Arguments.Count = 1 Then
    strFileName = WScript.Arguments(0)
Else
    wscript.echo “Specify a filename containing the output of dnscmd. eg DNSScavengeTest.vbs DNS_Records.txt”
    wscript.quit(2)
End If

If Not objFSO.FileExists(strFileName) Then
    WScript.Echo “Error: ” & strFileName & ” file not found.”
    wscript.quit(2)
End If

Set objTextStream = objFSO.OpenTextFile(strFileName, ForReading)
strZoneRecords = objTextStream.ReadAll
WScript.Echo “name,timestamp,wouldBeScavengedIn”

For Each strLine in Split(strZoneRecords, vbCRLF)
    intStart = InStr(1, strLine, AGING_TOKEN, 1)
    If intStart 0 Then                                ‘ Does this line contain an aging value?
        intStart = intStart + Len(AGING_TOKEN)
        intEnd = InStr(intStart, strLine, “]”)
        If intEnd 0 Then intLength = intEnd – intStart
        strHost = Left(strLine, InStr(strLine, ” “)-1)                ‘ Yes, extract the host

        intAging = Mid(strLine, intStart, intLength)                ‘ Extract the aging value, expressed in the decimal number of hours since 01/01/1601
       
        dtmDate = DateAdd(“h”, intAging, “01/01/1601 00:00:00 AM”)        ‘ Convert to a date timestamp
        dtmDate = DateAdd(“h”, GMT_OFFSET, dtmDate)                ‘ Add the current GMT offset

        intDiff = DateDiff(“h”, dtmDate, Now)                    ‘ The difference between now and the timestampe
        intHourDiff = intDiff – ((DDNS_NO_REFRESH * 24) + (DDNS_REFRESH * 24))    ‘ Based on the dynamic DNS no-refresh and refresh periods combined
        If intHourDiff > 0 Then                            ‘ Is this a positive number, indicating the record will be scavenged
            intDay = CInt(intHourDiff / 24)                    ‘ Yes, convert to a number of days for output
            WScript.Echo strHost & “, ” & dtmDate & “, ” & intDay + DDNS_NO_REFRESH + DDNS_REFRESH    ‘This record would be scavenged
        Else
            WScript.Echo “*” & strHost & “, ” & dtmDate            ‘ This record won’t be scavenged
            intDay = 0
        End If
    End If
Next

Windows 2003 : Certificate Services – Repair CA Virtual Directories

Today I had an issue with a subordinate CA, its AIA/CDP/CRL HTTP locations were showing as down. On further investigation I noted that the virtual directories for the CA had in fact vanished out of IIS. The files themselves for the CA were present in the CertEnroll directory, so it was an IIS issue.

To restore the Virtual Directory configuration use the following command: certutil -vroot