Archive | Azure

Hidden or UnDocumented Network Security Group (NSG) default rule in Azure (DNS)

I have been working to get a Citrix Netscaler up and running in Azure. It has not been easy, as all the documentation is for ASM.

Our network configuration has IPSec tunnels going from OnPrem to Azure, and I have created two SubNets in Azure – a DMZ and a LAN. The DMZ has the following Outbound NSG rules (ACLs) for the NetScaler to talk to a LAN SubNet.

Get-AzureRmNetworkSecurityGroup -ResourceGroupName ResourceGroupName | Select SecurityRules -ExpandProperty SecurityRules | where {$_.Direction -eq "Outbound"} | Select Priority,Name,Protocol,SourceAddressPrefix,SourcePortRange,DestinationAddressPrefix,DestinationPortRange,Access | Sort-Object Priority|ft -AutoSize

DMZ Netscaler = 192.10.8.100
LAN DC = 192.10.9.10

Priority Name                           Protocol SourceAddressPrefix SourcePortRange DestinationAddressPrefix DestinationPortRange Access
-------- ----                           -------- ------------------- --------------- ------------------------ -------------------- ------
     101 LDAP_From_NSIP                 TCP      192.10.8.100        *               192.10.9.10              389                  Allow
     102 DNSUDP_From_NSIP               Udp      192.10.8.100        *               192.10.9.10              53                   Allow
     103 DNSTCP_From_NSIP               TCP      192.10.8.100        *               192.10.9.10              53                   Allow
     104 RADIUS_From_NSIP               Udp      192.10.8.100        *               192.10.9.10              1812                 Allow
    4095 Subnet_To_Internet             *        *                   *               Internet                 *                    Allow
    4096 Deny_All_Outbound              *        *                   *               *                        *                    Deny

As you can see, I add a DenyAll at the end even though there is one in the DefaultSecurityRules. I just like to see it there. I find it comforting.

I found that from then Netscaler, I could do a DNS lookup against my OnPrem DC. How can that be?
Rule 101-104 are only for the Azure LAN DC. Then I DenyAll with 4096.
How can the Netscaler look up via the OnPrem DC?
I am DenyingAll!
I was pulling my hair out.

I realized that I had never changed my DNS server settings for my Virtual Network in Azure (I needed it to join the domain for the local DC when I build it!). I forgot to switch it the local Azure LAN DC.

Therefore, even though there is a DenyAll in my NSG rules, there has to be a Hidden or UnDocumented rule that allows queries to the DNS servers listed in the Virtual Network settings.

As soon as I changed the DNS server settings to the local Azure LAN DC, I could no longer query the OnPrem DC.

I understand why it is there. If you put in a DenyAll (like I did), Windows Servers will panic. They do not like it if they can’t access a DNS server.

I think Azure needs to move the DNS server settings down to the SubNet level, since all VMs are DHCP (Reservations). If they do this, a DMZ and LAN can use different DNS server settings, or none at all.

Just something I ran across today.

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PowerShell to delete blobs in Azure

I was trying to delete a VHD in Azure via PowerShell, and I couldn’t find a good solution. Here is how you delete a blob in Azure

$resourceGroupName="Default"
$storageAccountname="StorageAccount01"
$storageAccountKey = (Get-AzureRmStorageAccountKey -ResourceGroupName $resourceGroupName -Name $storageAccountname).Key1
$storageContext = New-AzureStorageContext -StorageAccountName $storageAccountName -StorageAccountKey $storageAccountKey
$containerName="vhds"
 
# List blobs
Get-AzureStorageBlob -Container $containerName -Context $storageContext
 
# Remove Blob
Get-AzureStorageBlob -Container $containerName -Context $storageContext -Blob "SystemDisk01.vhd" | Remove-AzureStorageBlob
Get-AzureStorageBlob -Container $containerName -Context $storageContext -Blob "DataDisk01.vhd" Remove-AzureStorageBlob

Hope that helps someone.

My Azure ASM to ARM script

This is the “script” I used to move our older classic environment VMs to the new Azure Resource Manager.
It it is not a function – I wanted to step through the process and make sure all was well at the different points in the script.
The script assumes that there is only one Data disk (or none), and that you have created your availability set before hand.
I based most of the script off this.

I hope this helps some one.

Add-AzureAccount 
Login-AzureRmAccount 
$VMName="ASMVM01"
$ServiceName="ASMVM01_Service"
$SourceVMSize="Standard_A3"
$DestinationAvailabilitySet="AvailabilitySet01"
$PrivateIpAddress="192.168.1.10"
$ResourceGroupName="ResourceGroup01"
$DestinationNetworkName="Network01"
$DestinationNetworkSubnet="SubeNet01"
$Location="East US"
$OSType="Windows"
#$OSType="Linux"
[switch]$DataDisk=$false
$DatDiskSize=100
$SourceStorageAccountName="srcstorageaccount"
$DestinationStorageAccountName="dststorageaccount"

# ---- Edit above
#region Get Source Storage
$SourceStorageAccountKey=(Get-AzureStorageKey -StorageAccountName $SourceStorageAccountName).Primary
$SourceContext = New-AzureStorageContext -StorageAccountName $SourceStorageAccountName -StorageAccountKey $SourceStorageAccountKey
#endregion

#region Get Destination Storage
$DestinationAccountKey=(Get-AzureRmStorageAccountKey -ResourceGroupName $ResourceGroupName -Name $DestinationStorageAccountName).Key1
$DestinationContext = New-AzureStorageContext -StorageAccountName $DestinationStorageAccountName -StorageAccountKey $DestinationAccountKey
#endregion

#region Get SourceVM
$SourceVM = Get-AzureVm  -ServiceName $ServiceName -Name $VMName
if (! $SourceVM.Status -eq "StoppedDeallocated"){
"You need to sopt $SourceVM first"
return;
}
#endregion

#region Copy SystemDisk
$SourceSystemDisk=Get-AzureDisk | Where-Object { $_.AttachedTo.RoleName -eq "$VMName" } | where {$_.OS -eq $OSType}
$DestinationSystemDiskName="$($VMNAME)_SYSTEM.vhd"
write-host "Copying System Disk"
Write-Host "Start-AzureStorageBlobCopy -Context $SourceContext -AbsoluteUri $($SourceSystemDisk.MediaLink.AbsoluteUri) -DestContainer ""vhds"" -DestBlob $DestinationSystemDiskName -DestContext $DestinationContext -Verbose"
$SystemBlob = Start-AzureStorageBlobCopy -Context $SourceContext -AbsoluteUri $($SourceSystemDisk.MediaLink.AbsoluteUri) -DestContainer "vhds" -DestBlob $DestinationSystemDiskName -DestContext $DestinationContext -Verbose 
$SystemBlob | Get-AzureStorageBlobCopyState
While ($($SystemBlob | Get-AzureStorageBlobCopyState).Status -ne "Success"){
sleep 5
$BlobCopyStatus=$SystemBlob | Get-AzureStorageBlobCopyState
"$($($BlobCopyStatus).Status) ($($BlobCopyStatus).BytesCopied) of $($($BlobCopyStatus).TotalBytes) bytes)"
}
#endregion

#region Copy Data Disk
if ($DataDisk){
$SourceDataDisk=Get-AzureDisk | Where-Object { $_.AttachedTo.RoleName -eq "$VMName" } | where {! $_.OS}
$DestinationDataDiskName="$($VMNAME)_DATA01.vhd"
write-host "Copying Data disk"
Write-Host "Start-AzureStorageBlobCopy -Context $SourceContext -AbsoluteUri $($SourceDataDisk.MediaLink.AbsoluteUri) -DestContainer ""vhds"" -DestBlob $DestinationDataDiskName -DestContext $DestinationContext -Verbose"
$DataDiskBlob = Start-AzureStorageBlobCopy -Context $SourceContext -AbsoluteUri $($SourceDataDisk.MediaLink.AbsoluteUri) -DestContainer "vhds" -DestBlob $DestinationDataDiskName -DestContext $DestinationContext -Verbose 
$DataDiskBlob | Get-AzureStorageBlobCopyState
While ($($DataDiskBlob | Get-AzureStorageBlobCopyState).Status -ne "Success"){
sleep 5
$BlobCopyStatus=$DataDiskBlob | Get-AzureStorageBlobCopyState
"$($($BlobCopyStatus).Status) ($($BlobCopyStatus).BytesCopied) of $($($BlobCopyStatus).TotalBytes) bytes)"
}
}
#endregion

#region Build New VM
$DestinationVM = New-AzureRmVMConfig -vmName $vmName -vmSize $SourceVMSize -AvailabilitySetId $(Get-AzureRmAvailabilitySet -ResourceGroupName $ResourceGroupName -Name $DestinationAvailabilitySet).Id
$nicName="$($VMName)_NIC01"
$vnet = Get-AzureRmVirtualNetwork -Name $DestinationNetworkName -ResourceGroupName $ResourceGroupName 
$subnet = $vnet.Subnets | where {$_.Name -eq $DestinationNetworkSubnet}
$nic = New-AzureRmNetworkInterface -Name $nicName -ResourceGroupName $ResourceGroupName -Location $Location -SubnetId $Subnet.Id -PrivateIpAddress $PrivateIpAddress
$DestinationVM = Add-AzureRmVMNetworkInterface -VM $DestinationVM -Id $nic.Id 
$DestinationSystemDiskUri = "$($DestinationContext.BlobEndPoint)vhds/$DestinationSystemDiskName"
$DestinationDataDiskUri = "$($DestinationContext.BlobEndPoint)vhds/$DestinationDataDiskName"

If ($OSType -eq "Windows"){
$DestinationVM = Set-AzureRmVMOSDisk -VM $DestinationVM -Name $DestinationSystemDiskName -VhdUri $DestinationSystemDiskUri -Windows -CreateOption attach
if ($DataDisk){
$DestinationVM = Add-AzureRmVMDataDisk -VM $DestinationVM -Name $DestinationDataDiskName -VhdUri $DestinationDataDiskUri -CreateOption attach -DiskSizeInGB $DatDiskSize
}
}
If ($OSType -eq "Linux"){
$DestinationVM = Set-AzureRmVMOSDisk -VM $DestinationVM -Name $SourceSystemDisk -VhdUri $DestinationOSDiskUri -Linux -CreateOption attach
if ($DataDisk){
$DestinationVM = Add-AzureRmVMDataDisk -VM $DestinationVM -Name $DestinationDataDiskName -VhdUri $DestinationDataDiskUri -CreateOption attach -DiskSizeInGB $DatDiskSize
}
}
 
New-AzureRmVM -ResourceGroupName $resourceGroupName -Location $Location -VM $DestinationVM
#endregion

Azure: Failed to save configuration changes to local network gateway

Seems you can’t remove a subnet from a local network with the Azure portal. Error: “Failed to save configuration changes to local network gateway”

To get around this, I had to delete and recreate the local network via PowerShell. Obviously leave out the subnet you don’t want!

Get-AzureRmLocalNetworkGateway -Name "HomeOffice" -ResourceGroupName "WestUS"
$localNetworkGw=Get-AzureRmLocalNetworkGateway -Name "HomeOffice" -ResourceGroupName "WestUS"
$addressPrefixes ="192.168.0.0/24","192.168.1.0/24","192.168.2.0/24","192.168.4.0/24"
Set-AzureRmLocalNetworkGateway -LocalNetworkGateway $localNetworkGw -AddressPrefix $addressPrefixes -Verbose

PowerShell to download and install most recent Azure PowerShell cmdlets

This script will pull down the most recent Azure PowerShell cmdlets from github. This script assumes that Microsoft has not renamed the installer file, and the most recent is at the top.

JBM-INSTALL-AzurePowerShell{
((Invoke-WebRequest https://github.com/Azure/azure-powershell/releases).Links).href | where {$_ -like "https*azure-powershell*msi*"} | Select-Object -first 1| foreach {
Invoke-WebRequest $_ -OutFile "./$([System.IO.Path]::GetFileName($_))"
start-process "./$([System.IO.Path]::GetFileName($_))"
}
}

hope that helps someone.

PowerShell script to recreate Azure Network Security Groups (NSGs)

I developed a habit when I was working with ACLs on a Cisco ASA firewall. I would keep a master list for each ACL, and when I needed to make a change, I would remove the entire ACL from the device and then recreate it each time I made a modification. For example I would run the following, and keep adding new rules when needed.

clear configure access-list dmz_acl
access-list dmz_acl extended permit tcp host 1.1.1.1 object-group DCs eq 389
. . . .

Add one line, look at the logs and if traffic is still being blocked then modify and try again.

I wanted the ability to do the same thing with Azure Network Security Groups. I wrote a PowerShell script that would look at the NSGs, dump the settings, and would display the commands to recreate them. here is the script I wrote. I hope it helps some one.

function JBM-AZURE-GetNetworkSecurityGroupRules{
 param(
    [String]$Name ,
    [Switch]$ShowCommands
    )
$Groups=$(Get-AzureNetworkSecurityGroup -Detailed)
If(!$Name){
  Write-Host
  Write-host "Select the number of the NSG"
  $NSGNumb = $(Read-Host -prompt "$($(for($i=0;$i-le $Groups.Count-1;$i++){$AllGroups=$AllGroups+"$i $($Groups[$i].Name)`n"});$AllGroups)" )
  $Name=$Groups[$NSGNumb].Name
}

$NSG=$Groups | where {$_.Name -eq $Name}
If ($NSG){
    $InboundRules=$NSG.Rules | where {$_.Type -eq "Inbound"}
    $OutBoundRules=$NSG.Rules | where {$_.Type -eq "Outbound"}
    Write-Output ""
    Write-Output "Inbound Rules"
    Write-Output $InboundRules | FT
    Write-Output "Outbound Rules"
    Write-Output $OutBoundRules | FT
    if ($ShowCommands){
    Write-Output "New-AzureNetworkSecurityGroup -Name ""$($NSG.Name)"" -Location ""$($NSG.Location)"""
    Write-Output ""
    foreach ($Rule in $($InboundRules | where {$_.Priority -lt 65000})){
        write-Output "Get-AzureNetworkSecurityGroup -Name ""$($NSG.Name)"" | Set-AzureNetworkSecurityRule -Name ""$($Rule.Name)"" -Type ""$($Rule.Type)"" -Priority ""$($Rule.Priority)"" -Action ""$($Rule.Action)"" -SourceAddressPrefix ""$($Rule.SourceAddressPrefix)"" -SourcePortRange ""$($Rule.SourcePortRange)"" -DestinationAddressPrefix ""$($Rule.DestinationAddressPrefix)"" -DestinationPortRange ""$($Rule.DestinationPortRange)"" -Protocol ""$($Rule.Protocol)"""
        Write-Output ""
    }
    foreach ($Rule in $($OutBoundRules | where {$_.Priority -lt 65000})){
        write-Output "Get-AzureNetworkSecurityGroup -Name ""$($NSG.Name)"" | Set-AzureNetworkSecurityRule -Name ""$($Rule.Name)"" -Type ""$($Rule.Type)"" -Priority ""$($Rule.Priority)"" -Action ""$($Rule.Action)"" -SourceAddressPrefix ""$($Rule.SourceAddressPrefix)"" -SourcePortRange ""$($Rule.SourcePortRange)"" -DestinationAddressPrefix ""$($Rule.DestinationAddressPrefix)"" -DestinationPortRange ""$($Rule.DestinationPortRange)"" -Protocol ""$($Rule.Protocol)"""
        Write-Output ""
    }
    }
}
Else {
Write-Host "Can't find a NSG with that name"
}
}

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