26 May 2022

Disable IP autoconfiguration

I ran into this last week when I was helping someone “fix” their server. They couldn’t reach, or ping, their host, and when running an “ipconfig /all” command it was returning that the machine’s IP was ‘duplicate’.

Worth Noting: So sometimes when a server reports that its’ IP is a ‘duplicate’ it can be a DHCP mishap. It can happen when a server is assigned a static IP that is within a DHCP pool, and because there was no reservation, DHCP hands the IP out to some other machine. Thus two machines are trying to use the same, duplicate, IP address. When that happens you’ll need to resolve it by creating an IP reservation for the “correct” machine, and then releasing the IP from the machine that “incorrectly” took the IP from the pool so it can be assigned a new IP.

The machine I was fixing lived in a subnet that did not use DHCP and only had machines that were statically assigned their IPs in it. So the possible resolution mentioned above did not fit my scenario. So, what could it be? Well if you have a static IP set, and the DHCP service is enabled, Windows likes to give you an address on the 169.x.x.x network. Which just breaks the ip traffic on your server. Here’s how to fix it…

Step 1.

Open a command prompt

Step 2. Enter

"ipconfig /all"

Find what your system’s preferred IP is and if autoconfiguration is enabled, and the name of the interface that they are on. You will need this for the next step.

Step 3. Enter

netsh interface ipv4 show interface

Find the index number that is assigned to the interface you identified in the step above, you will need it in the next step.

Step 4.

Run the command below, but replace ’69’ with the index number that you identified in the step above.

netsh interface ipv4 set interface 69 dadtransmits=0 store=persistent

Step 5. Enter


Disable the DHCP Client service. If you ever revert from a static IP back to a DHCP IP, you will need to re-enable this service and set it back to automatic.

Step 6.

Restart your computer.
After your system reboots, its static IP should now be the correct IP you had configured on it, and your IP traffic to/from it should be back to normal.

Congratulations, autoconfiguration has been disabled.

26 May 2020

My Ubiquiti Network

Ubiquiti makes some interesting gear and they are quite well known for their disrupting the status quo by offering top-notch grade network and wifi devices. Their gear ranges from prosumer to enterprise-grade. Depending on how far down the rabbit hole you go, it can become a bit of an expensive eco-system that you are buying into. On the plus side, if you ever decide to leave any Ubiquiti, it shouldn’t be hard to resell the gear as they have a large community of followers.

I was leaving one job and starting another and decided that it was time to upgrade my home network to allow for some more diverse home-lab options. I decided to jump on the Ubiquiti bandwagon and set-up on their Unifi product line. Being new to Ubiquiti and Unifi I have a lot to learn!

I’m starting off my Unifi environment with a Ubiquiti Dream Machine (UDM), a Unifi 8-port POE switch (US-8-60W), and a Unifi AP (UAP-AC-Lite). I’m starting small. 😂 But who knows how large it’ll grow!

Here are some things I’ve setup in my Unifi environment….

23 January 2020

Migrating NPS Configuration

I recently had to migrate some services from an old Windows 2008 server to Windows 2016. One of those services was a Network Policy Server (NPS) service, which is used by RADIUS to authenticate users into some more secure resources.

I was kind of dreading the task, as I had no recollection of how I had configured it, some five or more years ago. My initial search on the subject landed me on this Microsoft documentation site, which was very informative. Luckily, the task of exporting and migrating your NPS configuration to import onto another server is quite simple. It can all be done with a few lines at a command prompt and a single XML file.

In Windows 2008 or 2008 R2, you use ‘netsh’.
In Windows 2012 and above, you can use PowerShell or ‘netsh’.

Both methods are equally simple, it really just comes down to which version of Windows Server are you migrating from.

Export and Import the NPS configuration by using Netsh

Log into to your source NPS server with your Administrative credentials.

Open a ‘Command Prompt’ as an administrator, type netsh, and then hit Enter.

At the netsh prompt, type nps, and then hit Enter.

At the netsh nps prompt, type export filename="<path>\<filename>.xml" exportPSK=YES
Update <path> with the folder location where you want to save your configuraation file. The path can be relative or absolute, or it can be a UNC path.
Update <filename> with what you want to name your xml file.

After you press Enter, you’ll see a message showing whether the export was successful or not.

Copy the xml file you created to the destination NPS server.

Open a ‘Command Prompt’ as an administrator on the destinantion NPS. Type the following command, then hit Enter. netsh nps import filename="<path>\<file>.xml"
A message will appear to show whether the import was successful or not.

Export and Import the NPS configuration by using Windows PowerShell

Log into to your source NPS server with your Administrative credentials.

Open a ‘PowerShell window’ as an administrator, type the following command, and then hit Enter. Export-NpsConfiguration –Path c:\NPSconfig.xml

There is no message after the command completes, but if you check your path location, you should see your xml file.

After you have exported the NPS configuration to a file, copy the file to the destination NPS server. I’m copying mine to the root of the c:\ so it’s easy to find.

Open a ‘PowerShell window’ as an administrator on the destination server. Type the following command, and then hit Enter, to import your configuration.

Import-NpsConfiguration -Path "c:\NPSconfig.xml"