RSS

Monthly Archives: October 2012

Remotely disable firewall

If you are on a network and you are required to perform some network operations on that particular PC that requires you to drop the firewall temporarily, and you can’t get to the PC or it is too far away for you to travel to, you can remotely disable the firewall using the cool tools in the PSTOOLS utilities – available from the Microsoft web site.

To disable the firewall, perform the following:

  1. Open up a command prompt on your administrator PC / server
  2. Type in the following: psexec \\machine -u username -p password cmd
  3. Once connected type: netsh firewall set opmode mode = disable. The output should just be ‘ok’

You have now successfully disabled the firewall and you can perform the tasks that you need to. Remember to enable the firewall when you have finished.

Advertisements
 
Leave a comment

Posted by on October 29, 2012 in Firewall

 

Failed to join domain

I was setting up a new Hyper-V Core server with 3 network cards – 2 x LAN and 1 x WAN. I configured all cards with static IP Addresses. But when I attempted to join the domain, I received a very unhelpful error message:

Failed to join domain

And that’s it! No event log, nothing! Great. Now where do I go?

After searching all the corners of the internet, I found a solution. The problem was in the way the Hyper-V box ordered the network cards. It made the WAN card the first in the queue, so of course, when I attempted to connect it to the domain, it was going out into the Internet to find our domain. Doh!

To change the “order” of the network cards, you need to change the “Interface Metric”. In a normal Windows GUI, you can change each NIC interface metric by going into the properties of the NIC’s IP address, choosing advanced, and then manually changing the metric that way. NOTE: lower numbered metrics go first – but don’t choose ‘0’ as this signals an automatic metric which will put you back to where you are now. After you have changed the values, reboot for good measure.

But, if you have a server core machine without a GUI, then you need to perform some command line work.

Open a command prompt and do the following:

To display all of the adapters in the computer with their current IP addresses to determine the correct adapter name, type the following command:

netsh interface ip show config

To change to a static address, type the following command:

netsh interface ip set address “Local Area Connection” static ipaddr subnetmask gateway metric

For example, I need to change my Local Area Connection #7 to a metric of 5, I would do this:

netsh interface ip set address “Local Area Connection 7” static 172.16.1.10 255.255.0.0 172.16.1.1 5

And after a reboot, you will be able to join your server / PC to the domain without a problem.

 

Hidden or phantom network adapters

After converting a server from a physical machine to a virtual machine, my network adapters did not find the network. A message appeared like this:

The IP address you have entered for this network adapter is already assigned to another adapter “<network card name>”. “<network card name>” is hidden from the Network Connections folder because it is not physically in the computer. If the same address is assigned to both adapters and they both become active,
only one of them will use this address. This may result in incorrect system configuration. Do you want to enter a different IP address for this adapter in the list of IP addresses in the Advanced dialog box? Yes/No

What the???

I thought that the NIC was hidden so I opened device manager and selected “Show hidden devices” from the menu. I expanded the network cards section but I could still not see the phantom network cards.

After a quick search on Google, I found a solution. Do the following:

  • Open a command prompt
  • Type the following: set DEVMGR_SHOW_NONPRESENT_DEVICES=1
  • Press enter
  • Type the following: devmgmt.msc

Your mystery network adapters will now be visible so you can right click and uninstall them.

 
 

Error (2916) VMM is unable to complete the request. The connection to the agent was lost.

This error message appeared when I built a new HyperV 2008 R2 server and a System Center Virtual Machine Manager server when I attempt to convert a physical server to a VM:

Error (2916) VMM is unable to complete the request. The connection to the agent <server name> was lost.

The easiest way to correct this error is to perform the following on the HyperV server:

  1. In the open command prompt, type the following: winrm quickconfig
  2. When prompted, enter Y for the default answer

You should now be able to add your physical server.