NST and Virtual Machines

General Virtual Machine Questions

What Virtual Machines Will NST Run Under?

NST is currently known to run under:

• The VMware product line.
• VirtualBox

What are the Disadvantages of Running NST within a Virtual Machine?

• Performance will be less than running NST on bare metal.
• Wireless tools will not work as physical wireless adapters appear are typically virtualized as Ethernet NICs.

What are the Advantages of Running NST within a Virtual Machine?

• You can monitor the traffic on the machine without any cables or hardware.
• You can easily move your NST system to a different machine.

VirtualBox Frequently Asked Questions

Why is the load so high when running under VirtualBox?

If you run different Linux distributions under VirtualBox, you will notice that Fedora and NST distributions put a much higher load on the system than other distributions (such as Ubuntu). We are not completely sure as to why this occurs. Our current best guess is that the stock Fedora kernel is compiled with a 1000Hz clock whereas many other distributions (such as Ubuntu) come with a kernel running with a 100Hz clock. This order of magnitude different in the clock rates creates a significant load difference between the two kernels when running under VirtualBox.

Short of compiling your own custom kernel, we don't know a good solution to the problem. We have experimented with kernel boot options such as:

clocksource=acpi_pm divider=10 highres=off

Unfortunately, we the boot options we've tried so far have not seemed to address the issue. If you happen to know the answer to this question, we would appreciate it if you could share it with us.

Why can't I monitor all traffic on the virtual network adapter?

There are two likely reasons that can trigger this issue:

1. The network adapter must be up and enabled on the host system before a virtualized NST system will be able to see any traffic on the adapter. If this is the issue, you will need to enable the network adapter on the machine which hosts the virtual NST (outside of the NST system).

2. VirtualBox allows one to specify the "virtual hardware implementation" when configuring network adapters. We have seen the case where some "virtual hardware implementations" do not properly support promiscuous mode operation within the NST environment (in particular some of the E1000 adapters).

So, if you run across this condition, we recommend that you try a different "virtual hardware implementation" (the PCnet Fast-III implementation has worked for us).

How do I install the VirutalBox Guest Additions?

• Install the following packages that are necessary to build the kernel modules:

yum install gcc kernel-devel

• From the Devices menu of VirtualBox, click on the Install Guest Additions options. If things go well, a virtual CD will appear on your GNOME desktop.

• Open a terminal window and login as root (if you aren't already logged in as root).

• Copy the contents of the CD to a temporary directory, run the installation script, and then remove the temporary directory (NOTE: While VBOX* will probably work as shown below, it is recommended to replace it with the actual directory name):

cp -rp /media/VBOX* /tmp/
cd /tmp/VBOX*
./VBoxLinuxAdditions-x86.run # NOTE: Run ./VBoxLinuxAdditions-amd64.run if 64 bit machine
cd
rm -fr /tmp/VBOX*

• Reboot the system (may not always be required - you can't do this step if running from a Live boot).