Virtual Computing

The purpose of this SIG is to explore virtual computing technologies and how to leverage them as additional system resources. Our main focus will be on the free VMWare products, but we will also take a look at other technologies and tools.

Contact: Rob Limbaugh, 203-826-8196. Group meets on the 4th Tuesday, 7:00 p.m. at the DACS Resource Center.

DACS Community Forum: http://forum.dacs.org/

News and Notes

In our February meeting, we talked about some advanced configuration of the virtual environment and reasons for doing so. Our focus was primarily on virtual networks within the virtual host environment. The virtual host can emulate different types of network switch connections. By default, VMware sets up a 'Bridged' network, a “NAT' network, and a 'Host Only' network. By leveraging the different topology types, some complex networks can all be built 'virtually'.

A 'Bridged' network connects a virtual machine to the same network segment as the host computer that is connected to. For illustrative purposes, think of this as just allowing another laptop or desktop computer access to your home network. 'Bridging' works across whatever adapter the host is using to connect to the physical network. If the host computer happens to be a laptop and it is running a Linux virtual machine, then the Linux virtual machine will think it has a standard hard-wired network card even though the 'Bridge' is built on a wireless adapter.

The virtual 'NAT' network behaves just like a Linksys or D-Link broadband router many of us use at home. One major difference is that the virtual 'NAT' uses the network card of the host system to connect to the physical LAN, but only virtual machines can plug into the virtual 'NAT'.

Our third type, 'Host Only', is a virtual network that is isolated but allows the virtual machines to access the host system. From the host system point of view, this is like having two network cards installed on the host. One card connects to the rest of the physical network, the other connects to a virtual switch that other virtual computers can connect to.

We demonstrated and discussed that depending on the hardware configuration of the host system, it is possible to create very complex physical and virtual networks all within one physical system that allow one to explore enterprise networking layouts. For example, one could operate production, test, and DMZ networks with clients (virtual and real). These configuration options make it possible to use a virtual firewall appliance that can provide more robust security features than a small home firewall and/or router device.

For more information, see:

http://nst.sourceforge.net/nst/docs/faq/ch13s10.html
http://wiki.untangle.com/index.php/Untangle_Virtual_Appliance_on_VMware

At press time, information for the March and April meetings was unavailable. All skill levels are welcome to join us for our April 22nd meeting.