VMware Workstation 5.5 for Linux Hosts
Besides virtual CPU, RAM, hard disks and network interfaces, virtual machines also can have virtual floppy disks, CD-ROM/DVD-ROM drives (data only, not movies), USB controllers, SCSI controllers, parallel ports, serial ports, sound cards and mice. Both floppy and CD/DVD drives can use either your host system's actual hardware, or disk-image or ISO files, respectively. In all cases, VMware mounts the real or virtual media for you; you don't need to run the mount command separately.
VMware's SCSI and USB support is similarly transparent. By default, if you plug in a SCSI or USB device to your host system while a virtual machine is running in the foreground (has focus), the virtual machine responds as though you plugged the device in to it. Whether this will actually work in a given situation depends both on VMware—the virtual USB controller supports only USB 1.1—and on the capabilities of the guest system. (Does it support USB? Have you installed the correct drivers for your device onto your virtual machine?)
Once you've created a virtual machine and installed its operating system, actually using the virtual machine is very, very similar to the real thing. Figure 2 shows the Debian 3.1 installer running on a virtual machine.
You can even, if you like, run the virtual machine in full-screen mode rather than within the VMware window. Installing the VMware Tools package on the guest system adds additional features, such as enhanced virtual-display-adapter support for your guest system and the ability to move your mouse pointer in and out of the VM window without having to click in and escape out.
A number of VMware features make the virtual machine experience better than using a real machine, especially for research/test scenarios. One is the ability to take snapshots of virtual machines. A snapshot captures a virtual machine's memory state, disk state and virtual machine settings at a given point, allowing you to roll back to that point later—for example, after losing control of a virus you were examining on the guest system.
Another feature is the ability to create teams of virtual machines. A team is a group of virtual machines with shared networking and startup characteristics. This lets you create, for example, a farm of database servers all connected to the same virtual LANs that all can be started simultaneously with a single-mouse click or command (VMware now has a command-line utility, vmrun, for operating virtual machines and teams).
As you'd probably expect, given that a virtual machine is nothing more than files in a directory, VMware also makes it easy to clone virtual machines. A full clone is simply a copy of the parent VM, identical to it except for having a new MAC address and UUID. A full clone, therefore, is highly portable, and it easily can be copied to other host systems.
Another option is to create a linked clone, which actually is made from a snapshot of the parent. Changes to the parent don't affect the clone, and vice versa, but the clone must have access to the parent's files at all times.
So, what are the downsides to VMware? Honestly, I've been a very happy user of this product over the years. I have no laundry list of gripes or bugs to share with you, other than one hardware-specific problem with VMware 4.0 on a ThinkPad T42 running Windows XP (which I solved by switching to the Linux version). VMware Workstation 5.5 is a stable, well-documented and easy-to-use product with a rich set of features that is particularly useful to information systems professionals and researchers.
None of that comes for free, of course. The downloadable version of VMware Workstation 5.5 for Linux costs $189 US, and the boxed version is $199 US. I think you'd be hard pressed though to assemble a very good physical computer for that little money, let alone an entire LAN's worth. If in doubt, you can download the full version for a 30-day evaluation (after which you must purchase and install a license to continue using VMware).
Or, you can opt for VMware Server, which is now completely free. Formerly known as VMware GSX Server, the current version of VMware Server was still in beta at the time of this writing, but it will remain a free product even when it reaches production status. Presumably, VMware Server lacks many of VMware Workstation's developer/researcher-oriented features—the server versions of VMware are targeted more for production server applications. Compare and decide for yourself. More information about all VMware products is available at www.vmware.com.
Mick Bauer (firstname.lastname@example.org) is Network Security Architect for one of the US's largest banks. He is the author of the O'Reilly book Linux Server Security, 2nd edition (formerly called Building Secure Servers With Linux), an occasional presenter at information security conferences and composer of the “Network Engineering Polka”.
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