VMWare Fusion – Network Basics

A while back, I switched over to using a MacBook Pro at work, and I’ve loved it. We have a company policy that all laptop hard drives must be fully encrypted. This poses a problem for the would be BootCampers. When you use the default utilities, you can’t have both OS X and Windows encrypted. It looks like Symantec might have a tool that will do this, but I haven’t tried. There’s also this blog that goes into some other details. At any rate though, our company has a policy against using BootCamp on laptops.

Because of this, I’ve been using VMWare Fusion for my Windows needs. I have never found any issues with using a VM for development. We do a bit of web application development, and occasionally I find the need to have someone hit my machine’s web server. This makes a little knowledge of networking essential.

Bridged Networking


Bridged network is described in VMWare Fusion’s network settings as follows:

The virtual machine appears as an additional computer on the same physical network connection as your Mac

Essentially, Host and Guest share physical hardware, but they both get their own IP address on the network. This is normally the fastest way to get your Guest on the network so you can access it’s web server.

Normally is really the key word. If I’m at home and I want to access my Guest, I set the network type to Bridged. Done. Nothing more to do. Unfortunately, the corporate world is a very different thing. In the corporate world, there are some guys monitoring the network to ensure someone doesn’t stick their personal computer on the network and start stealing data.

Basically, in the corporate world, you’ll have to get ahold of your system administrators to get your VM access to the network. This can sometimes be more trouble than it’s worth. I’ve had experience with admins having to get me on the phone to explain to them exactly what I wanted to do, because they don’t normally set up Bridged access for VM’s.

Network Address Translation


NAT is described in VMWare Fusion’s network settings as follows:

The virtual machine shares the IP address of the Mac on the external network. The Mac provides Network Address Translation (NAT) for the network traffic from the virtual machine.

That is a lot of words. Here’s what it all means. A private network is set up between the Guest and Host. The Host then acts as a proxy for the Guest. This is how most VM’s are set up by default. It makes things easy. All of your Guest’s network traffic goes through the Host, so the system administrators don’t have to do anything special.

If you need to get a port opened up on your company’s firewall, you have the admins open it for the Host, and it’s automagically open for the Guest. The only problem is that if you want to access the Guest from the network, you need to set up some port forwarding.

Unfortunately, even in the world of VMWare Fusion – VMWare still hasn’t figured out that port forwarding is a thing that people have to do. Fusion supports port forwarding, but not in the GUI, and sometimes when you change network settings for one of your VM’s, it resets all of the manual changes you make to the config files. Nevertheless, we can make changes to the config files to suit our needs anyway.

This blog post turned out to be a lot longer than I expected, so head on over to another of my posts to learn about DHCP and Port Forwarding.

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