VMWare Fusion 5.0 and Remote Desktop (RDP) Port Forwarding

So, the dilemma with my previous post’s setup is that I now have two VM’s that reside on the same VLAN, and one of them is an AD.

The current problem is that I want to access the second (non-AD) server from the outside world, outside of the host machine.  Normally, this is a private VLAN and there’s no access, but you can configure port forwarding so that you map port 3389 (external host) to one of the statically mapped internal hosts (for me, located at

Here’s the deal:

The file /Library/Preferences/VMware Fusion/networking appears to be produced by the VMWare Fusion networking configuration dialogs.  It appears to drive the creation of the files /Library/Preferences/VMware Fusion/vmnet8/dhcp.conf and /Library/Preferences/VMware Fusion/vmnet8/nat.conf.

The latter of these two files, nat.conf, contains the location where we need to change the NAT settings to allow port 3389 requests to the host to be forwarded to the private VLAN.  The problem?  This file is periodically overwritten by VMWare processes when VMWare is restarted, network configuration changes are made in the GUI, etc.

I don’t have a long term fix for you here -> I can’t find any answers online or in the documentation.  Ideally, you would make the changes to the /Library/Preferences/VMware Fusion/networking file, and restart VMWare or reset the VMware network stack, and the system would regenerate working copies of the nat.conf file.  The problem is the VMWare GUI doesn’t support port forwarding configurations, and you can “hand hack” the nat.conf file if you’re willing to backup you changes or risk losing them periodically.

Networking file sample (/Library/Preferences/VMware Fusion/networking)

answer VNET_1_DHCP yes
answer VNET_1_DHCP_CFG_HASH 4DB1B0245BA0BF9FBCD5D55DA675F9D605B179EF
answer VNET_8_DHCP yes
answer VNET_8_DHCP_CFG_HASH 946433F88FFC278E2E5B8A325353B972A0B5D762
answer VNET_8_NAT yes
add_bridge_mapping en1 2

Basically, you can see there are no available settings for port forwarding.  None the less, this file is transformed by backend processes into nat.conf, which includes this snippet at the end:


# Use these with care – anyone can enter into your VM through these…
# The format and example are as follows:
# = <VM’s IP address>:<VM’s port number>
#8080 =
3389 =

I’ve added the last line to this file to map the RDP service into the VLAN’ed VM.  So, any RDP requests coming into my host machine will be redirected into one of my VM’s.

Once this change is made, you can reset the network interface and load these changes as follows:

sudo /Applications/VMware\ Fusion.app/Contents/Library/vmnet-cli --stop
sudo /Applications/VMware\ Fusion.app/Contents/Library/vmnet-cli --start

The only problem now?  This file is overwritten when restarting VMware, so I’ve backup up the configuration, and have a script that I quick rerun prior to starting the VM’s (copy over file, stop, then start the interface).  Clunky, but workable.  If you know a way around this, let me know….

Another way, BTW, to see this “overwrite” process is to simply run the configure command:

sudo /Applications/VMware\ Fusion.app/Contents/Library/vmnet-cli --configure

This will blow away your nat.conf changes, which you’ll need to reset.