I'm looking for some insight into best practices for network traffic isolation within a virtual environment, specifically under VMWARE ESXi.

Currently I have (in testing) 1 hardware server running ESXi but i expect to expand this to multiple pieces of hardware.

The current setup is as follows:

1 pfsense VM, this VM accepts all outside (WAN/internet) traffic and performs firewall/port forwarding/NAT functionality. I have multiple public IP addresses sent to the this VM that are used for access to individual servers (via per incoming IP port forwarding rules). This VM is attached to the private (virtual) network that all other VMs are on. It also manages a VPN link into the private network with some access restrictions. This isn't the perimeter firewall but rather the firewall for this virtual pool only.

I have 3 VMs that communicate with each other, as well as have some public access requirements:

1 LAMP server running an eCommerce site, public internet accessible

1 accounting server, access via windows server 2008 RDS services for remote access by users

1 inventory/warehouse management server, VPN to client terminals in warehouses

These servers constantly talk with each other for data synchronization.

Currently all the servers are on the same subnet/virtual network and connected to the internet through the pfsense VM. The pfsense firewall uses port forwarding and NAT to allow outside access to the servers for services and for server access to the internet.

My main question is this:

Is there a security benefit to adding a second virtual network adapter to each server and controlling traffic such that all server to server communication is on one separate virtual network, while any access to the outside world is routed through the other network adapter, through the firewall, and on the the internet.

This is the type of architecture i would use if these were all physical servers, but i'm unsure if the networks being virtual changes the way i should approach locking down this system.

Thank you for any thoughts or direction to any appropriate literature.

  • Have you considered VMWare's vShield product range?
    – Chopper3
    Oct 1, 2010 at 10:02

4 Answers 4


Your current configuration is fine. THe private switch data is only accessible by any of the machines attached to it. You have a limited scope of access so you should be safe. If you were do do anything, you could possibly add a second NIC to PF sense to a separate private vSwitch to basically have a DMZ but its not necessary and a bit excessive. Your milage may vary..

  • One item to add to jzaymes' naqwe - If your VMWare Management NIC is the same as your VM NIC you DEFINITELY want to split those up (your management NIC should only be accessible on your organization's intranet, safely away from prying eyes/hackers). Otherwise your configuration sounds fine.
    – voretaq7
    Jan 24, 2011 at 17:44

Only if you see benefits in separating "inter-server" versus "client access" traffic, otherwise you already have a "private"/"protected" network with your current arrangement.


by separating the VM trafic you may also be benefited by not choking a single network.

  • If you're choking a single network, wouldn't it be better to bond the interfaces on the physical server and switch to increase the maximum throughput instead of having the production websites/databases/synchronization go slow?
    – Reece45
    Jan 17, 2011 at 11:59

Though, your current configuration looks OK, I suggest add another network adapter, to avoid any future increases in usage of bandwidth.

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