Virtual network on top of physical network problem, help/ideas welcome!

[Macetrix]

Hello all

After abit of advice from the experts...

I'm currently planning my final year project at university and vmware will be my main platform, I'm going to be creating a virtual ethical hacking networking for educational purposes. I'm abit undecided about how to go about the networking, ideally I would like to run the virtual machines over multiple physical machines and have a virtual dhcp server giving only the virtual machines addresses so i could keep it on a different subnet but i'm guessing this is pretty much impossible? I couldn't really have static addresses as each machine when switched on would conflict with each other. The main problem of my task is getting running a virtual network over multiple computers as I would have a class of students each using a computer of their own. I don't want to go down the route of them all having a virtual network on one host as it will use alot of computer resources and I would like to be able to change the server they are 'experimenting with'.

Any help would be greatly appreciated on this, it just keeps racking my brain!

Thanks

[rbos3 · Accepted solution]

Hi macetrix,

Maybe DHCP Reservations can make a difference for you?

As you can filter MAC addresses here, you can easily add them when you created a new machine. The current MAC address should be displayed in the vCenter Client.

And another idea is to find out if you can use asterisk signs in the MAC-address field of your DHCP reservations. Since VMware uses the same MAC-address format, you could enter this MAC-address "range" and only give VMware machines a DHCP lease.

Hopefully this helps the brain crack less

René

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[Macetrix]

Thank you!! great idea, I didn't know you could filter it by mac address, should have really thought of a technique such as that, doh!

anyway just one more question, would i have 2 virtual nics, the bridged one then the dynamic dhcp assigned one. keep the default bridged nic on the virtual machine so i can communicate across the physical network and grab an address for the virtual machines second nic. would the second nic be able to see the virtual dhcp server if its on a different subnet to the physical host network and is there anything stopping the physical dhcp server assigning my virtual machine an address, i suppose the mac filtering could work here too

Thanks for the help again, really appreciate it!

[rbos3]

Hi Macetrix,

No problem! Glad to help

Any DHCP server will serve any client whom sends a DHCP request. So if you attach two NIC's to a VM (One in the physical network (public) and one in a "private" vSwitch with no connectivity to the physical network) both will try to receive an address using DHCP if you configure them using DHCP assigned addresses.

The "public" nic will receive DHCP thru the NIC on your host machine which is on the public network. The "private" nic wil receive DHCP from whatever DHCP server is on that same virtual network since it's not bridged to your physical LAN.

If you want to stop the DHCP server from serving IP addresses to your VM's you could try working with Windows Firewall and block the DHCP port. I don't think you can create a DHCP MAC filter and pick "Do not serve IP addresses to this MAC address". Maybe a 0.0.0.0 IP address but I don't think that's how you would like it

All together it's a creative solution but if you have to work with equipment you already own, sometimes you can't afford different equipment so hopefully this will allow you to finish the lab for the students

René

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