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I am trying to create an isolated network within Virtualbox so I can run its own Server with DHCP. It needs access to the external LAN to get to the ADSL Router but cannot be allowed to detect services such as DHCP.

I have built an XP machine with two network cards. One bridged to the hardware NIC the other set to Host Only, IPRouting enabled

The Host Only adapter is set to 192.168.56.1 and has DHCP disabled, the virtual NIC having a static address of 192.168.53.2.

The new server (SBS2011) has a single NIC (the only configuration allowed) set to 192.168.56.3 DG 192.168.56.2

The DHCP will not run as it reports an exisiting server on the network at 192.168.56.100?

arp report from the server

C:\Users\IT25Admin>arp -a

Interface: 192.168.56.3 --- 0xb
Internet Address Physical Address Type
192.168.56.1 08-00-27-00-cc-41 dynamic
192.168.56.2 08-00-27-c3-24-8c dynamic
192.168.56.100 08-00-27-c4-d3-79 dynamic
192.168.56.255 ff-ff-ff-ff-ff-ff static
224.0.0.22 01-00-5e-00-00-16 static
224.0.0.252 01-00-5e-00-00-fc static
239.255.255.250 01-00-5e-7f-ff-fa static
255.255.255.255 ff-ff-ff-ff-ff-ff static

No ping response from this address, what is it, how do I get rid of it? From the MAC it is something to do with Virtualbox

That's the host-only DHCP server. You can disable it in the preference -> network section.

You should also consider using the internal network method if this is a test environment to isolate from the local lan.

My Host Only adapter is set to 192.168.56.1 not .100 and I have already disabled DHCP in the Virtualbox->File->Preferences->Network->Edit dialogue.

So what is this .100 address?

Open the network section in Windows 7 and see what the address is associated with.
I believe you will see it there. Still using host-only or bridged is going to make things complicated IMHO and simulate a multi-homed environment to the Windows domain. That's why I suggested to use the Internal network mode. Of course the final decision is yours.

Even in the Windows 7 Network config it is .1

The way I read the guide if I use internal mode each VM is in its own network and cannot see other VM's. I need to attach at least one client VM to the server VM and both of these need access to the internet via the external LAN's gateway router.

If I use NAT then the external DHCP server assigns addresses and is visible to the SBS2011 Server which stops the DHCP server on SBS running which it does not allow. Neither does SBS2011 allow dual nics or I would have one bridged and the other Host only. I did try bridged mode on the server but this also stopped the DHCP server. I assumed this also was the external DHCP but now I am not sure as I did not check what address was the DHCP it had found.

Although not neat I have seen this solution of using a dual homed VM as a router elsewhere and I have even done it myself before in hardware. In this case my host can ping the server once I add a static route pointing to the XP VM's bridged NIC for the 192.168.56 subnet so I know the routes are working. It is just where is this *@$* .100 DHCP server?

HairyFool wrote:if I use internal mode each VM is in its own network and cannot see other VM's.

Attach every VM to the same internal lan.

In internal mode all guests can see each other if they are in the same intnet. Internal emulates a network switch. To be able to access the Internet you would add an additional guest to act as a router/ICS. Setup Windows Domain in VirtualBox

Hi,

I'm having the same issue - dhcp server disabled, virtualbox restarted, but the guests keep getting DHCPOFFER from 192.168.56.100. Can anyone explain?

Thanks.

geofreyr wrote:Hi,
I'm having the same issue - dhcp server disabled, virtualbox restarted, but the guests keep getting DHCPOFFER from 192.168.56.100. Can anyone explain?
Thanks.

Post the results of VBoxManage list dhcpservers from a terminal

Same problem here, found and fixed . You need to make sure that the virtual box only host adapter in your windows adapters section (on the real computer / control panel / network adapters) is enabled and has a checkbox set for ip4 and driver (put a check in all boxes just to be safe) then run your virualbox management program and go to file - preferences - network. you should see the host only adapter listed there. select it and select the screwdriver icon to edit it. Go to the DHCP tab and remove checkmark from box. You should leave the address set in the previous box (adapter settings) as you will get an error when starting if you clear this default address out. Now you will not get that phantom dhcp server address 192.168.56.100. Drove me nuts trying to figure this one out. Now you can setup GNS3 and have your dhcp servers actually work with virutalbox. Hope this helps.