Two IP addresses on 1 host (1 for host and one for guest)

sopel1000 · 08-14-2012, 08:19 AM

Hi,

I have a problem with setting up a working environment with a following configuration:

1 host OS on a dedicated server (Ubuntu, it's already working). It has an IP address XX.XXX.YY.YY with a mask of: 255.255.255.252 and the operator has assigned a second IP address: XX.XXX.YZ.VW, mask: 255.255.255.255

Gateway is the same of course.

I want to assign the second ip address to a VirtualBox VM. I have no idea how to do that, could you please help?

malekmustaq · 08-14-2012, 12:49 PM

Open a terminal and read these:

Quote:

--$ man route

and

Quote:

--$ man ifconfig

Good luck and enjoy.

sopel1000 · 08-14-2012, 01:11 PM

But the thing is: what do I set on VirtualBox? Do I set the new IP and enable bridging? Or Do I set host-guest communication only, or NAT or what?

I have tried it, but it causes so many problems that I thought it might be wise to ask..

KinnowGrower · 08-14-2012, 10:32 PM

Did you tried NAT.?. As for as I know, Virtual box by default assign IP address using DHCP in range of 10.xx.xx.xx. With NAT your guest OS should work fine.

r0b0 · 08-15-2012, 03:54 AM

Hi,

We have a similar situation here - additional IP addresses with netmask /32 assigned by ISP. You need to bridge the VM in virtual box. Then in your VM, put something like this in your /etc/network/interfaces:

Code:

auto eth0
iface eth0 inet static
        address XX.XXX.YZ.VW
        netmask 255.255.255.255
        post-up ip route add XX.XXX.YY.YQ/255.255.255.252 dev eth0; route add default gw XX.XXX.YY.YP eth0

Where XX.XXX.YY.YP is the default gateway IP and XX.XXX.YY.YQ/255.255.255.252 is the network.

sopel1000 · 08-16-2012, 09:14 AM

Hi,

I tried what you wrote. In the configuration you wrote, there is absolutely nothing to configure on the host, only in the VM? If that is the case, then it's not working for me. I did apply what you wrote, but have not tampered with ifconfig on the host - it has it's first IP address. Doesn't work.

Regards!

sopel1000 · 08-16-2012, 10:07 AM

Basically, I am using virtualbox on my other dedicated server but there I have no problems at all -> because one of the providers allows me to use DHCP, so I bridge my VBox interfaces and if I have several of them, I get different IP's for different MAC addresses.

Unfortunately now I have to cope with different provider... So, to sum up:

First ip address I have (for the host):

Code:

IP: XX.XXX.Z4.42
Mask: 255.255.255.252
GW: XX.XXX.Z4.41

Second IP I got (which I need assign for a guest OS running on VirtualBox):

Code:

IP: XX.XXX.Z3.61
Mask: 255.255.255.255 (mask: /32!)
GW: XX.XXX.Z4.41

Gateways are the same. As I was instructed by r0b0, I changed config on the guest OS (inside VM) and set VM into bridging.

Code:

auto eth0
iface eth0 inet static
        address XX.XXX.Z3.61
        netmask 255.255.255.255
        post-up ip route add XX.XXX.Z4.40/255.255.255.252 dev eth0; route add default gw XX.XXX.Z4.41 eth0

After doing that, if I ping from the host os, I get:

Code:

 From XX.XXX.Z4.41: icmp_seq=1 Redirect Host(New nexthop: XX.XXX.Z4.42)

How to finally get it done? I'm fed up!

sopel1000 · 08-16-2012, 11:54 AM

I have just received the e-mail from my provider:

"You have to create a virtual interface, we are routing IP to the main IP of your server: XX.XXX.Z4.42.
You have to resign from bridging because it is not going to work."

So, what do I do? How do I route it to vboxnet0?

sopel1000 · 08-16-2012, 05:39 PM

What if I used DNAT and SNAT? I read it would be a good idea, but I have no bloody idea how to do that...

r0b0 · 08-22-2012, 07:17 AM

If .41 is refusing to route packets coming from .61, maybe you can route them through .42. To make that work, allow IP forwarding, FORWARD iptables chain and set static route on .42 and set default gateway on .61 to .42 instead of .41:

Code:

# on .42:
echo "1" > /proc/sys/net/ipv4/ip_forward
iptables -A FORWARD -s XX.XXX.Z3.61 -j ACCEPT
iptables -A FORWARD -d XX.XXX.Z3.61 -j ACCEPT
ip route add XX.XXX.Z3.61/255.255.255.255 dev eth0

# on .61:
auto eth0
iface eth0 inet static
        address XX.XXX.Z3.61
        netmask 255.255.255.255
        post-up ip route add XX.XXX.Z4.40/255.255.255.252 dev eth0; route add default gw XX.XXX.Z4.42 eth0

Let's see if this works...

sopel1000 · 08-29-2012, 10:52 AM

So, basically I have vboxnet0 interface with 192.168.56.1 on host machine. Virtualbox is in host-only mode. Virtualbox has 192.168.56.101 IP address assigned.

What I did and that seems to be working fine:

Code:

sudo iptables -t nat -I PREROUTING -d NEW_IP -j DNAT --to-destination 192.168.56.101
sudo iptables -t nat -I POSTROUTING -s 192.168.56.101 -j SNAT --to NEW_IP
sudo iptables -I FORWARD -d NEW_IP -j ACCEPT
sudo iptables -I FORWARD -d 192.168.56.101 -j ACCEPT

Thanks to that, the 192.168.56.101 address is available outside as NEW_IP. Thanks for your help!