Network problem on my host after installing Virtualbox

[Fyra]

Hi everyone,

I'm not sure if this is the right place to post this.

But anyway, i have this laptop which i have installed VMWare workstation. Installed in it is Ubuntu 14.04 and within Ubuntu, i have installed Virtualbox configured with Windows XP SP3(nested VMs). The problem that i'm getting is that whenever i start up Virtualbox, other laptops on the same network will be unable to ping my host (Ubuntu). They will only be able to ping when the interface vboxnet0 is not up in my ifconfig.

Between my laptop and ubuntu, i have set bridged networking and between ubuntu and virtualbox, i have set up host only networking.
I have also the following lines in my /etc/rc.local file to ensure Windows XP SP3 is able to get access to the Internet.
iptables -A FORWARD -o eth0 -i vboxnet0 -s 192.168.0.0/24 -m conntrack --ctstate NEW -j ACCEPT
iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
iptables -A POSTROUTING -t nat -j MASQUERADE
sysctl -w net.ipv4.ip_forward=1


I have noticed the following:
- As long as the interface vboxnet0 is not up, i can ping properly to google and other laptops can ping my host
- Once i start up virtualbox and vboxnet0 is up, i can only ping between my host and xp inside virtualbox. xp within virtualbox can also ping google. However my host no longer is able to ping google, but is able to ping google's ip address directly however.. And other laptops will no longer be able to ping my host.

I have been debugging this for days but i'm still unable to determine the issue. Hope someone can help me please!

Regards,
Fyra

[noteirak]

Few things here :
- Nested Virtualization is not supported
- Virtualbox does not modify anything routing wise when using host-only
- You enable MASQUERADE on everything in ubuntu, instead of only taking the specific host-only traffic. Not sure it's a good idea in this case...

Do packet sniffing to see where your traffic is going - this is matter of system configuration, nothing related to Virtualbox (unless you can show otherwise)