Bridging eth0 and vboxnet0 and using ISC DHCP server to provide dynamic IPs

Question

I have Lubuntu 12.04 (64bit) with VirtualBox 4.2 installed and the setup below:

1. eth0 adapter connected to LAN (having static IP 192.168.0.1 and it is the default gateway).
2. ISC DHCP server listening on eth0, to configure PCs (in LAN) with dynamic IPs.
3. ppp0 adapter (wirless Mblaze USB modem) to connect to Internet.
4. eth0 has NATed to ppp0, so that all PCs connected to the LAN can have Internet.
5. vboxnet0 host only network (selected for the Virtual Machines).

I would like to have a bridge combining vboxnet0 and eth0 to make it a single network (say br0) and have the DHCP server serve IPs through this new bridge. br0 now should take the static IP of eth0, so that the bridge can be the new gateway.

Please note I neither need Bridged Adapter nor NAT solution in VirtualBox setting UI. I would like to configure all these manually editing all the associated configuration files.

Any help deeply appreciated. Thanks in advance.

Solution

This is fixed. For anyone interested please see the details below.

1. Install bridge-utils.

2. sudo leafpad /etc/network/interfaces

   auto lo
   iface lo inet loopback
   
   auto eth0
   iface eth0 inet static
   address 192.168.0.1
   netmask 255.255.255.0
   dns-nameservers 10.228.129.113 10.228.129.114
   

3. sudo leafpad /etc/rc.d/rc.local

   vboxmanage hostonlyif ipconfig vboxnet0 --ip 192.168.0.3 --netmask 255.255.255.0
   
   brctl addbr br0
   
   ifconfig eth0 0.0.0.0 down
   ifconfig vboxnet0 0.0.0.0 down
   
   brctl addif br0 eth0
   brctl addif br0 vboxnet0
   
   ifconfig eth0 up
   ifconfig vboxnet0 up
   ifconfig br0 192.168.0.1 netmask 255.255.255.0 up
   
   /sbin/iptables -P FORWARD ACCEPT
   /sbin/iptables --append FORWARD --in-interface br0 -j ACCEPT
   /sbin/iptables --table nat -A POSTROUTING -s 192.168.0.0/24 -o ppp0 -j MASQUERADE
   
   restart isc-dhcp-server
   
   exit 0
   

4. sudo leafpad /etc/default/isc-dhcp-server

   INTERFACES="br0 eth0"
   

5. Restart your computer