[OT] help me with virtualbox

[Luca Ferrari]

Hi all,
I'd like to setup a virtual box guest (ubuntu linux) hosted into another 
ubuntu linux so that the guest system has a fixed ip address and the host can 
reach it using a pseudointerface, but with the guest able also to use the host 
to route to other networks. I've set up the virtual machine so that networking 
is host-only-adapter, and setting up properly ip I can communicate from the 
host to the guest using the same ip address.
Then I enabled forwarding on the host system, but I cannot get out from the 
guest:


iptables -F
iptables -t nat -F
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o ppp0 -s 192.168.200.203 -j MASQUERADE

(here 192.168.200.203 is the guest ip address).

Anybody can give me a clue?

Thanks,
Luca