Thanks, I just have a question:

If I would only want to connect to my N900 with wifi but without using it as a hot-spot (so, without gprs0), I guess I would just need to take out these lines:

HOSTIDEV="gprs0"
modprobe ipt_MASQUERADE
iptables -t nat -A POSTROUTING -o $HOSTIDEV -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward

would I need to keep:
iptables -t nat -F

I would say that I don't need iptables at all, is that right?

i.