I have done the guest and the host setup as described here and can network both ways between a qemu guest and the host: https://mail-index.netbsd.org/netbsd-users/2014/08/18/msg015139.html
The guest is just not able to access the external network. It has set the host as default route. So host is blocking it in some way. How to configure the host bridge so that the guest will be able get internet access? Mayuresh
