Network device cannot communicate with host machine

I know this used to work but it doesnt work any more using qemu 1.4.2  on fedora 19 everything works fine
except when i add a NIC sharing the main interface from the host (not the virtual network)

the hosts ip is 10.0.0.4, the router is 10.0.0.1 so when i boot my virtual machine it gets an ip from the router no problem 
i get on the internet fine, and i can connect (ping,ftp, samba whatever) to all the computers on the network except the host
10.0.0.4 i can't ping it, i cant do anything to it, but i can connect to all the other computers on the network and i know i used to be able to do this because thats how i shared files between the host and windows guest, with samba... but now i can't browse the host computer because it can't communicate... please help.