This is what I 've done.
my default Getway 10.0.0.2
my fedora host Ip 10.0.0.5
my bridge Ip 10.0.0.10
my ubuntu Guest 10.0.0.7
VBoxAddIF vbox0 myname br0
ifconfig br0 10.0.0.10 netmask 255.0.0.0
brctl addif br0 eth0
route add net 10.0.0.0 netmask 255.0.0.0 br0
ifdown br0
ifdown eth0
ifup br0
ifup eth0
route add default gw 10.0.0.2 br0
brctl utility show successfully vbox0 and eth0 has connected
my Fedora Host successfully connect to the internet
I ping successfully between host and guest
but when I tried to ping ubuntu guest to my default gw it returned me
ubuntu~$ ping 10.0.0.2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
From 10.0.0.10 icmp_seq=1 Destination Host Prohibited
From 10.0.0.10 icmp_seq=2 Destination Host Prohibited
From 10.0.0.10 icmp_seq=3 Destination Host Prohibited
From 10.0.0.10 icmp_seq=4 Destination Host Prohibited
I don't know why the bridge's stopped my ubuntu connect to the internet ?
(And one thing very annoying me is br0 is not enabled at startup so can not add vbox0 to the br0 at start up..and I do it by script when login to gnome...Is there any chance for br0 enabled at boot up.