QEMU Question:

To build bridges in QEMU the configuration files has to be changed and the firewall has to be set up such that it doesn't interfere in between the process. If firewall creates problem then there is a possibility of loosing the network connection to QEMU virtual machines. So, to enable the firewall to all the traffic to the servers configure the IP addresses by using the command like:

# allow incoming packets for qemu
IPTABLES -A FORWARD -d $IPADDR_FROM_CLIENT_OS -j ACCEPT
# allow outgoing packets from qemu
IPTABLES -A FORWARD -s $IPADDR_FROM_CLIENT_OS -j ACCEPT

These commands will take care of the firewall settings and will help in allowing the traffic to flow to the virtual machine's IP address. To add a range add the network address and netmask in the configuration file.