Static IPs on KVM + (minimal) Fedora 16 installation

Getting networking to work the way you want it to in a VM can be scary sometimes.
 
I recently found it was tricky to have both a STATIC IP as well as internet connectivity inside of KVM provisioned VMs.   The ultimate reason was that the “GATEWAY” field was not being set right. 

The moral of the story:  On KVM boxes, when bridging in a virtual network, the virt managed default bridged IP address needs to be set as the gateway… Thus, when your guests are in a “virtual network” – the “gateway” is the internal IP address provided to them by the hypervisor that represents the “outside” of their internal network.   

1) Stop the firewalls in iptables:

         iptables -F

2) Edit /etc/sysconfig/network-scripts/ifcfg-eth0 like so (obviously the “IPADDR” can be anything you want as long as its in the right range.

DEVICE=”eth0″

HWADDR=”52:54:00:94:AF:F4″

BOOTPROTO=”static” <— Change this from “dhcp” to “static”

ONBOOT=”yes”

NM_CONTROLLED=”yes”

IPADDR=192.168.122.171 <— this is any old arbitrary IP in-range.

NETMASK=255.255.255.0

GATEWAY=192.168.122.1 <— this is aliased ipaddress of your host inside of KVM.

USERCTL=”no”

3) Restart networking so that the IP and GATEWAY can be reset.

       service network restart

4) Ping somebody and watch the magic unfold:

       ping www.yahoo.com

Yay!

If you get a “Destination Host Unreachable”: 

Your gateway is wrong.   Make sure your gateway is the same as your host vm’s ipaddress. 
 

If you get an unknown host: 

You may not have an assigned IP (IPADDR wrong or out of range).

A strange note to keep in mind — somehow, even with a bad gateway (i.e. destination host unreachable), I could still resolve hostnames – not sure why.