using KVM w/o dnsmasq on CentOS 5.2 X64

["Stefan Krümmel" <skruemmel@wheregroup.com>]

Hi,

I'm trying to convert some of our virtual machines from VMWare Server 2 to
KVM on CentOS 5.2 X64.

KVM constantly gives me headaches when it comes to networking  
configuration.

Being used to VMWare, there are some things that don't work as expected.

1. kvm/libvirt manipulate iptables, effectivly breaking the hosts  
networking
iptables is usually turned off on the dev machine( iptables -F, no rules  
set during boot)

2. kvm/libvirt comes with dnsmasq, which gets started automagically,  
colliding
with out existing DDNS setup(ISC's bind/dhcpd3 )

I'm hope some of you might shed some light on howto
1) bridge a KVM-VM to an exisiting Ethernet interface, behaving exactly  
like
a real/physical NIC, being able to handle any  
ARP/BOOTP/PXE/DHCP/IP/whatever requests.

and 2) setup a virtual ethernet-network, which is completely isolated
 from the host's networking WITHOUT using NAT/dnsmasq.

e.g. we have a JEOS VM which acts as a tightly restricted dual-homed GW for
VMs that are required to run in a completely isolated network.

I've browsed thru several docus/wikis related to xen/kvm
but none them gave any clues about this custom networking setup.

regards
Stefan Kruemmel