朴泊斋

1. sudo gvim /etc/network/interfaces: 
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto br0
iface br0 inet dhcp
        bridge_ports eth0

2. sudo /etc/init.d/networking restart
3. install guest os
4. modify /etc/libvirt/qemu/guest_os_name.xml
    <interface type='bridge'>
      <mac address='your mac address'/>
      <source bridge='br0'/>
    </interface>
5. sudo virsh define guest_os_name.xml
6. start kvm again

 http://en.wikipedia.org/wiki/KVM_switch

A KVM switch (with KVM being an abbreviation for Keyboard, Video or Visual Display Unit, Mouse) is a hardware device that allows a user to control multiple computers from a single keyboard, video monitor and mouse.  Although multiple computers are connected to the KVM, typically a smaller number of computers can be controlled at any given time. Modern devices have also added the ability to share USB devices and speakers with multiple computers. Some KVM switches can also function in reverse - that is, a single PC can be connected to multiple monitors, keyboards, and mice. While not as common as the former, this configuration is useful when the operator wants to access a single computer from two or more (usually close) locations - for example, a public kiosk machine that also has a staff maintenance interface behind the counter, or a home office computer that doubles as a home theater PC.

There are two types of remote KVM devices that are best described as Local Remote and KVM over IP.

Local Remote

Local Remote KVM device design allows users to control computer equipment up to 1000 feet away from the user consoles (keyboard, monitor and mouse). They include support for standard category 5 cabling between computers and users interconnected by the switch device. In contrast, USB powered KVM devices such as the KVM2USB [1] are able to control computer equipment using a combination of USB, keyboard, mouse and monitor cables of up to 5 meters.

KVM over IP

KVM over IP devices use a dedicated microcontroller and potentially specialized video capture hardware to capture the video, keyboard, and mouse signals, compress and convert them into packets, and send them over an Ethernet link to a remote console application that unpacks and reconstitutes the dynamic graphical image. This KVM over IP subsystem is typically connected to a system's standby power plane so that it's available during the entire BIOS boot process. These devices allow multiple computers to be controlled remotely across a wide area network, local area network or telephone-line using the TCP/IP protocols. There are performance issues related with LAN/WAN hardware, standard protocols and network latency so user management is commonly referred to as "near real time". And, remote KVM over IP devices offer much smaller matrix frameworks.