Free hypervisors software for linux

Virtual Machine Manager software (virt-manager for short package name) is a desktop user interface for managing virtual machines. The project presents a summary view of running domains and their live performance & resource utilization statistics. A detailed view presents graphs showing performance & utilization over time. Ultimately it will allow creation of new domains, and configuration & adjustment of a domains resource allocation & virtual hardware. Finally an embedded VNC client viewer presents a full graphical console to the guest domain.

The application logic is written in Python, while the UI is constructed with Glade and GTK+, based on mockups provided by UI interaction designers. The libvirt Python bindings are used to interacting with the underlying hypervisor. This enables the application to be written independant of any particular hypervisor technology. Initially Xen was the primary platform supported, however, since libvirt 0.2.0 and virt-manager 0.3.1 it is possible to manage QEMU and KVM guests too. It is expected that support for additional hypervisors / virtualization products will expand even further over time as additional libvirt drivers are written.
The "Virt Install" tool (virtinst for short package name) is a command line tool which provides an easy way to provision operating systems into virtual machines. It also provides an API to the virt-manager application for its graphical VM creation wizard.

The "Virt Clone" tool (virtinst for short package name) is a command line tool for cloning existing inactive guests. It copies the disk images, and defines a config with new name, UUID and MAC address pointing to the copied disks.
The "Virtual Machine Viewer" application (virt-viewer for short package name) is a lightweight interface for interacting with the graphical display of virtualized guest OS. It uses GTK-VNC as its display capability, and libvirt to lookup the VNC server details associated with the guest. It is intended as a replacement for the traditional vncviewer client, since the latter does not support SSL/TLS encryption of x509 certificate authentication.

GNS-3 is a graphical network simulator that allows you to design complex network topologies. You may run simulations, or configure each device, from a simple workstation to a powerful Cisco router.
To allows complete simulations, GNS-3 is based on two existing projects:
- NS-3 , a discrete-event network simulator for Internet systems, targeted primarily for research and educational use.
- Dynamips, an IOS emulator which allows users to run IOS binary images from Cisco Systems.
This application is an open source product that may be used on multiple platforms, including Windows, Linux, and MacOS X.
Main features:
- Design of high quality network topologies.
- Emulation of Cisco routers.
- Load-balancing on multiple hosts/hypervisors when in emulation mode.
- Topology import and export.
- Image exports (PNG, JPEG, BMP, XPM).
Enhancements:
- Hypervisor load-balancing is now used to address the per process limit problem (http://dynagen.org/tutorial.htm#_Toc165530762).
- Configuration of multiple nodes may be done. The user can change hostnames.