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Advanced Bash-Scripting Guide
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Bash Beginners Guide
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  Description

  This script is a replacement script for the xen network-bridge, network-nat and network-route scripts. It allows for the creation of multiple bridges of differing types.

  There are 2 versions of network-multinet:

  Version 1:
  -All bridges created by this script are named xenbrX (i.e. xenbr0, xenbr1, etc.)
  -This script depends on the network-bridge script that ships with xen.
  -This script can create 4 types of bridges:
    traditional bridges:
        -Bridges that contain both a physical network device (ethX) and a virtual network device (vethX) from Dom0.
        -This is the traditional type of network bridge created in xen by the network-bridge script.
    local bridges:
        -Bridges that contain only a virtual network device (vethX) from Dom0.
        -These can be configured as:
          hostonly networks: (similar to a VMware "Host Only" networks)
          NAT networks: (similar to a VMware "NAT" networks)
          Routed networks:
    empty bridges:
        -Bridges that do not contain any physical or virtual network devices from Dom0.
        -These can be used to allow VMs in DomUs to communicate only with other DomUs and not Dom0.
    nohost bridges:
        -Bridges that contain a physical network device but no virtual network devices from Dom0.
        -These can be used to allow virtual machines to communicate with the outside world but not with Dom0.
         (Usefull if you want to isolate traffic away from Dom0)

  Version 2:
  -This script does not depend on any scripts that ship with xen (other than vif-bridge).
  -This script now has its own include file named multinet-common.sh.
  -The networks created by this script are called different names (as listed below).
  -This script can create 6 types of networks (bridges are now called networks):
    Bridged networks:
        -Bridges that contain both a physical network device (ethX) and a virtual network device (vethX) from Dom0.
        -This is the traditional type of network bridge created in xen by the network-bridge script.
        -named xenbrX (i.e. xenbr0, xenbr1, etc.).
    NAT networks:
        -Bridges that contain only a virtual network device (vethX) from Dom0.
        -NAT networks are similar to VMware "NAT" networks
        -named xennatX (i.e. xennat0, xennat1, etc.).
    Hostonly networks:
        -Bridges that contain only a virtual network device (vethX) from Dom0.
        -Hostonly networks are similar to VMware "Hostonly" networks
        -named xenhostX (i.e. xenhost0, xenhost1, etc.).
    Routed networks:
        -Bridges that contain only a virtual network device (vethX) from Dom0.
        -Routed networks are similar to VMware "NAT" networks except the network traffic is not NATed.
        -named xenrouteX (i.e. xenroute0, xenroute1, etc.).
    Empty bridges:
        -Bridges that do not contain any physical or virtual network devices from Dom0.
        -These can be used to allow VMs in DomUs to communicate only with other DomUs and not Dom0.
        -named xenemptyX (i.e. xenempty0, xenempty1, etc.).
    Nohost bridges:
        -Bridges that contain a physical network device but no virtual network devices from Dom0.
        -These can be used to allow virtual machines to communicate with the outside world but not with Dom0.
         (Usefull if you want to isolate traffic away from Dom0)
        -named xennohostX (i.e. xennohost0, xennohost1, etc.).

  The script's variables are stored inside a configuration file called /etc/sysconfig/xend.
  (The xend config file is compatible with both Version 1 and Version 2 of the script.)

  Starting with version 1.3.0 a new script named xen-dhcpd will be provided along with the network-multinet script.
  This script will allow you to configure a DHCP server in Dom0 to listen on selected virtual networks. If the xen-dhcpd script is not present then network-multinet will not attempt to execute it.
  The xen-dhcpd script's variables are also stored inside the /etc/sysconfig/xend config file.

  Note: The xen-dhcpd script requires the ipcalc package to be installed.

©Ron Terry

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