Anterior: Ponte de rede para QEMU, Acima: Máquinas Virtuais [Conteúdo][Índice]
If the machine hosting your virtual machines is connected wirelessly to the
network, you won’t be able to use a true network bridge as explained in the
preceding section (veja Ponte de rede para QEMU). In this case, the next
best option is to use a virtual bridge with static routing and to
configure a libvirt-powered virtual machine to use it (via the
virt-manager
GUI for example). This is similar to the default
mode of operation of QEMU/libvirt, except that instead of using NAT (Network Address Translation), it relies on static routes to join the
VM (virtual machine) IP address to the LAN (local area
network). This provides two-way connectivity to and from the virtual
machine, which is needed for exposing services hosted on the virtual
machine.
A virtual network bridge consists of a few components/configurations, such
as a TUN (network tunnel) interface, DHCP server (dnsmasq) and
firewall rules (iptables). The virsh
command, provided by the
libvirt
package, makes it very easy to create a virtual bridge. You
first need to choose a network subnet for your virtual bridge; if your home
LAN is in the ‘192.168.1.0/24’ network, you could opt to use e.g.
‘192.168.2.0/24’. Define an XML file, e.g. /tmp/virbr0.xml,
containing the following:
<network> <name>virbr0</name> <bridge name="virbr0" /> <forward mode="route"/> <ip address="192.168.2.0" netmask="255.255.255.0"> <dhcp> <range start="192.168.2.1" end="192.168.2.254"/> </dhcp> </ip> </network>
Then create and configure the interface using the virsh
command,
as root:
virsh net-define /tmp/virbr0.xml virsh net-autostart virbr0 virsh net-start virbr0
The ‘virbr0’ interface should now be visible e.g. via the ‘ip address’ command. It will be automatically started every time your libvirt virtual machine is started.
If you configured your virtual machine to use your newly created ‘virbr0’ virtual bridge interface, it should already receive an IP via DHCP such as ‘192.168.2.15’ and be reachable from the server hosting it, e.g. via ‘ping 192.168.2.15’. There’s one last configuration needed so that the VM can reach the external network: adding static routes to the network’s router.
In this example, the LAN network is ‘192.168.1.0/24’ and the router configuration web page may be accessible via e.g. the http://192.168.1.1 page. On a router running the libreCMC firmware, you would navigate to the Network → Static Routes page (https://192.168.1.1/cgi-bin/luci/admin/network/routes), and you would add a new entry to the ‘Static IPv4 Routes’ with the following information:
lan
192.168.2.0
255.255.255.0
server-ip
unicast
where server-ip is the IP address of the machine hosting the VMs, which should be static.
After saving/applying this new static route, external connectivity should work from within your VM; you can e.g. run ‘ping gnu.org’ to verify that it functions correctly.
Anterior: Ponte de rede para QEMU, Acima: Máquinas Virtuais [Conteúdo][Índice]