Wiki Ubuntu-it

Indice
Partecipa
FAQ
Wiki Blog
------------------
Ubuntu-it.org
Forum
Chiedi
Chat
Cerca
Planet
  • Pagina non alterabile
  • Informazioni
  • Allegati

Versione 3 del 26/03/2010 18.30.46

Nascondi questo messaggio

Gestione diretta di KVM

Siccome il resto di questa documentazione è focalizzato sull'uso di KVM attraverso libvirt, ricordiamo che è possibile anche la gestione diretta di KVMW. Non è un metodo raccomandabile, ma in alcuni casi può tornare utile.

KVM è molto simile a qemu e rende possibile l'esecuzione di macchine da riga di comando. La sintassi di base è: 

kvm -m 512 -hda disk.img -cdrom ubuntu.iso -boot d -smp 2
  • -m = memoria (in MB)
  • -hda = primo disco rigido
    • Si possono usare vari tipi di file immagine inclusi .img, .cow

    • È possibile avviare un disco rigido. Prestare attenzione nell'uso di questa opzione se non si vuole avviare la partizione di root del host

      • Sintassi -hda /dev/sda
      • Questo richiama il menu di grub dal MBR quando viene lanciato KVM.
  • -cdrom può essere sia un'immagine iso che un lettore CD/DVD.
  • -boot [a|c|d|n] avvio da floppy (a), disco rigido (c), CD-ROM (d), oppure rete (n)
  • -smp = numbero delle CPU
  • -alt-grab change Ctrl-Alt mouse grab combination for Ctrl-Alt-Shift (very practical if you often use some control key combinations like Ctrl-Alt-Del or Windows-E)

There are a number of additional options and additional help is available with : 

kvm --help

Bridged Networking

In order to run KVM using bridged networking as a user we need to perform some configuration.

1. First bridge your network card as above KVM/Networking#Creating a network bridge on the host

2. Install uml-utilities 

  •  sudo apt-get install uml-utilities

3. Set permissions on your tun device. Using any editor, edit /etc/udev/rules.d/40-permissions.rules, add this line at the bottom of the file : 

  •  KERNEL=="tun", GROUP="kvm", MODE="0660"

4. Reboot (to bring up your bridge and tun device).

5. Edit /etc/kvm/kvm-ifup adding sudo in front of the ifconfig and brctl commands 

  •  #!/bin/sh

 switch=$(ip route ls | awk '/^default / { for(i=0;i<NF;i++) { if ($(i) == "dev") print $(i+1) }}')
 '''sudo''' /sbin/ifconfig $1 0.0.0.0 up
 '''sudo''' /usr/sbin/brctl addif ${switch} $1
 exit 0

6. We need a wrapper script for launching kvm. I put this script in ~/bin and call it kvm-bridge. If ~/bin is on your path you can call the command directly with kvm-bridge. This script was modified from a number of sources 

  •  #!/usr/bin/env bash
 # script to manage tap interface allocation
 # for linux kernels >= 2.6.18

 # modified by bodhi.zazen from :
 # http://calamari.reverse-dns.net:980/cgi-bin/moin.cgi/FrequentlyAskedQuestions#head-2511814cb92c14dbe1480089c04f83c281117a86
 # http://ubuntuforums.org/showthread.php?t=528046
 # http://www.howtoforge.com/using-kvm-on-ubuntu-gutsy-gibbon

 # set up a tap interface for qemu
 # USERID - uid qemu is being run under.
 USERID=`whoami`

 # generate a random mac address for the qemu nic
 # shell script borrowed from user pheldens @ qemu forum

 ranmac=$(echo -n DE:AD:BE:EF ; for i in `seq 1 2` ; \
 do echo -n `echo ":$RANDOM$RANDOM" | cut -n -c -3` ;done)

 # specify which NIC to use - see qemu.org for others
 # model=r8169
 # Set model based on this how-to
 # http://www.howtoforge.com/using-kvm-on-ubuntu-gutsy-gibbon

 model=rtl8139
 iface=`sudo tunctl -b -u $USERID`

 # start kvm with our parameters
 # echo "Bringing up interface $iface with mac address $ranmac"
 # nohup added to allow kvm to run independent of the terminal
 nohup kvm -net nic,vlan=0,macaddr=$ranmac -net tap,vlan=0,ifname=$iface $@

 # kvm has stopped - no longer using tap interface
 sudo tunctl -d $iface &> /dev/null

7. Set the executable bit on the new script you just created: 

  •  chmod 0755 ~/bin/kvm-bridge

8. Modify sudoers to allow members of the kvm group to run the wrapper kvm-bridge and create a bridged network interface without running KVM as root. 

  •  visudo

Add these line at the end of the file : 

  •  # Allow members of the kvm group to configure a bridged virtual network interface
 %kvm ALL=(ALL) NOPASSWD: /sbin/ifconfig, /usr/sbin/brctl, /usr/sbin/tunctl

9. Now start kvm from the command line. You do not need to declare a network interface 

  •  kvm-bridge -m 512 -hda disk.img -cdrom ubuntu.iso -boot -d -smp 2

iptables

Add these rules to iptables : 

# allow incoming packets for kvm guest
IPTABLES -A FORWARD -d $IPADDR_FROM_GUEST_OS -j ACCEPT
# allow outgoing packets from kvm
IPTABLES -A FORWARD -s $IPADDR_FROM_GUEST_OS -j ACCEPT

Change "$IPADDR_FROM_GUEST_OS" to the actual ip address of the kvm guest (I advise you configure your guests to have a static IP address).

If you use ufw, add these rules to /etc/ufw/before.rules

CategoryHomepage CategoryInTraduzione