Results 1 to 2 of 2

Thread: Networking problems with KVM/QEMU under 12.04

  1. #1
    Join Date
    Dec 2006
    Location
    Munich, Germany
    Beans
    125
    Distro
    Ubuntu 12.04 Precise Pangolin

    Networking problems with KVM/QEMU under 12.04

    I have just installed a fresh Ubuntu 12.04 on my server. Previously I was using 10.04 (which worked fine), but had a disk crash (on the Root/OS disk), and had ni usable backup.

    I have installed KVM, and have been trying to get my virtual machines to work. I mainly use 2 VMs: one running Ubuntu 9.04, for web, database, and LDAP services, and one running Windows-XP (for MS-Office).

    The VMs will both start, but network access is not working. Neither VM is getting an IP address assigned via DHCP from my Internet modem. Assigning static IP addresses doesn't help much; I can't reach any network resource beyond the host, and port forwarding (set up on the Internet modem) is not working.

    I am using bridged networking for my VMs, so that they can be accessed by external systems. I created a bridge (br0). The host gets an IP address via DHCP, and has working network access. This is the output from the 'brctl show br0' command:

    Code:
    bridge name	bridge id		STP enabled	interfaces
    br0		8000.0019b91573b5	no		eth0
    							tap0
    							tap1
    In this output, tap0 is the Ubuntu 9.04 VM, and tap1 is the XP VM.

    This is my host's interfaces file, which was fine with Ubuntu 10.04:
    Code:
    auto lo
    iface lo inet loopback
    
    auto eth0
    iface eth0 inet manual
    
    auto br0
    iface br0 inet dhcp
            network 192.168.0.0
            netmask 255.255.255.0 
            broadcast 192.168.0.255 
            bridge_ports eth0
            bridge_fd 9
            bridge_hello 2
            bridge_maxage 12
            bridge_stp off
    This is the output from the 'route' command on the host:
    Code:
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    default         192.168.0.1     0.0.0.0         UG    100    0        0 br0
    link-local      *               255.255.0.0     U     1000   0        0 br0
    192.168.0.0     *               255.255.255.0   U     0      0        0 br0
    If it ain't broke, don't fix it.

  2. #2
    Join Date
    Dec 2006
    Location
    Munich, Germany
    Beans
    125
    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: Networking problems with KVM/QEMU under 12.04

    Finally (after 2 days) solved it. Thought I would post the answer, for other forum users.

    I use the Firestarter firewall. In the Firestarter preferences, I set the Internet Connection Sharing to on (pretty sure that I didn't have this set on the 10.04 system), and suddenly everything works OK.
    If it ain't broke, don't fix it.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •