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Thread: KVM QEMU Virtual Networking - Class A Virtual Network which shouldn't exist?

  1. #1
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    Default KVM QEMU Virtual Networking - Class A Virtual Network which shouldn't exist?

    Hoping someone with KVM virtual networking experience or with more detailed know-how than myself can interpret what I'm looking at, the VMs I'm creating are being setup on a virtual network and access to a virtual DHCP I don't know where from.

    TIA,
    TS

    Setup:
    Host:
    openSUSE 12.1
    KDE
    KVM-QEMU
    virt-tools
    VMware Workstation 8.0
    Ordinarily, there is no active real networking (physically disconnected from network) although I've tried with an active connection also, no diff

    Guest VM :
    Full Virtualization
    openSUSE 11.4/Gnome/nm-applet (changed from ifup/ifdown)

    Problem:
    KVM VM Guest networking is somehow picking up a Class A Private address from some unknown DHCP, need to understand how/why this is happening. The VM can ping the gateway on its virtual network but otherwise cannot communicate beyond the gateway. Since the Class A network does not exist in any of the Host configurations I've displayed below (ifconfig and route), the Host cannot communicate with the VM except using VMM. Curiously, VMM is using TightVNC to communicate with the VM which AFAIK requires TCP/IP but am unable to determine how that is happening.

    Virtual Machine Manager, Virtual Networking Configuration:
    Started default Virtual Network
    Name default
    Device irbr0
    State: Active

    iPv4 configuration
    Network 192.168.122.0/24
    DHCP start 192.168.122.2
    DHCP end: 192.168.122.164
    Forwarding NAT

    Known Virtual Networks
    (From running ifconfig on Host)

    VMware VMnet 192.168.252.0 /24
    VMware VMnet 172.16.16.0 /24
    KVM Netowrking 192.168.122.0 /24

    Host ifconfig and route

    Code:
    openSUSE:/home/User # ifconfig
    eth0      Link encap:Ethernet  HWaddr 00:1B:24:7F:EC:54  
              UP BROADCAST MULTICAST  MTU:1500  Metric:1
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0
              TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
              Interrupt:45 Base address:0xe000 
    
    lo        Link encap:Local Loopback  
              inet addr:127.0.0.1  Mask:255.0.0.0
              inet6 addr: ::1/128 Scope:Host
              UP LOOPBACK RUNNING  MTU:16436  Metric:1
              RX packets:35145 errors:0 dropped:0 overruns:0 frame:0
              TX packets:35145 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0 
              RX bytes:14429052 (13.7 Mb)  TX bytes:14429052 (13.7 Mb)
    
    usb0      Link encap:Ethernet  HWaddr AA:9D:6F:4A:5B:B2  
              inet6 addr: fe80::a89d:6fff:fe4a:5bb2/64 Scope:Link
              UP BROADCAST MULTICAST  MTU:1500  Metric:1
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0
              TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
    
    virbr0    Link encap:Ethernet  HWaddr 00:00:00:00:00:00  
              inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
              UP BROADCAST MULTICAST  MTU:1500  Metric:1
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0
              TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:0 
              RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
    
    vmnet1    Link encap:Ethernet  HWaddr 00:50:56:C0:00:01  
              inet addr:172.16.112.1  Bcast:172.16.112.255  Mask:255.255.255.0                      
              inet6 addr: fe80::250:56ff:fec0:1/64 Scope:Link                                       
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1                                    
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0                                    
              TX packets:35 errors:0 dropped:0 overruns:0 carrier:0                                 
              collisions:0 txqueuelen:1000                                                          
              RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)                                                
                                                                                                    
    vmnet8    Link encap:Ethernet  HWaddr 00:50:56:C0:00:08                                         
              inet addr:192.168.252.1  Bcast:192.168.252.255  Mask:255.255.255.0                    
              inet6 addr: fe80::250:56ff:fec0:8/64 Scope:Link                                       
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1                                    
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0                                    
              TX packets:37 errors:0 dropped:0 overruns:0 carrier:0                                 
              collisions:0 txqueuelen:1000                                                          
              RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)                                                
                                                                                                    
    wlan0     Link encap:Ethernet  HWaddr 00:13:E8:5B:7B:71                                         
              UP BROADCAST MULTICAST  MTU:1500  Metric:1                                            
              RX packets:0 errors:0 dropped:0 overruns:0 frame:0                                    
              TX packets:0 errors:0 dropped:0 overruns:0 carrier:0                                  
              collisions:0 txqueuelen:1000                                                          
              RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)                                                
                                                                                                    
    openSUSE:/home/User # route
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    172.16.112.0    *               255.255.255.0   U     0      0        0 vmnet1
    192.168.122.0   *               255.255.255.0   U     0      0        0 virbr0
    192.168.252.0   *               255.255.255.0   U     0      0        0 vmnet8
    Guest route

    Code:
    linux-4nqz:/home/User/Desktop # route
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    10.0.2.0        *              255.255.255.0    U     1      0        0   eth0
    loopback        *              255.0.0.0        U     0      0        0   lo
    default         10.0.2.2       0.0.0.0          UG    0      0        0   eth0

  2. #2
    Join Date
    Feb 2009
    Location
    Spain
    Posts
    25,547

    Default Re: KVM QEMU Virtual Networking - Class A Virtual Network which shouldn'texist?

    On 2012-06-02 22:46, tsu2 wrote:
    >
    > Hoping someone with KVM virtual networking experience or with more
    > detailed know-how than myself can interpret what I'm looking at, the VMs
    > I'm creating are being setup on a virtual network and access to a
    > virtual DHCP I don't know where from.


    I don't know about KVM, but you are using vmware workstation, and this does
    create such networks.

    There is a "/etc/vmware" directory, and under it there are two directories,
    vmnet1/ and vmnet8/. The dhcp configuration and leases are inside.

    By the way, if you edit that configuration and update to a new version of
    vmware, your changes are deleted. I discovered this just now.


    --
    Cheers / Saludos,

    Carlos E. R.
    (from 11.4 x86_64 "Celadon" at Telcontar)

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