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7 Replies Latest reply: Nov 24, 2011 8:35 AM by 828733 RSS

Oracle VM Server NAT network

828733 Newbie
Currently Being Moderated
Hi,
I have a VM server (v2.2.1) host and I want to set up NAT network for my Virtual Machine guests. I have tried setting this up but could not set this up. I could not find any step by step guide specifying the steps to do this.

Any help is greatly appreciated.


Regards
CP
  • 1. Re: Oracle VM Server NAT network
    Sebastian Solbach (DBA Community) Guru
    Currently Being Moderated
    Hi,

    Standard of OVM Server is to work in Bridged Mode. There is also the possibility to chane this to NAT, but in most cases this is not very favorable.
    I normally remove the XEN default configuration and do anything by hand.

    So remove the following entries from /etc/xen/xend-config.sxp:
    # vi /etc/xen/xend-config.sxp
    
    Uncomment following entries:
    # (network-script network-bridge)
    # (vif-script vif-bridge)
    
    Stop the existing bridges and restart xen:
    # /etc/xen/scripts/network-bridges stop
    # service xend restart
    Then create new bridges with own networks. Xenbr0 is bridges / xenbr1 nated:
    # brctl addbr xenbr0
    # brctl stp xenbr0 off
    # brctl setfd xenbr0 0
    
    # brctl addbr xenbr1
    # brctl stp xenbr1 off
    # brctl setfd xenbr1 0
    
    # ip addr add 192.168.5.1/24 brd + dev xenbr0
    # ip link set up xenbr0
    
    # ip addr add 10.10.5.1/24 brd + dev xenbr1
    # ip link set up xenbr1
    To make this permanent over reboot, you create the following in /etc/sysconfig/network-scripts/ifcfg-xenbr0 and ifcfg-xenbr1.
    # vi /etc/sysconfig/network-scripts/ifcfg-xenbr0
    
    DEVICE=xenbr0
    TYPE=Bridge
    BOOTPROTO=none
    ONBOOT=yes
    IPADDR=192.168.5.1
    NETMASK=255.255.255.0
    BROADCAST=192.168.5.255
    DELAY=0
    STP=off
    
    # vi /etc/sysconfig/network-scripts/ifcfg-xenbr1
    
    DEVICE=xenbr0
    TYPE=Bridge
    BOOTPROTO=none
    ONBOOT=yes
    IPADDR=10.10.5.1
    NETMASK=255.255.255.0
    BROADCAST=10.10.5.255
    DELAY=0
    STP=off
    
    # service network restart
    To enable NAT you need to activate IP forwarding in Dom0 and configure iptable to forward the packages.
    # vi /etc/sysctl.conf
    net.ipv4.ip_forward=1
    
    # sysctl -p              
    
    # iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
    Permanentes Speichern der iptables Regeln:
    # service iptables save
    To test, it should look like:
    # route -na
    Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    192.168.5.0     0.0.0.0         255.255.255.0   U     0      0        0 xenbr0
    10.10.5.0       0.0.0.0         255.255.255.0   U     0      0        0 xenbr1
    192.168.2.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
    169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth0
    0.0.0.0         192.168.2.1     0.0.0.0         UG    0      0        0 eth0
    Regards
    Sebastian
  • 2. Re: Oracle VM Server NAT network
    828733 Newbie
    Currently Being Moderated
    Hi Sebastian,
    I was losing hope on setting this up :)

    Thanks for your quick reply. I will try it out now and post the results.


    Regards
    CP
  • 3. Re: Oracle VM Server NAT network
    828733 Newbie
    Currently Being Moderated
    Hi Sebastian,
    I tried your steps and could set up xenbr1 but it did not work. I do not have connection from inside the Virtual machines :-(.

    Regards
    CP
  • 4. Re: Oracle VM Server NAT network
    Sebastian Solbach (DBA Community) Guru
    Currently Being Moderated
    Hi,

    can you post form Dom0
    brctl show
    ifconfig -a
    route -n

    Then from DomU:
    ifconfig -a
    route -n

    Thx
    Sebastian
  • 5. Re: Oracle VM Server NAT network
    828733 Newbie
    Currently Being Moderated
    Hi Sebastian
    How can I check from Dom0 and DomU?

    What I understand is Dom0 will be the host and DomU will be the guest? Am I right?

    Regards
    CP
  • 6. Re: Oracle VM Server NAT network
    Sebastian Solbach (DBA Community) Guru
    Currently Being Moderated
    Yes.

    Dom0 is the server.
    DomU your guest(s).

    Regards
    Sebastian
  • 7. Re: Oracle VM Server NAT network
    828733 Newbie
    Currently Being Moderated
    Hi Sebastian,
    I just got it resolved today by hit and trial. I tried everything that you suggested and then shut down xenbr0 (default one) . And now I can access the internet from inside my VM. Thanks

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