Multiple NICs with static IP address, default gateway problems

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Edit /etc/network/interface and remove all but one of the gateway statements.

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hxuanhung
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hxuanhung

Updated on September 17, 2022

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  • hxuanhung
    hxuanhung almost 2 years

    My server is running Ubuntu 10.04 64bit and have 2 NICs, my configuration is one interface for incoming/outgoing traffic of all the KVM guest running on this server, the other interface for different purpose.

    I set both NIC card and the virtual bridge with static IP address; here is my /etc/network/interface

    # The primary network interface
    auto eth0
    iface eth0 inet static
    address 192.168.5.10
    netmask 255.255.255.0
    network 192.168.5.0
    broadcast 192.168.5.255
    gateway 192.168.5.5
    
    auto eth1
    iface eth1 inet static
    address 192.168.5.12
    netmask 255.255.255.0
    network 192.168.3.0
    broadcast 192.168.3.255
    gateway 192.168.5.5
    
    auto br0
    iface br0 inet static
    address 192.168.5.11
    netmask 255.255.255.0
    network 192.168.5.0
    broadcast 192.168.5.255
    gateway 192.168.5.5
    bridge_ports eth1
    bridge_stp off
    bridge_fd 0
    bridge_maxwait 0
    

    and here is my netstat -nr output

    Kernel IP routing table
    Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
    192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
    192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 br0
    192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
    192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0 virbr0
    0.0.0.0         192.168.5.5     0.0.0.0         UG        0 0          0 eth1
    0.0.0.0         192.168.5.5     0.0.0.0         UG        0 0          0 br0
    0.0.0.0         192.168.5.5     0.0.0.0         UG        0 0          0 eth0
    

    I can not access the internet. I manually delete all the default gw using route del and add only 1 default gw for the device eth0 to access the internet

    192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
    192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 br0
    192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
    192.168.122.0   0.0.0.0         255.255.255.0   U         0 0          0 virbr0
    0.0.0.0         192.168.5.5     0.0.0.0         UG        0 0          0 eth0
    

    The problem is when I reboot the server I manually run the route del command again and if I delete the default gw of eth1 in /etc/network/interface all the guest host can not access the internet.

    Please help me how to configure that way

    • Philip
      Philip over 13 years
      Whoa that's one weird configuration... probably not what you were looking for.
  • Steven Monday
    Steven Monday over 13 years
    +1. Also, the config for eth1 appears to be inconsistent. On second thought, eth1 should probably be left unconfigured, since it is slaved to bridge br0.