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This one has been cracking my head for quite a bit and I can't seem to find a decent answer for it, hoping you guys can shed some light to it...

# Loopback interface:
auto lo
iface lo inet loopback


# Ethernet 0 interface:
auto eth0
iface eth0 inet static
    address 10.10.20.100
    netmask 255.255.255.0
    network 10.10.20.0
    broadcast 10.10.20.255
    gateway 10.10.20.1
    dns-nameservers 10.10.20.1 8.8.8.8
    hwaddress ether XXXXXXXX
    dns-search defaultdomain


# Ethernet 1 interface:
auto eth1
iface eth1 inet static
    address 10.10.20.125
    netmask 255.255.255.0
    network 10.10.20.0
    broadcast 10.10.20.255
    gateway 10.10.20.1
    dns-nameservers 10.10.20.1 8.8.8.8
    hwaddress ether XXXXXX
    dns-search defaultdomain

When i reboot the machine i'm able to have the correct ip addresses

eth0      Link encap:Ethernet  HWaddr XXXXXXXXXXXXXX
          inet addr:10.10.20.100  Bcast:10.10.20.255  Mask:255.255.255.0
          inet6 addr: XXXXXXXXXXXXXX/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:27 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:1879 (1.8 KB)  TX bytes:398 (398.0 B)

eth1      Link encap:Ethernet  HWaddr XXXXXXXXXXXXXX
          inet addr:10.10.20.125  Bcast:10.10.20.255  Mask:255.255.255.0
          inet6 addr: XXXXXXXXXXXXXXX/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:69 errors:0 dropped:0 overruns:0 frame:0
          TX packets:113 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:8910 (8.9 KB)  TX bytes:8607 (8.6 KB)

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:304 errors:0 dropped:0 overruns:0 frame:0
          TX packets:304 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:35420 (35.4 KB)  TX bytes:35420 (35.4 KB)

However when I change anything on the networking file i can only get it to apply by doing a machine reboot at the moment (plain stupid workaround)

  • service networking restart doesn't seem to do anything
  • ifdown eth0 && ifup eth0 gives ifdown: interface eth0 not configured RTNETLINK answers: File exists Failed to bring up eth0.
  • ip link set eth0 down && ip link set eth0 up doesn't seem to do anything

How on earth do I make the network pickup the changes, seriously this is getting on my nerves...

I'm using ubuntu 12.04 virtualized using KVM inside an Ubuntu 12.04 Dom0

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2 Answers 2

Old question, I know. But to answer anyway: you cannot have two default gateways. That's where the RTNETLINK answers: File exists error comes from when issuing ifdown and ifup. Remove the gateway 10.10.20.1 line from either eth0 or eth1.

And more general: /etc/init.d/networking restart or service networking restart were never really supported and are not guaranteed to work correctly. The supported way of reconfiguring network interfaces is with ifdown and ifup.

This issue became much more relevant with the release of Ubuntu 14.04. See this discussion for details: https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1301015

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/etc/init.d/networking restart

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