I have a Ubuntu 14.04.1 Server system where the interface em1 is bounded to a bridge:

ifconfig em1

em1       Link encap:Ethernet  direcciónHW c4:34:6b:ae:ea:a8
          Paquetes RX:677380321 errores:0 perdidos:0 overruns:0 frame:0
          Paquetes TX:396179860 errores:0 perdidos:0 overruns:0 carrier:0
          colisiones:0 long.colaTX:1000
          Bytes RX:839163556407 (839.1 GB)  TX bytes:372594438191 (372.5 GB)
          Interrupción:64 Memoria:fb800000-fbffffff

ifconfig br0

br0       Link encap:Ethernet  direcciónHW c4:34:6b:ae:ea:a8
          Direc. inet:  Difus.:  Másc:
          Dirección inet6: fe80::c634:6bff:feae:eaa8/64 Alcance:Enlace
          Paquetes RX:147880064 errores:0 perdidos:2217 overruns:0 frame:0
          Paquetes TX:189723115 errores:0 perdidos:0 overruns:0 carrier:0
          colisiones:0 long.colaTX:0
          Bytes RX:797220818733 (797.2 GB)  TX bytes:225007583950 (225.0 GB)

The network is fine but I cannot find the configuration of either the interface or the bridge in the file /etc/network/interfaces whose content is this now (I configured both the interface and the bridge through interfaces file):

# The loopback network interface
auto lo
iface lo inet loopback

I checked is there's some process related to Network Manager but I don't find it.

In addition, the content of the directory /etc/network is this:

ls /etc/network
if-down.d  if-post-down.d  if-pre-up.d  if-up.d  interfaces     interfaces.1479200968  interfaces.1479201325  interfaces.1479203373  run

Not a single file in this directory has configuration of the interfaces.

When could I find the current configuration of the network?

Thank you very much

  • The interfaces file is supposed to source files in interfaces.d/, and that's typically where automatic configurations put interface data (as individual files for interfaces is easier to manage automatically). When you say that the /etc/interfaces file is "this now", do you mean that you filled it with information but now it has nothing? Also, what are the contents of interfaces.1479200968, interfaces.1479201325, and interfaces.1479203373? I suspect you'll probably find your configuration in there. – Spooler Nov 21 '16 at 10:59
  • Yes,I filled interfaces file with the configuration but now for some reason it has the content I've put in my first message. The three files interfaces.* have the same content as interfaces that is "auto lo iface lo inet loopback" – user328339 Nov 21 '16 at 12:11

This is normal By default an Ubuntu desktop system usesNetwork Manager to manage network connections automatically and dynamically. This does not require (and in fact typically requires there not be) entries detailing configuration of your physical interfaces in /etc/network/interfaces.





  • Hi, as far as I know Network Manager is not running. There isn't any package related to Network Manager and there isn't any directories for Network Manager within /etc. – user328339 Nov 21 '16 at 12:24
  • is your internet working now ? – Sukhjinder Singh Nov 22 '16 at 6:34
  • Hi yes, internet works (it never failed) but my problem is that I cannot find the current network configuration (and my system doesn't run NetworkManager). – user328339 Nov 24 '16 at 16:01

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