Comment 18 for bug 455045

Can NetworkManager (ie, gnome's, and its tray applet) do that job?

Aside from that, I don't know. Mind you that when I ran " ifconfig lo" and *had* those lines commented, I didn't have an empty output. I had something similar with what is bellow (which was taken just now, after uncommenting the lines). I'm not sure if there was something in the place of "UP", though.

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:1855 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1855 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:574202 (574.2 KB) TX bytes:574202 (574.2 KB)