Test Automatic Connectivity

Question

I tried Test Automatic Connectivity on 11.04 beta 2 and as I try to follow these instructions:

Using Unity

1. Ensure that NetworkManager is running (computer icon in the notification area) and that no networks are currently connected.
2. Click on Ubuntu Logo and search Terminal.
3. In the terminal, run ifconfig. Verify that only the loopback device ("lo") is listed.
4. Right-click on the NetworkManager icon and ensure that Enable Wireless is checked.
5. After approximately 30 seconds, left-click on the NetworkManager icon. Verify that one or more wireless networks are visible.
6. Select an open (no "shield" symbol next to it) network and left-click it. Verify that the network connection succeeds and that a series of bars replaces the NetworkManager icon.
7. In the terminal, run ifconfig. Verify that a new network interface is listed.
8. In the terminal, run route -n. Note the IP address that is not "0.0.0.0" in the Gateway column.
9. In the terminal, run ping -c 5 [gateway] where [gateway] is the IP address of the Gateway, above. Verify that the command reports "5 packets transmitted, 5 packets received".

In my case It is not only loopback listed:

eth0      Link encap:Ethernet  HWaddr 00:1b:38:b4:3e:a3  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:44 Base address:0xc000 

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:60 errors:0 dropped:0 overruns:0 frame:0
          TX packets:60 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:4496 (4.4 KB)  TX bytes:4496 (4.4 KB)

wlan0     Link encap:Ethernet  HWaddr 00:1b:9e:8e:c8:46  
          inet6 addr: fe80::21b:9eff:fe8e:c846/64 Scope:Link
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:1143 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1193 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:759864 (759.8 KB)  TX bytes:186146 (186.1 KB)

The same thing with Verify Release of Device test. In instruction it's written to get just "lo" in terminal, but I get also eth0:

eth0      Link encap:Ethernet  HWaddr 00:1b:38:b4:3e:a3  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:44 Base address:0xc000 

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:60 errors:0 dropped:0 overruns:0 frame:0
          TX packets:60 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:4496 (4.4 KB)  TX bytes:4496 (4.4 KB)

In instruction it is written, that it should be only loopback. I obviously have more than just "lo". What's the deal with this?

Answer 1

The command ifconfig lists every networking device it finds. So usually the lo-device exists on every computer and you will at least see this. However many computers have a networking card and this is configured at system start. So you see two devices in that case. The name eth0 means ethernet card number 0.

The description above now activates your wireless card. So you see a device called wlan0. On some computers (or with some wireless cards) this name can also be like eth1 or so. The command ifconfig shows you that there are now two (eth0, lo) or three (eth0, wlan0, lo) configured interfaces. Your computer transferred some bytes (see RX bytes and TX bytes) with your wireless card.

However the command ifconfig lists every networking device it is aware of. So in your case it seems quite natural that it shows also the networking card which is probably built into your computer.