$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:1d:ba:b1:6c:5e brd ff:ff:ff:ff:ff:ff
inet 192.168.100.7/24 brd 192.168.100.255 scope global eth0
inet6 fe80::21d:baff:feb1:6c5e/64 scope link
valid_lft forever preferred_lft forever
3: wmaster0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
link/ieee802.11 00:22:fb:20:c1:04 brd ff:ff:ff:ff:ff:ff
4: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:22:fb:20:c1:04 brd ff:ff:ff:ff:ff:ff
5: pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
link/ether 12:7e:41:96:2d:ee brd ff:ff:ff:ff:ff:ff
$ cat /etc/network/interfaces
auto lo
iface lo inet loopback