The command netstat -i shows the network interfaces defined on
your machine:
$ netstat -in Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll en0* 2000 127.29.13 127.29.13.9 514 0 534 0 0 lo0 2048 127 127.0.0.1 996 0 996 0 0
The first entry is for the computer's own ethernet. The * next to the entry shows that the interface has been marked down, that is, shut off. Ethernet interfaces are generally labeled en0, le0, or un0. The entry lo0 is the loopback. It is a special software network (no wires) on which the machine talks to itself, as, for example, showing how X Windows communicates with the displays. If the network is marked down, then it may indicate that the system has turned itself off because it found some necessary piece of hardware or software missing. If that is the case, your best approach to solving the problem may be to reboot your workstation. Carefully watch the console for any error messages concerning the network as the machine comes up. (How're your speed reading skills?) Then investigate the indicated problems; it may be as simple as an adapter not responding because of a loose connection that occurred because you moved some wires.