I'm setting up my own test (Cisco) ASA 5505 firewall. I needed to set it up from scratch (software was installed) with the console. Later I used the ASDM application. All the Ethernet interfaces were assigned to the 'inside' interface after basic setup. So I created an 'outside' interface (DHCP client) for port 0/0 and enabled it.
I have the 1200+ page handbook, followed instructions provided there and as far as I can tell things should be working. But no matter what I try, the status of the outside interface is "Interface is down". I'm sure I misconfigured it somewhere, but where exactly would that be?