Installation problems on a domain-name-less server

Set server_name to the IP address, eg:

server {
    listen   80;
    server_name 0.1.2.3;
    // other stuff
}

You could also leave it out, because the default in ngninx is an empty string. But then all those pieces in WordPress that don’t validate $_SERVER['SERVER_NAME'] and similar values … will just break.

See ticket #25239 for the progress on this front.

If only WordPress had a Request object, like everyone else. Then it would be easy to prepare all these global values. See Symfony for an example.