Can't connect to localhost:3000 0.0.0.0:3000

I'm able to do this:
=> Booting WEBrick
=> Rails 3.2.11 application starting in development on
url http://0.0.0.0:3000 /url
=> Call with -d to detach
=> Ctrl-C to shutdown server
[2013-08-11 13:38:11] INFO WEBrick 1.3.1
[2013-08-11 13:38:11] INFO ruby 1.9.3 (2013-01-15) [x86_64-linux]
[2013-08-11 13:38:11] INFO WEBrick::HTTPServer#start: pid=35 port=3000

But I've been searching forums for a while now but can't seem to get to
the "Welcome aboard, you're riding Ruby on Rails" page. I've tried
0.0.0.0:3000, localhost:3000, and 127.0.0.1:3000 in Safari, Firefox, and
Chrome with my firewall turned off. I also tried doing rails server -p
3001 and changing the above addresses accordingly. Any idea why this
could be?

You have told us what you don't get but you have not told us what you
/do/ get when you try those addresses.

Colin