Cannot connect to Localhost:3000 for Rails but 127.0.0.1:3000 works

I am learning Ruby on Rails with railstutorial.org and met this strange problem.

I ran "rails server" and the following information showed:

=> Booting WEBrick
=> Rails 4.0.4 application starting in development on
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2014-04-02 01:28:18] INFO WEBrick 1.3.1
[2014-04-02 01:28:18] INFO ruby 2.0.0 (2014-02-24) [x86_64-darwin12.5.0]
[2014-04-02 01:28:18] INFO WEBrick::HTTPServer#start: pid=13004 port=3000

I try connecting to localhost:3000 on various browsers and they all cannot establish a connection to the server.

I also tried rails server -p 3001 and connect to localhost:3001, which failed as well.

However, I tried 0.0.0.0:3000 , 127.0.0.1:3000, both of them worked and rendered the default welcome for rails.

Then I tried localhost:80, which successfully told me "It Works" and I can actually connect to my another local project using PHP+Apache.

So I really wonder why this happens and could anyone possibly give me any hint on it.

Thank you in advance:)

2 Answers

Please check your host file. I assume you are using ubuntu then just type

sudo nano /etc/hosts

If the below line exists then ok else just insert the line.

127.0.0.1 localhost

And use localhost:3000 not Localhost:3000

localhost is just an alias for 127.0.0.1

If localhost:3000 doesn't work, but 127.0.0.1:3000 does, it will likely be the case that you don't have the localhost alias set up (in your hosts file), which is what Sabyasachi Ghosh recommended

If you let us know your operating environment, we'll be able to provide more specific advice