Rails Authentication with OAuth 2.0 and OmniAuth

Hey, thank you for this nice tutorial. Now I’ve completed only up-to Twitter integration, and struck with a problem.

I run rails server inside Virtual Box with Ubuntu server guest. Hence to access rails app from host, I force rails server with this command “rails s -p 80 -b 192.168.x.xx”, So that in host browser entering just IP address will open my rails app and its working fine.
The problem is
In my Twitter app (https://apps.twitter.com/) I have given Website as “http://192.168.x.xx” and Callback URL as “http://192.168.x.xx/auth/twitter/callback”, but when I click twitter link from my app, Its showing error “OAuth::Unauthorized”. After I googled this issue, I found from StackOverflow that it happens when callback URL is wrongly specified. In this tutorial it is suggested to use “http://localhost:3000” which is not possible in my situation.

Any ideas?
Thank you.