Rails application behind firewall

Hi there!

I have the following problem:
rails app runs on linux server with particular ip.
This ip is not accesible from the internet.
When you enter application url filewall is configed such that it takes
incomming connections on port 80 for that url and forwards them to

so the firewall does the following forwarding:
http://public_app_url:80 -> http://internal_ip:8080/

But when I use redirect_to method it returns http://internal_ip host, so
I get the error.

Is there any solution for this problem?
As far as I know redirect_to uses url_for internally to generate
redirection url. Maybe it is possible to describe this configuration as
mapping in the routes.rb file or should I redefine url_for (redirect_to)