Virtual Box port forwarding misery with Ruby Sinatra:4567 / Shotgun:9292

I've got a VirtualBox CentOS 7.0 Guest OS on a Windows Ten Host for the purposes of development, and the port forwarding simply isn't working.

I have a NAT'd network adapter (I can't use Bridged Adapters on this network) and to be fair I am much more comfortable with Bridged Adapters. But everything else works swimmingly. Except the ports 4567 and 9292 will not forward, while port 22 and port 80 work fine.

I have

Added port forwarding on the client for the ports 22,80,4567,9292 in VirtualBox on the NAT'd adapter.
disabled the firewalld on CentOS 7.0 completely (and restarted) then ruled that out
all ports work fine on local host i.e. in the vm localhost:4567 is perfect as is localhost:9292
switched of SELINUX on guest (for good measure)
restarted the whole VM on host systematically every time I did a network->portforward alteration
tried 10.0.2.15:4567 / 10.0.2.15:9292 in a vain attempt to get purchase

all the time I am ssh'd in on port 22 and port 80 works fine

Is this a traffic issue or a firewall issue, is there some sort of network filtering on the VirtualBox interface that's hidden from me?

I'd love some help.

Solution

NB: THE CAUSE IS SHOTGUN/RUBY NOT VirtualBox nor Firewalls nor port forwarding

@Matt fixed this... his link in the comments is correct, the fix to this is one of two things: (it's actually shotgun running ruby in development mode that causes it)

CAUSE:

RUBY running in default set :bind, 'localhost' development mode. (link)

SOLUTION:

RUBY runs with options set :bind, '0.0.0.0' (can also be in the config.ru)

Good news is if you're looking to make localhost:4567 work this is your ticket, add the line set :bind, '0.0.0.0' to your config and you're good to go

ANNOYINGLY IF YOU RUN SHOTGUN THIS ISN'T GOING TO BE PICKED UP

Bad news is if you're looking to make localhost:9292 work shotgun does it's own thing here:

in fact shotgun won't LOOK at those ruby configs, it'll adopt it's own boot strategy, so you have to MAKE shotgun run in --host=0.0.0.0 mode: EG:
# shotgun --server=thin --port=9292 --host=0.0.0.0 config.ru