socat tips (Rails)

A Ruby-on-Rails development app running under localhost on a remote server may be exposed to to public access as follows:

Start a Rails app on the remote server:

rails s

On the remote server execute the following socat command:

socat TCP-LISTEN:8090,fork TCP:localhost:3000

Now the Rails application will be available publicly at:

yourserver.com:8090

For example, if the server is at tomgdow.com, the app will be available at www.johndow.com:8090.

Notes

Netcat may be used to check that all is well

 netcat -z -v localhost 8090  
 » Connection to localhost 8090 port [tcp/*] succeeded!

Alternative method with ssh tunnel

After starting the Rails server, open an ssh tunnel on the remote server:

ssh -R 4000:localhost:3000  janedow@johndow.com -N

In a separate teminal window, use socat to open a port on the server to public access:

socat TCP-LISTEN:8090,fork,reuseaddr TCP-CONNECT:127.0.0.1:4000 &

As for the previous method, the Rails development app is available publicly at yourserver.com:8090.

Notes

janedow@johndow.com are the user credentials on the remote machine

Based on enabling public access to development machine from the development diary of Joon You.

Securely Access a Remote Ruby-on-Rails Development App with ssh

A Ruby-on-Rails development app running under localhost on a remote server may be securely accessed from a local machine as follows:

Start a Rails app on the remote server (port 3000)

rails s

On the local machine execute:

 ssh -N -f -L localhost:4000:localhost:3000 janedow@johndow.com

The Rails application will now be accessible from a local machine at:

localhost:4000

Notes

A password will be required for ssh access to the remote machine

janedow@johndow.com are the user credentials on the remote machine

Find the hostname of the remote machine

ssh -t janedow@johndow.com -- hostname

List the home directory of the remote machine

ssh -t janedow@johndow.com -- ls

Other Useful Commands

lsof -i  # lsof: list open files 
lsof -wni tcp:3000
ps -aux | grep ruby # ps snapshot of current processes
netstat -antlp |grep "LISTEN" | grep 'ruby'

Log for the Creation of a Simple Rails App

This Rails app was created on a Digital Ocean Droplet with Ubuntu as OS

Some preliminaries. (remote server command line)

uname -ro; rails -v; ruby -v; nodejs -v; lynx -version

» 3.13.0-57-generic GNU/Linux
» Rails 4.2.5
» ruby 2.1.1p76 (2014-02-24 revision 45161) [x86_64-linux]
» v0.10.25
» Lynx Version 2.8.8pre.4 (04 Feb 2014)

The Rails project was created as follows

mkdir railsProjects && cd $_
rails new myrailsapp && cd $_
bundle install
rails s        
# Check that all is well:
curl localhost:3000 | grep -i 'Welcome'
» <h1>:Welcome aboard</h1>  # (abridged) 
# Generate a scaffold
rails generate scaffold Product name:string description:text price:float
rake db:migrate
# Set the routes
sed -i "s/'welcome#index'/'products#index'/" config/routes.rb
sed -i 's/#\{1,2\}[[:space:]]\{0,10\}root/\ root/' config/routes.rb
# Open a remote port to public access
socat TCP-LISTEN:8090,fork TCP:localhost:3000
# Check that all is well
netcat -z -v localhost 8090
» Connection to localhost 8090 port [tcp/*] succeeded!
# On browser:
johndow.com:8090 # (ie server-name.com:port-number)
# From the browser, added some products
# The final result was something like the following:Rails Development App on Remote Server

Notes

Lynx, a text web browser, may be used instead of curl to check that all is well

Sed Commands

The sed commands used to programatically change text in config/routes.rb are specific to Ubuntu,and may not work as expected on the Mac OS, as the GNU and BSD versions of sed behave differently
The first command merely changes the default root 'welcome#index' to root 'products#index' in config/routes.rb
The second command uncomments the line (removes the '#') containing the word root in config.rb.
These changes may be easily made with any text editor or IDE, instead of using sed

Local access over ssh

Instead of using socat to open a port to public access, the Rails app was securely accessed over ssh as follows:

# On server:
rails s 
# On local machine:
# (here a Windows 10 computer, using Powershell to execute ssh command.  Putty will work equally well)
ssh -N -f -L localhost:4000:localhost:3000  janedow@johndow.com
# enter password
# On local browser (here Firefox running on Windows 10):
localhost:3000

Socat and ssh Tips for Ruby-on-Rails

Allow Public Access to a Remote Ruby-on-Rails Development App with Socat

Securely Access a Remote Ruby-on-Rails Development App with ssh

Other ssh Tips

Other Useful Commands

Log for the Creation of a Simple Rails App