reverse_ssh.rb

require 'rubygems'
require 'net/ssh'
 
# Run this on the machine (node) which needs to tunnel out to forward the UI to the remote system (console)
Net::SSH.start("remote_host", "remote_user") do |ssh|
  # since we are running sinatra locally we will forward 43210 on the remote_host to our localhost 4567
  # This is effectively the same as:
  # ssh -R 4567:localhost:43210 remote_user@remote_host
  ssh.forward.remote(4567, "localhost", 43210)
  ssh.loop { true }
end
 
# If we wanted to actually forward ssh to the remote all we do is change our local port
# Net::SSH.start("remote_host", "remote_user") do |ssh|
#   ssh.forward.remote(22, "localhost", 43210)
#   ssh.loop { true }
# end

I created a blogpost out of this...http://www.gabekoss.com/blog/2013/11/ssh_port_forwarding_with_ruby_net_ssh/