I spend a lot of time trying to figure out how to correctly implement port forwarding, then I took inspiration from net/ssh/gateway library. I needed a robust solution that works after various possible connection errors. This is what I'm using now, hope it helps:
require 'net/ssh'
ssh_options = ['host', 'login', :password => 'password']
tunnel_port = 2222
begin
run_tunnel_thread = true
tunnel_mutex = Mutex.new
ssh = Net::SSH.start *ssh_options
tunnel_thread = Thread.new do
begin
while run_tunnel_thread do
tunnel_mutex.synchronize { ssh.process 0.01 }
Thread.pass
end
rescue => exc
puts "tunnel thread error: #{exc.message}"
end
end
tunnel_mutex.synchronize do
ssh.forward.local tunnel_port, 'tunnel_host', 22
end
begin
ssh_tunnel = Net::SSH.start 'localhost', 'tunnel_login', :password => 'tunnel_password', :port => tunnel_port
puts ssh_tunnel.exec! 'date'
rescue => exc
puts "tunnel connection error: #{exc.message}"
ensure
ssh_tunnel.close if ssh_tunnel
end
tunnel_mutex.synchronize do
ssh.forward.cancel_local tunnel_port
end
rescue => exc
puts "tunnel error: #{exc.message}"
ensure
run_tunnel_thread = false
tunnel_thread.join if tunnel_thread
ssh.close if ssh
end