port_forwarding.rb

#!/usr/bin/ruby -w
require 'socket'

server = TCPServer.open(7788)
loop do
  Thread.start(server.accept) do |client|
    client.write "[Host]:[Port]> "
    target = ""
    while s = client.getc.chr
      client.write s
      break if s == "\n" || s == "\r"
      target += s
    end
    target = target.split(":")
    client.write "Connecting to #{target.inspect}...\n"
    remote = TCPSocket.open(target[0], target[1] || 23)
    loop do
      r, w, e = IO.select([client, remote], nil, nil, 0)
      (r || []).each do |f|
        if f == remote
          client.write remote.getc.chr
        else
          remote.write client.getc.chr
        end
      end
    end
  end
end