connect.rb

#!/usr/bin/env ruby

require 'yaml'
require 'uri'
require 'socket'
require 'timeout'

def knock(host, ports)
  ports.each do |port|
    puts "Knocking port #{port}"
    begin
      Timeout::timeout(2) do
        begin
          s = TCPSocket.new(host, port)
          s.close
        rescue Errno::ECONNREFUSED, Errno::EHOSTUNREACH

        end
      end
    rescue Timeout::Error

    end
  end
end

host   = ARGV[0]
db     = YAML.load_file(File.expand_path('~/.ssh/connections.yml'))
config = db[host]
uri    = URI.parse(config['uri'])

command = ['ssh']

command << %(-i #{config['keyfile']}) if config['keyfile']
command << %(-p #{uri.port}) if uri.port
command << %(-l #{uri.user}) if uri.user
command << uri.host

if config['knocking']
  knock(uri.host, config['knocking'])
end
exec command.join(' ')