Gateway ssh

gwssh.rb

#!/usr/bin/env ruby

# gwssh: ssh via a gateway host. Just use gwssh instead of ssh,
# and your options, commands, etc. will be preserved.

GATEWAY_HOST = 'gate.example.com'
DOMAIN = 'example.com'
DEBUG = false

OPTIONS_WITH_ARGUMENTS = 'bcDeFiLlmOopRSw'

def main
  host = get_hostname
  ssh  = %w{ssh -t -A}

  original_host = host.dup
  unless host =~ /\d+\.\d+\.\d+\.\d+/ || host.end_with?(DOMAIN)
    host += ".#{DOMAIN}"
  end

  args = ARGV.dup
  args[args.index(original_host)] = host

  if host == GATEWAY_HOST
    command = [*ssh, *args]
  else
    command = [*ssh, GATEWAY_HOST, *ssh, *args]
  end

  puts command.inspect if DEBUG
  Kernel.exec(*command)

end

# The hostname will be the first argument that isn't an option (-v)
# and that isn't an argument for an option (-F file).

def get_hostname
  trash = []
  ARGV.each_with_index do |arg, index|
    next if trash.include?(index)

    if arg.start_with?('-')
      trash << index
      if OPTIONS_WITH_ARGUMENTS.include?(arg[1])
        trash << index + 1
      end
    end
  end

  other_args = ARGV.reject.with_index { |_, i| trash.include?(i) }
  other_args.first
end

main