diff --git a/tools/metasm_shell.rb b/tools/metasm_shell.rb
new file mode 100755
index 0000000000..5328e0da7c
--- /dev/null
+++ b/tools/metasm_shell.rb
@@ -0,0 +1,77 @@
+#!/usr/bin/env ruby
+#
+# This tool provides an easy way to see what opcodes are associated with
+# certain x86 instructions by making use of Metasm!
+#
+
+#    This file is part of Metasm, the Ruby assembly manipulation suite
+#    Copyright (C) 2007 Yoann GUILLOT
+#
+#    Licence is LGPL, see LICENCE in the top-level directory
+
+$:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
+
+require 'metasm'
+
+
+class String
+	@@cpu = Metasm::Ia32.new
+	class << self
+		def cpu()   @@cpu   end
+		def cpu=(c) @@cpu=c end
+	end
+
+	# encodes the current string as a Shellcode, returns the resulting EncodedData
+	def encode_edata
+		s = Metasm::Shellcode.assemble @@cpu, self
+		s.encoded
+	end
+
+	# encodes the current string as a Shellcode, returns the resulting binary String
+	# outputs warnings on unresolved relocations
+	def encode
+		ed = encode_edata
+		if not ed.reloc.empty?
+			puts 'W: encoded string has unresolved relocations: ' + ed.reloc.map { |o, r| r.target.inspect }.join(', ')
+		end
+		ed.fill
+		ed.data
+	end
+
+	# decodes the current string as a Shellcode, with specified base address
+	# returns the resulting Disassembler
+	def decode_blocks(base_addr=0, eip=base_addr)
+		sc = Metasm::Shellcode.decode(self, @@cpu)
+		sc.base_addr = base_addr
+		sc.disassemble(eip)
+	end
+
+	# decodes the current string as a Shellcode, with specified base address
+	# returns the asm source equivallent
+	def decode(base_addr=0, eip=base_addr)
+		decode_blocks(base_addr, eip).to_s
+	end
+end
+
+# get in interactive assembler mode
+def asm
+	puts 'type "exit" or "quit" to quit', 'use ";" for newline', ''
+	while (print "asm> " ; $stdout.flush ; l = gets)
+		break if %w[quit exit].include? l.chomp
+	
+		begin
+			data = l.gsub(';', "\n")
+			next if data.strip.empty?
+			data = data.encode
+			puts '"' + data.unpack('C*').map { |c| '\\x%02x' % c }.join + '"'
+		rescue Metasm::Exception => e
+			puts "Error: #{e.class} #{e.message}"
+		end
+	end
+
+	puts
+end
+
+if __FILE__ == $0
+	asm
+end