diff --git a/lib/rex/post/meterpreter/extensions/stdapi/railgun/railgun.rb b/lib/rex/post/meterpreter/extensions/stdapi/railgun/railgun.rb
index 35770e47f9..2dded94495 100644
--- a/lib/rex/post/meterpreter/extensions/stdapi/railgun/railgun.rb
+++ b/lib/rex/post/meterpreter/extensions/stdapi/railgun/railgun.rb
@@ -277,6 +277,22 @@ class Railgun
 	def const(str)
 		return constant_manager.parse(str)
 	end
+	
+	#
+	# Return an array of windows constants names matching +winconst+
+	#
+	
+	def const_reverse_lookup(winconst,filter_regex=nil)
+		return constant_manager.rev_lookup(winconst,filter_regex)
+	end
+	
+	#
+	# Returns an array of windows error code names for a given windows error code matching +err_code+ 
+	#
+	
+	def error_lookup (err_code,filter_regex=/^ERROR_/)
+		return constant_manager.rev_lookup(err_code,filter_regex)
+	end
 
 	#
 	# The multi-call shorthand (["kernel32", "ExitProcess", [0]])
diff --git a/lib/rex/post/meterpreter/extensions/stdapi/railgun/win_const_manager.rb b/lib/rex/post/meterpreter/extensions/stdapi/railgun/win_const_manager.rb
index 8d4fb7dab1..7f54dea079 100644
--- a/lib/rex/post/meterpreter/extensions/stdapi/railgun/win_const_manager.rb
+++ b/lib/rex/post/meterpreter/extensions/stdapi/railgun/win_const_manager.rb
@@ -70,6 +70,30 @@ class WinConstManager
 	def is_parseable(s)
 		return parse(s) != nil
 	end
+	
+	# looks up a windows constant (integer or hex) and returns an array of matching winconstant names
+	#
+	# this function will NOT throw an exception but return "nil" if it can't find an error code
+	def rev_lookup(winconst, filter_regex=nil)
+		c = winconst.to_i # this is what we're gonna reverse lookup
+		arr = [] # results array
+		@consts.each_pair do |k,v|
+			arr << k if v == c
+		end
+		if filter_regex # this is how we're going to filter the results
+			# in case we get passed a string instead of a Regexp
+			filter_regex = Regexp.new(filter_regex) unless filter_regex.class == Regexp
+			# do the actual filtering
+			arr.select! do |item|
+				item if item =~ filter_regex
+			end
+		end
+		return arr
+	end
+
+	def is_parseable(s)
+		return parse(s) != nil
+	end	
 end
 
 end; end; end; end; end; end
diff --git a/test/modules/post/test/railgun_reverse_lookups.rb b/test/modules/post/test/railgun_reverse_lookups.rb
new file mode 100644
index 0000000000..513cebca38
--- /dev/null
+++ b/test/modules/post/test/railgun_reverse_lookups.rb
@@ -0,0 +1,58 @@
+
+##
+# $Id$
+##
+
+##
+# This file is part of the Metasploit Framework and may be subject to
+# redistribution and commercial restrictions. Please see the Metasploit
+# Framework web site for more information on licensing and terms of use.
+# http://metasploit.com/framework/
+##
+
+require 'msf/core'
+require 'rex'
+
+class Metasploit3 < Msf::Post
+
+	def initialize(info={})
+		super( update_info( info,
+				'Name'          => 'railgun_testing',
+				'Description'   => %q{ This module will test railgun code used in post modules},
+				'License'       => MSF_LICENSE,
+				'Author'        => [ 'kernelsmith'],
+				'Version'       => '$Revision$',
+				'Platform'      => [ 'windows' ]
+			))
+		register_options(
+		[
+				OptInt.new("ERR_CODE" , [true, "Error code to reverse lookup", 0x420]),
+				OptInt.new("WIN_CONST", [true, "Windows constant to reverse lookup", 4]),
+				OptString.new("WCREGEX", [false,"Regexp to apply to constant rev lookup", "^SERVICE"]),
+				OptString.new("ECREGEX", [false,"Regexp to apply to error code lookup", "^ERROR_SERVICE_"]),
+			], self.class)
+
+	end
+
+	def run
+		print_status("Running against session #{datastore["SESSION"]}")
+		print_status("Session type is #{session.type}")
+
+		@rg = session.railgun
+
+		print_status()
+		print_status("TESTING:  const_reverse_lookup on #{datastore['WIN_CONST']} filtering by #{datastore['WCREGEX'].to_s}")
+		results = @rg.const_reverse_lookup(datastore['WIN_CONST'],datastore['WCREGEX'])
+		print_status("RESULTS:  #{results.class} #{results.pretty_inspect}")
+		
+		print_status()
+		print_status("TESTING:  error_lookup on #{datastore['ERR_CODE']} filtering by #{datastore['ECREGEX'].to_s}")
+		results = @rg.error_lookup(datastore['ERR_CODE'],datastore['ECREGEX'])
+		print_status("RESULTS:  #{results.class} #{results.inspect}")
+		
+		print_status()
+		print_status("Testing Complete!")
+	end
+end
+
+