o [NSE] Added a rsync library and two new script:

+ rsync-list-modules - list available rsync modules
  + rsync-brute - attempts to brute force passwords against a rsync module
  [Patrik]

scripts/rsync-brute.nse

@@ -0,0 +1,103 @@
+description = [[
+Performs brute force password auditing against rsync.
+]]
+
+---
+-- @usage
+-- nmap -p 873 --script rsync-brute --script-args 'rsync-brute.module=www' <ip>
+--
+-- @output
+-- PORT    STATE SERVICE REASON
+-- 873/tcp open  rsync   syn-ack
+-- | rsync-brute: 
+-- |   Accounts
+-- |     user1:laptop - Valid credentials
+-- |     user2:password - Valid credentials
+-- |   Statistics
+-- |_    Performed 1954 guesses in 20 seconds, average tps: 97
+--
+-- @args rsync-brute.module - the module against which brute forcing should be performed
+
+
+require 'shortport'
+require 'brute'
+require 'rsync'
+
+author = "Patrik Karlsson"
+license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
+categories = {"brute", "intrusive"}
+
+portrule = shortport.port_or_service(873, "rsync", "tcp")
+
+Driver = {
+	
+	new = function(self, host, port, options)
+		local o = {	host = host, port = port, options = options	}
+		setmetatable(o, self)
+		self.__index = self
+		return o
+	end,
+	
+	connect = function(self)
+		self.helper = rsync.Helper:new(self.host, self.port, self.options)
+		return self.helper:connect()
+	end,
+	
+	login = function(self, username, password)
+
+		local status, data = self.helper:login(username, password)
+		-- retry unless we have an authentication failed error
+		if( not(status) and data ~= "Authentication failed" ) then
+			local err = brute.Error:new( data )
+			err:setRetry( true )
+			return false, err
+		elseif ( not(status) ) then
+			return false, brute.Error:new( "Login failed" )
+		else
+			return true, brute.Account:new(username, password, creds.State.VALID)
+		end
+	end,
+	
+	disconnect = function( self )
+		return self.helper:disconnect()
+	end		
+		
+}
+
+local function isModuleValid(host, port, module)
+	local helper = rsync.Helper:new(host, port, { module = module })
+	if ( not(helper) ) then
+		return false, "Failed to create helper"
+	end
+	local status, data = helper:connect()
+	if ( not(status) ) then
+		return false, "Failed to connect to server"
+	end
+	status, data = helper:login()
+	if ( status and data == "No authentication was required" ) then
+		return false, data
+	elseif ( not(status) and data == "Authentication required" ) then
+		return true
+	elseif ( not(status) and data == ("Unknown module '%s'"):format(module) ) then
+		return false, data
+	end
+	return false, ("Brute pre-check failed for unknown reason: (%s)"):format(data)
+end
+
+action = function(host, port)
+	
+	local mod = stdnse.get_script_args(SCRIPT_NAME .. ".module")
+	if ( not(mod) ) then
+		return "\n  ERROR: rsync-brute.module was not supplied"
+	end
+	
+	local status, err = isModuleValid(host, port, mod)
+	if ( not(status) ) then
+		return ("\n  ERROR: %s"):format(err)
+	end
+	
+	local engine = brute.Engine:new(Driver, host, port, { module = mod })
+	engine.options.script_name = SCRIPT_NAME
+	status, result = engine:start()
+	return result
+end