fix an undefined variable bug in the DTP module

Author: zeroSteiner

modules/auxiliary/spoof/cisco/dtp.rb

@@ -17,7 +17,7 @@ def initialize(info = {})
 			'Description'	=> %q{
 				This module forges DTP packets to initialize a trunk port.
 			},
-			'Author'		=> [ 'Spencer McIntyre <zerosteiner [at] gmail.com>' ],
+			'Author'		=> [ 'Spencer McIntyre' ],
 			'License'		=> MSF_LICENSE,
 			'Actions'     =>
 				[
@@ -54,15 +54,15 @@ def is_mac?(mac)
 
 	def smac
 		@spoof_mac ||= datastore['SMAC']
-		@spoof_mac ||= get_mac(interface) if netifaces_implemented?
+		@spoof_mac ||= get_mac(datastore['INTERFACE']) if netifaces_implemented?
 		return @spoof_mac
 	end
 
 	def run
 		unless smac()
 			print_error 'Source MAC (SMAC) should be defined'
 		else
-			unless is_mac? smac()
+			unless is_mac? smac
 				print_error "Source MAC (SMAC) `#{smac}' is badly formatted."
 			else
 				print_status "Starting DTP spoofing service..."