Land rapid7#5977, Ignore SMB exceptions during fingerprinting

Author: wchen-r7

lib/msf/core/exploit/smb/client.rb

@@ -327,7 +327,14 @@ def smb_fingerprint
         # Connect to the server if needed
         if not self.simple
           connect()
-          smb_login()
+          # The login method can throw any number of exceptions, we don't
+          # care since we still get the native_lm/native_os.
+          begin
+            smb_login()
+          rescue ::Rex::Proto::SMB::Exceptions::NoReply,
+                 ::Rex::Proto::SMB::Exceptions::ErrorCode,
+                 ::Rex::Proto::SMB::Exceptions::LoginError
+          end
         end
 
         fprint['native_os'] = smb_peer_os()