fixed DHCPv6 processing

dhcp_protect.c

 			if ( conf->debug ) printf("this is a relay msg\n");
 			break;
 		default: // all other msgtypes
-			offset += 2; // msg-type, hop-count
+			offset += 4; // msg-type, transaction-id
 	}
 
 	if ( conf->debug ) printf("offset=%i\n",offset);