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  • How can I compute the average cost for this solution of the element uniqueness problem?

    - by Alceu Costa
    In the book Introduction to the Design & Analysis of Algorithms, the following solution is proposed to the element uniqueness problem: ALGORITHM UniqueElements(A[0 .. n-1]) // Determines whether all the elements in a given array are distinct // Input: An array A[0 .. n-1] // Output: Returns "true" if all the elements in A are distinct // and false otherwise. for i := 0 to n - 2 do for j := i + 1 to n - 1 do if A[i] = A[j] return false return true How can I compute the average cost (i.e. number of comparisons for a given n) for this algorithm? What is a reasonable assumption about the input?

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  • Django Problem - trying to access data entered into a form and feed it through a different page

    - by John Hoke
    OK, so let me give you an overview first. I have this site and in it there is a form section. When you access that section you can view or start a new project. Each project has 3-5 different forms. My problem is that I don't want viewers to have to go through all 3-5 pages to see the relevant information they need. Instead I want to give each project a main page where all the essential data entered into the forms is shown as non-editable data. I hope this makes sense. So I need to find a way to access all that data from the different forms for each project and to feed that data into the new page I'll be calling "Main". Each project will have a separate main page for itself. I'm pretty much clueless as to how I should do this, so any help at all would be appreciated. Thanks

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  • How to use TestAndSet() for solving the critical section problem?

    - by Dan Mantyla
    I'm studying for an exam and I'm having difficulty with a concept. This is the pseudo code I am given: int mutex = 0; do { while (TestAndSet(&mutex)); // critical section mutiex = 0; // remainder section } while (TRUE); My instructor says that only two of the three necessary conditions (mutual exclusion, progress, and bounded waiting) are met with this code, but I don't understand which one isn't being met...?? How should the code be modified to support the missing condition to solve the critical region problem? Thanks in advance for any insight!

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  • Association in Entity Framework 4

    - by Marsharks
    I have two tables, a problem table and a problem history table. As you can expect, a problem can have many histories associated with it. CREATE TABLE [dbo].[Problem]( [Last_Update] [datetime] NULL, [Problem_Id] [int] NOT NULL, [Incident_Count] [int] NULL ) ALTER TABLE [dbo].[Problem] ADD CONSTRAINT [PK_Problem] PRIMARY KEY CLUSTERED ( [Problem_Id] ASC ) CREATE TABLE [dbo].[Problem_History]( [Last_Update] [datetime] NULL, [Problem_Id] [int] NOT NULL, [Severity_Chg_Flag] [char](1) NULL ) ALTER TABLE [dbo].[Problem_History] ADD [Create_DateTime] [datetime] NOT NULL ALTER TABLE [dbo].[Problem_History] WITH CHECK ADD CONSTRAINT [FK_Problem_History_Problem] FOREIGN KEY([Problem_Id]) REFERENCES [dbo].[Problem] ([Problem_Id]) The problem is when I drag this into an Entity Model, the associations are not included. Any ideas? I would like to point out that the problem history table has no separate key of its own, it shares the problem id

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  • problem with iOS 4.2 when user press the list view item to go to UIwebview page and the navigation button disappears on the second visit

    - by seahorse
    My app is a Navigation based application. The main menu contains the list view items. if I clicks one of them, it goes to next view which in this case take me to UIwebview embedded web site. Everything is looking great. I can view the content of web page, the navigation control back button which takes to the main menu if I press it. However, I'm having issue when I try to go back to main menu if i visit that subview the second time. It loads the content of UIwebview web page, but the navigation button is gone and won't let me go back to main menu. This problem only appears on latest iOS 4.2 version. Otherwise it works great on 3.1 to 4.1. I would appreciate any hints or inputs. Note this seems not working for subview using UIWebview embedded web content. I don't have any issue with other subviews

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  • A problem with .NET 2.0 project, using a 3.0 DLL which implements WCF services.

    - by avance70
    I made a client for accessing my WCF services in one project, and all classes that work with services inherit from this class: public abstract class ServiceClient<TServiceClient> : IDisposable where TServiceClient : ICommunicationObject This class is where I do stuff like disposing, logging when the client was called, etc. some common stuff which all service classes would normally do. Everything worked fine, until I got the task to implement this on an old system. I got into a problem when I used this project (DLL) in an other project which cannot reference System.ServiceModel (since it's an old .NET 2.0 software that I still maintain, and upgrading it to 3.0 is out of the question). Here, if I omit where TServiceClient : ICommunicationObject then the project can build, but the ServiceClient cannot use, for example, client.Close() or client.State So, is my only solution to drop the where statement, and rewrite the service classes?

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  • C#.NET Problem with locking of page after writing stream to window.

    - by godlikeskills
    The code below works fine, the problem is the 1st two lines are appearing on screen. It basically loads the PDF but I can't see the btnAcceptProposal change name or become enabled. Tried a Thread for the load but it broke. Anyone got any ideas - it's a web application protected void btnPDFProposal_Click(object sender, EventArgs e) { btnAcceptProposal.Enabled = true; btnAcceptProposal.Text = "sss"; byte[] p = Order.Proposal; Response.AppendHeader("content-disposition", "attachment; filename=Proposal.pdf"); Response.ContentType = "Application/pdf"; Response.Clear(); Response.BinaryWrite(p); Response.End(); }

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  • Simple HTML form with POST to SQL function encoding problem?

    - by Spoonk
    Hi again, I have a simple html form that submits information with POST function. But when information contains a Cyrillic characters, in table in MySql there becomes азазаза symbols instead of text. The table is on utf-8_general_ci, the site is on UTF-8 encoding. I visualize the result from this table with $query = " SELECT ".$db->nameQuote('ingredients')." FROM ".$db->nameQuote('other')." ORDER by id DESC "; $db->setQuery($query); $ingredients = $db->loadResult(); I cant understand how to tell the form to send chyrillic characters correct. Or where is the problem at all? How to fetch this characters correctly? Or how to send them correctly?

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  • How is this problem usually solved without using sever-side scripting?

    - by cyggi
    Simple problem I have so far always solved via PHP: You have a site with header, menu, footer and content field. Header, menu and footer are usually the same for each page. How do you, without PHP or any other server-side language, have the header, menu and footer data exist only in one file? So that for example you don't have ten sites (like home.html, products.html, about.html, ..) all having a copy of the static header and menu in their html files. Now if you want to change the header you have to change ten files. I hope I made my question clear enough, if not please leave a comment :)

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  • Drawing problem does ShowWindow(hWnd, SW_HIDE) automatically invalidate rectangles?

    - by wk1989
    Hello, I'm running into a problem where, I have a Window that contains a child window. The child window contains another child window where a video is playing using Windows Media Player. Whenever I do call ShowWindow (hWnd, SW_HIDE) on the parent Window and paint over the entire surface, the region occupied by the grand-child window (where the video was playing) is not overridden. I used spy++ and found that that region which was not overridden was set to hidden BEFORE the repaint occurs. I monitored the hwnd of the grand-child window and it did not seem to receive any WM_EraseBKGND or WM_NCPAINT messages. Does this mean the area it occupied had not been invalidated and therefore could not be drawn over? I'm new to winforms. Thanks!

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  • What is the problem with this code? How to solve it? (fork)

    - by sb2367
    What is the problem with this code? How to solve it? Parent processes goto in if or child process? first code produce zombie process or second code or both or non ? #include <signal.h> #include <sys/wait.h> main() { for (;;) { if (!fork()) { exit(0); } sleep(1); } } what about this code : #include <signal.h> #include <sys/wait.h> main() { for (;;) { if (fork()) { exit(0); } sleep(1); } }

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  • How to overcome case sensitive problem with contains method.??

    - by Srikanth
    Is there any solution to overcome case-sensitive problem for contains method. I have code like below string str = m_name; return avobj.Viewname.Contains(str); Eg: Welcome Here welcome here Both are same names but case is different. If I give 'W' in search box it is returning only 1st one. but I need both names display. I am storing the names in collection. And resultant values ( searched values ) are storing in List.

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  • .NET prerequisites, 3.5sp1 but no 3.5? problem with 4.0?

    - by acidzombie24
    The title is confusing but the problem is not so much. I made a prerequisite with the default 3.5sp1 and windows installer 3.1. I ran it in my VM and to my surprise it asked me to install .NET. I checked the version and i have .NET 2 sp1, 3 sp1, 3.5, and two variants of 4.0 (client and extended beta). I looked in prerequisites and there doesnt seem to be an options for a non 3.5sp1. Is there some way i can select the non sp1? or compile so i dont need sp1? (it crashes upon startup but i am willing to bet i forgot a resource file)

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  • What Counts For A DBA: ESP

    - by Louis Davidson
    Now I don’t want to get religious here, and I’m not going to, but what I’m going to describe in this ‘What Counts for a DBA’ installment sometimes feels like magic. Often  I will spend hours thinking about the solution to a design issue or coding problem, working diligently to try to come up with a solution and then finally just give up with the feeling that I’m not even qualified to be a data entry clerk, much less a data architect.  At this point I often take a walk (or sometimes a nap), and then it hits me. I realize that I have the answer just sitting in my brain, ready to implement.  This phenomenon is not limited to walks either; it can happen almost any time after I stop my obsession about a problem. I call this phenomena ESP (or Extra-Sensory Programming.)  Another term for this could be ‘sleeping on it’, and while the idiom tends to mean to let time pass to actively think about a problem, sleeping on a problem also lets you relax and let your brain do the work. I first noticed this back in my college days when I would play video games for hours on end. We would get stuck deep in some dungeon unable to find a way out, playing for days on end until we were beaten down tired. Once we gave up and walked away, the solution would usually be there waiting for one of us before we came back to play the next day.  Sometimes it would be in the form of a dream, and sometimes it would just be that the problem was now easy to solve when we started to play again.  While it worked great for video games, it never occurred when I studied English Literature for hours on end, or even when I worked for the same sort of frustrating hours attempting to solve a homework problem in Calculus.  I believe that the difference was that I was passionate about the video game, and certainly far less so about homework where people used the word “thou” instead of “you” or x to represent a number. This phenomenon occurs somewhat more often in my current work as a professional data programmer, because I am very passionate about SQL and love those aspects of my career choice.  Every day that I get to draw a new data model to solve a customer issue, or write a complex SELECT statement to ferret out the answer to a complex data question, is a great day. I hope it is the same for any reader of this blog.  But, unfortunately, while the day on a whole is great, a heck of a lot of noise is generated in work life. There are the typical project deadlines, along with the requisite project manager sitting on your shoulders shouting slogans to try to make you to go faster: Add in office politics, and the occasional family issues that permeate the mind, and you lose the ability to think deeply about any problem, not to mention occasionally forgetting your own name.  These office realities coupled with a difficult SQL problem staring at you from your widescreen monitor will slowly suck the life force out of your body, making it seem impossible to solve the problem This is when the walk starts; or a nap. Maybe you hide from the madness under your desk like George Costanza hides from Steinbrenner on Seinfeld.  Forget about the problem. Free your mind from the insanity of the problem and your surroundings. Then let your training and education deep in your brain take over and see if it will passively do the rest for you. If you don’t end up with a solution, the worst case scenario is that you have a bit of exercise or rest, and you won’t have heard the phrase “better is the enemy of good enough” even once…which certainly will do your brain some good. Once you stop expecting whipping your brain for information, inspiration may just strike and instead of a humdrum solution you find a solution you hadn’t even considered, almost magically. So, my beloved manager, next time you have an urgent deadline and you come across me taking a nap, creep away quietly because I’m working, doing some extra-sensory programming.

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  • Many to Many Logic in ASP.NET MVC

    - by Jonathan Stowell
    Hi All, I will restrict this to the three tables I am trying to work with Problem, Communications, and ProbComms. The scenario is that a Student may have many Problems concurrently which may affect their studies. Lecturers may have future communications with a student after an initial problem is logged, however as a Student may have multiple Problems the Lecturer may decide that the discussion they had is related to more than one Problem. Here is a screenshot of the LINQ representation of my DB: LINQ Screenshot At the moment in my StudentController I have a StudentFormViewModel Class: // //ViewModel Class public class StudentFormViewModel { IProbCommRepository probCommRepository; // Properties public Student Student { get; private set; } public IEnumerable<ProbComm> ProbComm { get; private set; } // // Dependency Injection enabled constructors public StudentFormViewModel(Student student, IEnumerable<ProbComm> probComm) : this(new ProbCommRepository()) { this.Student = student; this.ProbComm = probComm; } public StudentFormViewModel(IProbCommRepository pRepository) { probCommRepository = pRepository; } } When I go to the Students Detail Page this runs: public ActionResult Details(string id) { StudentFormViewModel viewdata = new StudentFormViewModel(studentRepository.GetStudent(id), probCommRepository.FindAllProblemComms(id)); if (viewdata == null) return View("NotFound"); else return View(viewdata); } The GetStudent works fine and returns an instance of the student to output on the page, below the student I output all problems logged against them, but underneath these problems I want to show the communications related to the Problem. The LINQ I am using for ProbComms is This is located in the Model class ProbCommRepository, and accessed via a IProbCommRepository interface: public IQueryable<ProbComm> FindAllProblemComms(string studentEmail) { return (from p in db.ProbComms where p.Problem.StudentEmail.Equals(studentEmail) orderby p.Problem.ProblemDateTime select p); } However for example if I have this data in the ProbComms table: ProblemID CommunicationID 1 1 1 2 The query returns two rows so I assume I somehow have to groupby Problem or ProblemID but I am not too sure how to do this with the way I have built things as the return type has to be ProbComm for the query as thats what Model class its located in. When it comes to the view the Details.aspx calls two partial views each passing the relevant view data through, StudentDetails works fine page: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MitigatingCircumstances.Controllers.StudentFormViewModel>" %> <% Html.RenderPartial("StudentDetails", this.ViewData.Model.Student); %> <% Html.RenderPartial("StudentProblems", this.ViewData.Model.ProbComm); %> StudentProblems uses a foreach loop to loop through records in the Model and I am trying another foreach loop to output the communication details: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<IEnumerable<MitigatingCircumstances.Models.ProbComm>>" %> <script type="text/javascript" language="javascript"> $(document).ready(function() { $("DIV.ContainerPanel > DIV.collapsePanelHeader > DIV.ArrowExpand").toggle( function() { $(this).parent().next("div.Content").show("slow"); $(this).attr("class", "ArrowClose"); }, function() { $(this).parent().next("div.Content").hide("slow"); $(this).attr("class", "ArrowExpand"); }); }); </script> <div class="studentProblems"> <% var i = 0; foreach (var item in Model) { %> <div id="ContainerPanel<%= i = i + 1 %>" class="ContainerPanel"> <div id="header<%= i = i + 1 %>" class="collapsePanelHeader"> <div id="dvHeaderText<%= i = i + 1 %>" class="HeaderContent"><%= Html.Encode(String.Format("{0:dd/MM/yyyy}", item.Problem.ProblemDateTime))%></div> <div id="dvArrow<%= i = i + 1 %>" class="ArrowExpand"></div> </div> <div id="dvContent<%= i = i + 1 %>" class="Content" style="display: none"> <p> Type: <%= Html.Encode(item.Problem.CommunicationType.TypeName) %> </p> <p> Problem Outline: <%= Html.Encode(item.Problem.ProblemOutline)%> </p> <p> Mitigating Circumstance Form: <%= Html.Encode(item.Problem.MCF)%> </p> <p> Mitigating Circumstance Level: <%= Html.Encode(item.Problem.MitigatingCircumstanceLevel.MCLevel)%> </p> <p> Absent From: <%= Html.Encode(String.Format("{0:g}", item.Problem.AbsentFrom))%> </p> <p> Absent Until: <%= Html.Encode(String.Format("{0:g}", item.Problem.AbsentUntil))%> </p> <p> Requested Follow Up: <%= Html.Encode(String.Format("{0:g}", item.Problem.RequestedFollowUp))%> </p> <p>Problem Communications</p> <% foreach (var comm in Model) { %> <p> <% if (item.Problem.ProblemID == comm.ProblemID) { %> <%= Html.Encode(comm.ProblemCommunication.CommunicationOutline)%> <% } %> </p> <% } %> </div> </div> <br /> <% } %> </div> The issue is that using the example data before the Model has two records for the same problem as there are two communications for that problem, therefore duplicating the output. Any help with this would be gratefully appreciated. Thanks, Jon

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  • Many to Many with LINQ-To-Sql and ASP.NET MVC

    - by Jonathan Stowell
    Hi All, I will restrict this to the three tables I am trying to work with Problem, Communications, and ProbComms. The scenario is that a Student may have many Problems concurrently which may affect their studies. Lecturers may have future communications with a student after an initial problem is logged, however as a Student may have multiple Problems the Lecturer may decide that the discussion they had is related to more than one Problem. Here is a screenshot of the LINQ-To-Sql representation of my DB: LINQ-To-Sql Screenshot At the moment in my StudentController I have a StudentFormViewModel Class: // //ViewModel Class public class StudentFormViewModel { IProbCommRepository probCommRepository; // Properties public Student Student { get; private set; } public IEnumerable<ProbComm> ProbComm { get; private set; } // // Dependency Injection enabled constructors public StudentFormViewModel(Student student, IEnumerable<ProbComm> probComm) : this(new ProbCommRepository()) { this.Student = student; this.ProbComm = probComm; } public StudentFormViewModel(IProbCommRepository pRepository) { probCommRepository = pRepository; } } When I go to the Students Detail Page this runs: public ActionResult Details(string id) { StudentFormViewModel viewdata = new StudentFormViewModel(studentRepository.GetStudent(id), probCommRepository.FindAllProblemComms(id)); if (viewdata == null) return View("NotFound"); else return View(viewdata); } The GetStudent works fine and returns an instance of the student to output on the page, below the student I output all problems logged against them, but underneath these problems I want to show the communications related to the Problem. The LINQ I am using for ProbComms is This is located in the Model class ProbCommRepository, and accessed via a IProbCommRepository interface: public IQueryable<ProbComm> FindAllProblemComms(string studentEmail) { return (from p in db.ProbComms where p.Problem.StudentEmail.Equals(studentEmail) orderby p.Problem.ProblemDateTime select p); } However for example if I have this data in the ProbComms table: ProblemID CommunicationID 1 1 1 2 The query returns two rows so I assume I somehow have to groupby Problem or ProblemID but I am not too sure how to do this with the way I have built things as the return type has to be ProbComm for the query as thats what Model class its located in. When it comes to the view the Details.aspx calls two partial views each passing the relevant view data through, StudentDetails works fine page: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<MitigatingCircumstances.Controllers.StudentFormViewModel>" %> <% Html.RenderPartial("StudentDetails", this.ViewData.Model.Student); %> <% Html.RenderPartial("StudentProblems", this.ViewData.Model.ProbComm); %> StudentProblems uses a foreach loop to loop through records in the Model and I am trying another foreach loop to output the communication details: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<IEnumerable<MitigatingCircumstances.Models.ProbComm>>" %> <script type="text/javascript" language="javascript"> $(document).ready(function() { $("DIV.ContainerPanel > DIV.collapsePanelHeader > DIV.ArrowExpand").toggle( function() { $(this).parent().next("div.Content").show("slow"); $(this).attr("class", "ArrowClose"); }, function() { $(this).parent().next("div.Content").hide("slow"); $(this).attr("class", "ArrowExpand"); }); }); </script> <div class="studentProblems"> <% var i = 0; foreach (var item in Model) { %> <div id="ContainerPanel<%= i = i + 1 %>" class="ContainerPanel"> <div id="header<%= i = i + 1 %>" class="collapsePanelHeader"> <div id="dvHeaderText<%= i = i + 1 %>" class="HeaderContent"><%= Html.Encode(String.Format("{0:dd/MM/yyyy}", item.Problem.ProblemDateTime))%></div> <div id="dvArrow<%= i = i + 1 %>" class="ArrowExpand"></div> </div> <div id="dvContent<%= i = i + 1 %>" class="Content" style="display: none"> <p> Type: <%= Html.Encode(item.Problem.CommunicationType.TypeName) %> </p> <p> Problem Outline: <%= Html.Encode(item.Problem.ProblemOutline)%> </p> <p> Mitigating Circumstance Form: <%= Html.Encode(item.Problem.MCF)%> </p> <p> Mitigating Circumstance Level: <%= Html.Encode(item.Problem.MitigatingCircumstanceLevel.MCLevel)%> </p> <p> Absent From: <%= Html.Encode(String.Format("{0:g}", item.Problem.AbsentFrom))%> </p> <p> Absent Until: <%= Html.Encode(String.Format("{0:g}", item.Problem.AbsentUntil))%> </p> <p> Requested Follow Up: <%= Html.Encode(String.Format("{0:g}", item.Problem.RequestedFollowUp))%> </p> <p>Problem Communications</p> <% foreach (var comm in Model) { %> <p> <% if (item.Problem.ProblemID == comm.ProblemID) { %> <%= Html.Encode(comm.ProblemCommunication.CommunicationOutline)%> <% } %> </p> <% } %> </div> </div> <br /> <% } %> </div> The issue is that using the example data before the Model has two records for the same problem as there are two communications for that problem, therefore duplicating the output. Any help with this would be gratefully appreciated. Thanks, Jon

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  • Bizarre Son of Suckerfish ie6/ie7 problem - 2 letters from right-most dropdown menu also appearing o

    - by Kevin Burke
    I'm interning for an NGO in India and trying to fix their website, including updating their menu so it's not the last item on the page to load, and it's centered on the screen. Everything works well enough but when I try out my new menu in IE6, I get this weird error where the content below the menu is padded an extra 30px or so and the material in the right-most drop down appears on the far left of the screen, always visible. When I drop down the rightmost link ("Publications") the content appears both in the correct location and in the same spot on the far left of the screen, and changes color when I hover as well. It's tough to describe, so it would probably be best if you took a look: visit http://sevamandir.org/a30/aboutus.htm in your IE6/IE7 browser to see for yourself. I really appreciate your help. Also I'm using a 1000px wide monitor, if there's more hijinks going on outside that space I'd like to know about that too. I took a look at the problem again and it's even weirder than I thought. Only two letters of the bottom-most drop down menu item are shown, no matter how many items are in the left-most drop down menu. When I delete the left-most drop down menu, the bottom item from the next left-most item shows up in the same space. The padding between the menu and the content is always the same. When I hover over the real menu item, the two letters on the left hand side change color to match the hover color. Unfortunately many people that visit our website are using old browsers so IE6 support is pretty crucial, this problem is really weird though, and I would appreciate some help. I uploaded a file with the entire style.css sheet in the and HTML code below, at http://sevamandir.org/a30/aboutus.htm. Here's the relevant code: in the html head: <script> sfHover = function() { var sfEls = document.getElementById("nav").getElementsByTagName("LI"); for (var i=0; i<sfEls.length; i++) { sfEls[i].onmouseover=function() { this.className+=" sfhover"; } sfEls[i].onmouseout=function() { this.className=this.className.replace(new RegExp(" sfhover\\b"), ""); } } } if (window.attachEvent) window.attachEvent("onload", sfHover); </script> text surrounding the menu - the menu is simply <ul id="nav"><li></li></ul> etc. <!--begin catchphrase--> <div style="float:left; height:27px; width:520px; margin:0px; font:16px Arial, Helvetica, sans-serif; font-weight:bold; color:#769841;"> Transforming lives through democratic &amp; participatory development </div> <?php include("menu.php"); ?> </div><!-- end header --> <!--begin main text div--> <div id="maincontent"> Relevant menu CSS: #nav, #nav ul { font:bold 11px Verdana, sans-serif; float: left; width: 980px; list-style: none; line-height: 1; background: white; font-weight: bold; padding: 0; border: solid #769841; border-width: 0; margin: 0 0 1em 0; } #nav a { display: block; width: 140px; /*this is the total width of the upper menu*/ w\idth: 120px; /*this is the width less horizontal padding */ padding: 5px 10px 5px 10px; /*horiz padding is the 2nd & 4th items here - goes Top Right Bottom Left */ color: #ffffff; background:#b6791e; text-decoration: none; } #nav a.daddy { background: url(rightarrow2.gif) center right no-repeat; } #nav li { float: left; padding: 0; width: 140px; /*this needs to be updated to match top #nav a */ background:#b6791e; } #nav li:hover, #nav li a:hover, #nav li:hover a { background:#769841; } #nav li:hover li a { background:#ffffff; color:#769841; } #nav li ul { position: absolute; left: -999em; height: auto; width: 14.4em; w\idth: 13.9em; font-weight: bold; border-width: 0.25em; /*green border around dropdown menu*/ margin: 0; } #nav li ul a { background:#ffffff; color:#769841; } #nav li li { padding-right: 1em; width: 13em; background:#ffffff; } #nav li ul a { width: 13em; w\idth: 9em; } #nav li ul ul { margin: -1.75em 0 0 14em; } #nav li:hover ul ul, #nav li:hover ul ul ul, #nav li.sfhover ul ul, #nav li.sfhover ul ul ul { left: -999em; } #nav li:hover ul, #nav li li:hover ul, #nav li li li:hover ul, #nav li.sfhover ul, #nav li li.sfhover ul, #nav li li li.sfhover ul { left: auto; } #nav li:hover, #nav li.sfhover, { background: #769841; color:#ffe400; } #nav li a:hover, #nav li li a:hover, #nav li:hover li:hover, #nav li.sfhover a:hover { background: #769841; color:#ffe400; }

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  • Toorcon14

    - by danx
    Toorcon 2012 Information Security Conference San Diego, CA, http://www.toorcon.org/ Dan Anderson, October 2012 It's almost Halloween, and we all know what that means—yes, of course, it's time for another Toorcon Conference! Toorcon is an annual conference for people interested in computer security. This includes the whole range of hackers, computer hobbyists, professionals, security consultants, press, law enforcement, prosecutors, FBI, etc. We're at Toorcon 14—see earlier blogs for some of the previous Toorcon's I've attended (back to 2003). This year's "con" was held at the Westin on Broadway in downtown San Diego, California. The following are not necessarily my views—I'm just the messenger—although I could have misquoted or misparaphrased the speakers. Also, I only reviewed some of the talks, below, which I attended and interested me. MalAndroid—the Crux of Android Infections, Aditya K. Sood Programming Weird Machines with ELF Metadata, Rebecca "bx" Shapiro Privacy at the Handset: New FCC Rules?, Valkyrie Hacking Measured Boot and UEFI, Dan Griffin You Can't Buy Security: Building the Open Source InfoSec Program, Boris Sverdlik What Journalists Want: The Investigative Reporters' Perspective on Hacking, Dave Maas & Jason Leopold Accessibility and Security, Anna Shubina Stop Patching, for Stronger PCI Compliance, Adam Brand McAfee Secure & Trustmarks — a Hacker's Best Friend, Jay James & Shane MacDougall MalAndroid—the Crux of Android Infections Aditya K. Sood, IOActive, Michigan State PhD candidate Aditya talked about Android smartphone malware. There's a lot of old Android software out there—over 50% Gingerbread (2.3.x)—and most have unpatched vulnerabilities. Of 9 Android vulnerabilities, 8 have known exploits (such as the old Gingerbread Global Object Table exploit). Android protection includes sandboxing, security scanner, app permissions, and screened Android app market. The Android permission checker has fine-grain resource control, policy enforcement. Android static analysis also includes a static analysis app checker (bouncer), and a vulnerablity checker. What security problems does Android have? User-centric security, which depends on the user to grant permission and make smart decisions. But users don't care or think about malware (the're not aware, not paranoid). All they want is functionality, extensibility, mobility Android had no "proper" encryption before Android 3.0 No built-in protection against social engineering and web tricks Alternative Android app markets are unsafe. Simply visiting some markets can infect Android Aditya classified Android Malware types as: Type A—Apps. These interact with the Android app framework. For example, a fake Netflix app. Or Android Gold Dream (game), which uploads user files stealthy manner to a remote location. Type K—Kernel. Exploits underlying Linux libraries or kernel Type H—Hybrid. These use multiple layers (app framework, libraries, kernel). These are most commonly used by Android botnets, which are popular with Chinese botnet authors What are the threats from Android malware? These incude leak info (contacts), banking fraud, corporate network attacks, malware advertising, malware "Hackivism" (the promotion of social causes. For example, promiting specific leaders of the Tunisian or Iranian revolutions. Android malware is frequently "masquerated". That is, repackaged inside a legit app with malware. To avoid detection, the hidden malware is not unwrapped until runtime. The malware payload can be hidden in, for example, PNG files. Less common are Android bootkits—there's not many around. What they do is hijack the Android init framework—alteering system programs and daemons, then deletes itself. For example, the DKF Bootkit (China). Android App Problems: no code signing! all self-signed native code execution permission sandbox — all or none alternate market places no robust Android malware detection at network level delayed patch process Programming Weird Machines with ELF Metadata Rebecca "bx" Shapiro, Dartmouth College, NH https://github.com/bx/elf-bf-tools @bxsays on twitter Definitions. "ELF" is an executable file format used in linking and loading executables (on UNIX/Linux-class machines). "Weird machine" uses undocumented computation sources (I think of them as unintended virtual machines). Some examples of "weird machines" are those that: return to weird location, does SQL injection, corrupts the heap. Bx then talked about using ELF metadata as (an uintended) "weird machine". Some ELF background: A compiler takes source code and generates a ELF object file (hello.o). A static linker makes an ELF executable from the object file. A runtime linker and loader takes ELF executable and loads and relocates it in memory. The ELF file has symbols to relocate functions and variables. ELF has two relocation tables—one at link time and another one at loading time: .rela.dyn (link time) and .dynsym (dynamic table). GOT: Global Offset Table of addresses for dynamically-linked functions. PLT: Procedure Linkage Tables—works with GOT. The memory layout of a process (not the ELF file) is, in order: program (+ heap), dynamic libraries, libc, ld.so, stack (which includes the dynamic table loaded into memory) For ELF, the "weird machine" is found and exploited in the loader. ELF can be crafted for executing viruses, by tricking runtime into executing interpreted "code" in the ELF symbol table. One can inject parasitic "code" without modifying the actual ELF code portions. Think of the ELF symbol table as an "assembly language" interpreter. It has these elements: instructions: Add, move, jump if not 0 (jnz) Think of symbol table entries as "registers" symbol table value is "contents" immediate values are constants direct values are addresses (e.g., 0xdeadbeef) move instruction: is a relocation table entry add instruction: relocation table "addend" entry jnz instruction: takes multiple relocation table entries The ELF weird machine exploits the loader by relocating relocation table entries. The loader will go on forever until told to stop. It stores state on stack at "end" and uses IFUNC table entries (containing function pointer address). The ELF weird machine, called "Brainfu*k" (BF) has: 8 instructions: pointer inc, dec, inc indirect, dec indirect, jump forward, jump backward, print. Three registers - 3 registers Bx showed example BF source code that implemented a Turing machine printing "hello, world". More interesting was the next demo, where bx modified ping. Ping runs suid as root, but quickly drops privilege. BF modified the loader to disable the library function call dropping privilege, so it remained as root. Then BF modified the ping -t argument to execute the -t filename as root. It's best to show what this modified ping does with an example: $ whoami bx $ ping localhost -t backdoor.sh # executes backdoor $ whoami root $ The modified code increased from 285948 bytes to 290209 bytes. A BF tool compiles "executable" by modifying the symbol table in an existing ELF executable. The tool modifies .dynsym and .rela.dyn table, but not code or data. Privacy at the Handset: New FCC Rules? "Valkyrie" (Christie Dudley, Santa Clara Law JD candidate) Valkyrie talked about mobile handset privacy. Some background: Senator Franken (also a comedian) became alarmed about CarrierIQ, where the carriers track their customers. Franken asked the FCC to find out what obligations carriers think they have to protect privacy. The carriers' response was that they are doing just fine with self-regulation—no worries! Carriers need to collect data, such as missed calls, to maintain network quality. But carriers also sell data for marketing. Verizon sells customer data and enables this with a narrow privacy policy (only 1 month to opt out, with difficulties). The data sold is not individually identifiable and is aggregated. But Verizon recommends, as an aggregation workaround to "recollate" data to other databases to identify customers indirectly. The FCC has regulated telephone privacy since 1934 and mobile network privacy since 2007. Also, the carriers say mobile phone privacy is a FTC responsibility (not FCC). FTC is trying to improve mobile app privacy, but FTC has no authority over carrier / customer relationships. As a side note, Apple iPhones are unique as carriers have extra control over iPhones they don't have with other smartphones. As a result iPhones may be more regulated. Who are the consumer advocates? Everyone knows EFF, but EPIC (Electrnic Privacy Info Center), although more obsecure, is more relevant. What to do? Carriers must be accountable. Opt-in and opt-out at any time. Carriers need incentive to grant users control for those who want it, by holding them liable and responsible for breeches on their clock. Location information should be added current CPNI privacy protection, and require "Pen/trap" judicial order to obtain (and would still be a lower standard than 4th Amendment). Politics are on a pro-privacy swing now, with many senators and the Whitehouse. There will probably be new regulation soon, and enforcement will be a problem, but consumers will still have some benefit. Hacking Measured Boot and UEFI Dan Griffin, JWSecure, Inc., Seattle, @JWSdan Dan talked about hacking measured UEFI boot. First some terms: UEFI is a boot technology that is replacing BIOS (has whitelisting and blacklisting). UEFI protects devices against rootkits. TPM - hardware security device to store hashs and hardware-protected keys "secure boot" can control at firmware level what boot images can boot "measured boot" OS feature that tracks hashes (from BIOS, boot loader, krnel, early drivers). "remote attestation" allows remote validation and control based on policy on a remote attestation server. Microsoft pushing TPM (Windows 8 required), but Google is not. Intel TianoCore is the only open source for UEFI. Dan has Measured Boot Tool at http://mbt.codeplex.com/ with a demo where you can also view TPM data. TPM support already on enterprise-class machines. UEFI Weaknesses. UEFI toolkits are evolving rapidly, but UEFI has weaknesses: assume user is an ally trust TPM implicitly, and attached to computer hibernate file is unprotected (disk encryption protects against this) protection migrating from hardware to firmware delays in patching and whitelist updates will UEFI really be adopted by the mainstream (smartphone hardware support, bank support, apathetic consumer support) You Can't Buy Security: Building the Open Source InfoSec Program Boris Sverdlik, ISDPodcast.com co-host Boris talked about problems typical with current security audits. "IT Security" is an oxymoron—IT exists to enable buiness, uptime, utilization, reporting, but don't care about security—IT has conflict of interest. There's no Magic Bullet ("blinky box"), no one-size-fits-all solution (e.g., Intrusion Detection Systems (IDSs)). Regulations don't make you secure. The cloud is not secure (because of shared data and admin access). Defense and pen testing is not sexy. Auditors are not solution (security not a checklist)—what's needed is experience and adaptability—need soft skills. Step 1: First thing is to Google and learn the company end-to-end before you start. Get to know the management team (not IT team), meet as many people as you can. Don't use arbitrary values such as CISSP scores. Quantitive risk assessment is a myth (e.g. AV*EF-SLE). Learn different Business Units, legal/regulatory obligations, learn the business and where the money is made, verify company is protected from script kiddies (easy), learn sensitive information (IP, internal use only), and start with low-hanging fruit (customer service reps and social engineering). Step 2: Policies. Keep policies short and relevant. Generic SANS "security" boilerplate policies don't make sense and are not followed. Focus on acceptable use, data usage, communications, physical security. Step 3: Implementation: keep it simple stupid. Open source, although useful, is not free (implementation cost). Access controls with authentication & authorization for local and remote access. MS Windows has it, otherwise use OpenLDAP, OpenIAM, etc. Application security Everyone tries to reinvent the wheel—use existing static analysis tools. Review high-risk apps and major revisions. Don't run different risk level apps on same system. Assume host/client compromised and use app-level security control. Network security VLAN != segregated because there's too many workarounds. Use explicit firwall rules, active and passive network monitoring (snort is free), disallow end user access to production environment, have a proxy instead of direct Internet access. Also, SSL certificates are not good two-factor auth and SSL does not mean "safe." Operational Controls Have change, patch, asset, & vulnerability management (OSSI is free). For change management, always review code before pushing to production For logging, have centralized security logging for business-critical systems, separate security logging from administrative/IT logging, and lock down log (as it has everything). Monitor with OSSIM (open source). Use intrusion detection, but not just to fulfill a checkbox: build rules from a whitelist perspective (snort). OSSEC has 95% of what you need. Vulnerability management is a QA function when done right: OpenVas and Seccubus are free. Security awareness The reality is users will always click everything. Build real awareness, not compliance driven checkbox, and have it integrated into the culture. Pen test by crowd sourcing—test with logging COSSP http://www.cossp.org/ - Comprehensive Open Source Security Project What Journalists Want: The Investigative Reporters' Perspective on Hacking Dave Maas, San Diego CityBeat Jason Leopold, Truthout.org The difference between hackers and investigative journalists: For hackers, the motivation varies, but method is same, technological specialties. For investigative journalists, it's about one thing—The Story, and they need broad info-gathering skills. J-School in 60 Seconds: Generic formula: Person or issue of pubic interest, new info, or angle. Generic criteria: proximity, prominence, timeliness, human interest, oddity, or consequence. Media awareness of hackers and trends: journalists becoming extremely aware of hackers with congressional debates (privacy, data breaches), demand for data-mining Journalists, use of coding and web development for Journalists, and Journalists busted for hacking (Murdock). Info gathering by investigative journalists include Public records laws. Federal Freedom of Information Act (FOIA) is good, but slow. California Public Records Act is a lot stronger. FOIA takes forever because of foot-dragging—it helps to be specific. Often need to sue (especially FBI). CPRA is faster, and requests can be vague. Dumps and leaks (a la Wikileaks) Journalists want: leads, protecting ourselves, our sources, and adapting tools for news gathering (Google hacking). Anonomity is important to whistleblowers. They want no digital footprint left behind (e.g., email, web log). They don't trust encryption, want to feel safe and secure. Whistleblower laws are very weak—there's no upside for whistleblowers—they have to be very passionate to do it. Accessibility and Security or: How I Learned to Stop Worrying and Love the Halting Problem Anna Shubina, Dartmouth College Anna talked about how accessibility and security are related. Accessibility of digital content (not real world accessibility). mostly refers to blind users and screenreaders, for our purpose. Accessibility is about parsing documents, as are many security issues. "Rich" executable content causes accessibility to fail, and often causes security to fail. For example MS Word has executable format—it's not a document exchange format—more dangerous than PDF or HTML. Accessibility is often the first and maybe only sanity check with parsing. They have no choice because someone may want to read what you write. Google, for example, is very particular about web browser you use and are bad at supporting other browsers. Uses JavaScript instead of links, often requiring mouseover to display content. PDF is a security nightmare. Executible format, embedded flash, JavaScript, etc. 15 million lines of code. Google Chrome doesn't handle PDF correctly, causing several security bugs. PDF has an accessibility checker and PDF tagging, to help with accessibility. But no PDF checker checks for incorrect tags, untagged content, or validates lists or tables. None check executable content at all. The "Halting Problem" is: can one decide whether a program will ever stop? The answer, in general, is no (Rice's theorem). The same holds true for accessibility checkers. Language-theoretic Security says complicated data formats are hard to parse and cannot be solved due to the Halting Problem. W3C Web Accessibility Guidelines: "Perceivable, Operable, Understandable, Robust" Not much help though, except for "Robust", but here's some gems: * all information should be parsable (paraphrasing) * if not parsable, cannot be converted to alternate formats * maximize compatibility in new document formats Executible webpages are bad for security and accessibility. They say it's for a better web experience. But is it necessary to stuff web pages with JavaScript for a better experience? A good example is The Drudge Report—it has hand-written HTML with no JavaScript, yet drives a lot of web traffic due to good content. A bad example is Google News—hidden scrollbars, guessing user input. Solutions: Accessibility and security problems come from same source Expose "better user experience" myth Keep your corner of Internet parsable Remember "Halting Problem"—recognize false solutions (checking and verifying tools) Stop Patching, for Stronger PCI Compliance Adam Brand, protiviti @adamrbrand, http://www.picfun.com/ Adam talked about PCI compliance for retail sales. Take an example: for PCI compliance, 50% of Brian's time (a IT guy), 960 hours/year was spent patching POSs in 850 restaurants. Often applying some patches make no sense (like fixing a browser vulnerability on a server). "Scanner worship" is overuse of vulnerability scanners—it gives a warm and fuzzy and it's simple (red or green results—fix reds). Scanners give a false sense of security. In reality, breeches from missing patches are uncommon—more common problems are: default passwords, cleartext authentication, misconfiguration (firewall ports open). Patching Myths: Myth 1: install within 30 days of patch release (but PCI §6.1 allows a "risk-based approach" instead). Myth 2: vendor decides what's critical (also PCI §6.1). But §6.2 requires user ranking of vulnerabilities instead. Myth 3: scan and rescan until it passes. But PCI §11.2.1b says this applies only to high-risk vulnerabilities. Adam says good recommendations come from NIST 800-40. Instead use sane patching and focus on what's really important. From NIST 800-40: Proactive: Use a proactive vulnerability management process: use change control, configuration management, monitor file integrity. Monitor: start with NVD and other vulnerability alerts, not scanner results. Evaluate: public-facing system? workstation? internal server? (risk rank) Decide:on action and timeline Test: pre-test patches (stability, functionality, rollback) for change control Install: notify, change control, tickets McAfee Secure & Trustmarks — a Hacker's Best Friend Jay James, Shane MacDougall, Tactical Intelligence Inc., Canada "McAfee Secure Trustmark" is a website seal marketed by McAfee. A website gets this badge if they pass their remote scanning. The problem is a removal of trustmarks act as flags that you're vulnerable. Easy to view status change by viewing McAfee list on website or on Google. "Secure TrustGuard" is similar to McAfee. Jay and Shane wrote Perl scripts to gather sites from McAfee and search engines. If their certification image changes to a 1x1 pixel image, then they are longer certified. Their scripts take deltas of scans to see what changed daily. The bottom line is change in TrustGuard status is a flag for hackers to attack your site. Entire idea of seals is silly—you're raising a flag saying if you're vulnerable.

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  • Box2D Joints in entity components system

    - by Johnmph
    I search a way to have Box2D joints in an entity component system, here is what i found : 1) Having the joints in Box2D/Body component as parameters, we have a joint array with an ID by joint and having in the other body component the same joint ID, like in this example : Entity1 - Box2D/Body component { Body => (body parameters), Joints => { Joint1 => (joint parameters), others joints... } } // Joint ID = Joint1 Entity2 - Box2D/Body component { Body => (body parameters), Joints => { Joint1 => (joint parameters), others joints... } } // Same joint ID than in Entity1 There are 3 problems with this solution : The first problem is the implementation of this solution, we must manage the joints ID to create joints and to know between which bodies they are connected. The second problem is the parameters of joint, where are they got ? on the Entity1 or Entity2 ? If they are the same parameters for the joint, there is no problem but if they are differents ? The third problem is that we can't limit number of bodies to 2 by joint (which is mandatory), a joint can only link 2 bodies, in this solution, nothing prevents to create more than 2 entities with for each a body component with the same joint ID, in this case, how we know the 2 bodies to joint and what to do with others bodies ? 2) Same solution than the first solution but by having entities ID instead of Joint ID, like in this example : Entity1 - Box2D/Body component { Body => (body parameters), Joints => { Entity2 => (joint parameters), others joints... } } Entity2 - Box2D/Body component { Body => (body parameters), Joints => { Entity1 => (joint parameters), others joints... } } With this solution, we fix the first problem of the first solution but we have always the two others problems. 3) Having a Box2D/Joint component which is inserted in the entities which contains the bodies to joint (we share the same joint component between entities with bodies to joint), like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } - Box2D/Joint component { Joint => (Joint parameters) } // Shared, same as in Entity2 Entity2 - Box2D/Body component { Body => (body parameters) } - Box2D/Joint component { Joint => (joint parameters) } // Shared, same as in Entity1 There are 2 problems with this solution : The first problem is the same problem than in solution 1 and 2 : We can't limit number of bodies to 2 by joint (which is mandatory), a joint can only link 2 bodies, in this solution, nothing prevents to create more than 2 entities with for each a body component and the shared joint component, in this case, how we know the 2 bodies to joint and what to do with others bodies ? The second problem is that we can have only one joint by body because entity components system allows to have only one component of same type in an entity. So we can't put two Joint components in the same entity. 4) Having a Box2D/Joint component which is inserted in the entity which contains the first body component to joint and which has an entity ID parameter (this entity contains the second body to joint), like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } - Box2D/Joint component { Entity2 => (Joint parameters) } // Entity2 is the entity ID which contains the other body to joint, the first body being in this entity Entity2 - Box2D/Body component { Body => (body parameters) } There are exactly the same problems that in the third solution, the only difference is that we can have two differents joints by entity instead of one (by putting one joint component in an entity and another joint component in another entity, each joint referencing to the other entity). 5) Having a Box2D/Joint component which take in parameter the two entities ID which contains the bodies to joint, this component can be inserted in any entity, like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } Entity2 - Box2D/Body component { Body => (body parameters) } Entity3 - Box2D/Joint component { Joint => (Body1 => Entity1, Body2 => Entity2, others parameters of joint) } // Entity1 is the ID of the entity which have the first body to joint and Entity2 is the ID of the entity which have the second body to joint (This component can be in any entity, that doesn't matter) With this solution, we fix the problem of the body limitation by joint, we can only have two bodies per joint, which is correct. And we are not limited by number of joints per body, because we can create an another Box2D/Joint component, referencing to Entity1 and Entity2 and put this component in a new entity. The problem of this solution is : What happens if we change the Body1 or Body2 parameter of Joint component at runtime ? We need to add code to sync the Body1/Body2 parameters changes with the real joint object. 6) Same as solution 3 but in a better way : Having a Box2D/Joint component Box2D/Joint which is inserted in the entities which contains the bodies to joint, we share the same joint component between these entities BUT the difference is that we create a new entity to link the body component with the joint component, like in this example : Entity1 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity3 Entity2 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity4 Entity3 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity1 - Box2D/Joint component { Joint => (joint parameters) } // Shared, same as in Entity4 Entity4 - Box2D/Body component { Body => (body parameters) } // Shared, same as in Entity2 - Box2D/Joint component { Joint => (joint parameters) } // Shared, same as in Entity3 With this solution, we fix the second problem of the solution 3, because we can create an Entity5 which will have the shared body component of Entity1 and an another joint component so we are no longer limited in the joint number per body. But the first problem of solution 3 remains, because we can't limit the number of entities which have the shared joint component. To resolve this problem, we can add a way to limit the number of share of a component, so for the Joint component, we limit the number of share to 2, because we can only joint 2 bodies per joint. This solution would be perfect because there is no need to add code to sync changes like in the solution 5 because we are notified by the entity components system when components / entities are added to/removed from the system. But there is a conception problem : How to know easily and quickly between which bodies the joint operates ? Because, there is no way to find easily an entity with a component instance. My question is : Which solution is the best ? Is there any other better solutions ? Sorry for the long text and my bad english.

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  • HTG Explains: Why Does Rebooting a Computer Fix So Many Problems?

    - by Chris Hoffman
    Ask a geek how to fix a problem you’ve having with your Windows computer and they’ll likely ask “Have you tried rebooting it?” This seems like a flippant response, but rebooting a computer can actually solve many problems. So what’s going on here? Why does resetting a device or restarting a program fix so many problems? And why don’t geeks try to identify and fix problems rather than use the blunt hammer of “reset it”? This Isn’t Just About Windows Bear in mind that this soltion isn’t just limited to Windows computers, but applies to all types of computing devices. You’ll find the advice “try resetting it” applied to wireless routers, iPads, Android phones, and more. This same advice even applies to software — is Firefox acting slow and consuming a lot of memory? Try closing it and reopening it! Some Problems Require a Restart To illustrate why rebooting can fix so many problems, let’s take a look at the ultimate software problem a Windows computer can face: Windows halts, showing a blue screen of death. The blue screen was caused by a low-level error, likely a problem with a hardware driver or a hardware malfunction. Windows reaches a state where it doesn’t know how to recover, so it halts, shows a blue-screen of death, gathers information about the problem, and automatically restarts the computer for you . This restart fixes the blue screen of death. Windows has gotten better at dealing with errors — for example, if your graphics driver crashes, Windows XP would have frozen. In Windows Vista and newer versions of Windows, the Windows desktop will lose its fancy graphical effects for a few moments before regaining them. Behind the scenes, Windows is restarting the malfunctioning graphics driver. But why doesn’t Windows simply fix the problem rather than restarting the driver or the computer itself?  Well, because it can’t — the code has encountered a problem and stopped working completely, so there’s no way for it to continue. By restarting, the code can start from square one and hopefully it won’t encounter the same problem again. Examples of Restarting Fixing Problems While certain problems require a complete restart because the operating system or a hardware driver has stopped working, not every problem does. Some problems may be fixable without a restart, though a restart may be the easiest option. Windows is Slow: Let’s say Windows is running very slowly. It’s possible that a misbehaving program is using 99% CPU and draining the computer’s resources. A geek could head to the task manager and look around, hoping to locate the misbehaving process an end it. If an average user encountered this same problem, they could simply reboot their computer to fix it rather than dig through their running processes. Firefox or Another Program is Using Too Much Memory: In the past, Firefox has been the poster child for memory leaks on average PCs. Over time, Firefox would often consume more and more memory, getting larger and larger and slowing down. Closing Firefox will cause it to relinquish all of its memory. When it starts again, it will start from a clean state without any leaked memory. This doesn’t just apply to Firefox, but applies to any software with memory leaks. Internet or Wi-Fi Network Problems: If you have a problem with your Wi-Fi or Internet connection, the software on your router or modem may have encountered a problem. Resetting the router — just by unplugging it from its power socket and then plugging it back in — is a common solution for connection problems. In all cases, a restart wipes away the current state of the software . Any code that’s stuck in a misbehaving state will be swept away, too. When you restart, the computer or device will bring the system up from scratch, restarting all the software from square one so it will work just as well as it was working before. “Soft Resets” vs. “Hard Resets” In the mobile device world, there are two types of “resets” you can perform. A “soft reset” is simply restarting a device normally — turning it off and then on again. A “hard reset” is resetting its software state back to its factory default state. When you think about it, both types of resets fix problems for a similar reason. For example, let’s say your Windows computer refuses to boot or becomes completely infected with malware. Simply restarting the computer won’t fix the problem, as the problem is with the files on the computer’s hard drive — it has corrupted files or malware that loads at startup on its hard drive. However, reinstalling Windows (performing a “Refresh or Reset your PC” operation in Windows 8 terms) will wipe away everything on the computer’s hard drive, restoring it to its formerly clean state. This is simpler than looking through the computer’s hard drive, trying to identify the exact reason for the problems or trying to ensure you’ve obliterated every last trace of malware. It’s much faster to simply start over from a known-good, clean state instead of trying to locate every possible problem and fix it. Ultimately, the answer is that “resetting a computer wipes away the current state of the software, including any problems that have developed, and allows it to start over from square one.” It’s easier and faster to start from a clean state than identify and fix any problems that may be occurring — in fact, in some cases, it may be impossible to fix problems without beginning from that clean state. Image Credit: Arria Belli on Flickr, DeclanTM on Flickr     

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  • I have to manually change the DNS suffix order every time I connect to VPN. Can I change this permanently or fix the problem somehow?

    - by CarlB
    Sorry in advance but I'm a programmer, not a network engineer, so I'm a noob at this stuff. Anyway, when I am not connected to VPN from my work PC at home, I have the following DNS suffixes listed (real domain names substituted): enterprise.org network.org company.com us.enterprise.org After connecting to VPN, one more DNS suffix is added to the very top of the list: problem-domain.com At this point, most network functions that I can normally perform when actually connected to the LAN in the office are unusable. I get error messages about the network paths not being found and what-not. Anyway, I played around with the suffixes and realized that if I just moved problem-domain.com down one spot to the second in the list, all the problems went away. Unfortunately, it returns to the top spot every time I reconnect, and I tend to get disconnected frequently. Is there something else I can do about this or should I just contact the IT department? I've had this problem before and they weren't able to resolve it but I suppose it would be worth trying again if I could get a different person on the job. What I don't understand is that I thought it didn't matter what order the suffixes were in? Isn't Windows supposed to go through each suffix until it finds a match (or has gone through all the suffixes)? Why is it quitting after the first one? Thanks in advance.

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  • How would you solve this graph theory handshake problem in python?

    - by Zachary Burt
    I graduated college last year with a degree in Psychology, but I also took a lot of math for fun. I recently got the book "Introductory Graph Theory" by Gary Chartrand to brush up on my math and have some fun. Here is an exercise from the book that I'm finding particularly befuddling: Suppose you and your husband attended a party with three other married couples. Several handshakes took place. No one shook hands with himself (or herself) or with his (or her) spouse, and no one shook hands with the same person more than once. After all the handshaking was completed, suppose you asked each person, including your husband, how many hands he or she had shaken. Each person gave a different answer. a) How many hands did you shake? b) How many hands did your husband shake? Now, I've been reasoning about this for a while, and trying to draw sample graphs that could illustrate a solution, but I'm coming up empty-handed. My logic is this: there are 8 different vertices in the graph, and 7 of them have different degrees. The values for the degrees must therefore be 0, 1, 2, 3, 4, 5, 6, and x. The # of degrees for one married couple is (0, 6). Since all graphs have an even number of odd vertices, x must be either 5, 3, or 1. What's your solution to this problem? And, if you could solve it in python, how would you do it? (python is fun.) Cheers.

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  • How would you solve this graph theory handshake problem in python?

    - by Zachary Burt
    I graduated college last year with a degree in Psychology, but I also took a lot of math for fun. I recently got the book "Introductory Graph Theory" by Gary Chartrand to brush up on my math and have some fun. Here is an exercise from the book that I'm finding particularly befuddling: Suppose you and your husband attended a party with three other married couples. Several handshakes took place. No one shook hands with himself (or herself) or with his (or her) spouse, and no one shook hands with the same person more than once. After all the handshaking was completed, suppose you asked each person, including your husband, how many hands he or she had shaken. Each person gave a different answer. a) How many hands did you shake? b) How many hands did your husband shake? Now, I've been reasoning about this for a while, and trying to draw sample graphs that could illustrate a solution, but I'm coming up empty-handed. My logic is this: there are 8 different vertices in the graph, and 7 of them have different degrees. The values for the degrees must therefore be 0, 1, 2, 3, 4, 5, 6, and x. The # of degrees for one married couple is (0, 6). Since all graphs have an even number of odd vertices, x must be either 5, 3, or 1. What's your solution to this problem? And, if you could solve it in python, how would you do it? (python is fun.) Cheers.

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  • Problem creating simple "windows script components" on Windows 7.

    - by Bigtoe
    Hi folks, I'm trying to get a Windows Script Component working on and x64 development machine. Works fine on x32 bit. But can't seem to get it running, I have the same problem with both JScript and VBScript. Here's the most simple wsc component possible. All that it does it pop up "Hello" in a message box. If you save the snippit below to a file called test_lib.wsc, you'll then be able to right click and register it. It's now available as a COM Component. <?xml version="1.0"?> <component> <?component error="true" debug="true"?> <registration description="Test Script Library" progid="TestScript.Lib" version="1.00" classid="{314042ea-1c42-4865-956f-08d56d1f00a8}" > </registration> <public> <method name="Hello"> </method> </public> <script language="VBScript"> <![CDATA[ Option Explicit Function Hello() MsgBox("Hello.") End Function ]]> </script> </component> Next create the following sample vb-script and save it to a file called test.vbs dim o set o = createobject("TestScript.Lib") o.hello() When I run the test.vbs with cscript or wscript I always get the following. "C:\test.vbs(3, 1) Microsoft VBScript runtime error: ActiveX component can't create object: 'TestScript.Lib'" This works perfectly fine on a 32 bit XP. Anyone got any ideas about what could be wrong? Thanks a bunch Noel.

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  • How to fix IE ClearType + jQuery opacity problem in this script?

    - by Justine
    Hello, I'm having a rather common problem (or so it seems, after some googling around...) with IE messing both bold text AND transparent pngs while animating opacity using jQuery. You can view the sample here: http://dev.gentlecode.net/dotme/index-sample.html (only occurs in IE, obviously) I've seen some blog posts saying the fix is to remove the filter attribute but I'm not sure how to apply it to the script I'm using since I got it from a tutorial and am still learning jQuery... The script goes as follows: $('ul.nav').each(function() { var $links = $(this).find('a'), panelIds = $links.map(function() { return this.hash; }).get().join(","), $panels = $(panelIds), $panelWrapper = $panels.filter(':first').parent(), delay = 500; $panels.hide(); $links.click(function() { var $link = $(this), link = (this); if ($link.is('.current')) { return; } $links.removeClass('current'); $link.addClass('current'); $panels.animate({ opacity : 0 }, delay); $panelWrapper.animate({ height: 0 }, delay, function() { var height = $panels.hide().filter(link.hash).show().css('opacity', 1).outerHeight(); $panelWrapper.animate({ height: height }, delay); }); return false; }); var showtab = window.location.hash ? '[hash=' + window.location.hash + ']' : ':first'; $links.filter(showtab).click(); }); I would appreciate if someone could go over it and show me how to fix the opacity issue. Will the filter method also fix the trouble I'm having with transparent pngs having pixelated ugly borders like the bold type as well? Thanks in advance for all help!

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