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  • How to implement a multi-part snake with smooth movement? [closed]

    - by Jamie
    Sorry that i couldnt answer on my previous post but it got closed. I couldnt answer because i had to prepair for my finals. As there were problems with understanding of what im trying to achieve, im going to describe a little bit more in depth. Im creating a game in which you steer a snake. I assume everybody knows how that works. But in my case the snake isnt just propagating in an array element by element. Imagine a 2Dgrid on which the snake moves. Its 10x10 tiles. Lets say one tile is 4x4 meters. The snakes head spawns in the middle of the (3,2) tile (beginning with (0,0)), so its position is (4*3+2,4*2+2)(the 2's are so that the snake is in the middle of the 4x4 tile). And heres where the fun begins. when the snake moves, it doesnt jump to next tile. Instead it moves a fraction of the way there. So lets say the snake is heading to tile (4,2). After it moved once, its position is (4*3+2+0.1,4*2+2), where 0.1 is the fraction of the way it moved. This is done to achieve smooth movement. So now im adding the rest of the body. The rest is supposed to move along the exact same path as the head did. I implemented it so that each part of the body has its own position and direction. Then i apply this algorithm: 1.Move each part in its direction. 2.If a part is in the middle of the tile(which implies all of them are), change each parts direction to the direction of the part proceeding it. As i said before i could make this work, but i cant stop thinking that im overlooking a much easier and cleaner solution. So this is my question. Is there any easier/better/faster way to do this?

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  • Why can't Java/C# implement RAII?

    - by mike30
    Question: Why can't Java/C# implement RAII? Clarification: I am aware the garbage collector is not deterministic. So with the current language features it is not possible for an object's Dispose() method to be called automatically on scope exit. But could such a deterministic feature be added? My understanding: I feel an implementation of RAII must satisfy two requirements: 1. The lifetime of a resource must be bound to a scope. 2. Implicit. The freeing of the resource must happen without an explicit statement by the programmer. Analogous to a garbage collector freeing memory without an explicit statement. The "implicitness" only needs to occur at point of use of the class. The class library creator must of course explicitly implement a destructor or Dispose() method. Java/C# satisfy point 1. In C# a resource implementing IDisposable can be bound to a "using" scope: void test() { using(Resource r = new Resource()) { r.foo(); }//resource released on scope exit } This does not satisfy point 2. The programmer must explicitly tie the object to a special "using" scope. Programmers can (and do) forget to explicitly tie the resource to a scope, creating a leak. In fact the "using" blocks are converted to try-finally-dispose() code by the compiler. It has the same explicit nature of the try-finally-dispose() pattern. Without an implicit release, the hook to a scope is syntactic sugar. void test() { //Programmer forgot (or was not aware of the need) to explicitly //bind Resource to a scope. Resource r = new Resource(); r.foo(); }//resource leaked!!! I think it is worth creating a language feature in Java/C# allowing special objects that are hooked to the stack via a smart-pointer. The feature would allow you to flag a class as scope-bound, so that it always is created with a hook to the stack. There could be a options for different for different types of smart pointers. class Resource - ScopeBound { /* class details */ void Dispose() { //free resource } } void test() { //class Resource was flagged as ScopeBound so the tie to the stack is implicit. Resource r = new Resource(); //r is a smart-pointer r.foo(); }//resource released on scope exit. I think implicitness is "worth it". Just as the implicitness of garbage collection is "worth it". Explicit using blocks are refreshing on the eyes, but offer no semantic advantage over try-finally-dispose(). Is it impractical to implement such a feature into the Java/C# languages? Could it be introduced without breaking old code?

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  • Redesigning an Information System - Part 1

    - by dbradley
    Through the next few weeks or months I'd like to run a small series of articles sharing my experiences from the largest of the project I've worked on and explore some of the real-world problems I've come across and how we went about solving them. I'm afraid I can't give too many specifics on the project right now as it's not yet complete so you'll have to forgive me for being a little abstract in places! To start with I'm going to run through a little of the background of the problem and the motivations to re-design from scratch. Then I'll work through the approaches taken to understanding the requirements, designing, implementing, testing and migrating to the new system. Motivations for Re-designing a Large Information System The system is one that's been in place for a number of years and was originally designed to do a significantly different one to what it's now being used for. This is mainly due to the product maturing as well as client requirements changing. As with most information systems this one can be defined in four main areas of functionality: Input – adding information to the system Storage – persisting information in an efficient, searchable structure Output – delivering the information to the client Control – management of the process There can be a variety of reasons to re-design an existing system; a few of our own turned out to be factors such as: Overall system reliability System response time Failure isolation and recovery Maintainability of code and information General extensibility to solve future problem Separation of business and product concerns New or improved features The factor that started the thought process was the desire to improve the way in which information was entered into the system. However, this alone was not the entire reason for deciding to redesign. Business Drivers Typically all software engineers would always prefer to do a project from scratch themselves. It generally means you don't have to deal with problems created by predecessors and you can create your own absolutely perfect solution. However, the reality of working within a business is that the bottom line comes down to return on investment. For a medium sized business such as mine there must be actual value able to be delivered within a reasonable timeframe for any work to be started. As a result, any long term project will generally take a lot of effort and consideration to be approved by those in charge and therefore it might be better to break down the project into more manageable chunks which allow more frequent deliverables and also value within a shorter timeframe. As the only thing of concern was the methods for inputting information, this is where we started with requirements gathering and design. However knowing that there might be more to the problem and not limiting your design decisions before the requirements is key to finding the best solutions.

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  • ADF Real World Developers Guide Book Review

    - by Grant Ronald
    I'm half way through my review of "Oracle ADF Real World Developer's Guide" by Jobinesh Purushothaman - unfortunately some work deadlines de-railed me from having completed my review by now but here goes.  First thing, Jobinesh works in the Oracle Product Management team with me, so is a colleague. That declaration aside, its clear that this is someone who has done the "real world" side of ADF development and that comes out in the book. In this book he addresses both the newbies and the experience developers alike.  He introduces the ADF building blocks like entity objects and view obejcts, but also goes into some of the nitty gritty details as well.  There is a pro and con to this approach; having only just learned about an entity or view object, you might then be blown away by some of the lower details of coding or lifecycle.  In that respect, you might consider this a book which you could read 3 or 4 times; maybe skipping some elements in the first read but on the next read you have a better grounding to learn the more advanced topics. One of the key issues he addresses is breaking down what happens behind the scenes.  At first, this may not seem important since you trust the framework to do everything for you - but having an understanding of what goes on is essential as you move through development.  For example, page 58 he explains the full lifecycle of what happens when you execute a query.  I think this is a great feature of his book. You see this elsewhere, for example he explains the full lifecycle of what goes on when a page is accessed : which files are involved,the JSF lifecycle etc. He also sprinkes the book with some best practices and advice which go beyond the standard features of ADF and really hits the mark in terms of "real world" advice. So in summary, this is a great ADF book, well written and covering a mass of information.  If you are brand new to ADF its still valid given it does start with the basics.  But you might want to read the book 2 or 3 times, skipping the advanced stuff on the first read.  For those who have some basics already then its going to be an awesome way to cement your knowledge and take it to the next levels.  And for the ADF experts, you are still going to pick up some great ADF nuggets.  Advice: every ADF developer should have one!

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  • The term "interface" in C++

    - by Flexo
    Java makes a clear distinction between class and interface. (I believe C# does also, but I have no experience with it). When writing C++ however there is no language enforced distinction between class and interface. Consequently I've always viewed interface as a workaround for the lack of multiple inheritance in Java. Making such a distinction feels arbitrary and meaningless in C++. I've always tended to go with the "write things in the most obvious way" approach, so if in C++ I've got what might be called an interface in Java, e.g.: class Foo { public: virtual void doStuff() = 0; ~Foo() = 0; }; and I then decided that most implementers of Foo wanted to share some common functionality I would probably write: class Foo { public: virtual void doStuff() = 0; ~Foo() {} protected: // If it needs this to do its thing: int internalHelperThing(int); // Or if it doesn't need the this pointer: static int someOtherHelper(int); }; Which then makes this not an interface in the Java sense anymore. Instead C++ has two important concepts, related to the same underlying inheritance problem: virtual inhertiance Classes with no member variables can occupy no extra space when used as a base "Base class subobjects may have zero size" Reference Of those I try to avoid #1 wherever possible - it's rare to encounter a scenario where that genuinely is the "cleanest" design. #2 is however a subtle, but important difference between my understanding of the term "interface" and the C++ language features. As a result of this I currently (almost) never refer to things as "interfaces" in C++ and talk in terms of base classes and their sizes. I would say that in the context of C++ "interface" is a misnomer. It has come to my attention though that not many people make such a distinction. Do I stand to lose anything by allowing (e.g. protected) non-virtual functions to exist within an "interface" in C++? (My feeling is the exactly the opposite - a more natural location for shared code) Is the term "interface" meaningful in C++ - does it imply only pure virtual or would it be fair to call C++ classes with no member variables an interface still?

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  • openGL textures in bitmap mode

    - by evenex_code
    For reasons detailed here I need to texture a quad using a bitmap (as in, 1 bit per pixel, not an 8-bit pixmap). Right now I have a bitmap stored in an on-device buffer, and am mounting it like so: glBindBuffer(GL_PIXEL_UNPACK_BUFFER, BFR.G[(T+1)%2]); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, W, H, 0, GL_COLOR_INDEX, GL_BITMAP, 0); The OpenGL spec has this to say about glTexImage2D: "If type is GL_BITMAP, the data is considered as a string of unsigned bytes (and format must be GL_COLOR_INDEX). Each data byte is treated as eight 1-bit elements..." Judging by the spec, each bit in my buffer should correspond to a single pixel. However, the following experiments show that, for whatever reason, it doesn't work as advertised: 1) When I build my texture, I write to the buffer in 32-bit chunks. From the wording of the spec, it is reasonable to assume that writing 0x00000001 for each value would result in a texture with 1-px-wide vertical bars with 31-wide spaces between them. However, it appears blank. 2) Next, I write with 0x000000FF. By my apparently flawed understanding of the bitmap mode, I would expect that this should produce 8-wide bars with 24-wide spaces between them. Instead, it produces a white 1-px-wide bar. 3) 0x55555555 = 1010101010101010101010101010101, therefore writing this value ought to create 1-wide vertical stripes with 1 pixel spacing. However, it creates a solid gray color. 4) Using my original 8-bit pixmap in GL_BITMAP mode produces the correct animation. I have reached the conclusion that, even in GL_BITMAP mode, the texturer is still interpreting 8-bits as 1 element, despite what the spec seems to suggest. The fact that I can generate a gray color (while I was expecting that I was working in two-tone), as well as the fact that my original 8-bit pixmap generates the correct picture, support this conclusion. Questions: 1) Am I missing some kind of prerequisite call (perhaps for setting a stride length or pack alignment or something) that will signal to the texturer to treat each byte as 8-elements, as it suggests in the spec? 2) Or does it simply not work because modern hardware does not support it? (I have read that GL_BITMAP mode was deprecated in 3.3, I am however forcing a 3.0 context.) 3) Am I better off unpacking the bitmap into a pixmap using a shader? This is a far more roundabout solution than I was hoping for but I suppose there is no such thing as a free lunch.

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  • What's the best way to cache a growing database table for html generation?

    - by McLeopold
    I've got a database table which will grow in size by about 5000 rows a hour. For a key that I would be querying by, the query will grow in size by about 1 row every hour. I would like a web page to show the latest rows for a key, 50 at a time (this is configurable). I would like to try and implement memcache to keep database activity low for reads. If I run a query and create a cache result for each page of 50 results, that would work until a new entry is added. At that time, the page of latest results gets new result and the oldest results drops off. This cascades down the list of cached pages causing me to update every cache result. It seems like a poor design. I could build the cache pages backwards, then for each page requested I should get the latest 2 pages and truncate to the proper length of 50. I'm not sure if this is good or bad? Ideally, the mechanism I use to insert a new row would also know how to invalidate the proper cache results. Has someone already solved this problem in a widely acceptable way? What's the best method of doing this? EDIT: If my understanding of the MYSQL query cache is correct, it has table level granularity in invalidation. Given the fact that I have about 5000 updates before a query on a key should need to be invalidated, it seems that the database query cache would not be used. MS SQL caches execution plans and frequently accessed data pages, so it may do better in this scenario. My query is not against a single table with TOP N. One version has joins to several tables and another has sub-selects. Also, since I want to cache the html generated table, I'm wondering if a cache at the web server level would be appropriate? Is there really no benefit to any type of caching? Is the best advice really to just allow a website site query to go through all the layers and hit the database every request?

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  • Is it smart to take a year off from school to get experience?

    - by user134147
    firstly I apologize if this question is not appropriate for the site, but I've seen other similar (though slightly deviant) questions on this sight before and I know the people here are the most qualified to answer my question. Anyways, I'm currently between my sophomore and junior years at a 4 year university, and after a bit of deliberation I've decided on computer science as a major (BA, by the way, as a BS would require me to stay at least an extra year the way our program is set up). I've been interested now in programming for a few months and I've developed a passion for it in a very short time. I began learning C++, migrating to Java recently when I learned my school focuses on this language. Now, I should mention that the concept of higher education has never sat well with me, so part of my motivation for wanting to take time off is to truly challenge myself and see what I can accomplish when I actually try at something. The autodidact in me finds it difficult to focus on my passions while trying to keep a high GPA in unrelated classes. However, I understand the times we live in and therefore would plan to complete my degree after this year. So my question is whether or not the skills I learn in a year off from college could justify the time off from school. Unfortunately, I don't believe I know enough yet to gain any professional experience (internship, etc.) so I would mostly focus my time on learning Java and another language, possibly Wordpress (to gain an understanding of web programming concepts as I have not yet decided what field I want to get into, and to make some money to fund my off-year), and to delve into security concepts, which also interest me. I'm hoping I could work on projects, such as simple applications or contributions to open source software during this time to enhance my resume once I do finish school, so I can find a job out of college easier. I do not want to be the new hire who knows nothing beyond the concepts of his Java textbooks. Does anyone have any input about these thoughts of mine, or any ideas for where I should focus my studies or how high I might set the bar for my work? Thanks a lot everyone!

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  • Strangling the life out of Software Testing

    - by MarkPearl
    I recently did a course at the local university on Software Engineering. At the beginning of the course I looked over the outline of the subject and there seemed to be some really good content. It covered traditional & agile project methodologies, some general communication and modelling chapters and finished off with testing. I was particularly excited to see the section on testing as this was something I learnt on my own and see great value in. The course has now just ended and I am very disappointed. I now know one of the reasons why so few people i.e. in my region do Test Driven Development, or perform even basic testing methodologies. The topic was to academic! Yes, you might be able to list 4 different types of black box test approaches vs. white box test approaches and describe the characteristics of Smoke Tests, but never during course did we see an example of an actual test or how it might be implemented! In fact, if I did not have personal experience of applying testing in actual projects, I wouldn’t even know what a unit test looked like. Now, what worries me is the following… It took us 6 months to cover the course material, other students more than likely came out of that course with little appreciation of the subject – in fact they now have a very complex view of what a test is – so complex that I think most of them will never attempt it again on their own. Secondly, imagine studying to be a dentist without ever actually seeing a tooth? Yes, you might be able to describe a tooth, and know what it is made out of – but nobody would want a dentist who has never seen a tooth to operate on them. Yet somehow we expect people studying software engineering to do the same? This is not right. Now, before I finish my rant let me say that I know this is not the same everywhere in the world, and that there needs to be a balance on practical implementation and academic understanding – I am just disappointed that this does not seem to be happening at the institution that I am currently studying at ;-( Please, if you happen to be a lecturer or teacher reading this post – a combination of theory and practical's goes a long way. We need to up the quality of software being produced and that starts at learner level!

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  • Should we persist with an employee still writing bad code after many years?

    - by user94986
    I've been assigned the task of managing developers for a well-established company. They have a single developer who specialises in all their C++ coding (since forever), but the quality of the work is abysmal. Code reviews and testing have revealed many problems, one of the worst being memory leaks. The developer has never tested his code for leaks, and I discovered that the applications could leak many MBs with only a minute of use. User's were reporting huge slowdowns, and his take was, "it's nothing to do with me - if they quit and restart, it's all good again." I've given him tools to detect and trace the leaks, and sat down with him for many hours to demonstrate how the tools are used, where the problems occur, and what to do to fix them. We're 6 months down the track, and I assigned him to write a new module. I reviewed it before it was integrated into our larger code base, and was dismayed to discover the same bad coding as before. The part that I find incomprehensible is that some of the coding is worse than amateurish. For example, he wanted a class (Foo) that could populate an object of another class (Bar). He decided that Foo would hold a reference to Bar, e.g.: class Foo { public: Foo(Bar& bar) : m_bar(bar) {} private: Bar& m_bar; }; But (for other reasons) he also needed a default constructor for Foo and, rather than question his initial design, he wrote this gem: Foo::Foo() : m_bar(*(new Bar)) {} So every time the default constructor is called, a Bar is leaked. To make matters worse, Foo allocates memory from the heap for 2 other objects, but he didn't write a destructor or copy constructor. So every allocation of Foo actually leaks 3 different objects, and you can imagine what happened when a Foo was copied. And - it only gets better - he repeated the same pattern on three other classes, so it isn't a one-off slip. The whole concept is wrong on so many levels. I would feel more understanding if this came from a total novice. But this guy has been doing this for many years and has had very focussed training and advice over the past few months. I realise he has been working without mentoring or peer reviews most of that time, but I'm beginning to feel he can't change. So my question is, would you persist with someone who is writing such obviously bad code?

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  • What does Active, Targetset, and Active targetset mean in the Output of dfsutil /pkiinfo?

    - by Kyle Brandt
    I could use some guidance in interpreting the output of dfsutil /pktinfo. Using the following example: PS C:\Users\kbrandt dfsutil.exe /pktinfo ... Entry: \long.biz.foo\Images ShortEntry: \long.biz.foo\Images Expires in 4 seconds UseCount: 1 Type:0x81 ( REFERRAL_SVC DFS ) 0:[\OR-UTIL01\Images] ( TARGETSET ) 1:[\NY-FS01\Images] AccessStatus: 0xc00000be ( TARGETSET ) 2:[\NY-UTIL01\Images] AccessStatus: 0 ( ACTIVE ) Entry: \NY-UTIL01\Images ShortEntry: \NY-UTIL01\Images Expires in 65 seconds UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS ) 0:[\or-util01\Images] ( TARGETSET ) 1:[\NY-FS01\Images] AccessStatus: 0xc00000be ( TARGETSET ) 2:[\NY-UTIL01\Images] AccessStatus: 0 ( ACTIVE ) Entry: \or-util01\Images ShortEntry: \or-util01\Images Expires in 0 seconds UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS ) 0:[\OR-UTIL01\Images] AccessStatus: 0 ( ACTIVE TARGETSET ) 1:[\NY-UTIL01\Images] ( TARGETSET ) 2:[\NY-FS01\Images] Entry: \FOO\Images ShortEntry: \FOO\Images Expires in 108 seconds UseCount: 0 Type:0x81 ( REFERRAL_SVC DFS ) 0:[\OR-UTIL01\Images] AccessStatus: 0 ( ACTIVE TARGETSET ) 1:[\NY-UTIL01\Images] ( TARGETSET ) 2:[\NY-FS01\Images] What do the three states TARGETSET, ACTIVE TARGETSET, and ACTIVE mean exactly? In particular, why might OR-UTIL01 be ACTIVE for \long.biz.foo\Images but the shortname version FOO\Images have NY-UTIL01 as ACTIVE TARGETSET? I'd like to have a better understanding of this to know if it is normal or not. Once I understand it, I might be looking at and issue with IPv6 being disabled (http://support.microsoft.com/kb/2003961) if this isn't normal.

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  • Setting up Tomcat6 properly in Ubuntu 10.04

    - by aasukisuki
    We have a Tomcat6 instance running on Ubuntu 10.04LTS. Our test box was just a Windows machine running Tomcat6. Both machines (Linux and Windows) have 1GB of ram. Via the Tomcat configuration tool in windows, I was able to set the min/max/permgen sizes of the JVM. Those were set to 256/512/128 respectively. Now on the Ubuntu box, I've tried setting the JVM options in several different places including: Adding JAVA_OPTS & CATALINA_OPTS in /etc/environment Adding JAVA_OPTS in $CATALINA_HOME/bin/catalina.sh Creating setenv.sh and adding JAVA_OPTS in $CATALINA_HOME/bin Adding JAVA_OPTS directly to /etc/init.d/tomcat6 Un-commenting the JAVA_OPTS and modifying it in /etc/default/tomcat6 Nearly all of those methods did not work, except for modifying /etc/init.d/tomcat6 directly (and possibly the /etc/default/tomcat6 change, but I just did that). However, my understanding is that when you change these settings, only one JVM should be used for the entire tomcat6 instance, and that memory is shared among the applications. On our windows box, tomcat6 is run as a service, and appears to behave this way. However, when I look at htop on the linux box, there are 20+ tomcat6 instances (I have an app that triggers internal jobs every X seconds using chron, so maybe these are threads? Or are they actual instances) all with those memory settings. The app runs fine for a bit, but eventually ends up locking up. I'm guessing each of these apps thinks it has 512m to work with and never GC's and then locks tomcat up completely. What is the proper way to set all of this up?

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  • Account Lockout with pam_tally2 in RHEL6

    - by Aaron Copley
    I am using pam_tally2 to lockout accounts after 3 failed logins per policy, however, the connecting user does not receive the error indicating pam_tally2's action. (Via SSH.) I expect to see on the 4th attempt: Account locked due to 3 failed logins No combination of required or requisite or the order in the file seems to help. This is under Red Hat 6, and I am using /etc/pam.d/password-auth. The lockout does work as expected but the user does not receive the error described above. This causes a lot of confusion and frustration as they have no way of knowing why authentication fails when they are sure they are using the correct password. Implementation follows NSA's Guide to the Secure Conguration of Red Hat Enterprise Linux 5. (pg.45) It's my understanding that that only thing changed in PAM is that /etc/pam.d/sshd now includes /etc/pam.d/password-auth instead of system-auth. If locking out accounts after a number of incorrect login attempts is required by your security policy, implement use of pam_tally2.so. To enforce password lockout, add the following to /etc/pam.d/system-auth. First, add to the top of the auth lines: auth required pam_tally2.so deny=5 onerr=fail unlock_time=900 Second, add to the top of the account lines: account required pam_tally2.so EDIT: I get the error message by resetting pam_tally2 during one of the login attempts. user@localhost's password: (bad password) Permission denied, please try again. user@localhost's password: (bad password) Permission denied, please try again. (reset pam_tally2 from another shell) user@localhost's password: (good password) Account locked due to ... Account locked due to ... Last login: ... [user@localhost ~]$

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  • VMRC equivalent for Hyper-V?

    - by Ian Boyd
    VMRC was the client tool used to connect to virtual machines running on Virtual Server. Upgrading to Windows Server 2008 R2 with the Hyper-V role, i need a way for people to be able to use the virtual machines. Note: not all virtual machines will have network connectivity not all virtual machines will be running Windows some people needing to connect to a virtual machine will be running Windows XP Hyper-V manager, allowing management of the hyper-v server, is less desirable (since it allows management of the hyper-v server (and doesn't work on all operating systems)) What is the Windows Server 2008 R2 equivalent of VMRC; to "vnc" to a virtual server? Update: i think Tatas was suggesting Microsoft System Center Virtual Machine Manager Self-Service Portal 2.0 (?): Which requires SQL Server IIS Installing those would unfortunately violate our Windows Server 2008 R2 license. i might be looking at the wrong product link, since commenter said there is a version that doesn't require "System Center". Update 2: The Windows Server 2008 R2 running HyperV is being licensed with the understanding that it only be used to host HyperV. From the [Windows Server 2008 R2 Licensing FAQ][4]: Q. If I have one license for Windows Server 2008 R2 Standard and want to run it in a virtual operating system environment, can I continue running it in the physical operating system environment? A. Yes, with Windows Server 2008 R2 Standard, you may run one instance in the physical operating system environment and one instance in the virtual operating system environment; however, the instance running in the physical operating system environment may be used only to run hardware virtualization software, provide hardware virtualization services, or to run software to manage and service operating system environments on the licensed server. This is why i'm weary about installing IIS or SQL Server.

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  • Zscaler. Certs, cookies, and port 80 traffic

    - by 54's_lol
    So I work at HQ for a large company that shall remain nameless. We use Zscaler and I had to roll out a 2048 cert per zscaler's request. People around me at work dont understand the technology and think that the cert's are what is allowing internet connectivity. From my understanding(and please chime in) is the cookie located C:\Users\$$$$$$4$$\AppData\Roaming\Macromedia\Flash Player#SharedObjects\Q3JQJQJV\gateway.zscaler.net\zscaler.swf here that gets created when you provide your creds the first time you use the browser. The cert's are just simply a way of inspecting the SSL traffic as zscaler had no way of doing this before without them. They are essentially using the classic MITM attack to parse your SSL traffic. Gmail is smart enough to recognize this as you get a warning. My question is this, is there a product or service that I can use to verify my web browser when at home(I.E. off company network) isn't still getting routed to zscaler's cloud? If i do a tracert that will work fine. It's the port 80 and 443 web traffic zscaler and my company is after. I would like to verify that when I'm off their premise that my web traffic is using only my isp and the path to whatever content I'm searching for. Do the cert's i'm pushing and browser authentication do something behind the curtain that forces web traffic to get routed to zscaler? I searched quite a bit and would very much like to know if I'm ever off company scrutiny. I do know zscaler offers the service to force the scenario im asking about. Can I prove how my web traffic is getting routed? Thanks for any insight. I've been a fan for a long time and your guy's kung fu is very strong:-)

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  • Apache: https to https redirect

    - by Klaas van Schelven
    I'm trying to get Apache to redirect all http and https traffic to a single endpoint www.example.org. The http part is easy: <VirtualHost *:80> ServerName example.org Redirect permanent / https://www.example.org/ </VirtualHost> # long list of other domains, all redirecting to https://www.example.org/ <VirtualHost *:80> ServerName www.example.org Redirect permanent / https://www.example.org/ </VirtualHost> I'm trying to do something similar for the https. It is my understanding that I need to specify one specific IP address, because the Host directive is also sent encrypted. So the below works: <VirtualHost xx.xx.xx.xx:443> ServerName www.example.org # actual stuff happening here </VirtualHost> However, when I start adding the redirects to the config, like so: <VirtualHost xx.x.xx.xx:443> ServerName example.org Redirect permanent / https://www.example.org/ </VirtualHost> # long list of other domains stuff breaks. $ apache2ctl configtest [warn] VirtualHost xx.xx.xx.xx:443 overlaps with VirtualHost xx.xx.xx.xx:443, the first has precedence, perhaps you need a NameVirtualHost directive If I add a directive like so: NameVirtualHost xx.xx.xx.xx:443 Connecting to the (ssl part of the) server starts to fail. How do I solve this?

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  • Synchronizing audio and video using MP4Box / ffmpeg to concatenate files

    - by jdl2003
    I have two H.264 encoded MPEG-4 files that I need to concatenate. I have been using MP4Box for this task by first ensuring the files are encoded identically (even went so far as to compare output from h264_parse on their video tracks) and then concatenating with this command: MP4Box -cat file1.mp4 -cat file2.mp4 output_file.mp4 This works and the output file is playable, but on playback in Quicktime or VLC the second video's audio starts too soon, making the entire second part of the concatenated file out of sync. I have tried reencoding the output through ffmpeg with -vcodec copy and -acodec copy but the sync issue persists. I have also tried converting to MPEG-2 format first, concatenating with a simple cat file1.mpg file2.mpg > output.mpg and reencoding the result with ffmpeg. This was even worse. I know that I can pass commands to MP4Box to adjust the start time of the audio track, but I am trying to do this programmatically for any input video (in the same encoding of course). I am looking for possible solutions that would not require human intervention / manual adjustments. Or, at least, an understanding of what is happening to make the second part of the concatenated video go out of sync.

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  • How to construct SELinux rules for a Glassfish server

    - by tronda
    I'm running Glassfish 3.1 on a CentOS 6 solution and by default SELinux is enabled. I have installed Sun's JDK version 1.6.0_29 on the server and extracted the Glassfish 3.1.1 to /opt/glassfish-3.1.1 with a link /opt/glassfish pointing to the latest Glassfish version. I've also created a system user named glassfish with a home directory /home/glassfish. When running with SELinux enabled I get all sorts of errors. For instance I'm not able to create the domain. I kind of like the concept of SELinux, and would like to be able to have SELinux enabled. I have the following requirements for the Glassfish server: Listening to port 8080 and 8081 Other ports 7676: JMS 8686: JMX monitoring, 4848: Admin console Forwarding from apache to Glassfish through mod_jk and port 8009 Starting OpenMQ as an separate process which listens to 7676 and it's JMX monitoring port 7776 Able to read and write files at a specified area (different from home directory) Able to use /tmp/ for temporary files I am aware of the audit2allow tool when running in permissive mode, but I struggle with understanding the rules that is generated from this tool, and thought that setting up these rule manually the first time would help me understand the SELinux rules better than the simplistic examples that I've seen so far. Can someone with SELinux experience help me form these SELinux rules with comments describing each part of the rules?

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  • Simple P2V help from Linux to Windows

    - by Ke.
    I have two OS's installed on different drives in my PC. One linux (Centos 5.4) and one windows 7. Its getting tiresome to constantly have to stop and restart the PC when I want to use either OS. I would very much like to use Windows 7 as my host OS and access my linux OS from within Windows. However, im having trouble deciphering exactly how to do this (many of the articles seem confusing and a bit overkill) From what i have seen its possible to use VMWare converter to convert the physical linux image to a virtual image so that I can use it in windows. As im having problems understanding how this is done, I would really appreciate a step by step guide (for a newbie), or any simple tutorials that you can point me at. Some questions beforehand: 1) My linux image is around 80gb, do i need to take this into consideration? The linux drive is around 180gb in total. All my other drives are NTFS non writeable in linux (as I use them in windows and ntfs is dodgy in linux), so probably not possible to move the image over to my ntfs drives 2) Can I just zip the linux files up somehow and transfer it to windows to create the p2v? 3) Is it possible to do the P2V conversion while I am logged into windows. I can see the actual linux drive loaded in disk manager, but windows doesnt read linux file systems so im confused as to how to access the linux drive if this is possible. 4) Or will i need to do the whole p2v conversion inside linux? Cheers, any help is much appreciated Ke (a confused p2v newbie)

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  • most reliable linux terminal app / general procedures for process stability

    - by intuited
    I've been using konsole (KDE 4.2) for a while now but it crashed recently. Konsole is efficiently designed to use one instance for all of the windows for your entire X session. Extra-unfortunately, because of this ingenuity the crash brought down all the humpty-dumptys and their bashes and their bashes' applications and all the begattens' begattens all the way down to Jebodiah Springfield into one big flat nonexistent omelette. The fact that this app is capable of crashing under any circumstances is pretty disappointing. Although KDE 4.2 is not expected to be entirely stable -- and yes, I know, I should update my distro -- it's still a no-sell for me, since if at all possible, this sort of thing Shouldn't Happen to something that's likely to be a foundation for an entire working environment. Maybe this is arrogant and unrealistic, but if it's possible to have something more stable, I want it. So other than running under screen -- which is fun, nifty, and thus far flawless in its reliability, but which has some issues with not understanding certain keycodes -- I'm looking for ways to improve my environment's reliability. The most obvious strategy is to cast about for a more reliable console app. A standard featureset -- which to me includes tabbed windows, Unicode support, and a decent level of keyboard shortcut configuration -- is pretty much essential. I'm currently running gnome-terminal and roxterm, both of which have acceptable featuresets (pretty much identical, actually; I think rox is actually the superset), and neither of which have provided me with extensive, objective reliability data. Not that they were expected to. Other strategies are also welcome. Were I responding to this question I would perhaps suggest backgrounding critical tasks with & and/or disowning them so they don't come down with the global pandemic. And stuff like that.

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  • Experiences with BIRD for BGP?

    - by Shtééf
    We're currently using Quagga with Debian Linux to run a full table BGP router. The set-up has been dead simple up to now, but we've come to a point where I have to reconfigure the router quite a bit, and want to tighten things up. I've never really understood Quagga, and always found its documentation to be lacking. It appears to be mimicking Cisco, of which I only have basic understanding. BIRD has caught my eye recently. The couple of articles / presentations I found promote it as lightweight and more responsive under stress compared to Quagga. And it actually seems to have very decent documentation. So I'd like to know: Who's running BIRD right now, and in what kind of set-up? How is it stability-wise? I've read about it running in a couple of sites in production. Let's say I don't care at all for a Cisco-feel to configuration. How is configuration, maintainance, monitoring, etc. of BIRD in general? And any other notable experiences you may have with it.

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  • Can compressing Program Files save space *and* give a significant boost to SSD performance?

    - by Christopher Galpin
    Considering solid-state disk space is still an expensive resource, compressing large folders has appeal. Thanks to VirtualStore, could Program Files be a case where it might even improve performance? Discovery In particular I have been reading: SSD and NTFS Compression Speed Increase? Does NTFS compression slow SSD/flash performance? Will somebody benchmark whole disk compression (HD,SSD) please? (may have to scroll up) The first link is particularly dreamy, but maybe head a little too far in the clouds. The third link has this sexy semi-log graph (logarithmic scale!). Quote (with notes): Using highly compressable data (IOmeter), you get at most a 30x performance increase [for reads], and at least a 49x performance DECREASE [for writes]. Assuming I interpreted and clarified that sentence correctly, this single user's benchmark has me incredibly interested. Although write performance tanks wretchedly, read performance still soars. It gave me an idea. Idea: VirtualStore It so happens that thanks to sanity saving security features introduced in Windows Vista, write access to certain folders such as Program Files is virtualized for non-administrator processes. Which means, in normal (non-elevated) usage, a program or game's attempt to write data to its install location in Program Files (which is perhaps a poor location) is redirected to %UserProfile%\AppData\Local\VirtualStore, somewhere entirely different. Thus, to my understanding, writes to Program Files should primarily only occur when installing an application. This makes compressing it not only a huge source of space gain, but also a potential candidate for performance gain. Testing The beginning of this post has me a bit timid, it suggests benchmarking NTFS compression on a whole drive is difficult because turning it off "doesn't decompress the objects". However it seems to me the compact command is perfectly capable of doing so for both drives and individual folders. Could it be only marking them for decompression the next time the OS reads from them? I need to find the answer before I begin my own testing.

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  • What is Apache Synapse?

    - by Aren B
    My website keeps getting hit by odd requests with the following user-agent string: Mozilla/4.0 (compatible; Synapse) Using our friendly tool Google I was able to determine this is the hallmark calling-card of our friendly neighborhood Apache Synapse. A 'Lightweight ESB (Enterprise Service Bus)'. Now, based on this information I was able to gather, I still have no clue what this tool is used for. All I can tell is that is has something to do with Web-Services, and supports a variety of protocols. The Info page only leads me to conclude it has something to do with proxies, and web-services. The problem I've run into is that while normally I wouldn't care, we're getting hit quite a bit by Russian IPs (not that russian's are bad, but our site is pretty regionally specific), and when they do they're shoving wierd (not xss/malicious at least not yet) values into our query string parameters. Things like &PageNum=-1 or &Brand=25/5/2010 9:04:52 PM. Before I go ahead and block these ips/useragent from our site, I'd like some help understanding just what is going on. Any help would be greatly appreciated :)

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  • How to make sysctl network bridge settings persist after a reboot?

    - by user183394
    I am setting up a notebook for software demo purpose. The machine has 8GB RAM, a Core i7 Intel CPU, a 128GB SSD, and runs Ubuntu 12.04 LTS 64bit. The notebook is used as a KVM host and runs a few KVM guests. All such guests use the virbr0 default bridge. To enable them to communicate with each other using multicast, I added the following to the host's /etc/sysctl.conf, as shown below net.bridge.bridge-nf-call-ip6tables = 0 net.bridge.bridge-nf-call-iptables = 0 net.bridge.bridge-nf-call-arptables = 0 Afterwards, following man sysctl(8), I issued the following: sudo /sbin/sysctl -p /etc/sysctl.conf My understanding is that this should make these settings persist over reboots. I tested it, and was surprised to find out the following: root@sdn1 :/proc/sys/net/bridge# more *tables :::::::::::::: bridge-nf-call-arptables :::::::::::::: 1 :::::::::::::: bridge-nf-call-ip6tables :::::::::::::: 1 :::::::::::::: bridge-nf-call-iptables :::::::::::::: 1 All defaults are coming back! Yes. I can use some kludgy "get arounds" such as putting a /sbin/sysctl -p /etc/sysctl.conf into the host's /etc/rc.local but I would rather "do it right". Did I misunderstand the man page or is there something that I missed? Thanks for any hints. -- Zack

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  • Windows 2003 R2 x86 Mini dump fails to write to disk

    - by Randy K
    I have 3 blade servers that are Blue Screening with a 0xC2 error as far as we can tell randomly. When it started happening I found that the servers weren't set to do provide a dump because they each have 16GB RAM and a 16GB swap file divided over 4 partitions in 4GB files. I set them to provided a small dump file (64K mini dump), but the dump files aren't being written. On start up the server event log is reporting both Event ID 45 "The system could not sucessfully load the crash dump driver." and Event ID 49 "Configuring the Page file for crash dump failed. Make sure there is a page file on the boot partition and that is large enough to contain all physical memory." I understanding is the the small dump shouldn't need a swap file large enough for all physical memory, but the error seems to point to this not being the case. The issue of course is that the max swap file size is 4GB, so this seems to be impossible. Can anyone point me where to go from here?

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