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  • Forwarding data between two interfaces

    - by user84471
    I installed Ubuntu server 12.04 after that I installed dhcp3-server and configured it like this: At isc-dhcp-server INTERFACES="eth0" And in dhcpd.conf # A slightly different configuration for an internal subnet. subnet 192.168.1.0 netmask 255.255.255.0 { range 192.168.1.5 192.168.1.100; option domain-name-servers 192.168.1.1; option domain-name "nazwa.local"; option routers 192.168.1.1; option broadcast-address 192.168.1.255; default-lease-time 600; max-lease-time 7200; } Also I have two eth interfaces: # second netowrk interface auto eth0 iface eth0 inet static address 192.168.1.1 netmask 255.255.255.0 # The primary network interface auto eth1 iface eth1 inet dhcp When I plug computer to eth0 I get propertly ip adress but I can't visit any sites. I do even this: echo 1 > /proc/sys/net/ipv4/ip_forward

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  • Why do we (really) program to interfaces?

    - by Kyle Burns
    One of the earliest lessons I was taught in Enterprise development was "always program against an interface".  This was back in the VB6 days and I quickly learned that no code would be allowed to move to the QA server unless my business objects and data access objects each are defined as an interface and have a matching implementation class.  Why?  "It's more reusable" was one answer.  "It doesn't tie you to a specific implementation" a slightly more knowing answer.  And let's not forget the discussion ending "it's a standard".  The problem with these responses was that senior people didn't really understand the reason we were doing the things we were doing and because of that, we were entirely unable to realize the intent behind the practice - we simply used interfaces and had a bunch of extra code to maintain to show for it. It wasn't until a few years later that I finally heard the term "Inversion of Control".  Simply put, "Inversion of Control" takes the creation of objects that used to be within the control (and therefore a responsibility of) of your component and moves it to some outside force.  For example, consider the following code which follows the old "always program against an interface" rule in the manner of many corporate development shops: 1: ICatalog catalog = new Catalog(); 2: Category[] categories = catalog.GetCategories(); In this example, I met the requirement of the rule by declaring the variable as ICatalog, but I didn't hit "it doesn't tie you to a specific implementation" because I explicitly created an instance of the concrete Catalog object.  If I want to test the functionality of the code I just wrote I have to have an environment in which Catalog can be created along with any of the resources upon which it depends (e.g. configuration files, database connections, etc) in order to test my functionality.  That's a lot of setup work and one of the things that I think ultimately discourages real buy-in of unit testing in many development shops. So how do I test my code without needing Catalog to work?  A very primitive approach I've seen is to change the line the instantiates catalog to read: 1: ICatalog catalog = new FakeCatalog();   once the test is run and passes, the code is switched back to the real thing.  This obviously poses a huge risk for introducing test code into production and in my opinion is worse than just keeping the dependency and its associated setup work.  Another popular approach is to make use of Factory methods which use an object whose "job" is to know how to obtain a valid instance of the object.  Using this approach, the code may look something like this: 1: ICatalog catalog = CatalogFactory.GetCatalog();   The code inside the factory is responsible for deciding "what kind" of catalog is needed.  This is a far better approach than the previous one, but it does make projects grow considerably because now in addition to the interface, the real implementation, and the fake implementation(s) for testing you have added a minimum of one factory (or at least a factory method) for each of your interfaces.  Once again, developers say "that's too complicated and has me writing a bunch of useless code" and quietly slip back into just creating a new Catalog and chalking any test failures up to "it will probably work on the server". This is where software intended specifically to facilitate Inversion of Control comes into play.  There are many libraries that take on the Inversion of Control responsibilities in .Net and most of them have many pros and cons.  From this point forward I'll discuss concepts from the standpoint of the Unity framework produced by Microsoft's Patterns and Practices team.  I'm primarily focusing on this library because it questions about it inspired this posting. At Unity's core and that of most any IoC framework is a catalog or registry of components.  This registry can be configured either through code or using the application's configuration file and in the most simple terms says "interface X maps to concrete implementation Y".  It can get much more complicated, but I want to keep things at the "what does it do" level instead of "how does it do it".  The object that exposes most of the Unity functionality is the UnityContainer.  This object exposes methods to configure the catalog as well as the Resolve<T> method which is used to obtain an instance of the type represented by T.  When using the Resolve<T> method, Unity does not necessarily have to just "new up" the requested object, but also can track dependencies of that object and ensure that the entire dependency chain is satisfied. There are three basic ways that I have seen Unity used within projects.  Those are through classes directly using the Unity container, classes requiring injection of dependencies, and classes making use of the Service Locator pattern. The first usage of Unity is when classes are aware of the Unity container and directly call its Resolve method whenever they need the services advertised by an interface.  The up side of this approach is that IoC is utilized, but the down side is that every class has to be aware that Unity is being used and tied directly to that implementation. Many developers don't like the idea of as close a tie to specific IoC implementation as is represented by using Unity within all of your classes and for the most part I agree that this isn't a good idea.  As an alternative, classes can be designed for Dependency Injection.  Dependency Injection is where a force outside the class itself manipulates the object to provide implementations of the interfaces that the class needs to interact with the outside world.  This is typically done either through constructor injection where the object has a constructor that accepts an instance of each interface it requires or through property setters accepting the service providers.  When using dependency, I lean toward the use of constructor injection because I view the constructor as being a much better way to "discover" what is required for the instance to be ready for use.  During resolution, Unity looks for an injection constructor and will attempt to resolve instances of each interface required by the constructor, throwing an exception of unable to meet the advertised needs of the class.  The up side of this approach is that the needs of the class are very clearly advertised and the class is unaware of which IoC container (if any) is being used.  The down side of this approach is that you're required to maintain the objects passed to the constructor as instance variables throughout the life of your object and that objects which coordinate with many external services require a lot of additional constructor arguments (this gets ugly and may indicate a need for refactoring). The final way that I've seen and used Unity is to make use of the ServiceLocator pattern, of which the Patterns and Practices team has also provided a Unity-compatible implementation.  When using the ServiceLocator, your class calls ServiceLocator.Retrieve in places where it would have called Resolve on the Unity container.  Like using Unity directly, it does tie you directly to the ServiceLocator implementation and makes your code aware that dependency injection is taking place, but it does have the up side of giving you the freedom to swap out the underlying IoC container if necessary.  I'm not hugely concerned with hiding IoC entirely from the class (I view this as a "nice to have"), so the single biggest problem that I see with the ServiceLocator approach is that it provides no way to proactively advertise needs in the way that constructor injection does, allowing more opportunity for difficult to track runtime errors. This blog entry has not been intended in any way to be a definitive work on IoC, but rather as something to spur thought about why we program to interfaces and some ways to reach the intended value of the practice instead of having it just complicate your code.  I hope that it helps somebody begin or continue a journey away from being a "Cargo Cult Programmer".

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  • Is there a better way to do bonded vlan tagged interfaces with XEN

    - by AJ01
    We have a number of XEN servers all running CentOS or RHEL. The VM's that they run are all required to be on their own VLAN for no other reason than the customer expects them to be. Long story short however, I can't change this right now. We are also required to have bonding enabled on the interfaces. So to accommodat this we enslave eth1 and eth2 to bond0. We then create a seperate interface called bond0.VLANID where VLANID corresponds to the correct vlan; eg ifcfg-bond0.204 DEVICE=bond0.204 BOOTPROTO=static ONBOOT=yes VLAN=yes BRIDGE=xenvlan204 Bridge to XEN As you will see, we eventually have to bridge this out to XEN, and we do this by adding another interface called xenvlan204 (in this instance) which contains; ifcfg-xenvlan204 DEVICE=xenvlan204 BOOTPROTO=none ONBOOT=yes TYPE=bridge XEN Vm Config Finally in our XEN config for each VM, we add vif = [ "bridge=xenvlan204" ] This then allows the vm host to access that particular vlan The Problem We've noticed a few problems with this setup. One being that we currently create the interfaces manually. Which means if we add more vlan enabled interfaces and bridges we usually have to restart xend which is something I'm not so hot about. Also lower level staff have their heads melted by the number of interfaces and the risk of a mistake occurring is high. Secondly, it can take sometime for a host to come up if it has a number of vlan taged interfaces. Thirdly, its just not scaling well on the management aspects The Question Is there a better more flexible way to do this (in particular with Xen that ships with centos 5.3, 5.4 and 5.5 as we have to support all three) that leverages either scripting or other solutions to allow an arbitrary amount of interfaces to be created when a vm is instanced. Your advise and expertise is more that welcomed.

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  • Java Interfaces Methodology: Should every class implement an interface?

    - by Amir Rachum
    I've been programming in Java for a few courses in the University and I have the following question: Is it methodologically accepted that every class should implement an interface? Is it considered bad practice not to do so? Can you describe a situation where it's not a good idea to use interfaces? Edit: Personally, I like the notion of using Interfaces for everything as a methodology and habit, even if it's not clearly beneficial. Eclipse automatically created a class file with all the methods, so it doesn't waste any time anyway.

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  • Go/Obj-C style interfaces with ability to extend compiled objects after initial release

    - by Skrylar
    I have a conceptual model for an object system which involves combining Go/Obj-C interfaces/protocols with being able to add virtual methods from any unit, not just the one which defines a class. The idea of this is to allow Ruby-ish open classes so you can take a minimalist approach to library development, and attach on small pieces of functionality as is actually needed by the whole program. Implementation of this involves a table of methods marked virtual in an RTTI table, which system functions are allowed to add to during module initialization. Upon typecasting an object to an interface, a Go-style lookup is done to create a vtable for that particular mapping and pass it off so you can have comparable performance to C/C++. In this case, methods may be added /afterwards/ which were not previously known and these new methods allow newer interfaces to be satisfied; while I like this idea because it seems like it would be very flexible (disregarding the potential for spaghetti code, which can happen with just about any model you use regardless). By wrapping the system calls for binding methods up in a set of clean C-compatible calls, one would also be able to integrate code with shared libraries and retain a decent amount of performance (Go does not do shared linking, and Objective-C does a dynamic lookup on each call.) Is there a valid use-case for this model that would make it worth the extra background plumbing? As much as this Dylan-style extensibility would be nice to have access to, I can't quite bring myself to a use case that would justify the overhead other than "it could make some kinds of code more extensible in future scenarios."

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  • Explanation of the definition of interface inheritance as described in GoF book

    - by Geek
    I am reading the first chapter of the Gof book. Section 1.6 discusses about class vs interface inheritance: Class versus Interface Inheritance It's important to understand the difference between an object's class and its type. An object's class defines how the object is implemented.The class defines the object's internal state and the implementation of its operations.In contrast,an object's type only refers to its interface--the set of requests on which it can respond. An object can have many types, and objects of different classes can have the same type. Of course, there's a close relationship between class and type. Because a class defines the operations an object can perform, it also defines the object's type . When we say that an object is an instance of a class, we imply that the object supports the interface defined by the class. Languages like c++ and Eiffel use classes to specify both an object's type and its implementation. Smalltalk programs do not declare the types of variables; consequently,the compiler does not check that the types of objects assigned to a variable are subtypes of the variable's type. Sending a message requires checking that the class of the receiver implements the message, but it doesn't require checking that the receiver is an instance of a particular class. It's also important to understand the difference between class inheritance and interface inheritance (or subtyping). Class inheritance defines an object's implementation in terms of another object's implementation. In short, it's a mechanism for code and representation sharing. In contrast,interface inheritance(or subtyping) describes when an object can be used in place of another. I am familiar with the Java and JavaScript programming language and not really familiar with either C++ or Smalltalk or Eiffel as mentioned here. So I am trying to map the concepts discussed here to Java's way of doing classes, inheritance and interfaces. This is how I think of of these concepts in Java: In Java a class is always a blueprint for the objects it produces and what interface(as in "set of all possible requests that the object can respond to") an object of that class possess is defined during compilation stage only because the class of the object would have implemented those interfaces. The requests that an object of that class can respond to is the set of all the methods that are in the class(including those implemented for the interfaces that this class implements). My specific questions are: Am I right in saying that Java's way is more similar to C++ as described in the third paragraph. I do not understand what is meant by interface inheritance in the last paragraph. In Java interface inheritance is one interface extending from another interface. But I think the word interface has some other overloaded meaning here. Can some one provide an example in Java of what is meant by interface inheritance here so that I understand it better?

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  • Difference between spring setter and interface injection?

    - by Satish Pandey
    I know how constructor and setter injection works in spring. Normally I use interfaces instead of classes to inject beans using setter and I consider it as interface injection, but in case of constructor we also use interfaces (I am confused). In following example I use JobProcessor interface instead of JobProcessorImpl class. public class JobScheduler { // JobProcessor interface private JobProcessor jobProcessor; // Dependecy injection public void setJobProcessor(JobProcessor jobProcessor){ this.jobProcessor = jobProcessor; } } I tried to find a solution by googling but there are different opinions by writers. Even some people says that spring doesn't support interface injection in their blogs/statements. Can someone help me by example?

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  • Open Source AI Bot interfaces

    - by David Young
    What are some open source AI Bot interfaces? Similar to Pogamut 3 GameBots2004 for custom Unreal Tournament bots or Brood Wars API for Starcraft bots etc. If you could please post one AI bot interface per answer (make sure to provide a link) and give a brief summary as to the content of the blog posts. Please include what type of bot interface structure it is, client/server, server/server, etc e.g. BWAPI is client/server which emulates a real player

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  • Héritage multiple en C++: Pourquoi l'héritage d'interfaces est insuffisant, Par Loïc Joly

    Bonjour à tous ! Je viens de mettre en ligne un article, intitulé : Héritage multiple en C++ : Pourquoi l'héritage d'interfaces est insuffisant N'hésitez pas à faire donner votre avis, faire des remarques. L'article compare aussi des fonctionnalités de différents langages orientés objet, principalement C++, C# et Java. En tant que tel, j'espère qu'il pourra susciter des discussions intéressantes, sans sombrer dans le troll inter-langages. Bonne lecture !...

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  • Getting Started with TypeScript – Classes, Static Types and Interfaces

    - by dwahlin
    I had the opportunity to speak on different JavaScript topics at DevConnections in Las Vegas this fall and heard a lot of interesting comments about JavaScript as I talked with people. The most frequent comment I heard from people was, “I guess it’s time to start learning JavaScript”. Yep – if you don’t already know JavaScript then it’s time to learn it. As HTML5 becomes more and more popular the amount of JavaScript code written will definitely increase. After all, many of the HTML5 features available in browsers have little to do with “tags” and more to do with JavaScript (web workers, web sockets, canvas, local storage, etc.). As the amount of JavaScript code being used in applications increases, it’s more important than ever to structure the code in a way that’s maintainable and easy to debug. While JavaScript patterns can certainly be used (check out my previous posts on the subject or my course on Pluralsight.com), several alternatives have come onto the scene such as CoffeeScript, Dart and TypeScript. In this post I’ll describe some of the features TypeScript offers and the benefits that they can potentially offer enterprise-scale JavaScript applications. It’s important to note that while TypeScript has several great features, it’s definitely not for everyone or every project especially given how new it is. The goal of this post isn’t to convince you to use TypeScript instead of standard JavaScript….I’m a big fan of JavaScript. Instead, I’ll present several TypeScript features and let you make the decision as to whether TypeScript is a good fit for your applications. TypeScript Overview Here’s the official definition of TypeScript from the http://typescriptlang.org site: “TypeScript is a language for application-scale JavaScript development. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. Any browser. Any host. Any OS. Open Source.” TypeScript was created by Anders Hejlsberg (the creator of the C# language) and his team at Microsoft. To sum it up, TypeScript is a new language that can be compiled to JavaScript much like alternatives such as CoffeeScript or Dart. It isn’t a stand-alone language that’s completely separate from JavaScript’s roots though. It’s a superset of JavaScript which means that standard JavaScript code can be placed in a TypeScript file (a file with a .ts extension) and used directly. That’s a very important point/feature of the language since it means you can use existing code and frameworks with TypeScript without having to do major code conversions to make it all work. Once a TypeScript file is saved it can be compiled to JavaScript using TypeScript’s tsc.exe compiler tool or by using a variety of editors/tools. TypeScript offers several key features. First, it provides built-in type support meaning that you define variables and function parameters as being “string”, “number”, “bool”, and more to avoid incorrect types being assigned to variables or passed to functions. Second, TypeScript provides a way to write modular code by directly supporting class and module definitions and it even provides support for custom interfaces that can be used to drive consistency. Finally, TypeScript integrates with several different tools such as Visual Studio, Sublime Text, Emacs, and Vi to provide syntax highlighting, code help, build support, and more depending on the editor. Find out more about editor support at http://www.typescriptlang.org/#Download. TypeScript can also be used with existing JavaScript frameworks such as Node.js, jQuery, and others and even catch type issues and provide enhanced code help. Special “declaration” files that have a d.ts extension are available for Node.js, jQuery, and other libraries out-of-the-box. Visit http://typescript.codeplex.com/SourceControl/changeset/view/fe3bc0bfce1f#samples%2fjquery%2fjquery.d.ts for an example of a jQuery TypeScript declaration file that can be used with tools such as Visual Studio 2012 to provide additional code help and ensure that a string isn’t passed to a parameter that expects a number. Although declaration files certainly aren’t required, TypeScript’s support for declaration files makes it easier to catch issues upfront while working with existing libraries such as jQuery. In the future I expect TypeScript declaration files will be released for different HTML5 APIs such as canvas, local storage, and others as well as some of the more popular JavaScript libraries and frameworks. Getting Started with TypeScript To get started learning TypeScript visit the TypeScript Playground available at http://www.typescriptlang.org. Using the playground editor you can experiment with TypeScript code, get code help as you type, and see the JavaScript that TypeScript generates once it’s compiled. Here’s an example of the TypeScript playground in action:   One of the first things that may stand out to you about the code shown above is that classes can be defined in TypeScript. This makes it easy to group related variables and functions into a container which helps tremendously with re-use and maintainability especially in enterprise-scale JavaScript applications. While you can certainly simulate classes using JavaScript patterns (note that ECMAScript 6 will support classes directly), TypeScript makes it quite easy especially if you come from an object-oriented programming background. An example of the Greeter class shown in the TypeScript Playground is shown next: class Greeter { greeting: string; constructor (message: string) { this.greeting = message; } greet() { return "Hello, " + this.greeting; } } Looking through the code you’ll notice that static types can be defined on variables and parameters such as greeting: string, that constructors can be defined, and that functions can be defined such as greet(). The ability to define static types is a key feature of TypeScript (and where its name comes from) that can help identify bugs upfront before even running the code. Many types are supported including primitive types like string, number, bool, undefined, and null as well as object literals and more complex types such as HTMLInputElement (for an <input> tag). Custom types can be defined as well. The JavaScript output by compiling the TypeScript Greeter class (using an editor like Visual Studio, Sublime Text, or the tsc.exe compiler) is shown next: var Greeter = (function () { function Greeter(message) { this.greeting = message; } Greeter.prototype.greet = function () { return "Hello, " + this.greeting; }; return Greeter; })(); Notice that the code is using JavaScript prototyping and closures to simulate a Greeter class in JavaScript. The body of the code is wrapped with a self-invoking function to take the variables and functions out of the global JavaScript scope. This is important feature that helps avoid naming collisions between variables and functions. In cases where you’d like to wrap a class in a naming container (similar to a namespace in C# or a package in Java) you can use TypeScript’s module keyword. The following code shows an example of wrapping an AcmeCorp module around the Greeter class. In order to create a new instance of Greeter the module name must now be used. This can help avoid naming collisions that may occur with the Greeter class.   module AcmeCorp { export class Greeter { greeting: string; constructor (message: string) { this.greeting = message; } greet() { return "Hello, " + this.greeting; } } } var greeter = new AcmeCorp.Greeter("world"); In addition to being able to define custom classes and modules in TypeScript, you can also take advantage of inheritance by using TypeScript’s extends keyword. The following code shows an example of using inheritance to define two report objects:   class Report { name: string; constructor (name: string) { this.name = name; } print() { alert("Report: " + this.name); } } class FinanceReport extends Report { constructor (name: string) { super(name); } print() { alert("Finance Report: " + this.name); } getLineItems() { alert("5 line items"); } } var report = new FinanceReport("Month's Sales"); report.print(); report.getLineItems();   In this example a base Report class is defined that has a variable (name), a constructor that accepts a name parameter of type string, and a function named print(). The FinanceReport class inherits from Report by using TypeScript’s extends keyword. As a result, it automatically has access to the print() function in the base class. In this example the FinanceReport overrides the base class’s print() method and adds its own. The FinanceReport class also forwards the name value it receives in the constructor to the base class using the super() call. TypeScript also supports the creation of custom interfaces when you need to provide consistency across a set of objects. The following code shows an example of an interface named Thing (from the TypeScript samples) and a class named Plane that implements the interface to drive consistency across the app. Notice that the Plane class includes intersect and normal as a result of implementing the interface.   interface Thing { intersect: (ray: Ray) => Intersection; normal: (pos: Vector) => Vector; surface: Surface; } class Plane implements Thing { normal: (pos: Vector) =>Vector; intersect: (ray: Ray) =>Intersection; constructor (norm: Vector, offset: number, public surface: Surface) { this.normal = function (pos: Vector) { return norm; } this.intersect = function (ray: Ray): Intersection { var denom = Vector.dot(norm, ray.dir); if (denom > 0) { return null; } else { var dist = (Vector.dot(norm, ray.start) + offset) / (-denom); return { thing: this, ray: ray, dist: dist }; } } } }   At first glance it doesn’t appear that the surface member is implemented in Plane but it’s actually included automatically due to the public surface: Surface parameter in the constructor. Adding public varName: Type to a constructor automatically adds a typed variable into the class without having to explicitly write the code as with normal and intersect. TypeScript has additional language features but defining static types and creating classes, modules, and interfaces are some of the key features it offers. So is TypeScript right for you and your applications? That’s a not a question that I or anyone else can answer for you. You’ll need to give it a spin to see what you think. In future posts I’ll discuss additional details about TypeScript and how it can be used with enterprise-scale JavaScript applications. In the meantime, I’m in the process of working with John Papa on a new Typescript course for Pluralsight that we hope to have out in December of 2012.

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  • Is this Hybrid of Interface / Composition kosher?

    - by paul
    I'm working on a project in which I'm considering using a hybrid of interfaces and composition as a single thing. What I mean by this is having a contain*ee* class be used as a front for functionality implemented in a contain*er* class, where the container exposes the containee as a public property. Example (pseudocode): class Visibility(lambda doShow, lambda doHide, lambda isVisible) public method Show() {...} public method Hide() {...} public property IsVisible public event Shown public event Hidden class SomeClassWithVisibility private member visibility = new Visibility(doShow, doHide, isVisible) public property Visibility with get() = visibility private method doShow() {...} private method doHide() {...} private method isVisible() {...} There are three reasons I'm considering this: The language in which I'm working (F#) has some annoyances w.r.t. implementing interfaces the way I need to (unless I'm missing something) and this will help avoid a lot of boilerplate code. The containee classes could really be considered properties of the container class(es); i.e. there seems to be a fairly strong has-a relationship. The containee classes will likely implement code which would have been pretty much the same when implemented in all the container classes, so why not do it once in one place? In the above example, this would include managing and emitting the Shown/Hidden events. Does anyone see any isseus with this Composiface/Intersition method, or know of a better way? EDIT 2012.07.26 - It seems a little background information is warranted: Where I work, we have a bunch of application front-ends that have limited access to system resources -- they need access to these resources to fully function. To remedy this we have a back-end application that can access the needed resources, with which the front-ends can communicate. (There is an API written for the front-ends for accessing back-end functionality as though it were part of the front-end.) The back-end program is out of date and its functionality is incomplete. It has made the transition from company to company a couple of times and we can't even compile it anymore. So I'm trying to rewrite it in my spare time. I'm trying to update things to make a nice(r) interface/API for the front-ends (while allowing for backwards compatibility with older front-ends), hopefully something full of OOPy goodness. The thing is, I don't want to write the front-end API after I've written pretty much the same code in F# for implementing the back-end; so, what I'm planning on doing is applying attributes to classes/methods/properties that I would like to have code for in the API then generate this code from the F# assembly using reflection. The method outlined in this question is a possible alternative I'm considering instead of implementing straight interfaces on the classes in F# because they're kind of a bear: In order to access something of an interface that has been implemented in a class, you have to explicitly cast an instance of that class to the interface type. This would make things painful when getting calls from the front-ends. If you don't want to have to do this, you have to call out all of the interface's methods/properties again in the class, outside of the interface implementation (which is separate from regular class members), and call the implementation's members. This is basically repeating the same code, which is what I'm trying to avoid!

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  • Two network adapters on Ubuntu Server 9.10 - Can't have both working at once?

    - by Rob
    I'm trying to set up two network adapters in Ubuntu (server edition) 9.10. One for the public internet, the other a private LAN. During the install, I was asked to pick a primary network adapter (eth0 or eth1). I chose eth0, gave the installer the details listed below in the contents of /etc/network/interfaces, and carried on. I've been using this adapter with these setting for the last few days, and every thing's been fine. Today, I decide it's time to set up the local adapter. I edit the /etc/network/interfaces to add the details for eth1 (see below), and restart networking with sudo /etc/init.d/networking restart. After this, attempting to ping the machine using it's external IP address fails, but I can ping it's local IP address. If I bring eth1 down using sudo ifdown eth1, I can successfully ping the machine via it's external IP address again (but obviously not it's internal IP address). Bringing eth1 back up returns us to the original problem state: external IP not working, internal IP working. Here's my /etc/network/interfaces (I've removed the external IP information, but these settings are unchanged from when it worked) rob@rhea:~$ cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary (public) network interface auto eth0 iface eth0 inet static address xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx network xxx.xxx.xxx.xxx broadcast xxx.xxx.xxx.xxx gateway xxx.xxx.xxx.xxx # The secondary (private) network interface auto eth1 iface eth1 inet static address 192.168.99.4 netmask 255.255.255.0 network 192.168.99.0 broadcast 192.168.99.255 gateway 192.168.99.254 I then do this: rob@rhea:~$ sudo /etc/init.d/networking restart * Reconfiguring network interfaces... [ OK ] rob@rhea:~$ sudo ifup eth0 ifup: interface eth0 already configured rob@rhea:~$ sudo ifup eth1 ifup: interface eth1 already configured Then, from another machine: C:\Documents and Settings\Rob>ping [external ip] Pinging [external ip] with 32 bytes of data: Request timed out. Request timed out. Request timed out. Request timed out. Ping statistics for [external ip]: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), Back on the Ubuntu server in question: rob@rhea:~$ sudo ifdown eth1 ... and again on the other machine: C:\Documents and Settings\Rob>ping [external ip] Pinging [external ip] with 32 bytes of data: Reply from [external ip]: bytes=32 time<1ms TTL=63 Reply from [external ip]: bytes=32 time<1ms TTL=63 Reply from [external ip]: bytes=32 time<1ms TTL=63 Reply from [external ip]: bytes=32 time<1ms TTL=63 Ping statistics for [external ip]: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms So... what am I doing wrong?

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  • Everything has an Interface [closed]

    - by Shane
    Possible Duplicate: Do I need to use an interface when only one class will ever implement it? I am taking over a project where every single real class is implementing an Interface. The vast majority of these interfaces are implemented by a single class that share a similar name and the exact same methods (ex: MyCar and MyCarImpl). Almost no 2 classes in the project implement more than the interface that shares its name. I know the general recommendation is to code to an interface rather than an implementation, but isn't this taking it a bit too far? The system might be more flexible in that it is easier to add a new class that behaves very much like an existing class. However, it is significantly harder to parse through the code and method changes now require 2 edits instead of 1. Personally, I normally only create interfaces when there is a need for multiple classes to have the same behavior. I subscribe to YAGNI, so I don't create something unless I see a real need for it. Am I doing it all wrong or is this project going way overboard?

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  • NTPD seems to delete all network interfaces

    - by Aurelin
    We have a couple of virtual interfaces configured on eth0 on a CentOS, and every now and then, they went down seemingly out of the blue. Now after going through the log files, I found out that apparently ntpd deletes all eth0 interfaces, and that dhclient automatically brings eth0 back up. The virtual interfaces, however, stay down which causes several of our websites to be inaccessible. Can someone explain to me why ntpd deletes interfaces? Can / should that be turned off, or can / should I configure dhclient to bring the virtual interfaces back up automatically, too? EDIT// The log files that I should've posted : Nov 12 13:10:28 raptor dhclient[20048]: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x6a825e97) Nov 12 13:10:42 raptor dhclient[20048]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8 (xid=0x24554092) Nov 12 13:10:42 raptor dhclient[20048]: DHCPOFFER from 96.126.108.78 Nov 12 13:10:42 raptor dhclient[20048]: DHCPREQUEST on eth0 to 255.255.255.255 port 67 (xid=0x24554092) Nov 12 13:10:42 raptor dhclient[20048]: DHCPACK from 96.126.108.78 (xid=0x24554092) Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #31 eth0, 50.116.50.97#123, interface stats: received=3255, sent=3256, dropped=0, active_time=1559394 secs Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #32 eth0:0, 50.116.53.56#123, interface stats: received=3, sent=0, dropped=0, active_time=1559391 secs Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #33 eth0:1, 66.175.211.192#123, interface stats: received=2, sent=0, dropped=0, active_time=1559389 secs Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #34 eth0:2, 50.116.53.95#123, interface stats: received=3, sent=0, dropped=0, active_time=1559387 secs Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #35 eth0:3, 97.107.132.32#123, interface stats: received=2, sent=0, dropped=0, active_time=1559385 secs Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #36 eth0:4, 50.116.56.201#123, interface stats: received=2, sent=0, dropped=0, active_time=1559383 secs Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #37 eth0:5, 66.175.212.121#123, interface stats: received=2, sent=0, dropped=0, active_time=1559381 secs Nov 12 13:10:42 raptor ntpd[2109]: Deleting interface #38 eth0:6, 66.175.215.137#123, interface stats: received=2, sent=0, dropped=0, active_time=1559379 secs Nov 12 13:10:44 raptor NET[1573]: /sbin/dhclient-script : updated /etc/resolv.conf Nov 12 13:10:44 raptor dhclient[20048]: bound to 50.116.50.97 -- renewal in 32692 seconds. Nov 12 13:10:45 raptor ntpd[2109]: Listening on interface #39 eth0, 50.116.50.97#123 Enabled The eth0 config : DEVICE="eth0" ONBOOT="yes" BOOTPROTO="dhcp" IPV6INIT="no" IPADDR=50.116.50.97 NETMASK=255.255.255.0 GATEWAY=50.116.50.1 And the virtual interfaces (I posted the first one only, they look the same for the most part) : # Configuration for eth0:0 DEVICE=eth0:0 BOOTPROTO=none # This line ensures that the interface will be brought up during boot. ONBOOT=yes # eth0:0 IPADDR=50.116.53.56 NETMASK=255.255.255.0

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  • Interfaces Reference Model available

    - by ACShorten
    With the implementation of an Oracle Utilities Application Framework based products, you can implement other Oracle technologies to augment your solution. There is a whitepaper available now to outline all the technology integrations possible with various versions of the Oracle Utilities Application Framework. The whitepaper outlines the possible integrations and implementations of other Oracle technologies to address customer requirements in association with Oracle Utilities Application Framework based products. The whitepaper covers a vast range of products including: Oracle Fusion Middleware Oracle SOA Suite Oracle Identity Management Suite Oracle ExaData and Oracle ExaLogic Oracle VM Data Options including Real Application Clustering, Real Application Testing, Data Guard/Active Data Guard, Compression, Partitioning, Database Vault, Audit Vault etc.. The whitepaper contains a summary of the integration solution possibilities, links to further information including product specific interfaces. The whitepaper is available from My Oracle Support at KB Id: 1506855.1

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  • tap interfaces always disabled in linux bridge

    - by Dani Camps
    I have a physical interface eth0, and I want to create two virtual interfaces and bridge them with eth0. For this purpose I do: #Create the virtual interfaces tunctl -t tap0 tunctl -t tap1 ifconfig tap0 up ifconfig tap1 up #Create the bridge brctl addbr br0 brctl stp br0 off brctl addif br0 eth0 brctl addif br0 tap0 brctl addif br0 tap1 #Turning up the bridge ifconfig br0 up However my problem if that the tap interfaces always appear disabled in the bridge, and no traffic flows to them. $brctl show br0 bridge name bridge id STP enabled interfaces br0 8000.080027cabeba no eth2 tap0 tap1 $brctl showstp br0 br0 bridge id 8000.080027cabeba designated root 8000.080027cabeba root port 0 path cost 0 max age 20.00 bridge max age 20.00 hello time 2.00 bridge hello time 2.00 forward delay 15.00 bridge forward delay 15.00 ageing time 300.01 hello timer 0.00 tcn timer 0.00 topology change timer 0.00 gc timer 298.42 flags eth2 (1) port id 8001 state forwarding designated root 8000.080027cabeba path cost 4 designated bridge 8000.080027cabeba message age timer 0.00 designated port 8001 forward delay timer 12.97 designated cost 0 hold timer 1.24 flags tap0 (2) port id 8002 state disabled designated root 8000.080027cabeba path cost 100 designated bridge 8000.080027cabeba message age timer 0.00 designated port 8002 forward delay timer 0.00 designated cost 0 hold timer 0.00 flags tap1 (3) port id 8003 state disabled designated root 8000.080027cabeba path cost 100 designated bridge 8000.080027cabeba message age timer 0.00 designated port 8003 forward delay timer 0.00 designated cost 0 hold timer 0.00 flags Is there any way to set the tap interfaces in forwarding state? I do not understand why they are not because STP is disabled. Cheers Daniel

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  • Switching between ethernet interfaces on Ubuntu 10.04 SERVER

    - by Chaitanya
    I have ubuntu 10.04 "SERVER" installed on a system with two ehternet ports. I use only one at a time. I wanted to know if I can switch between ports without using ifup and ifdown every time. That means when I connect my Lan cable on eth0 it should work and it does. But when I disconnect the lan cable and connect it on eth1 I have to ifdown eth0 and only then it works. In my /etc/network/interfaces file I have configured both eth0 and eth1. there is no problem other than I have to switch it manually with ifdown and ifup everytime. Please guide. Thanks in advance

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  • SproutCore : un framework JavaScript pour enrichir les interfaces web et les rendre semblables à des

    SproutCore : un framework JavaScript pour enrichir les UI Et les rendre semblables à celles d'applications desktop SproutCore est un framework JavaScript encore confidentiel, mais qui commence à faire parler de lui. Edité par le société Sproutit, cette technologie s'adresse aux développeurs webs. Elle leur permet d'enrichir les interfaces utilisateurs pour les rendre quasi-semblables à celles d'applications desktop. «*AJAX a été utilisé pour créer des pages web qui peuvent se mettre à jour sans avoir à se recharger dans le navigateur. Mais elles ressemblent toujours à des pages webs et elles sont généralement limitées au niveau de l'interactivité » peut-on lire sur ...

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  • Can only bring up one of two interfaces

    - by mstaessen
    I'm having a bizarre issue with my HP Proliant DL 360 G4p server. It has two gigabit ethernet interfaces but I can bring up only one of them. This is starting to freak me out and that's why I turned here. I'm running the x64 ubuntu 11.10 server edition. lshw -c network shows that the second interface is disabled. I have no idea why ans how to enable it. $ sudo lshw -c network *-network:0 description: Ethernet interface product: NetXtreme BCM5704 Gigabit Ethernet vendor: Broadcom Corporation physical id: 2 bus info: pci@0000:02:02.0 logical name: eth0 version: 10 serial: 00:18:71:e3:6d:26 size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 66MHz capabilities: pcix pm vpd msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.119 duplex=full firmware=5704-v3.27b, ASFIPMIc v2.36 ip=10.48.8.x latency=64 link=yes mingnt=64 multicast=yes port=twisted pair speed=100Mbit/s resources: irq:25 memory:fdf70000-fdf7ffff *-network:1 DISABLED description: Ethernet interface product: NetXtreme BCM5704 Gigabit Ethernet vendor: Broadcom Corporation physical id: 2.1 bus info: pci@0000:02:02.1 logical name: eth1 version: 10 serial: 00:18:71:e3:6d:25 capacity: 1Gbit/s width: 64 bits clock: 66MHz capabilities: pcix pm vpd msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.119 firmware=5704-v3.27b latency=64 link=no mingnt=64 multicast=yes port=twisted pair resources: irq:26 memory:fdf60000-fdf6ffff If I try to ifup eth1, then I get $ sudo ifup eth1 Ignoring unknown interface eth1=eth1. I figured that's what happens when there is no eth1 listed in /etc/network/interfaces. But when I add the configuration for eth1, I still can't ifup. $ sudo ifup eth1 RTNETLINK answers: File exists Failed to bring up eth1. I've also tried ifconfig eth1 up but without any result. For clarity, I have added a masked version of /etc/network/interfaces. I don't think it is the cause of the problem though. $ cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet static address 10.48.8.x netmask 255.255.255.y network 10.48.8.z broadcast 10.48.8.t gateway 10.48.8.u auto eth1 iface eth1 inet static address 193.190.253.x netmask 255.255.255.y network 193.190.253.z broadcast 193.190.253.t gateway 193.190.253.u I really need some help fixing this. It's driving me crazy. Thanks.

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  • Should primitive types or non-primitive types be preferred in Java interfaces?

    - by Greg Mattes
    (I thought I once read something about this in a book, but now I'm not sure where to find it. If this question reminds you of some material that you've read, please post a reference!) What are the pros and the cons of primitives in interfaces? In other words, is one of these preferable to the other and why? Perhaps one is preferable to the other in certain contexts? public interface Foo { int getBar(); } or public interface Foo { Integer getBar(); } Similarly: public interface Boz { void someOperation(int parameter); } or public interface Boz { void someOperation(Integer parameter); } Obviously there's the issue of having to deal with nulls in the non-primitive case, but are there deeper concerns?

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  • Host is unreacheble with static networking configuration via /etc/network/interfaces while GUI NetworkManager is ok

    - by Riccardo
    I have some trouble setting-up the network interface using the static IP configuration. I run ubuntu 12.04 kernel 3.11.0-22 with the back-ports enabled. I followed these instructions from help.ubuntu.com but there seems to exist some conflict between the GUI approach (NetworkManager) and the command line approach. $ sudo nano /etc/network/interfaces auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 10.1.1.50 gateway 10.1.1.10 netmask 255.255.255.0 dns-nameservers 192.168.3.45 192.168.8.10 $ sudo /etc/init.d/networking restart I than try to ping for example google.com ping -c 3 www.google.com the response is that the host is unreachable. The icon on the top right of the desktop says: wired network disconnected. If I work using the GUI approach (Edit Connections and so on...) all works great. Can same one explain to me where I wrong? $ ifconfig eth0 eth0 Link encap:Ethernet HWaddr 90:e6:ba:07:4a:77 inet addr:10.1.1.50 Bcast:10.1.1.255 Mask:255.255.255.0 inet6 addr: fe80::92e6:baff:fe07:4a77/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:39619 errors:0 dropped:0 overruns:0 frame:0 TX packets:18520 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:19030895 (19.0 MB) TX bytes:2768769 (2.7 MB) $ netstat -rn Kernel IP routing table Destination Gateway Genmask Flags MSS Window irtt Iface 10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0

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  • Working with multiple interfaces on a single mock.

    - by mehfuzh
    Today , I will cover a very simple topic, which can be useful in cases we want to mock different interfaces on our expected mock object.  Our target interface is simple and it looks like:   public interface IFoo : IDisposable {     void Do(); } Now, as we can see that our target interface has implemented IDisposable and in normal cases if we have to implement it in class where language rules require use to implement that as well[no doubt about it] and whether or not there can be more complex cases, we want to ensure that rather having an extra call(..As()) or constructs to prepare it for us, we should do it in the simplest way possible. Therefore, keeping that in mind, first we create a mock of IFoo var foo = Mock.Create<IFooDispose>(); Then, as we are interested with IDisposable, we simply do: var iDisposable = foo as IDisposable;   Finally, we proceed with our existing mock code. Considering the current context, we I will check if the dispose method has invoked our mock code successfully.   bool called = false;   Mock.Arrange(() => iDisposable.Dispose()).DoInstead(() => called = true);     iDisposable.Dispose();   Assert.True(called);   Further, we assert our expectation as follows: Mock.Assert(() => iDisposable.Dispose(), Occurs.Once());   Hopefully that will help a bit and stay tuned. Enjoy!!

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