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  • Ubuntu with KVM guest VM and broken bridges

    - by MadPsy
    I have an Ubuntu box with a KVM guest VM running. They use bridging so the guest VM attaches to the physical network of its host. The guest VM has 2 NICs in 2 different bridges. First NIC of the VM is tap5 and is in bridge br0 br0 8000.46720f5c572e no eth0.500 tap5 Second NIC of the VM is tap2 and is in bridge br100 br100 8000.76ad2fc96661 no eth0.100 eth0.101 eth0.103 eth0.104 eth0.105 tap2 On the host, br0 has an IP and br100 does not 21: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP link/ether 46:72:0f:5c:57:2e brd ff:ff:ff:ff:ff:ff inet 192.168.100.4/24 brd 192.168.10.255 scope global br0 inet6 fe80::d6ae:52ff:febe:777/64 scope link valid_lft forever preferred_lft forever On the guest, its eth0 and eth1 interfaces both have IP addresses 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:3e:61:fb:7a:da brd ff:ff:ff:ff:ff:ff inet 192.168.100.6/24 brd 192.168.100.255 scope global eth0 inet6 fe80::23e:61ff:fefb:7ada/64 scope link valid_lft forever preferred_lft forever 3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 00:3e:61:fb:7a:ea brd ff:ff:ff:ff:ff:ff inet 172.16.50.129/25 brd 172.16.50.255 scope global eth1 inet6 fe80::23e:61ff:fefb:7aea/64 scope link valid_lft forever preferred_lft forever On the guest VM, a tcpdump of its eth1 interface (tap2) shows traffic from its eth0 interface (tap5), as if the 2 bridges are themselves bridged. This means any interface on br100 is now bridged across to br0 - which is completely broken. root@chillispot:~# tcpdump -c 1 -n -v -i eth1 net 192.168.100.0/24 tcpdump: listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes 16:31:24.175583 IP (tos 0x0, ttl 64, id 48054, offset 0, flags [DF], proto TCP (6), length 148) 192.168.100.6.22 > 192.168.100.4.59505: Flags [P.], cksum 0x6c2b (correct), seq 1056321648:1056321744, ack 398642983, win 1700, options [nop,nop,TS val 197473436 ecr 200655363], length 96 What could be bridging the 2 bridges, except the guest VM (which is a stock Ubuntu install)? I am at a complete loss! Thanks.

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  • Writing an unthemed view while still using Orchard shapes and helpers

    - by Bertrand Le Roy
    This quick tip will show how you can write a custom view for a custom controller action in Orchard that does not use the current theme, but that still retains the ability to use shapes, as well as zones, Script and Style helpers. The controller action, first, needs to opt out of theming: [Themed(false)] public ActionResult Index() {} .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Then, we still want to use a shape as the view model, because Clay is so awesome: private readonly dynamic _shapeFactory; public MyController(IShapeFactory shapeFactory) { _shapeFactory = shapeFactory; } [Themed(false)] public ActionResult Index() { return View(_shapeFactory.MyShapeName( Foo: 42, Bar: "baz" )); } As you can see, we injected a shape factory, and that enables us to build our shape from our action and inject that into the view as the model. Finally, in the view (that would in Views/MyController/Index.cshtml here), just use helpers as usual. The only gotcha is that you need to use “Layout” in order to declare zones, and that two of those zones, Head and Tail, are mandatory for the top and bottom scripts and stylesheets to be injected properly. Names are important here. @{ Style.Include("somestylesheet.css"); Script.Require("jQuery"); Script.Include("somescript.js"); using(Script.Foot()) { <script type="text/javascript"> $(function () { // Do stuff }) </script> } } <!DOCTYPE html> <html> <head> <title>My unthemed page</title> @Display(Layout.Head) </head> <body> <h1>My unthemed page</h1> <div>@Model.Foo is the answer.</div> </body> @Display(Layout.Tail) </html> Note that if you define your own zones using @Display(Layout.SomeZone) in your view, you can perfectly well send additional shapes to them from your controller action, if you injected an instance of IWorkContextAccessor: _workContextAccessor.GetContext().Layout .SomeZone.Add(_shapeFactory.SomeOtherShape()); Of course, you’ll need to write a SomeOtherShape.cshtml template for that shape but I think this is pretty neat.

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  • Switching the layout in Orchard CMS

    - by Bertrand Le Roy
    The UI composition in Orchard is extremely flexible, thanks in no small part to the usage of dynamic Clay shapes. Every notable UI construct in Orchard is built as a shape that other parts of the system can then party on and modify any way they want. Case in point today: modifying the layout (which is a shape) on the fly to provide custom page structures for different parts of the site. This might actually end up being built-in Orchard 1.0 but for the moment it’s not in there. Plus, it’s quite interesting to see how it’s done. We are going to build a little extension that allows for specialized layouts in addition to the default layout.cshtml that Orchard understands out of the box. The extension will add the possibility to add the module name (or, in MVC terms, area name) to the template name, or module and controller names, or module, controller and action names. For example, the home page is served by the HomePage module, so with this extension you’ll be able to add an optional layout-homepage.cshtml file to your theme to specialize the look of the home page while leaving all other pages using the regular layout.cshtml. I decided to implement this sample as a theme with code. This way, the new overrides are only enabled as the theme is activated, which makes a lot of sense as this is going to be where you’ll be creating those additional layouts. The first thing I did was to create my own theme, derived from the default TheThemeMachine with this command: codegen theme CustomLayoutMachine /CreateProject:true /IncludeInSolution:true /BasedOn:TheThemeMachine .csharpcode, .csharpcode pre { font-size: 12px; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Once that was done, I worked around a known bug and moved the new project from the Modules solution folder into Themes (the code was already physically in the right place, this is just about Visual Studio editing). The CreateProject flag in the command-line created a project file for us in the theme’s folder. This is only necessary if you want to run code outside of views from that theme. The code that we want to add is the following LayoutFilter.cs: using System.Linq; using System.Web.Mvc; using System.Web.Routing; using Orchard; using Orchard.Mvc.Filters; namespace CustomLayoutMachine.Filters { public class LayoutFilter : FilterProvider, IResultFilter { private readonly IWorkContextAccessor _wca; public LayoutFilter(IWorkContextAccessor wca) { _wca = wca; } public void OnResultExecuting(ResultExecutingContext filterContext) { var workContext = _wca.GetContext(); var routeValues = filterContext.RouteData.Values; workContext.Layout.Metadata.Alternates.Add( BuildShapeName(routeValues, "area")); workContext.Layout.Metadata.Alternates.Add( BuildShapeName(routeValues, "area", "controller")); workContext.Layout.Metadata.Alternates.Add( BuildShapeName(routeValues, "area", "controller", "action")); } public void OnResultExecuted(ResultExecutedContext filterContext) { } private static string BuildShapeName( RouteValueDictionary values, params string[] names) { return "Layout__" + string.Join("__", names.Select(s => ((string)values[s] ?? "").Replace(".", "_"))); } } } This filter is intercepting ResultExecuting, which is going to provide a context object out of which we can extract the route data. We are also injecting an IWorkContextAccessor dependency that will give us access to the current Layout object, so that we can add alternate shape names to its metadata. We are adding three possible shape names to the default, with different combinations of area, controller and action names. For example, a request to a blog post is going to be routed to the “Orchard.Blogs” module’s “BlogPost” controller’s “Item” action. Our filters will then add the following shape names to the default “Layout”: Layout__Orchard_Blogs Layout__Orchard_Blogs__BlogPost Layout__Orchard_Blogs__BlogPost__Item Those template names get mapped into the following file names by the system (assuming the Razor view engine): Layout-Orchard_Blogs.cshtml Layout-Orchard_Blogs-BlogPost.cshtml Layout-Orchard_Blogs-BlogPost-Item.cshtml This works for any module/controller/action of course, but in the sample I created Layout-HomePage.cshtml (a specific layout for the home page), Layout-Orchard_Blogs.cshtml (a layout for all the blog views) and Layout-Orchard_Blogs-BlogPost-Item.cshtml (a layout that is specific to blog posts). Of course, this is just an example, and this kind of dynamic extension of shapes that you didn’t even create in the first place is highly encouraged in Orchard. You don’t have to do it from a filter, we only did it this way because that was a good place where we could get the context that we needed. And of course, you can base your alternate shape names on something completely different from route values if you want. For example, you might want to create your own part that modifies the layout for a specific content item, or you might want to do it based on the raw URL (like it’s done in widget rules) or who knows what crazy custom rule. The point of all this is to show that extending or modifying shapes is easy, and the layout just happens to be a shape. In other words, you can do whatever you want. Ain’t that nice? The custom theme can be found here: Orchard.Theme.CustomLayoutMachine.1.0.nupkg Many thanks to Louis, who showed me how to do this.

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  • Creating shapes on the fly

    - by Bertrand Le Roy
    Most Orchard shapes get created from part drivers, but they are a lot more versatile than that. They can actually be created from pretty much anywhere, including from templates. One example can be found in the Layout.cshtml file of the ThemeMachine theme: WorkContext.Layout.Footer .Add(New.BadgeOfHonor(), "5"); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } What this is really doing is create a new shape called BadgeOfHonor and injecting it into the Footer global zone (that has not yet been defined, which in itself is quite awesome) with an ordering rank of "5". We can actually come up with something simpler, if we want to render the shape inline instead of sending it into a zone: @Display(New.BadgeOfHonor()) Now let's try something a little more elaborate and create a new shape for displaying a date and time: @Display(New.DateTime(date: DateTime.Now, format: "d/M/yyyy")) For the moment, this throws a "Shape type DateTime not found" exception because the system has no clue how to render a shape called "DateTime" yet. The BadgeOfHonor shape above was rendering something because there is a template for it in the theme: Themes/ThethemeMachine/Views/BadgeOfHonor.cshtml. We need to provide a template for our new shape to get rendered. Let's add a DateTime.cshtml file into our theme's Views folder in order to make the exception go away: Hi, I'm a date time shape. Now we're just missing one thing. Instead of displaying some static text, which is not very interesting, we can display the actual time that got passed into the shape's dynamic constructor. Those parameters will get added to the template's Model, so they are easy to retrieve: @(((DateTime)Model.date).ToString(Model.format)) Now that may remind you a little of WebForm's user controls. That's a fair comparison, except that these shapes are much more flexible (you can add properties on the fly as necessary), and that the actual rendering is decoupled from the "control". For example, any theme can override the template for a shape, you can use alternates, wrappers, etc. Most importantly, there is no lifecycle and protocol abstraction like there was in WebForms. I think this is a real improvement over previous attempts at similar things.

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  • So what are zones really?

    - by Bertrand Le Roy
    There is a (not so) particular kind of shape in Orchard: zones. Functionally, zones are places where other shapes can render. There are top-level zones, the ones defined on Layout, where widgets typically go, and there are local zones that can be defined anywhere. These local zones are what you target in placement.info. Creating a zone is easy because it really is just an empty shape. Most themes include a helper for it: Func<dynamic, dynamic> Zone = x => Display(x); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } With this helper, you can create a zone by simply writing: @Zone(Model.Header) .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Let's deconstruct what's happening here with that weird Lambda. In the Layout template where we are working, the Model is the Layout shape itself, so Model.Header is really creating a new Header shape under Layout, or getting a reference to it if it already exists. The Zone function is then called on that object, which is equivalent to calling Display. In other words, you could have just written the following to get the exact same effect: @Display(Model.Header) The Zone helper function only exists to make the intent very explicit. Now here's something interesting: while this works in the Layout template, you can also make it work from any deeper-nested template and still create top-level zones. The difference is that wherever you are, Model is not the layout anymore so you need to access it in a different way: @Display(WorkContext.Layout.Header) This is still doing the exact same thing as above. One thing to know is that for top-level zones to be usable from the widget editing UI, you need one more thing, which is to specify it in the theme's manifest: Name: Contoso Author: The Orchard Team Description: A subtle and simple CMS themeVersion: 1.1 Tags: business, cms, modern, simple, subtle, product, service Website: http://www.orchardproject.net Zones: Header, Navigation, HomeFeaturedImage, HomeFeaturedHeadline, Messages, Content, ContentAside, TripelFirst, TripelSecond, TripelThird, Footer Local zones are just ordinary shapes like global zones, the only difference being that they are created on a deeper shape than layout. For example, in Content.cshtml, you can find our good old code fro creating a header zone: @Display(Model.Header) The difference here is that Model is no longer the Layout shape, so that zone will be local. The name of that local zone is what you specify in placement.info, for example: <Place Parts_Common_Metadata_Summary="Header:1"/> Now here's the really interesting part: zones do not even know that they are zones, and in fact any shape can be substituted. That means that if you want to add new shapes to the shape that some part has been emitting from its driver for example, you can absolutely do that. And because zones are so barebones as shapes go, they can be created the first time they are accessed. This is what enables us to add shapes into a zone before the code that you would think creates it has even run. For example, in the Layout.cshtml template in TheThemeMachine, the BadgeOfHonor shape is being injected into the Footer zone on line 47, even though that zone will really be "created" on line 168.

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  • What programming language best bridges the gap between pseudocode and code?

    - by Kai
    As I write code from now on, I plan to first lay out everything in beautiful, readable pseudocode and then implement the program around that structure. If I rank the languages that I currently know from easiest to most difficult to translate, I'd say: Lisp, Python, Lua, C++, Java, C I know that each language has its strength and weaknesses but I'm focusing specifically on pseudocode. What language do you use that is best suited for pseudocode-to-code? I always enjoy picking up new languages. Also, if you currently use this technique, I'd love to hear any tips you have about structuring practical pseudocode. Note: I feel this is subjective but has a clear answer per individual preference. I'm asking this here because the SO community has a very wide audience and is likely to suggest languages and techniques that I would otherwise not encounter.

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  • links for 2010-03-23

    - by Bob Rhubart
    Edward Clay: 10 Best Practices for a Successful Customer Solution Engagement Edward Clay based this new Oracle white paper on information from ITIL, ISO, and other IT models and methodologies, and on his 17+ years in the IT industry. (tags: entarch oracle otn solutionarchitect itil iso) John Brunswick: ?Portal Content Personalization John Brunswick's very thorough post covers terminology and concepts, example scenarios and technical implementation strategies to showcase how content personalization can be achieved within a portal from a technical and strategic standpoint. (tags: otn oracle enterprise2.0 contentmanagement portal)

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  • The Ultimate Claymation Chess Game [Video]

    - by Asian Angel
    Watch as these game pieces morph into creatures such as a Pegasi, Unicorn, Shark, Cobra, and more in their battle for final victory. Every game of chess should be this fun! scacchi clay stop motion – chess clay stop motion [via Geeks are Sexy] How to Enable Google Chrome’s Secret Gold IconHTG Explains: What’s the Difference Between the Windows 7 HomeGroups and XP-style Networking?Internet Explorer 9 Released: Here’s What You Need To Know

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  • Diving into OpenStack Network Architecture - Part 1

    - by Ronen Kofman
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} rkofman Normal rkofman 83 3045 2014-05-23T21:11:00Z 2014-05-27T06:58:00Z 3 1883 10739 Oracle Corporation 89 25 12597 12.00 140 Clean Clean false false false false EN-US X-NONE HE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi; mso-bidi-language:AR-SA;} Before we begin OpenStack networking has very powerful capabilities but at the same time it is quite complicated. In this blog series we will review an existing OpenStack setup using the Oracle OpenStack Tech Preview and explain the different network components through use cases and examples. The goal is to show how the different pieces come together and provide a bigger picture view of the network architecture in OpenStack. This can be very helpful to users making their first steps in OpenStack or anyone wishes to understand how networking works in this environment.  We will go through the basics first and build the examples as we go. According to the recent Icehouse user survey and the one before it, Neutron with Open vSwitch plug-in is the most widely used network setup both in production and in POCs (in terms of number of customers) and so in this blog series we will analyze this specific OpenStack networking setup. As we know there are many options to setup OpenStack networking and while Neturon + Open vSwitch is the most popular setup there is no claim that it is either best or the most efficient option. Neutron + Open vSwitch is an example, one which provides a good starting point for anyone interested in understanding OpenStack networking. Even if you are using different kind of network setup such as different Neutron plug-in or even not using Neutron at all this will still be a good starting point to understand the network architecture in OpenStack. The setup we are using for the examples is the one used in the Oracle OpenStack Tech Preview. Installing it is simple and it would be helpful to have it as reference. In this setup we use eth2 on all servers for VM network, all VM traffic will be flowing through this interface.The Oracle OpenStack Tech Preview is using VLANs for L2 isolation to provide tenant and network isolation. The following diagram shows how we have configured our deployment: This first post is a bit long and will focus on some basic concepts in OpenStack networking. The components we will be discussing are Open vSwitch, network namespaces, Linux bridge and veth pairs. Note that this is not meant to be a comprehensive review of these components, it is meant to describe the component as much as needed to understand OpenStack network architecture. All the components described here can be further explored using other resources. Open vSwitch (OVS) In the Oracle OpenStack Tech Preview OVS is used to connect virtual machines to the physical port (in our case eth2) as shown in the deployment diagram. OVS contains bridges and ports, the OVS bridges are different from the Linux bridge (controlled by the brctl command) which are also used in this setup. To get started let’s view the OVS structure, use the following command: # ovs-vsctl show 7ec51567-ab42-49e8-906d-b854309c9edf     Bridge br-int         Port br-int             Interface br-int type: internal         Port "int-br-eth2"             Interface "int-br-eth2"     Bridge "br-eth2"         Port "br-eth2"             Interface "br-eth2" type: internal         Port "eth2"             Interface "eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2" ovs_version: "1.11.0" We see a standard post deployment OVS on a compute node with two bridges and several ports hanging off of each of them. The example above is a compute node without any VMs, we can see that the physical port eth2 is connected to a bridge called “br-eth2”. We also see two ports "int-br-eth2" and "phy-br-eth2" which are actually a veth pair and form virtual wire between the two bridges, veth pairs are discussed later in this post. When a virtual machine is created a port is created on one the br-int bridge and this port is eventually connected to the virtual machine (we will discuss the exact connectivity later in the series). Here is how OVS looks after a VM was launched: # ovs-vsctl show efd98c87-dc62-422d-8f73-a68c2a14e73d     Bridge br-int         Port "int-br-eth2"             Interface "int-br-eth2"         Port br-int             Interface br-int type: internal         Port "qvocb64ea96-9f" tag: 1             Interface "qvocb64ea96-9f"     Bridge "br-eth2"         Port "phy-br-eth2"             Interface "phy-br-eth2"         Port "br-eth2"             Interface "br-eth2" type: internal         Port "eth2"             Interface "eth2" ovs_version: "1.11.0" Bridge "br-int" now has a new port "qvocb64ea96-9f" which connects to the VM and tagged with VLAN 1. Every VM which will be launched will add a port on the “br-int” bridge for every network interface the VM has. Another useful command on OVS is dump-flows for example: # ovs-ofctl dump-flows br-int NXST_FLOW reply (xid=0x4): cookie=0x0, duration=735.544s, table=0, n_packets=70, n_bytes=9976, idle_age=17, priority=3,in_port=1,dl_vlan=1000 actions=mod_vlan_vid:1,NORMAL cookie=0x0, duration=76679.786s, table=0, n_packets=0, n_bytes=0, idle_age=65534, hard_age=65534, priority=2,in_port=1 actions=drop cookie=0x0, duration=76681.36s, table=0, n_packets=68, n_bytes=7950, idle_age=17, hard_age=65534, priority=1 actions=NORMAL As we see the port which is connected to the VM has the VLAN tag 1. However the port on the VM network (eth2) will be using tag 1000. OVS is modifying the vlan as the packet flow from the VM to the physical interface. In OpenStack the Open vSwitch agent takes care of programming the flows in Open vSwitch so the users do not have to deal with this at all. If you wish to learn more about how to program the Open vSwitch you can read more about it at http://openvswitch.org looking at the documentation describing the ovs-ofctl command. Network Namespaces (netns) Network namespaces is a very cool Linux feature can be used for many purposes and is heavily used in OpenStack networking. Network namespaces are isolated containers which can hold a network configuration and is not seen from outside of the namespace. A network namespace can be used to encapsulate specific network functionality or provide a network service in isolation as well as simply help to organize a complicated network setup. Using the Oracle OpenStack Tech Preview we are using the latest Unbreakable Enterprise Kernel R3 (UEK3), this kernel provides a complete support for netns. Let's see how namespaces work through couple of examples to control network namespaces we use the ip netns command: Defining a new namespace: # ip netns add my-ns # ip netns list my-ns As mentioned the namespace is an isolated container, we can perform all the normal actions in the namespace context using the exec command for example running the ifconfig command: # ip netns exec my-ns ifconfig -a lo        Link encap:Local Loopback           LOOPBACK  MTU:16436 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) We can run every command in the namespace context, this is especially useful for debug using tcpdump command, we can ping or ssh or define iptables all within the namespace. Connecting the namespace to the outside world: There are various ways to connect into a namespaces and between namespaces we will focus on how this is done in OpenStack. OpenStack uses a combination of Open vSwitch and network namespaces. OVS defines the interfaces and then we can add those interfaces to namespace. So first let's add a bridge to OVS: # ovs-vsctl add-br my-bridge Now let's add a port on the OVS and make it internal: # ovs-vsctl add-port my-bridge my-port # ovs-vsctl set Interface my-port type=internal And let's connect it into the namespace: # ip link set my-port netns my-ns Looking inside the namespace: # ip netns exec my-ns ifconfig -a lo        Link encap:Local Loopback           LOOPBACK  MTU:65536 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) my-port   Link encap:Ethernet HWaddr 22:04:45:E2:85:21           BROADCAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) Now we can add more ports to the OVS bridge and connect it to other namespaces or other device like physical interfaces. Neutron is using network namespaces to implement network services such as DCHP, routing, gateway, firewall, load balance and more. In the next post we will go into this in further details. Linux Bridge and veth pairs Linux bridge is used to connect the port from OVS to the VM. Every port goes from the OVS bridge to a Linux bridge and from there to the VM. The reason for using regular Linux bridges is for security groups’ enforcement. Security groups are implemented using iptables and iptables can only be applied to Linux bridges and not to OVS bridges. Veth pairs are used extensively throughout the network setup in OpenStack and are also a good tool to debug a network problem. Veth pairs are simply a virtual wire and so veths always come in pairs. Typically one side of the veth pair will connect to a bridge and the other side to another bridge or simply left as a usable interface. In this example we will create some veth pairs, connect them to bridges and test connectivity. This example is using regular Linux server and not an OpenStack node: Creating a veth pair, note that we define names for both ends: # ip link add veth0 type veth peer name veth1 # ifconfig -a . . veth0     Link encap:Ethernet HWaddr 5E:2C:E6:03:D0:17           BROADCAST MULTICAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) veth1     Link encap:Ethernet HWaddr E6:B6:E2:6D:42:B8           BROADCAST MULTICAST  MTU:1500 Metric:1           RX packets:0 errors:0 dropped:0 overruns:0 frame:0           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000           RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) . . To make the example more meaningful this we will create the following setup: veth0 => veth1 => br-eth3 => eth3 ======> eth2 on another Linux server br-eth3 – a regular Linux bridge which will be connected to veth1 and eth3 eth3 – a physical interface with no IP on it, connected to a private network eth2 – a physical interface on the remote Linux box connected to the private network and configured with the IP of 50.50.50.1 Once we create the setup we will ping 50.50.50.1 (the remote IP) through veth0 to test that the connection is up: # brctl addbr br-eth3 # brctl addif br-eth3 eth3 # brctl addif br-eth3 veth1 # brctl show bridge name     bridge id               STP enabled     interfaces br-eth3         8000.00505682e7f6       no              eth3                                                         veth1 # ifconfig veth0 50.50.50.50 # ping -I veth0 50.50.50.51 PING 50.50.50.51 (50.50.50.51) from 50.50.50.50 veth0: 56(84) bytes of data. 64 bytes from 50.50.50.51: icmp_seq=1 ttl=64 time=0.454 ms 64 bytes from 50.50.50.51: icmp_seq=2 ttl=64 time=0.298 ms When the naming is not as obvious as the previous example and we don't know who are the paired veth interfaces we can use the ethtool command to figure this out. The ethtool command returns an index we can look up using ip link command, for example: # ethtool -S veth1 NIC statistics: peer_ifindex: 12 # ip link . . 12: veth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 Summary That’s all for now, we quickly reviewed OVS, network namespaces, Linux bridges and veth pairs. These components are heavily used in the OpenStack network architecture we are exploring and understanding them well will be very useful when reviewing the different use cases. In the next post we will look at how the OpenStack network is laid out connecting the virtual machines to each other and to the external world. @RonenKofman

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  • How long should my Html Page Title Really be?

    - by RandomBen
    How long should my text within my <title></title> tags really be? I know Google cuts it off at some point but when? When I used IIS7's SEO Toolkit 1.0 I get error stating my title should be under 65 characters. I have a book by Bruce Clay that states I should use from 62-70 characters and roughly 9 +/- 3 words. I also have used SenSEO's Firefox Add-on and it states I should use a max of 65 characters or roughly 15 words. What is the max really? I have 2 sources saying 65 and 1 saying 72 but Bruce Clay is generally kept in high regard.

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  • Would knowing Python help with creating iPhone applications?

    - by Josh
    Here is what the apple site says: With Snow Leopard, Mac OS X makes it easy to use scripting languages as full application development tools. Snow Leopard ships with support for the RubyCocoa Bridge and the PyObjC bridge. These two bridges give developers access not only to system APIs, but to Cocoa frameworks such as AppKit and Core Data, enabling you to build fully native Mac OS X applications in Ruby or Python. The RubyCocoa and PyObjC bridges allow you to freely mix code written in Objective-C with code written in the scripting language. You can quickly build prototypes and then optimise by implementing performance-critical pieces in Objective-C. How could Python help in this case?

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  • Friday Fun: Dynamite Train

    - by Asian Angel
    This week’s game involves an ‘explosive’ combination of trains, bridges, and dynamite! Your mission is to stop these trains from crossing the various bridges using ingenuity and a limited supply of explosives. Can you destroy all the bridge designs and building materials you encounter or will your carefully thought out plans of destruction fail? HTG Explains: Is ReadyBoost Worth Using? HTG Explains: What The Windows Event Viewer Is and How You Can Use It HTG Explains: How Windows Uses The Task Scheduler for System Tasks

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  • Integrating Java webapps with Adobe Professional: Resources?

    - by Steve
    I'm interested in learning what resources there are for integrating Java and Adobe Professional, in general. If it helps, my projects already use the Spring Framework. My boss is particularly interested in being able to fill out a PDF form from within a Java webapp and have that data go directly to our database. She mentioned that .net had a lot of bridges to Adobe Professional. I would rather new projects be in Java so I am eager to find if there are any easy bridges between Java and Adobe Professional. Thanks in advance for any information. So far a Google search on "Java Adobe Professional" didn't turn up anything, so I thought I would ask here. Thanks.

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  • httpd running as _www instead of www as it used to

    - by Ethon Bridges
    OSX Mountain Lion and Apache 2.2.22. I have always had the httpd.conf set as: User www Group www and it was running as such. Until today. Rebooted the server for another reason and when I tried to make some changes to a website via FTP this evening, it said access denied. Got to looking at the processes and httpd is now running as _www. WTH? Now of course all of my users are getting denied messages I assume because they were all created and permitted with the www user, not _www. Any idea why this happened or what I may have done to cause it?

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  • Apache virtual server httpd-vhosts undocumented issue

    - by Ethon Bridges
    I have read the Apache documentation on the https-vhosts.conf file and after a couple of hours fighting this problem, figured it out on my own. Here's the situation: We have a domain that ends in a .ws Apparently you can't do this in the conf file. You MUST use the ? wildcard or it will not work. The * wildcard will not work either. Further, in the ServerAlias directive, anything past the first entry will not work if the first entry in the ServerAlias directive is not correct. Here is an example of an entry that does NOT work. Note that anotherdomain.com and yetanotherdomain.com will fail because thedomain.ws is not configured correctly: <VirtualHost *:80> DocumentRoot /opt/local/apache2/sites/ourdomain ServerName www.thedomain.ws ServerAlias thedomain.ws another domain.com yetanotherdomain.com <Directory /opt/local/apache2/sites/ourdomain> allow from all </Directory> </VirtualHost> Here is an example of our working entry: <VirtualHost *:80> DocumentRoot /opt/local/apache2/sites/ourdomain ServerName www.thedomain.ws? ServerAlias thedomain.ws? another domain.com yetanotherdomain.com <Directory /opt/local/apache2/sites/ourdomain> allow from all </Directory> </VirtualHost> If there is documentation of this, I sure didn't see it.

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  • Should OpenID clients accept adding WWW to the domain?

    - by Steve Clay
    For a long time I've used OpenID delegation on my site: http://example.org/ delegated to: http://example.openid-provider.com/, so I logged into OpenID-consuming sites using the former as ID. Recently I added www. to my site's canonical domain so http://example.org/ now redirects to http://www.example.org/. Should I be able to continue logging into existing OpenID accounts using http://example.org/? StackExchange sites say "yes". I can use either URL. At least one other doesn't recognize my existing account. Who's "right" (per spec) and is there anything I can fix on my end?

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  • What is wrong with my Dot Product?

    - by Clay Ellis Murray
    I am trying to make a pong game but I wanted to use dot products to do the collisions with the paddles, however whenever I make a dot product objects it never changes much from .9 this is my code to make vectors vector = { make:function(object){ return [object.x + object.width/2,object.y + object.height/2] }, normalize:function(v){ var length = Math.sqrt(v[0] * v[0] + v[1] * v[1]) v[0] = v[0]/length v[1] = v[1]/length return v }, dot:function(v1,v2){ return v1[0] * v2[0] + v1[1] * v2[1] } } and this is where I am calculating the dot in my code vector1 = vector.normalize(vector.make(ball)) vector2 = vector.normalize(vector.make(object)) dot = vector.dot(vector1,vector2) Here is a JsFiddle of my code currently the paddles don't move. Any help would be greatly appreciated

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  • What is wrong with my Dot Product? [Javascript]

    - by Clay Ellis Murray
    I am trying to make a pong game but I wanted to use dot products to do the collisions with the paddles, however whenever I make a dot product objects it never changes much from .9 this is my code to make vectors vector = { make:function(object){ return [object.x + object.width/2,object.y + object.height/2] }, normalize:function(v){ var length = Math.sqrt(v[0] * v[0] + v[1] * v[1]) v[0] = v[0]/length v[1] = v[1]/length return v }, dot:function(v1,v2){ return v1[0] * v2[0] + v1[1] * v2[1] } } and this is where I am calculating the dot in my code vector1 = vector.normalize(vector.make(ball)) vector2 = vector.normalize(vector.make(object)) dot = vector.dot(vector1,vector2) Here is a JsFiddle of my code currently the paddles don't move. Any help would be greatly appreciated

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  • Marketplace to buy Templates for Twitter Bootstrap framework?

    - by Clay Nichols
    Are there any sites where I could buy a site template designed in Twitter Bootstrap (so that it's easy to modify)? I'm working on a site redesign and I think finding a template that looks close enough and modifying it is an economical way to go. (We're pretty niche so I don't need us to have a super cool website.) But folks I've talked to say that many of those templates are hard to modify. So I'm thinking that finding a template designed in a customizable framework would be easy to modify.

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  • Is there a rule of thumb for what a bing map's zoom setting should be based on how many miles you want to display?

    - by Clay Shannon
    If a map contains pushpins/waypoints that span only a couple of miles, the map should be zoomed way in and show a lot of detail. If the pushpins/waypoints instead cover vast areas, such as hundreds or even thousands of miles, it should be zoomed way out. That's clear. My question is: is there a general guideline for mapping (no pun intended) Bing Maps zoom levels to a particular number of miles that separate the furthest apart points? e.g., is there some chart that has something like: Zoom level N shows 2 square miles Zoom level N shows 5 square miles etc.?

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  • Cannot access Adsense funds after switching to third-party partnership program

    - by Clay
    I had a Google Adsense partnership with $80 in it, but then switched to a different partnership and now can't get my money. When I first started YouTube, I joined the Adsense partnership program. After gaining $80 in my Adsense account, I got an offer to join a third party partnership program called Zoomin.tv. I accepted, and it is paying me monthly now. The problem is that my Adsense account still has the $80 in it, and is not gaining more cash. The Zoomin.tv money is going directly to my PayPal. The payment threshold in Adsense is $100, and you can't make it lower. Therefore, my money is stuck in Adsense and I'd love a solution that allows me to access my money.

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