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• Bidirectional/Loopback UDP in .net

  - by Jason Williams

  I've got an app that needs to transmit and receive on the same port. This can happen in two cases: Where the PC is talking to a piece of remote hardware. It "replies to sender", so the datagrams come back in to my PC via the sending port. Where the PC is talking to itself (loopback mode) for testing and demoing (a test app feeds fake data into our main app via UDP). This only seems to fail when trying to achieve loopback. The only way I can get it working is to ensure that the receiver is set up first - something I cannot guarantee. Can anyone help narrow down my search by suggesting a "correct" way to implement the UdpClient(s) to handle the above situations reliably? (The only solution that I've found to work reliably with the remote hardware is to use a single UdpClient in a bidirectional manner, although I'm working with legacy code that may be influencing that finding. I've tried using two UdpClients, but they step on each others toes - In some cases, once one client is started up, the other client cannot connect. With ExclusiveAddressUse/ReuseAddress set up to allow port sharing, I can almost get it to work, apart from the receiver having to start first)

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• Wrappers of primitive types in arraylist vs arrays

  - by ismail marmoush

  Hi, In "Core java 1" I've read CAUTION: An ArrayList is far less efficient than an int[] array because each value is separately wrapped inside an object. You would only want to use this construct for small collections when programmer convenience is more important than efficiency. But in my software I've already used Arraylist instead of normal arrays due to some requirements, though "The software is supposed to have high performance and after I've read the quoted text I started to panic!" one thing I can change is changing double variables to Double so as to prevent auto boxing and I don't know if that is worth it or not, in next sample algorithm public void multiply(final double val) { final int rows = getSize1(); final int cols = getSize2(); for (int i = 0; i < rows; i++) { for (int j = 0; j < cols; j++) { this.get(i).set(j, this.get(i).get(j) * val); } } } My question is does changing double to Double makes a difference ? or that's a micro optimizing that won't affect anything ? keep in mind I might be using large matrices.2nd Should I consider redesigning the whole program again ?

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• How can I set the name of the class xml by constructor?

  - by spderosso

  Hi, I want to be able to do something like this: @Root(name="events") class XMLEvents { @ElementList(inline=true) ArrayList<XMLEvent> events = Lists.newArrayList(); XMLEvents(){ ... events.add(new XMLEvent(time, type, professorP)); events.add(new XMLEvent(time, type, student)); events.add(new XMLEvent(time, type, course)); ... } } The XMLEvent class to go something like: class XMLEvent { @Root(name="professor") XMLEvent(DateTime time, LogType type, Professor p){ ... } @Root(name="student") XMLEvent(DateTime time, LogType type, Student st){ ... } @Root(name="course") XMLEvent(DateTime time, LogType type, Course c){ ... } } For the output to be: <events> <professor> ... </professor> <student> ... </student> <course> ... </course> </events> So depending on the constructor I call to create a new XMLEvent the root name to which is mapped is different. Is this even possible? Of course the past example was just to transmit what I need. Putting the @Root annotation there didn't change anything Thanks!

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• When downloading a file using FileStream, why does page error message refers to aspx page name, not

  - by StuperUser

  After building a filepath (path, below) in a string (I am aware of Path in System.IO, but am using someone else's code and do not have the opportunity to refactor it to use Path). I am using a FileStream to deliver the file to the user (see below): FileStream myStream = new FileStream(path, FileMode.Open, FileAccess.Read); long fileSize = myStream.Length; byte[] Buffer = new byte[(int)fileSize + 1]; myStream.Read(Buffer, 0, (int)myStream.Length); myStream.Close(); Response.ContentType = "application/csv"; Response.AddHeader("content-disposition", "attachment; filename=" + filename); Response.BinaryWrite(Buffer); Response.Flush(); Response.End(); I have seen from: http://stackoverflow.com/questions/736301/asp-net-how-to-stream-file-to-user reasons to avoid use of Response.End() and Response.Close(). I have also seen several articles about different ways to transmit files and have diagnosed and found a solution to the problem (https and http headers) with a colleague. However, the error message that was being displayed was not about access to the file at path, but the aspx file. Edit: Error message is: Internet Explorer cannot download MyPage.aspx from server.domain.tld Internet Explorer was not able to open this Internet site. The requested site is either unavailable or cannot be found. Please try again later. (page name and address anonymised) Why is this? Is it due to the contents of the file coming from the HTTP response .Flush() method rather than a file being accessed at its address?

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• How to debug problems in Linux kernel module `init()`?

  - by Kimvais

  I am using remote (k)gdb to debug a problem in a module that causes a panic when loaded e.g. when init() is called. The stack trace just shows that do_one_initcall(mod->init) causes the crash. In order to get the symbol file loaded in the gdb, I need to get the address of the module text section, and to get that I need to get the module loaded. Because the insmod in busybox (1.16.1) doesn't support -m so I'm stuck to grep modulename /proc/modules + adding the offset from nm to figure out the address. So I'm facing a sort a of a chicken and an egg problem here - to be able to debug the module loading, I need to get the module loaded - but in order to get the module loaded, I need to debug the problem... So I am currently thinking about two options - is there a way to get the address information either: by printk() in the module init code by printk() somewhere in the kernel code all this prior to calling the mod->init() - so I could place a breakpoint there, load the symbol file, hit c and see it crash and burn...

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• Sharing a COM port over TCP

  - by guinness

  What would be a simple design pattern for sharing a COM port over TCP to multiple clients? For example, a local GPS device that could transmit co-ordinates to remote hosts in realtime. So I need a program that would open the serial port and accept multiple TCP connections like: class Program { public static void Main(string[] args) { SerialPort sp = new SerialPort("COM4", 19200, Parity.None, 8, StopBits.One); Socket srv = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); srv.Bind(new IPEndPoint(IPAddress.Any, 8000)); srv.Listen(20); while (true) { Socket soc = srv.Accept(); new Connection(soc); } } } I would then need a class to handle the communication between connected clients, allowing them all to see the data and keeping it synchronized so client commands are received in sequence: class Connection { static object lck = new object(); static List<Connection> cons = new List<Connection>(); public Socket socket; public StreamReader reader; public StreamWriter writer; public Connection(Socket soc) { this.socket = soc; this.reader = new StreamReader(new NetworkStream(soc, false)); this.writer = new StreamWriter(new NetworkStream(soc, true)); new Thread(ClientLoop).Start(); } void ClientLoop() { lock (lck) { connections.Add(this); } while (true) { lock (lck) { string line = reader.ReadLine(); if (String.IsNullOrEmpty(line)) break; foreach (Connection con in cons) con.writer.WriteLine(line); } } lock (lck) { cons.Remove(this); socket.Close(); } } } The problem I'm struggling to resolve is how to facilitate communication between the SerialPort instance and the threads. I'm not certain that the above code is the best way forward, so does anybody have another solution (the simpler the better)?

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• Flex + PHP + ValueObjects

  - by Tempname

  I have a php/flex value object that I am using to transmit data to/from in my application. Everything works great php-flex, but I am having an issue with flex-php. In my MergeTemplateService.php service I have the following code. This is the method that flex hits directly: function updateTemplate($valueObject){ $object = DAOFactory::getMergeTemplateDAO()->update($valueObject); return $object; } I am passing a value object that from flex looks like this: (com.rottmanj.vo::MergeTemplateVO)#0 communityID = 0 creationDate = (null) enterpriseID = 0 lastModifyDate = (null) templateID = 2 templateName = "My New Test Template" userID = 0 The issue I am having is that my updateTemplate method sees the value object as an array and not an object. In my amfphp globals.php I have set my voPath as: $voPath = "services/class/dto/"; Any help with this is greatly appreciated Here are my two value objects: AS3 VO: package com.rottmanj.vo { [RemoteClass(alias="MergeTemplate")] public class MergeTemplateVO { public var templateID:int; public var templateName:String; public var communityID:int; public var enterpriseID:int; public var userID:int; public var creationDate:String; public var lastModifyDate:String public function MergeTemplateVO(data:Object = null):void { if(data != null) { templateID = data.templateID; templateName = data.templateName; communityID = data.communityID; enterpriseID = data.enterpriseID; userID = data.userID; creationDate = data.creationDate; lastModifyDate = data.lastModifyDate; } } } } PHPVO: <?php class MergeTemplate{ var $templateID; var $templateName; var $communityID; var $enterpriseID; var $userID; var $creationDate; var $lastModifyDate; var $_explictType = 'MergeTemplate'; } ?>

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• How do I send data between two computers over the internet

  - by Johan

  I have been struggling with this for the entire day now, I hope somebody can help me with this. My problem is fairly simple: I wish to transfer data (mostly simple commands) from one PC to another over the internet. I have been able to achieve this using sockets in Java when both computers are connected to my home router. I then connected both computers to the internet using two different mobile phones and attempted to transmit the data again. I used the mobile phones as this provides a direct route to the internet and if I use my router I have to set up port forwarding, at least, that is how I understand it. I think the problem lies in the method that I set up the client socket. I used: Socket kkSocket = new Socket(ipAddress, 3333); where ipAddress is the IP address of the computer running the server. I got the IP address by right-clicking on the connection, status, support. Is that the correct IP address to use or where can I obtain the address of the server? Also, is it possible to get a fixed name for my computer that I can use instead of entering the IP address, as this changes every time I connect to the internet using my mobile phone? Alternatively, are there better methods to solving my problem such as using http, and if so, where can I find more information about this? Thanks!

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• S3 file Uploading from Mac app though PHP?

  - by Ilija Tovilo

  I have asked this question before, but it was deleted due too little information. I'll try to be more concrete this time. I have an Objective-C mac application, which should allow users to upload files to S3-storage. The s3 storage is mine, the users don't have an Amazon account. Until now, the files were uploaded directly to the amazon servers. After thinking some more about it, it wasn't really a great concept, regarding security and flexibility. I want to add a server in between. The user should authenticate with my server, the server would open a session if the authentication was successful, and the file-sharing could begin. Now my question. I want to upload the files to S3. One option would be to make a POST-request and wait until the server would receive the file. Problems here are, that there would be a delay, when the file is being uploaded from my server to the S3 servers, and it would double the uploading time. Best would be, if I could validate the request, and then redirecting it, so the client uploads it directly to the s3-storage. Not sure if this is possible somehow. Uploading directly to S3 doesn't seem to be very smart. After looking into other apps like Droplr and Dropmark, it looks like they don't do this. Btw. I did this using Little Snitch. They have their api on their own web-server, and that's it. Could someone clear things up for me? EDIT How should I transmit my files to S3? Is there a way to "forward" it, or do I have to upload it to my server and then upload it from there to S3? Like I said, other apps can do this efficiently and without the need of communicating with S3 directly.

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• Deterministic floating point and .NET

  - by code2code

  How can I guarantee that floating point calculations in a .NET application (say in C#) always produce the same bit-exact result? Especially when using different versions of .NET and running on different platforms (x86 vs x86_64). Inaccuracies of floating point operations do not matter. In Java I'd use strictfp. In C/C++ and other low level languages this problem is essentially solved by accessing the FPU / SSE control registers but that's probably not possible in .NET. Even with control of the FPU control register the JIT of .NET will generate different code on different platforms. Something like HotSpot would be even worse in this case... Why do I need it? I'm thinking about writing a real-time strategy (RTS) game which heavily depends on fast floating point math together with a lock stepped simulation. Essentially I will only transmit user input across the network. This also applies to other games which implement replays by storing the user input. Not an option are: decimals (too slow) fixed point values (too slow and cumbersome when using sqrt, sin, cos, tan, atan...) update state across the network like an FPS: Sending position information for hundreds or a few thousand units is not an option Any ideas?

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• How to limit TCP writes to particular size and then block untlil the data is read

  - by ustulation

  {Qt 4.7.0 , VS 2010} I have a Server written in Qt and a 3rd party client executable. Qt based server uses QTcpServer and QTcpSocket facilities (non-blocking). Going through the articles on TCP I understand the following: the original implementation of TCP mentioned the negotiable window size to be a 16-bit value, thus maximum being 65535 bytes. But implementations often used the RFC window-scale-extension that allows the sliding window size to be scalable by bit-shifting to yield a maximum of 1 gigabyte. This is implementation defined. This could have resulted in majorly different window sizes on receiver and sender end as the server uses Qt facilities without hardcoding any window size limit. Client 1st asks for all information it can based on the previous messages from the server before handling the new (accumulating) incoming messages. So at some point Server receives a lot of messages each asking for data of several MB's. This the server processes and puts it into the sender buffer. Client however is unable to handle the messages at the same pace and it seems that client’s receiver buffer is far smaller (65535 bytes maybe) than sender’s transmit window size. The messages thus get accumulated at sender’s end until the sender’s buffer is full too after which the TCP writes on sender would block. This however does not happen as sender buffer is much larger. Hence this manifests as increase in memory consumption on the sender’s end. To prevent this from happening, I used Qt’s socket’s waitForBytesWritten() with timeout set to -1 for infinite waiting period. This as I see from the behaviour blocks the thread writing TCP data until the data has actually been sensed by the receiver’s window (which will happen when earlier messages have been processed by the client at application level). This has caused memory consumption at Server end to be almost negligible. is there a better alternative to this (in Qt) if i want to restrict the memory consumption at server end to say x MB's? Also please point out if any of my understandings is incorrect.

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• How to avoid mouse move on Touch

  - by VirtualBlackFox

  I have a WPF application that is capable of being used both with a mouse and using Touch. I disable all windows "enhancements" to just have touch events : Stylus.IsPressAndHoldEnabled="False" Stylus.IsTapFeedbackEnabled="False" Stylus.IsTouchFeedbackEnabled="False" Stylus.IsFlicksEnabled="False" The result is that a click behave like I want except on two points : The small "touch" cursor (little white star) appears where clicked an when dragging. Completely useless as the user finger is already at this location no feedback is required (Except my element potentially changing color if actionable). Elements stay in the "Hover" state after the movement / Click ends. Both are the consequences of the fact that while windows transmit correctly touch events, he still move the mouse to the last main-touch-event. I don't want windows to move the mouse at all when I use touch inside my application. Is there a way to completely avoid that? Notes: Handling touch events change nothing to this. Using SetCursorPos to move the mouse away make the cursor blink and isn't really user-friendly. Disabling the touch panel to act as an input device completely disable all events (And I also prefer an application-local solution, not system wide). I don't care if the solution involve COM/PInvoke or is provided in C/C++ i'll translate. If it is necessary to patch/hook some windows dlls so be it, the software will run on a dedicated device anyway. I'm investigating the surface SDK but I doubt that it'll show any solution. As a surface is a pure-touch device there is no risk of bad interaction with the mouse.

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• Concurrent Threads in C# using BackgroundWorker

  - by Jim Fell

  My C# application is such that a background worker is being used to wait for the acknowledgement of some transmitted data. Here is some psuedo code demonstrating what I'm trying to do: UI_thread { TransmitData() { // load data for tx // fire off TX background worker } RxSerialData() { // if received data is ack, set ack received flag } } TX_thread { // transmit data // set ack wait timeout // fire off ACK background worker // wait for ACK background worker to complete // evaluate status of ACK background worker as completed, failed, etc. } ACK_thread { // wait for ack received flag to be set } What happens is that the ACK BackgroundWorker times out, and the acknowledgement is never received. I'm fairly certain that it is being transmitted by the remote device because that device has not changed at all, and the C# application is transmitting. I have changed the ack thread from this (when it was working)... for( i = 0; (i < waitTimeoutVar) && (!bAckRxd); i++ ) { System.Threading.Thread.Sleep(1); } ...to this... DateTime dtThen = DateTime.Now(); DateTime dtNow; TimeSpan stTime; do { dtNow = DateTime.Now(); stTime = dtNow - dtThen; } while ( (stTime.TotalMilliseconds < waitTimeoutVar) && (!bAckRxd) ); The latter generates a very acurate wait time, as compared to the former. However, I am wondering if removal of the Sleep function is interferring with the ability to receive serial data. Does C# only allow one thread to run at a time, that is, do I have to put threads to sleep at some time to allow other threads to run? Any thoughts or suggestions you may have would be appreciated. I am using Microsoft Visual C# 2008 Express Edition. Thanks.

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• Mysterious HttpSession and session-config dependency

  - by OneMoreVladimir

  Good day. I'm developing a Java web app with Servlets\JSP using Tomcat 7.0. During request from client I put and object into the session and use forward. After the forward processing the same request the object can be retreived if the secure parameter is false otherwise it is not stored in session. <session-config> <session-timeout>15</session-timeout> <cookie-config> <http-only>true</http-only> <secure>true</secure> </cookie-config> <tracking-mode>COOKIE</tracking-mode> </session-config> I've figured out that "...cookies can be created with the 'secure' flag, which ensures that the browser will never transmit the specified cookie over non-SSL...". I've configured Tomcat to use SSL, but that haven't helped. Changing the tracking mode to SSL haven't helped as well. How do session-config and HttpSession object correlate in this case? What could be the problem?

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• selenium and firefox timeout behavior

  - by Md. Reazul Karim

  I am facing this strange timeout behavior. I tried to load some page using: WebDriver drv = new FirefoxDriver(); drv.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); drv.get(url); String email = ""; try { WebElement aElem = Util.safeFindElementByXpath(drv, "//p[1]/a[1]"); if (aElem != null) { email = aElem.getAttribute("href"); } } catch (Exception e) { } drv.quit(); return email; The safeFindElementByXpath is: static WebElement safeFindElementByXpath(WebDriver driver, String xpath) { try { return driver.findElement(By.xpath(xpath)); } catch (NoSuchElementException e) { return null; } } Now I set the firefox network.http.connection-timeout and network.http.connection-retry-timeout both to 10. Now if I restart the firefox I can see the new values. But if I try to run the above code - the firefox window opens and it waits for a particular website for a long time. Hence I open another tab in the same firefox window and check the values of timeout and find them to be 90 and 250. If I change the values on that same window, the selenium code immediately finishes requesting for the page (ie it goes after the exception block). So the thing is that the same code will work on many sites and I don't know beforehand which site is invalid/down and I was thinking of putting this code in a separate thread and kill the thread after some time from the calling thread. But that is not possible I guess because the child thread has no way to poll anything as it is stuck at page request and can't go to the polling code afterwards. Now the thing is that I want any kind of hack/workaround to accomplish this: try getting the emails for good sites and if there are bad sites just give up after a certain period (press the panic button sorta thing). Thanks

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• How to preserve the state of JavaScript closure?

  - by Uccio

  I am working on a migration platform to migrate web applications from a device to another. I am extending it to add the support for preserving JavaScript state. My main task is to create a file representing the current state of the executing application, to transmit it to another device and to reload the state in the destination device. The basic solution I adopted is to navigate the window object and to save all its descendant properties using JSON as base format for exportation and extending it to implement some features: preserving object reference, even if cyclic (dojox.json.ref library) support for timers Date non-numericproperties of arrays reference to DOM elements The most important task I need to solve now is exportation of closures. At this moment I didn't know how to implement this feature. I read about the internal EcmaScript property [[scope]] containing the scope chain of a function, a list-like object composed by all the nested activation context of the function. Unfortunately it is not accessible by JavaScript. Anyone know if there is a way to directly access the [[scope]] property? Or another way to preserve the state of a closure?

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• Detecting TCP dropout over an unreliable network

  - by yx

  I am doing some experimentation over an unreliable radio network (home brewed) using very rudimentary java socket programming to transfer messages back and forth between the end nodes. The setup is as follows: Node A --- Relay Node --- Node B One problem I am constantly running into is that somehow the connection drops out and neither Node A or B knows that the link is dead, and yet continues to transmit data. The TCP connection does not time out either. I have added in a heartbeat message that causes a timeout after a while, but I still would like to know what is the underlying cause of why TCP does not time out. Here are the options I am enabling when setting up a socket: channel.socket().setKeepAlive(false); channel.socket().setTrafficClass(0x08); // for max throughput This behavior is strange since it is totally different than when I have a wired network. On a wired network, I can simulate a disconnected connection by pulling out the ethernet cord, however, once I plug the cord back in, the connection becomes restablished and messages begin to be passed through once more. On the radio network, the connection is never reestablished and once it silently dies, the messages never resume. Is there some other unknown java implentation or setting for a socket that I can use, also, why am I seeing this behavior in the first place? And yes, before anyone says anything, I know TCP is not the preffered choice over an unreliable network, but in this case I wanted to ensure no packet loss.

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• How do you send an extended-ascii AT-command (CCh) from Android bluetooth to a serial device?

  - by softex

  This one really has me banging my head. I'm sending alphanumeric data from an Android app, through the BluetoothChatService, to a serial bluetooth adaptor connected to the serial input of a radio transceiver. Everything works fine except when I try to configure the radio on-the-fly with its AT-commands. The AT+++ (enter command mode) is received OK, but the problem comes with the extended-ascii characters in the next two commands: Changing the radio destination address (which is what I'm trying to do) requires CCh 10h (plus 3 hex radio address bytes), and exiting the command mode requires CCh ATO. I know the radio can be configured OK because I've done it on an earlier prototype with the serial commands from PIC basic, and it also can be configured by entering the commands directly from hyperterm. Both these methods somehow convert that pesky CCh into a form the radio understands. I've have tried just about everything an Android noob could possibly come up with to finagle the encoding such as: private void command_address() { byte[] addrArray = {(byte) 0xCC, 16, 36, 65, 21, 13}; CharSequence addrvalues = EncodingUtils.getString(addrArray, "UTF-8"); sendMessage((String) addrvalues); } but no matter what, I can't seem to get that high-order byte (CCh/204/-52) to behave as it should. All other (< 127) bytes, command or data, transmit with no problem. Any help here would be greatly appreciated. -Dave

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• How to iterate & retrieve values from NSArray of NSArrays of NSDictionaries

  - by chinjazz

  I'm stumpped on how iterate and get values for an Array of Arrays of NSDictionaries (different classes/entities). Here's what I'm currently doing: 1) Constructing two separate arrays of NSDictionaries (different entities) 2) Combining both arrays with: NSMutableArray *combinedArrayofDicts = [[NSMutableArray alloc] initWithObjects: sizesArrayOfDicts, wishListArrayOfDicts , nil]; 3) Then archive combinedArrayofDicts : NSData *dataToSend = [NSKeyedArchiver archivedDataWithRootObject:combinedArrayofDicts]; 4) Transmit over GameKit [self.session sendDataToAllPiers:dataToSend withDataMode: GKSendDataReliable error:nil]; 5) How would I manage traversing thru this array on the receiving end? I want to fetch values by for each class which is key'ed by classname: Here's how it looks via NSLog (2 Sizes Dicts, and 1 Wishlist Dict) Printing description of receivedArray: <__NSArrayM 0xbc65eb0>( <__NSArrayM 0xbc651f0>( { classname = Sizes; displayOrder = 0; share = 1; sizeType = Neck; value = "13\" or 33 (cm)"; }, { classname = Sizes; displayOrder = 0; share = 1; sizeType = Sleeve; value = "34\" or 86 (cm)"; } ) , <__NSArrayM 0xbc65e80>( { classname = Wishlist; detail = ""; displayOrder = 0; imageString = ""; latitude = "30.33216666666667"; link = "http://maps.google.com/maps?q=loc:30.332,-81.41"; longitude = "-81.40949999999999"; name = bass; share = 1; store = ""; } ) ) (lldb) In my for loop I'm issuing this: NSString *value = [dict objectForKey:@"classname"]; and get an exception: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM objectForKey:]: unrecognized selector sent to instance 0xbc651f0' Is this frowned upon as far as mixing object types in arrays of arrays?

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• How to approach socket programming between C# -> Java (Android)

  - by Alex

  I've recently knocked up a server/client app for Windows & Android that allows one to send a file from Windows to an android phone over a socket connection. It works great for a single file but trying to send multiple files over in a single stream is causing me problems. I've also realised that aside from the binary data, I will need to send messages over the socket to indicate error states and other application messages. I have little experience with network programming and and wondering what is the best way forward. Basically the C# server side of the app just goes into a listening state and uses Socket.SendFile to transmit the file. On Android I use the standard Java Socket.getInputStream() to receive the file. That works great for a single file transfer, but how should I handle multiple files and error/messaging information? Do I need to use a different socket for each file? Should I be using a higher level framework to handle this or can I send everything over the single socket? Any other suggestions for frameworks or learning materials?

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• Windows Server 2012 Branchcache vs. DFS-R

  - by TheCleaner

  Warning, subjective question ahead! But hopefully a good one that won't get closed. SCENARIO: I have a branch office that currently has no on-premise server. They access everything including a DC across a 12Mbps WAN link (MPLS). The link isn't saturated, averaging around 20% utilization. The circuit is very stable and has a high SLA and excellent uptime. However, large file transfers (mainly reads, not writes) from the file server across the WAN can be slow. We don't currently utilize DFS. RESEARCH DONE: I'm aware of WAN acceleration, using either dedicated hardware (Riverbed) or a dedicated software VM (Silver Peak) for example. But the pricing is outside of our current budget and the need isn't quite there yet from our perspective (since the issue is mainly in a "pull" scenario not necessarily push/pull). I'm mainly looking at deploying a Windows server at this branch office and either utilizing DFS-R or BranchCache. Looking at a table comparison and assuming we are looking at a "hosted branchcache server" and not simply distributed: It would appear there are benefits to both, even if both are "hosted" on a server. QUESTIONS I ACTUALLY HAVE: In what scenarios do each of these techs shine and where do you choose one over the other? Looking at a hosted Branchcache server, can you set "pre-fetching" of certain folders/files on the central file server so that they are immediately accessible locally at the branch? Do you have to do this on a schedule (if it is possible)? Looking at DFS-R my concern (and apparently solved with 3rd party apps) is file locking and making sure the file gets updated properly during a write operation (ie, making sure if both copies are accessed and both are written to, which file takes precedence and what happens to the changes?). Ideal it would seem would be to lock any alternate replicas of the data, but is it really that big of an issue? Does Branchcache lock the central file for editing? Does branchcache only transmit the deltas back to the central file of what has changed? Would either technology be ill advised if the branch office server was going to be utilized as a domain controller as well?

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• ESXI Crash need help to understand log and support about nexentastor on virtual machine

  - by Bgnt44

  If i understand right, the following core dump means that the cpu4 has crashed the Host if i read the next line it seem that at the time the CPU 4 was assigned to the NexentaStore Vm ... SO if im right i can say that NexentaStor Vm crash my esxi Am i right ? Does that core dump can provide me some more informations ? 2012-11-14T03:48:01.046Z cpu4:6089)0x41221f25ba08:[0x41803007abff]PanicvPanicInt@vmkernel#nover+0x56 stack: 0x3000000008, 0x41221f25ba 2012-11-14T03:48:01.046Z cpu4:6089)0x41221f25bae8:[0x41803007b4a7]Panic@vmkernel#nover+0xae stack: 0x2e067c00000010, 0x0, 0x1f25bb38, 2012-11-14T03:48:01.047Z cpu4:6089)0x41221f25bc18:[0x4180300a7823]TLBDoInvalidate@vmkernel#nover+0x45a stack: 0xca, 0x0, 0x0, 0x0, 0x0 2012-11-14T03:48:01.047Z cpu4:6089)0x41221f25bc68:[0x418030489e17]UserMem_CartelFlush@<None>#<None>+0xce stack: 0xcaa0b, 0x0, 0x0, 0x4 2012-11-14T03:48:01.047Z cpu4:6089)0x41221f25bd78:[0x41803048ab91]UserMemUnmapStateCleanup@<None>#<None>+0x58 stack: 0x0, 0x41221f25bd 2012-11-14T03:48:01.047Z cpu4:6089)0x41221f25be58:[0x41803048b97d]UserMemUnmap@<None>#<None>+0x104 stack: 0x41221f267000, 0x41221f25bf 2012-11-14T03:48:01.048Z cpu4:6089)0x41221f25be98:[0x41803048bf20]UserMem_Unmap@<None>#<None>+0xe3 stack: 0x426, 0x0, 0x41221f25bef8, 2012-11-14T03:48:01.048Z cpu4:6089)0x41221f25beb8:[0x4180304a5985]UW64VMKSyscallUnpackReleasePhysMemMap@<None>#<None>+0x18 stack: 0x10 2012-11-14T03:48:01.048Z cpu4:6089)0x41221f25bef8:[0x418030476791]User_LinuxSyscallHandler@<None>#<None>+0x17c stack: 0x41803004cc70, 2012-11-14T03:48:01.048Z cpu4:6089)0x41221f25bf18:[0x4180300a82be]User_LinuxSyscallHandler@vmkernel#nover+0x19 stack: 0x3ffe63bed80, 0 2012-11-14T03:48:01.049Z cpu4:6089)0x41221f25bf28:[0x418030110064]gate_entry@vmkernel#nover+0x63 stack: 0x10b, 0x0, 0x0, 0x426, 0xcf76 2012-11-14T03:48:01.049Z cpu4:6089)VMware ESXi 5.1.0 [Releasebuild-799733 x86_64] PCPU 1 locked up. Failed to ack TLB invalidate (total of 1 locked up, PCPU(s): 1). 2012-11-14T03:48:01.050Z cpu4:6089)cr0=0x80010031 cr2=0xcaa0b750 cr3=0x197d7b000 cr4=0x42768 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:0 world:6111 name:"vmm0:Windows_2012_-_SQL" (V) 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:1 world:6032 name:"vmm0:Windows_2012_-_AD" (V) 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:2 world:6098 name:"vmm0:Windows_2012_-_App" (V) 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:3 world:4099 name:"idle3" (IS) 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:4 world:6089 name:"vmx-vcpu-0:NexentaStor" (U) 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:5 world:6134 name:"vmm0:Ubuntu_-_NGINX" (V) 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:6 world:4102 name:"idle6" (IS) 2012-11-14T03:48:01.050Z cpu4:6089)pcpu:7 world:4103 name:"idle7" (IS) 2012-11-14T03:48:01.050Z cpu4:6089)@BlueScreen: PCPU 1 locked up. Failed to ack TLB invalidate (total of 1 locked up, PCPU(s): 1).

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• Why Does Wireless Gear Degrade Over Time?

  - by bahamat

  I saw this originally posted on slashdot, but their comment format is not conducive to actually getting a correct answer. Having directly experienced this phenomenon myself, I'm now asking here where I think I can actually get an educated answer. Here's the original question verbatim: Lately I have replaced several home wireless routers because the signal strength has been found to be degraded. These devices, when new (2+ years ago) would cover an entire house. Over the years, the strength seems to decrease to a point where it might only cover one or two rooms. Of the three that I have replaced for friends, I have not found a common brand, age, etc. It just seems that after time, the signal strength decreases. I know that routers are cheap and easy to replace but I'm curious what actually causes this. I would have assumed that the components would either work or not work; we would either have a full signal or have no signal. I am not an electrical engineer and I can't find the answer online so I'm reaching out to you. Can someone explain how a transmitter can slowly go bad? Common (incorrect, but repeated) answers from slashdot include: Back then your neighbors didn't have wifi, now they do. They drowning you out. I don't think this is likely because replacing the access point with a new one and using the same frequencies solves the problem. Older devices had low transmit power. Crank that baby. As mentioned by a FreeBSD wireless developer this violates regulations and can physically damage the equipment. It was also mentioned that higher power in one direction is not necessarily reciprocated. This shows higher bars, but not necessarily a better connection. Manufacturers make cheap crap designed to wear out. This one actually may be legitimate although it is overly broad. What specifically causes damage over time? Heat? Excessive power? So can anyone provide an informed answer on this? Is there any way to fix these older access points?

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• networking tunnel adapter connections?

  - by Karthik Balaguru

  I understand that Tunnel Adapter LAN is for encapsulating IPv6 packets with an IPv4 header so that they can be sent across an IPv4 network. Few queries popped up in my mind based on this :- If i do 'ipconfig', Apart from ethernet adapter LAN details, I get a series of statments as below - Tunnel adapter Local Area Connection* 6 Tunnel adapter Local Area Connection* 7 Tunnel adapter Local Area Connection* 12 Tunnel adapter Local Area Connection* 13 Tunnel adapter Local Area Connection* 14 Tunnel adapter Local Area Connection* 15 Tunnel adapter Local Area Connection* 16 Except for the *16, all the other Tunnel Adapter Local Area Connections show Media Disconnected. Why is the numbering for the Tunnel adapter LAN not sequential? It is like 6, 7, 12, 13, 14, 15, 16. A strange numbering scheme! I tried to figure it out by thinking of some arithmetic series. But, it does not seem to fit in. There is a huge gap between 7 and 12. Any ideas? What is the need for so many Tunnel Adapter LAN connections? Can you tell me a scenario that requires all of those ? I did ipconfig /all to get more information. From the listing, I understand that: 16, 15, 14, 12 are Microsoft 6to4 Adapters 13, 6 are isatap Adapters 7 is Teredo Tunneling Pseudo-interface I understand that the above are for automatic tunneling so that the tunnel endpoints are determined automatically by the routing infrastructure. 6to4 is recommended by RFC3056 for automatic tunneling that uses protocol 41 for encapsulation. It is typically used when an end-user wants to connect to the IPv6 Internet using their existing IPv4 connection. Teredo is an automatic tunneling technique that uses UDP encapsulation across multiple NATs. That is, It is to grant IPv6 connectivity to nodes that are located behind IPv6-unaware NAT devices ISATAP treats the IPv4 network as a virtual IPv6 local link, with mappings from each IPv4 address to a link-local IPv6 address. That is to transmit IPv6 packets between dual-stack nodes on top of an IPv4 network. That is, to put in simple words, ISATAP is an intra-site mechanism, while the 6to4 and Teredo are for inter-site tunnelling mechanisms. It seems that Teredo should alone enabled by default in Vista, But my system does not show it to be enabled by default. Interestingly, it shows a 6to4 tunnel adapter (Tunnel adapter LAN connection 16) to be enabled by default? Any specific reasons for it? If i do ipconfig /all, why is only one Teredo present while four 6to4 are present ? I searched the internet for answers to the above queries, but I am unable to find clear answers.

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• Building NanoBSD inside a jail

  - by ptomli

  I'm trying to setup a jail to enable building a NanoBSD image. It's actually a jail on top of a NanoBSD install. The problem I have is that I'm unable to mount the md device in order to do the 'build image' part. Is it simply not possible to mount an md device inside a jail, or is there some other knob I need to twiddle? On the host /etc/rc.conf.local jail_enable="YES" jail_mount_enable="YES" jail_list="build" jail_set_hostname_allow="NO" jail_build_hostname="build.vm" jail_build_ip="192.168.0.100" jail_build_rootdir="/mnt/zpool0/jails/build/home" jail_build_devfs_enable="YES" jail_build_devfs_ruleset="devfsrules_jail_build" /etc/devfs.rules [devfsrules_jail_build=5] # nothing Inside the jail [root@build /usr/obj/nanobsd.PROLIANT_MICROSERVER]# sysctl security.jail security.jail.param.cpuset.id: 0 security.jail.param.host.hostid: 0 security.jail.param.host.hostuuid: 64 security.jail.param.host.domainname: 256 security.jail.param.host.hostname: 256 security.jail.param.children.max: 0 security.jail.param.children.cur: 0 security.jail.param.enforce_statfs: 0 security.jail.param.securelevel: 0 security.jail.param.path: 1024 security.jail.param.name: 256 security.jail.param.parent: 0 security.jail.param.jid: 0 security.jail.enforce_statfs: 1 security.jail.mount_allowed: 1 security.jail.chflags_allowed: 1 security.jail.allow_raw_sockets: 0 security.jail.sysvipc_allowed: 0 security.jail.socket_unixiproute_only: 1 security.jail.set_hostname_allowed: 0 security.jail.jail_max_af_ips: 255 security.jail.jailed: 1 [root@build /usr/obj/nanobsd.PROLIANT_MICROSERVER]# mdconfig -l md2 md0 md1 md0 and md1 are the ramdisks of the host. bsdlabel looks sensible [root@build /usr/obj/nanobsd.PROLIANT_MICROSERVER]# bsdlabel /dev/md2s1 # /dev/md2s1: 8 partitions: # size offset fstype [fsize bsize bps/cpg] a: 1012016 16 4.2BSD 0 0 0 c: 1012032 0 unused 0 0 # "raw" part, don't edit newfs runs ok [root@build /usr/obj/nanobsd.PROLIANT_MICROSERVER]# newfs -U /dev/md2s1a /dev/md2s1a: 494.1MB (1012016 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 123.55MB, 7907 blks, 15872 inodes. with soft updates super-block backups (for fsck -b #) at: 160, 253184, 506208, 759232 mount fails [root@build /usr/obj/nanobsd.PROLIANT_MICROSERVER]# mount /dev/md2s1a _.mnt/ mount: /dev/md2s1a : Operation not permitted UPDATE: One of my colleagues pointed out There are some file systems types that can't be securely mounted within a jail no matter what, like UFS, MSDOFS, EXTFS, XFS, REISERFS, NTFS, etc. because the user mounting it has access to raw storage and can corrupt it in a way that it will panic entire system. From http://www.mail-archive.com/[email protected]/msg160389.html So it seems that the standard nanobsd.sh won't run inside a jail while it uses the md device to build the image. One potential solution I'll try is to chroot from the host into the build jail, rather than jexec a shell.

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