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  • vc++ - static member is showing error

    - by prabhakaran
    I am using vc++(2010). I am trying to create a class for server side socket. Here is the header file #include<winsock.h> #include<string> #include<iostream> using namespace std; class AcceptSocket { // static SOCKET s; protected: SOCKET acceptSocket; public: AcceptSocket(){}; void setSocket(SOCKET socket); static void EstablishConnection(int portNo,string&); static void closeConnection(); static void StartAccepting(); virtual void threadDeal(); static DWORD WINAPI MyThreadFunction(LPVOID lpParam); }; SOCKET AcceptSocket::s; and the corresponding source file #include<NetWorking.h> #include<string> void AcceptSocket::setSocket(SOCKET s) { acceptSocket=s; } void AcceptSocket::EstablishConnection(int portno,string &failure) { WSAData w; int error = WSAStartup(0x0202,&w); if(error) failure=failure+"\nWSAStartupFailure"; if(w.wVersion != 0x0202) { WSACleanup(); failure=failure+"\nVersion is different"; } SOCKADDR_IN addr; addr.sin_family=AF_INET; addr.sin_port=htons(portno); addr.sin_addr.s_addr=htonl(INADDR_ANY); AcceptSocket::s=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); if(AcceptSocket::s == INVALID_SOCKET) failure=failure+"\nsocket creating error"; if(bind(AcceptSocket::s,(LPSOCKADDR) &addr,sizeof(addr)) == SOCKET_ERROR) failure=failure+"\nbinding error"; listen(AcceptSocket::s,SOMAXCONN); } void AcceptSocket::closeConnection() { if(AcceptSocket::s) closesocket(AcceptSocket::s); WSACleanup(); } void AcceptSocket::StartAccepting() { sockaddr_in addrNew; int size=sizeof(addrNew); while(1) { SOCKET temp=accept(AcceptSocket::s,(sockaddr *)&addrNew,&size); AcceptSocket * tempAcceptSocket=new AcceptSocket(); tempAcceptSocket->setSocket(temp); DWORD threadId; HANDLE thread=CreateThread(NULL,0,MyThreadFunction,(LPVOID)tempAcceptSocket,0,&threadId); } } DWORD WINAPI AcceptSocket::MyThreadFunction(LPVOID lpParam) { AcceptSocket * acceptsocket=(AcceptSocket *) lpParam; acceptsocket->threadDeal(); return 1; } void AcceptSocket::threadDeal() { "You didn't define threadDeal in the derived class"; } Now the main.cpp is #include<Networking.h> int main() { } When I am compiling The error I got is Error 1 error LNK2005: "private: static unsigned int AcceptSocket::s" (?s@AcceptSocket@@0IA) already defined in NetWorking.obj C:\Documents and Settings\prabhakaran\Desktop\check\check\main.obj check Error 2 error LNK1169: one or more multiply defined symbols found C:\Documents and Settings\prabhakaran\Desktop\check\Debug\check.exe 1 1 check Now anybody please enlighten me about this issue

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  • Trying to debug a 'Assertion failure in -[UIActionSheet showInView:]' error....

    - by dsobol
    I am working through "Beginning iPad Application Development" and am getting hung up in Chapter 3 where I have created a project that works with an Action Sheet. As it stands now, my application loads into the simulator just fine with no errors that I am aware of, but as it runs, it crashes with the following errors showing up in the debugger window: 2010-05-31 19:44:39.703 UsingViewsActionSheet[49538:207] * Assertion failure in -[UIActionSheet showInView:], /SourceCache/UIKit_Sim/UIKit-1145.66/UIAlert.m:7073 2010-05-31 19:44:39.705 UsingViewsActionSheet[49538:207] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid parameter not satisfying: view != nil' I am sure that this is the block where the app breaks based upon my use of breakpoints. //Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { UIActionSheet *action = [[UIActionSheet alloc] initWithTitle:@"This is my Action Sheet!" delegate:self cancelButtonTitle:@"OK" destructiveButtonTitle:@"Delete Message!" otherButtonTitles:@"Option 1", @"Option 2", @"Option 3", nil]; [action showInView:self.view]; // <-- This line seems to trigger the crash.... [action release]; [super viewDidLoad]; } Am I missing something obvious, or is there more to the problem than is shown here? I have looked at the abstract for showInView and cannot divine anything there yet. I appreciate any and all asssitance. Regards, Steve O'Sullivan

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  • How can I get JUnit test (driven from Ant script) to dump the stack of exception that causes failure

    - by Matt Wang
    We run JUnit test from Ant script, as follows. When the test failed, I expect it to output the stack dump of the exception that casuses the failure, but it doesn't. Is there any trick to get it dumped? <target description="Run JUnit tests" name="run-junit" depends="build-junit"> <copy file="./AegisLicense.txt" tofile="test/junit/classes/AegisLicense.txt" overwrite="true"/> <junit printsummary="yes" haltonfailure="no" fork="yes" forkmode="once" failureproperty="run-aegis-junit-failed" showoutput="yes" filtertrace="off"> <classpath refid="Aegisoft.testsupport.classpath"/> <classpath> <pathelement location="test/junit/classes"/> </classpath> <batchtest> <fileset dir="test/junit/src"> <include name="**"/> </fileset> </batchtest> </junit> <fail

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  • How do I trace SQL Server Failure Audit events?

    - by Tim Perry
    I recently took over management of a Windows 2003 server. The application log is being filled up with messages like these: Event Type: Failure Audit Event Source: MSSQLSERVER Event Category: (4) Event ID: 18456 Date: 3/5/2010 Time: 4:00:30 PM User: N/A Computer: FAIROAKS1 Description: Login failed for user 'administrator'. [CLIENT: <local machine>] Data: 0000: 18 48 00 00 0e 00 00 00 .H...... 0008: 0a 00 00 00 46 00 41 00 ....F.A. 0010: 49 00 52 00 4f 00 41 00 I.R.O.A. 0018: 4b 00 53 00 31 00 00 00 K.S.1... 0020: 07 00 00 00 6d 00 61 00 ....m.a. 0028: 73 00 74 00 65 00 72 00 s.t.e.r. 0030: 00 00 .. For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. I'd like to figure out what program is causing these. Is there a way to trace and find out which process is causing these errors?

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  • BizTalk Server 2009 - Architecture Options

    - by StuartBrierley
    I recently needed to put forward a proposal for a BizTalk 2009 implementation and as a part of this needed to describe some of the basic architecture options available for consideration.  While I already had an idea of the type of environment that I would be looking to recommend, I felt that presenting a range of options while trying to explain some of the strengths and weaknesses of those options was a good place to start.  These outline architecture options should be equally valid for any version of BizTalk Server from 2004, through 2006 and R2, up to 2009.   The following diagram shows a crude representation of the common implementation options to consider when designing a BizTalk environment.         Each of these options provides differing levels of resilience in the case of failure or disaster, with the later options also providing more scope for performance tuning and scalability.   Some of the options presented above make use of clustering. Clustering may best be described as a technology that automatically allows one physical server to take over the tasks and responsibilities of another physical server that has failed. Given that all computer hardware and software will eventually fail, the goal of clustering is to ensure that mission-critical applications will have little or no downtime when such a failure occurs. Clustering can also be configured to provide load balancing, which should generally lead to performance gains and increased capacity and throughput.   (A) Single Servers   This option is the most basic BizTalk implementation that should be considered. It involves the deployment of a single BizTalk server in conjunction with a single SQL server. This configuration does not provide for any resilience in the case of the failure of either server. It is however the cheapest and easiest to implement option of those available.   Using a single BizTalk server does not provide for the level of performance tuning that is otherwise available when using more than one BizTalk server in a cluster.   The common edition of BizTalk used in single server implementations is the standard edition. It should be noted however that if future demand requires increased capacity for a solution, this BizTalk edition is limited to scaling up the implementation and not scaling out the number of servers in use. Any need to scale out the solution would require an upgrade to the enterprise edition of BizTalk.   (B) Single BizTalk Server with Clustered SQL Servers   This option uses a single BizTalk server with a cluster of SQL servers. By utilising clustered SQL servers we can ensure that there is some resilience to the implementation in respect of the databases that BizTalk relies on to operate. The clustering of two SQL servers is possible with the standard edition but to go beyond this would require the enterprise level edition. While this option offers improved resilience over option (A) it does still present a potential single point of failure at the BizTalk server.   Using a single BizTalk server does not provide for the level of performance tuning that is otherwise available when using more than one BizTalk server in a cluster.   The common edition of BizTalk used in single server implementations is the standard edition. It should be noted however that if future demand requires increased capacity for a solution, this BizTalk edition is limited to scaling up the implementation and not scaling out the number of servers in use. You are also unable to take advantage of multiple message boxes, which would allow us to balance the SQL load in the event of any bottlenecks in this area of the implementation. Any need to scale out the solution would require an upgrade to the enterprise edition of BizTalk.   (C) Clustered BizTalk Servers with Clustered SQL Servers   This option makes use of a cluster of BizTalk servers with a cluster of SQL servers to offer high availability and resilience in the case of failure of either of the server types involved. Clustering of BizTalk is only available with the enterprise edition of the product. Clustering of two SQL servers is possible with the standard edition but to go beyond this would require the enterprise level edition.    The use of a BizTalk cluster also provides for the ability to balance load across the servers and gives more scope for performance tuning any implemented solutions. It is also possible to add more BizTalk servers to an existing cluster, giving scope for scaling out the solution as future demand requires.   This might be seen as the middle cost option, providing a good level of protection in the case of failure, a decent level of future proofing, but at a higher cost than the single BizTalk server implementations.   (D) Clustered BizTalk Servers with Clustered SQL Servers – with disaster recovery/service continuity   This option is similar to that offered by (C) and makes use of a cluster of BizTalk servers with a cluster of SQL servers to offer high availability and resilience in case of failure of either of the server types involved. Clustering of BizTalk is only available with the enterprise edition of the product. Clustering of two SQL servers is possible with the standard edition but to go beyond this would require the enterprise level edition.    As with (C) the use of a BizTalk cluster also provides for the ability to balance load across the servers and gives more scope for performance tuning the implemented solution. It is also possible to add more BizTalk servers to an existing cluster, giving scope for scaling the solution out as future demand requires.   In this scenario however, we would be including some form of disaster recovery or service continuity. An example of this would be making use of multiple sites, with the BizTalk server cluster operating across sites to offer resilience in case of the loss of one or more sites. In this scenario there are options available for the SQL implementation depending on the network implementation; making use of either one cluster per site or a single SQL cluster across the network. A multi-site SQL implementation would require some form of data replication across the sites involved.   This is obviously an expensive and complex option, but does provide an extraordinary amount of protection in the case of failure.

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  • What might cause https failure when not specifying SSL protocol?

    - by user35042
    I have a VBScript program that retrieves a web page from a server not under my control. The URL looks something like https://someserver.xxx/index.html. I use this code to create the object that does the page getting: Set objWinHttp = CreateObject("WinHttp.WinHttpRequest.5.1") When I wrote my program it had no problem retrieving this page. Recently, the web server serving this page went through an upgrade. Now my program can no longer fetch the page. Some clues: Clue 1. I can fetch the web page if I use a browser (I tried Firefox, IE, and Chrome). Clue 2. The VBScript code yields this error: The message received was unexpected or badly formatted. Clue 3. I can fetch the web page from the command line in certain cases but not in others: curl --sslv3 -v -k 'https://someserver.xxx/index.html' # WORKS! curl --sslv2 -v -k 'https://someserver.xxx/index.html' # WORKS! curl -v -k 'https://someserver.xxx/index.html' # FAILS curl --tlsv1 -v -k 'https://someserver.xxx/index.html' # FAILS In the case where I do not specify a protocol I get this error: * SSLv3, TLS handshake, Client hello (1): * error:14077417:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert illegal parameter * Closing connection #0 In the case where I specify --tlsv1 I get this error: * SSLv3, TLS handshake, Client hello (1): * SSLv3, TLS alert, Server hello (2): * error:14094417:SSL routines:SSL3_READ_BYTES:sslv3 alert illegal parameter * Closing connection #0 A. Does anyone have any suggestions or ideas on what might be going on at the web server end (I am unable to talk to the admins of the web server to find out what they changed). B. Is there a way I can change my VBScript code to work around this issue? Can the SSL version be forced?

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  • How can I resolve Oracle 11g XE connection failure straight after installation?

    - by d3vid
    I have just installed Oracle 11g XE on a Windows 7 VirtualBox VM, using all the default options. "Getting Started" fails When I click on Getting Started I get taken to http://127.0.0.1:8080/apex/f?p=4950 which fails. After some browsing I came across a suggestion to confirm the HTTP port, but I can't get this far, because I can't connect. connect system fails If I select Run SQL command line I get taken to a SQL prompt. I enter connect system and get prompted for a password. I enter the password. I immediately get the following error: ERROR: ORA-01033: ORACLE initialization or shutdown in progress Process ID: 0 Session ID: 0 Serial number: 0 Info: Start database This happens whether or not I run Start database first. (Start database just opens a Windows command prompt window.) Info: Windows services My Oracle services start as follows: Starting the manual services doesn't resolve the problem. Enabling and starting the disabled service doesn't resolve the problem. Is there something I haven't done? How can I resolve this connection error?

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  • How to troubleshoot a remote wmi query/access failure?

    - by Roman
    Hi I'm using Powershell to query a remote computer in a domain for a wmi object, eg: "gwmi -computer test -class win32_bios". I get this error message: Value does not fall within the expected range Executing the query local under the same user works fine. It seems to happen on both windows 2003 and also 2008 systems. The user that runs the shell has admin rights on the local and remote server. I checked wmi and dcom permissions as far as I know how to do this, they seem to be the same on a server where it works, and another where it does not. I think it is not a network issue, all ports are open that are needed, and it also happens within the same subnet. When sniffing the traffic we see the following errors: RPC: c/o Alter Cont Resp: Call=0x2 Assoc Grp=0x4E4E Xmit=0x16D0 Recv=0x16D0 Warning: GssAPIMechanism is not found, either caused by not reassembled, conversation off or filtering. And an errormessage from Kerberos: Kerberos: KRB_ERROR - KDC_ERR_BADOPTION (13) The option code in the packet is 0x40830000 Any idea what I should look into?

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  • Failure to install NetFX3 on Windows Server 2012: Error 3017 -- Am I missing something here?

    - by Nick
    I am really struggling to get this installed. I have tried the suggestions here in an attempt to rectify any possible corruption. I mounted the disk image to 'G' to do an offline install. I also attempted an online install with similar results. Output as follows: Microsoft Windows [Version 6.2.9200] (c) 2012 Microsoft Corporation. All rights reserved. C:\Users\Administrator>dism /online /enable-feature /featurename:NetFX3 /All /So urce:G:\sources\sxs /LimitAccess Deployment Image Servicing and Management tool Version: 6.2.9200.16384 Image Version: 6.2.9200.16384 Enabling feature(s) [==========================100.0%==========================] Error: 3017 The requested operation failed. A system reboot is required to roll back changes made. The DISM log file can be found at C:\Windows\Logs\DISM\dism.log Log as follows (Errors/Warnings Only): 2013-04-08 23:40:17, Error DISM DISM Package Manager: PID=3756 TID=3768 Failed finalizing changes. - CDISMPackageManager::Internal_Finalize(hr:0x80070bc9) 2013-04-08 23:40:17, Error DISM DISM Package Manager: PID=3756 TID=3768 Failed processing package changes with session options - CDISMPackageManager::ProcessChangesWithOptions(hr:0x80070bc9) 2013-04-08 23:40:17, Error DISM DISM Package Manager: PID=3756 TID=3768 Failed ProcessChanges. - CPackageManagerCLIHandler::Private_ProcessFeatureChange(hr:0x80070bc9) 2013-04-08 23:40:17, Error DISM DISM Package Manager: PID=3756 TID=3768 Failed while processing command enable-feature. - CPackageManagerCLIHandler::ExecuteCmdLine(hr:0x80070bc9) 2013-04-08 23:40:17, Error DISM DISM.EXE: DISM Package Manager processed the command line but failed. HRESULT=80070BC9 2013-04-08 23:38:10, Warning DISM DISM Provider Store: PID=3160 TID=3172 Failed to Load the provider: C:\Windows\TEMP\505F54F1-4977-4233-835C-8B6DA83BCAEB\PEProvider.dll. - CDISMProviderStore::Internal_GetProvider(hr:0x8007007e) 2013-04-08 23:39:23, Warning DISM DISM Provider Store: PID=3756 TID=3768 Failed to Load the provider: C:\Users\ADMINI~1\AppData\Local\Temp\2\F1B7A223-F380-4F42-84BF-396D374EE80B\PEProvider.dll. - CDISMProviderStore::Internal_GetProvider(hr:0x8007007e) 2013-04-08 23:39:23, Warning DISM DISM Provider Store: PID=3756 TID=3768 Failed to Load the provider: C:\Users\ADMINI~1\AppData\Local\Temp\2\F1B7A223-F380-4F42-84BF-396D374EE80B\IBSProvider.dll. - CDISMProviderStore::Internal_GetProvider(hr:0x8007007e) 2013-04-08 23:39:23, Warning DISM DISM Provider Store: PID=3756 TID=3768 Failed to get the IDismObject Interface - CDISMProviderStore::Internal_LoadProvider(hr:0x80004002) 2013-04-08 23:39:23, Warning DISM DISM Provider Store: PID=3756 TID=3768 Failed to Load the provider: C:\Users\ADMINI~1\AppData\Local\Temp\2\F1B7A223-F380-4F42-84BF-396D374EE80B\Wow64provider.dll. - CDISMProviderStore::Internal_GetProvider(hr:0x80004002) 2013-04-08 23:39:23, Warning DISM DISM Provider Store: PID=3756 TID=3768 Failed to Load the provider: C:\Users\ADMINI~1\AppData\Local\Temp\2\F1B7A223-F380-4F42-84BF-396D374EE80B\EmbeddedProvider.dll. - CDISMProviderStore::Internal_GetProvider(hr:0x8007007e) None of my error codes align with any of those on this MS support page. I would really appreciate your assistance. I am really struggling with a solution. Am I missing something obvious here? EDIT: I have verified the checksum of my ISO image: File Name: en_windows_server_2012_x64_dvd_915478.iso SHA1: D09E752B1EE480BC7E93DFA7D5C3A9B8AAC477BA

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  • How to customize Windows Failover clustering to trigger on failure of custom window service?

    - by melaos
    i'm a total newbie on windows failover clustering. and what i want to do now is to setup the FC (failover clustering) on two win 2008 R2 server. and right now i have my custom window service running on both machine. But they cannot run concurrently as it will mess up the DB, thus i just want one to be available at all time (high availability). so i'm wondering if there's any way to set the failover policy to include this custom window service that i've installed on these machines so that if this service goes down or die, then it will automatically trigger the failover to the second node. is this possible? or must it be done programatically? and if so what is the best way? thanks ~m

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  • Mac OS X printing to CUPS - More intuitive authentication failure?

    - by Moduspwnens
    We have a network-wide CUPS server that offers authenticated printer access to all our campus users. We've been pretty disappointed with the way Mac clients handle bad printing authentication, though. In any other authentication dialog, when a user types in a bad username or password, the window shakes briefly, allowing the user to re-enter. With printers, this isn't the case. It'll happily accept (and even save to the keychain, if specified) bad credentials. The authentication dialog is dismissed, and the user then has to deal with the print jobs showing up as "On hold (authentication required)". To get their job printed, they need to select it in the printer's queue, click "Resume", then re-enter appropriate credentials. Is there a way to get failed printing authentication to work more intuitively for Mac OS X clients? We're trying to support a BYOD environment, but our end users have been really confused by this. It's made even worse by the way it pre-populates the user's full login name (e.g. "Smith, John"), which tends to make them think to use their local machine passwords.

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  • How to add nvidia drivers after previous failure with linux mint?

    - by LessThanMe
    Before today, I had perfectly good drivers from nvidia for my linux mint (15) box. I decided to update it because my performance in TF2 is less than stellar, and then things went south. I used synaptic to install nvidia-331 and then rebooted, but when I selected Mint in GRUB I waited...and waited...and waited. Nothing happened, but the display stayed on (a completely black video was being output). So I went into recovery mode from GRUB, went to root access, and apt-get remove --purge nvidia*'d my way out of that mess, and installed nvidia-common. Now my performance in graphic intensive stuff (read: games, blender) sucks, so I've been through the same thing a few times trying to re-install nvidia-current. I just want to get it back how it was. Thanks for any help! Nvidia GTX 560

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  • Win 7 (SP1) Creationg of System Image failure... seems absurd. (0x80780119)

    - by DSKauai16
    This question seems to keep coming up in Microsoft Answers. Unfortunately, it never seems to be solved... on Microsoft Answers. Hopefully someone here will have a better idea. I'm trying to create a system image. It's not working. I have just re-installed windows as of a few hours ago. I have an admittedly older Western Digital 148 GB USB portable HDD which is not just completely empty, but I even did a long format with the NTFS file system just to be sure. The reinstallation of windows and a couple of programs take up 40 GB (seen below) When I try to create a System Image onto the USB HDD, I am told that there is not enough room. Obviously, this is wrong. The screen captures show exactly the steps that are happening to lead me to 0x80780119. I haven't done anything but put on Windows 7 (32bit; SP1) and install some programs. I haven't even done anything with them. There's almost zero in the way of data, and I checked that yes, the HDD works to accept data, send data and work with data. I've used the drive successfully for a long, long time. What's going wrong?

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  • Ubuntu Wubi "drive" failure; mount drive in XP?

    - by 618034
    Hi there, I installed the Wubi distribution of Ubuntu on a separate partition (which is silly, since why do I care if Windows can still manage the partition?) a few months back; it was pretty awesome, until Linux hosed. At this point, I can get Ubuntu to boot if I try really hard through grub, but once it does start, the screen is hosed, so no dice. At this point, I'd like to wipe it all and start over, but I need to get some stuff off the "disk". The Wubi install makes this difficult, since the "disk" is a flat file on an NTFS partition. I've done just about everything I can think of — I renamed the virtual disk .iso, mounted it with VirtualCloneDrive, then used whatever magic EXT3 (EXT4?) readers I could dig up on the Internet to parse the mount — but nothing's working. Can you offer any suggestions? The "disk" is currently in D:\ubuntu\disks\root.iso. Many thanks! (I may be high-latency at the moment, apologies if I don't address follow-ups quickly)

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  • Is my hard drive about to fail?

    - by Cody Harlow
    I hear some squeaking noises sometimes when I use my computer so I ran smartctl. This is the results: === START OF READ SMART DATA SECTION === SMART Self-test log structure revision number 1 Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error # 1 Short offline Completed: read failure 90% 5953 37922655 # 2 Extended offline Completed: read failure 90% 5953 37922655 # 3 Short offline Completed: read failure 90% 5953 37922655 # 4 Short offline Completed without error 00% 429 - # 5 Extended offline Aborted by host 90% 429 - # 6 Short offline Completed without error 00% 429 - # 7 Short offline Completed without error 00% 429 - Is this a bad sign?

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  • Snow Leopard connecting to Unbuntu 10.04 through Samba failure -- need help fixing.

    - by Chris Altman
    I have a Ubuntu 10.04 web server. I want to connect to it with my OSX 10.6 machine and Finder. I have installed openSSH and Samba on the Ubuntu machine. In my smb.conf I have a Share Definition: [www] comment = Development Computer WWW path = /var/www writeable = yes browseable = yes allow hosts = 192.168.1. I can connect to the machine through Finder using a non-root user. When I attempt to add files thought Finder I get an "Insufficient Permissions" error. Please help. I am not sure if the issue is in the Samba configuration or OSX 10.6 Thank you

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  • How do I diagnose Windows XP failure to automatically suspend on idle?

    - by Software Monkey
    Since upgrading my hardware (mobo, CPU and memory) a couple months ago my computer no longer automatically suspends and hibernates after the configured idle periods. Both functions work just fine manually, but if I leave the computer on overnight it's still active the next morning even though it's configured to sleep after 3 hours and hibernate after 6 hours. How do I diagnose the cause of this?

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  • Is there a theory for "transactional" sequences of failing and no-fail actions?

    - by Ross Bencina
    My question is about writing transaction-like functions that execute sequences of actions, some of which may fail. It is related to the general C++ principle "destructors can't throw," no-fail property, and maybe also with multi-phase transactions or exception safety. However, I'm thinking about it in language-neutral terms. My concern is with correctly designing error handling in C++ functions that must be reliable. I would like to know what the concepts below are called so that I can learn more about them. I'm sorry that I can't ask the question more directly. Since I don't know this area I have provided an example to explain my question. The question is at the end. Here goes: Consider a sequence of steps or actions executed sequentially, where actions belong to one of two classes: those that always succeed, and those that may fail. In the examples below: S stands for an action that always succeeds (called "no-fail" in some settings). F stands for an action that may fail (for example, it might fail to allocate memory or do I/O that could fail). Consider a sequences of actions (executed sequentially from left to right): S->S->S->S Since each action in the sequence above succeeds, the whole sequence succeeds. On the other hand, the following sequence may fail because the last action may fail: S->S->S->F So, claim: a sequence has the no-fail (S) property if and only if all of its actions are no-fail. Now, I'm interested in action sequences that form "atomic transactions", with "failure atomicity," i.e. where either the whole sequence completes successfully, or there is no effect. I.e. if some action fails, the earlier ones must be rolled back. This requires that any successfully executed actions prior to a failing action must always be able to be rolled back. Consider the sequence: S->S->S->F S<-S<-S In the example above, the first row is the forward path of the transaction, and the second row are inverse actions (executed from right to left) that can be used to roll back if the final top row actions fails. It seems to me that for a transaction to support failure atomicity, the following invariant must hold: Claim: To support failure atomicity (either completion or complete roll-back on failure) all actions preceding the latest failable (F) action on the forward path (marked * in the example below) must have no-fail (S) inverses. The following is an example of a sequence that supports failure atomicity: * S->F->F->F S<-S<-S Further, if we want the transaction to be able to attempt cancellation mid-way through, but still guarantee either full completion or full rollback then we need the following property: Claim: To support failure atomicity and cancellation mid-way through execution, in the face of errors in the inverse (cancellation) path, all actions following the earliest failable (F) inverse on the reverse path (marked *) must be no-fail (S). F->F->F->S->S S<-S<-F<-F * I believe that these two conditions guarantee that an abortable/cancelable transaction will never get "stuck". My questions are: What is the study and theory of these properties called? are my claims correct? and what else is there to know? UPDATE 1: Updated terminology: what I previously called "robustness" is called atomicity in the database literature. UPDATE 2: Added explicit reference to failure atomicity, which seems to be a thing.

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  • Failure to obtain IP with ARP over Wi-Fi with personal Wi-Fi router in client mode

    - by axk
    I'm trying to connect a Samsung TV to the Internet using a TL-MR3020 personal wireless router in client mode. The TV fails to connect to the network. It sees the ethernet cable connected though. Here's my network topology: Here's what I've captured with Wireshark filtering for ARP (eth.type == 0x0806): It appears the TV fails to get the IP of the gateway (DSL modem/router) for some reason. One thing I've noticed is that the source MAC for the ARP requests coming from the TV is the MAC of the Portable wireless router (that is cd:89:00), not the TV itself and the modem sends the responses to that MAC (I'm not an expert and don't know if its okay or it may make the TV fail to get the requested IP). Also I'm able to ping the TV from the DSL router (through the telnet interface) and the router has an entry in its MAC table for the TV's IP with the Portable wireless router's MAC (that is cd:89:00). If I'm able to ping the TV I suppose it should know the router's MAC to respond to the ping, but then why these continuous ARP requests... I've also tried to connect my desktop trough this Portable wireless router the same way I'm trying to connect the TV and it works fine, I can set the DSL Modem's IP as the default gateway on the desktop's NIC and connect to the Internet. The TV can connect to the Internet when connected to the DSL Router with a wired connection. Any suggestions on what may be the cause of the problem / how to further debug it are welcome. Thanks!

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  • How to troubleshoot a remote wmi query/access failure?

    - by Roman
    I'm using Powershell to query a remote computer in a domain for a wmi object, eg: "gwmi -computer test -class win32_bios". I get this error message: Value does not fall within the expected range Executing the query local under the same user works fine. It seems to happen on both windows 2003 and also 2008 systems. The user that runs the shell has admin rights on the local and remote server. I checked wmi and dcom permissions as far as I know how to do this, they seem to be the same on a server where it works, and another where it does not. I think it is not a network issue, all ports are open that are needed, and it also happens within the same subnet. When sniffing the traffic we see the following errors: RPC: c/o Alter Cont Resp: Call=0x2 Assoc Grp=0x4E4E Xmit=0x16D0 Recv=0x16D0 Warning: GssAPIMechanism is not found, either caused by not reassembled, conversation off or filtering. And an errormessage from Kerberos: Kerberos: KRB_ERROR - KDC_ERR_BADOPTION (13) The option code in the packet is 0x40830000 Any idea what I should look into?

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  • File copying utility like rsync with error handling like ddrescue, for data recovery from a hard drive with bad sectors or hardware failure

    - by purefusion
    I have a hard drive with either bad blocks or sectors that are failing to read due to potential mechanical issues, such as a bad disk head, bad motor, or some other issue that is causing the hard drive to read data excruciatingly slowly and with lots of read errors. I'm seeing an average of 50 KB/sec, with some reads dropping below 10 KB/sec, and frequently it gets stuck on a file or sector altogether, usually for quite a long time—from 2-10 minutes or more (when using rsync, before it times out). Speed seems to vary wildly, and it gets stuck on files a lot, and when it finally gets "unstuck" it only seems to last for a short burst before it gets stuck again. The drive is also very quiet with only an occasional sound of files copying (usually when it gets stuck/unstuck for a brief time, before getting stuck again). Thus, there are none of those evil sounds that are normally associated with HDD death. Someone suggested that the problems sounded like they might be caused by a misaligned disk head, which requires a lot of re-reads before it finally reads data with success. Sounds plausible, but I digress... Anyway, the problem with rsync is that it seems to have no decent error handling support. Obviously, it wasn't meant for use in recovering data from failing hard drives, but all the so-called "data recovery" utilities out there that are meant for such use usually focus on recovery of deleted files or messed up partitions, rather than copying files off dying hard drives. Deleted file recovery is not what I need, obviously, so perhaps you can understand my disappointment in not being able to find what I'm after yet. Naturally, this is where you'd probably say "You should use ddrescue!" Well, that's all fine and dandy, but I've already got most of the data backed up, so I just want to recover certain files. I'm not concerned with trying to recover a full partition block-by-block as ddrescue does. I am only interested in rescuing just specific files and directories. Ideally, what I'd like is some sort of cross between rsync and ddrescue: something that lets me specify source and destination as directories of normal files like rsync (rather than two full partitions as ddrescue requires), with a way to skip files with errors in an initial run, and then allows me to attempt recovery of those files with errors in a later run (with a slightly altered command, of course), perhaps even offering an option to specify the number of retry attempts ...just like how ddrescue works with blocks, only I want a utility that works with specific files/directories like rsync does. So am I daydreaming here, or does something out there exist that can do this? Or, maybe even a way to make rsync or ddrescue work in such a way? I'm really open to whatever solutions might work, so long as they let me choose which files I want to "rescue", and can skip files with errors in the initial run, and try/retry those errors again later. So far I've tried rsync with the following options, but it often gets stuck on a file for longer than the timeout, and ideally I'd just like it to move on to the next file and come back later to the files it gets stuck on. I don't think that's possible though. Anyway, here's what I've been using up till now: rsync -avP --stats --block-size=512 --timeout=600 /path/to/source/* /path/to/destination/

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  • Can a power failure or forceful shutdown damage hardware?

    - by Vilx-
    Can computer hardware suffer damage from forceful shutdowns (holding the power button for five (5) seconds) or power failures? I believe that normal PC hardware does not suffer from this - after all, it's not much different than what they experience under a standard shutdown. But elsewhere I've read tht another person thought that it could do physical harm to the hard drive and possibly other components as well. He also said that the journaling features of filesystems are useless in face of power failures and were intended to help mitigate damage from system crashes. I think this is nonsense, but then again I lack the experience and knowledge to say it with certainty.

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  • What is the reason for this DNSSEC validation failure of dnsviz.net?

    - by grifferz
    On trying to resolve dnsviz.net from a host using an Unbound resolver that is configured to use DNSSEC validation, the result is "no servers could be reached": $ dig -t soa dnsviz.net ; <<>> DiG 9.6-ESV-R4 <<>> -t soa dnsviz.net ;; global options: +cmd ;; connection timed out; no servers could be reached Nothing is logged by Unbound to suggest why this is the case. Here is the /etc/unbound/unbound.conf: server: verbosity: 1 interface: 192.168.0.8 interface: 127.0.0.1 interface: ::0 access-control: 0.0.0.0/0 refuse access-control: ::0/0 refuse access-control: 127.0.0.0/8 allow_snoop access-control: 192.168.0.0/16 allow_snoop chroot: "" auto-trust-anchor-file: "/etc/unbound/root.key" val-log-level: 2 python: remote-control: control-enable: yes If I add: module-config: "iterator" (thus disabling DNSSEC validation) then I am able to resolve this host normally. The domain and its DNSSEC check out fine according to http://dnscheck.iis.se/ so there must be something wrong with my resolver configuration. What is it and how do I go about debugging that?

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  • Win 7 Remote Desktop connection failure when already logged in.

    - by Andy E
    I have a bit of a strange problem, magnified recently by my broadband dropouts. I wasn't sure whether to post this on SU or SF, so I thought I'd start here as more users would be likely to know what the problem is. In short, when I try and connect to my server (Windows Server 2008) from my laptop running Windows 7, I can only connect if my remote account was previously logged out. If I'm still logged in I get the error message: Windows cannot connect to the remote server. No explanation or anything. If my IP address is the same, I don't have this problem. If I boot up Windows XP Mode and run XP's remote desktop connection it works just fine -- I think the difference there is it takes me to the remote server's logon screen. With Win 7 RDC you never see the logon screen, it asks you for credentials before entering full screen mode. The real problem is that I'm having random broadband dropouts and my IP isn't static. If I logon via Win XP RDC, log out and then run Win 7 RDC then it works fine. I realize I can just use Win XP's RDC for now, but I don't really like keeping XP Mode open if I can help it. Does anyone know a way around this problem? Maybe forcing Win 7 RDC to go to the logon screen, or changing some server-side settings to work around the IP address issue?

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  • Windows 7 / TCP/IP network share guide - looking for to resolve failure to mount lacie network drive but works on XP,Linux,Mac.

    - by Rob
    Can anyone advise me of a really good, readable, Windows 7 TCP/IP network share guide, book, or reference. I want this because I cannot mount my Lacie 2big ethernet network drive in Windows 7 (32 bit home), but I can mount it in Windows XP Home 32bit, Ubuntu Linux 10.04 and Apple MacOS X. This drive is being mounted via the accompanying Lacie Ethernet Agent in XP (which I believe uses "Bonjour" protocol), on Mac and Linux it works without further need for software. Another Super User user has the same problem, but no answer: Trouble accessing network drives in Windows 7 I hope my take on the question shows a better willingness to investigate and do some digging - and therefore invite some suggestions to help with this. The drive is detected by Windows 7 (i.e. speech bubble "network drive found") but on trying to open an Explorer window, this remains blank with the Windows busy pointer. I'd prefer not to reinstall Windows 7 to see if that cures the problem, I'd rather understand what is happening/not happening, perhaps even compare differences with Windows XP. Suggestions, please for such guides or even the original problem itself. Update Edit Rewrote question more comprehensively here: Mhttp://superuser.com/questions/304209/looking-for-definitive-answer-to-accessing-a-network-share-via-windows-7-home-and

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