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• nfs mount with nfs 3

  - by rahrahruby

  I am running CentOS 6.4 Kernel version 2.6.32-358.23.2.el6.x86_64 #1 SMP and have the following nfs info: nfs-utils-lib-1.1.5-6.el6.x86_64 nfs4-acl-tools-0.3.3-6.el6.x86_64 nfs-utils-1.2.3-36.el6.x86_64 and am trying to mount an nfs volume with nfs3. I have the following line in my fstab: 172.16.11.87:/volume1/web /home/nas nfsver=3 rsize=8192,wsize=8192,timeo=14,intr(no_root_squach) When I run nfsstat it still shows the client as nfs4 Server rpc stats: calls badcalls badauth badclnt xdrcall 0 0 0 0 0 Client rpc stats: calls retrans authrefrsh 1988817 6 1988818 Client nfs v4: null read write commit open open_conf 0 0% 36943 1% 21606 1% 401 0% 392369 19% 375986 18% open_noat open_dgrd close setattr fsinfo renew 0 0% 0 0% 387945 19% 22904 1% 3 0% 2914 0% setclntid confirm lock lockt locku access 1 0% 1 0% 0 0% 0 0% 0 0% 97856 4% getattr lookup lookup_root remove rename link 613996 30% 29888 1% 1 0% 1248 0% 253 0% 414 0% symlink create pathconf statfs readlink readdir 26 0% 226 0% 2 0% 3 0% 0 0% 3825 0% server_caps delegreturn getacl setacl fs_locations rel_lkowner 5 0% 0 0% 0 0% 0 0% 0 0% 0 0% exchange_id create_ses destroy_ses sequence get_lease_t reclaim_comp 0 0% 0 0% 0 0% 0 0% 0 0% 0 0% layoutget layoutcommit layoutreturn getdevlist getdevinfo ds_write 0 0% 0 0% 0 0% 0 0% 0 0% 0 0% ds_commit 0 0%

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• Re-installing Windows on an old laptop

  - by Khaled

  I have an old laptop and I want to re-install Windows XP on it. The problem is that this laptop does not have an optical drive. I checked the boot sequence in the BIOS. It does not show an option to boot from USB. It have only two options: Boot from HD. Boot using Realtek agent (network boot). I tried to copy the Windows CD to second drive D:\ and run the installed from there. However, I could not format the C:\ drive. Windows complaints about setup files will be removed or something like that. I tried to boot the laptop using PXE, but I could not. It seems that the DHCP request did not get answered. I thought I could use a USB CD-ROM drive (I don't have one to try), but it might not work as there is no option to boot from USB. Do you think it will work? Do I have other options to try? Any recommendations?

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• Percona-server time out on /etc/init.d/mysql start

  - by geekmenot

  Every time I start mysql, using /etc/init.d/mysql start or service mysql start, it always times out. * Starting MySQL (Percona Server) database server mysqld [fail] However, I can get into mysql. Just wanted to know if there is a problem with the install because it happens all the time, not a one off error. mysql-error.log shows: 121214 11:25:56 mysqld_safe Starting mysqld daemon with databases from /data/mysql/ 121214 11:25:56 [Note] Plugin 'FEDERATED' is disabled. 121214 11:25:56 InnoDB: The InnoDB memory heap is disabled 121214 11:25:56 InnoDB: Mutexes and rw_locks use GCC atomic builtins 121214 11:25:56 InnoDB: Compressed tables use zlib 1.2.3 121214 11:25:56 InnoDB: Using Linux native AIO 121214 11:25:56 InnoDB: Initializing buffer pool, size = 14.0G 121214 11:25:58 InnoDB: Completed initialization of buffer pool 121214 11:26:01 InnoDB: Waiting for the background threads to start 121214 11:26:02 Percona XtraDB (http://www.percona.com) 1.1.8-rel29.2 started; log sequence number 9333955393950 121214 11:26:02 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306 121214 11:26:02 [Note] - '0.0.0.0' resolves to '0.0.0.0'; 121214 11:26:02 [Note] Server socket created on IP: '0.0.0.0'. 121214 11:26:02 [Note] Slave SQL thread initialized, starting replication in log 'mysql-bin.005163' at position 624540946, relay log '/data/mysql/mysql-relay-bin.000043' position: 624541092 121214 11:26:02 [Note] Slave I/O thread: connected to master '[email protected]:3306',replication started in log 'mysql-bin.005180' at position 823447620 121214 11:26:02 [Note] Event Scheduler: Loaded 0 events 121214 11:26:02 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.5.28-29.2-log' socket: '/data/mysql/mysql.sock' port: 3306 Percona Server (GPL), Release 29.2

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• Learn Many Languages

  - by Jeff Foster

  My previous blog, Deliberate Practice, discussed the need for developers to “sharpen their pencil” continually, by setting aside time to learn how to tackle problems in different ways. However, the Sapir-Whorf hypothesis, a contested and somewhat-controversial concept from language theory, seems to hold reasonably true when applied to programming languages. It states that: “The structure of a language affects the ways in which its speakers conceptualize their world.” If you’re constrained by a single programming language, the one that dominates your day job, then you only have the tools of that language at your disposal to think about and solve a problem. For example, if you’ve only ever worked with Java, you would never think of passing a function to a method. A good developer needs to learn many languages. You may never deploy them in production, you may never ship code with them, but by learning a new language, you’ll have new ideas that will transfer to your current “day-job” language. With the abundant choices in programming languages, how does one choose which to learn? Alan Perlis sums it up best. “A language that doesn‘t affect the way you think about programming is not worth knowing“ With that in mind, here’s a selection of languages that I think are worth learning and that have certainly changed the way I think about tackling programming problems. Clojure Clojure is a Lisp-based language running on the Java Virtual Machine. The unique property of Lisp is homoiconicity, which means that a Lisp program is a Lisp data structure, and vice-versa. Since we can treat Lisp programs as Lisp data structures, we can write our code generation in the same style as our code. This gives Lisp a uniquely powerful macro system, and makes it ideal for implementing domain specific languages. Clojure also makes software transactional memory a first-class citizen, giving us a new approach to concurrency and dealing with the problems of shared state. Haskell Haskell is a strongly typed, functional programming language. Haskell’s type system is far richer than C# or Java, and allows us to push more of our application logic to compile-time safety. If it compiles, it usually works! Haskell is also a lazy language – we can work with infinite data structures. For example, in a board game we can generate the complete game tree, even if there are billions of possibilities, because the values are computed only as they are needed. Erlang Erlang is a functional language with a strong emphasis on reliability. Erlang’s approach to concurrency uses message passing instead of shared variables, with strong support from both the language itself and the virtual machine. Processes are extremely lightweight, and garbage collection doesn’t require all processes to be paused at the same time, making it feasible for a single program to use millions of processes at once, all without the mental overhead of managing shared state. The Benefits of Multilingualism By studying new languages, even if you won’t ever get the chance to use them in production, you will find yourself open to new ideas and ways of coding in your main language. For example, studying Haskell has taught me that you can do so much more with types and has changed my programming style in C#. A type represents some state a program should have, and a type should not be able to represent an invalid state. I often find myself refactoring methods like this… void SomeMethod(bool doThis, bool doThat) { if (!(doThis ^ doThat)) throw new ArgumentException(“At least one arg should be true”); if (doThis) DoThis(); if (doThat) DoThat(); } …into a type-based solution, like this: enum Action { DoThis, DoThat, Both }; void SomeMethod(Action action) { if (action == Action.DoThis || action == Action.Both) DoThis(); if (action == Action.DoThat || action == Action.Both) DoThat(); } At this point, I’ve removed the runtime exception in favor of a compile-time check. This is a trivial example, but is just one of many ideas that I’ve taken from one language and implemented in another.

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• A few tables are still out of sync after running mk-table-sync

  - by smusumeche

  I have 1 master and 2 slaves. I am using MySQL 5.1.42 on all servers. I am attempting to use mk-table-checksum to verify that their data is in sync, but I am getting unexpected results on one of the slaves. First, I generate the checksums on the master like this: mk-table-checksum h=localhost --databases MYDB --tables {$table_list} --replicate=MYDB.mk_checksum --chunk-size=10M My understanding is that this runs the checksum queries on the master which then propagate via normal replication to the slaves. So, no locking is needed because the slaves will be at the same logical point in time when they run the checksum queries on themselves. Is this correct? Next, to verify that the checksums match, I run this on the master: mk-table-checksum --databases MYDB --replicate=IRC.mk_checksum --replicate-check 1 h=localhost,u=maatkit,p=xxxx If there are any differences, I repair the slaves like this: mk-table-sync --execute --verbose --replicate IRC.mk_checksum h=localhost,u=maatkit,p=xxxx After doing all of this, I repaired both slaves with mk-table-sync. However, everytime I run this sequence (after everything has already been repaired), one slave is perfectly in sync but one slave always has a few tables out of sync. I am 99.999% sure that the data on the slaves matches, since I repaired everything and the tables were not even updated on the master between runs of the checksum script. What would cause a few tables to always show out of sync on only one of the slaves? I am stuck. Here is the output: Differences on h=x.x.x.x,p=...,u=maatkit DB TBL CHUNK CNT_DIFF CRC_DIFF BOUNDARIES IRC product 10 0 1 product_id = 147377 AND product_id < 162085 IRC post_order_survey 0 0 1 1=1 IRC mk_heartbeat 0 0 1 1=1 IRC mailing_list 0 0 1 1=1 IRC honey_pot_log 0 0 1 1=1 IRC product 12 0 1 product_id = 176793 AND product_id < 191501 IRC product 18 0 1 product_id = 265041 IRC orders 26 0 1 order_id = 694472 IRC orders_product 6 0 1 op_id = 935375

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• Second monitor stopped being recognized by Windows

  - by Eric J.

  One of the developer PC's running Windows Vista Ultimate had the second monitor stop being recognized in Windows overnight. There were no hardware or driver changes at the time, though I have subsequently updated to the latest nVidia drivers (card is NVIDIA GeForce 210). The non-recognized monitor IS recognized during the boot sequence. In fact, only the "bad" one shows the POST or the Windows loading screen. At some point during Windows initialization after the loading screen disappears and before the logon screen appears, the active monitor switches. Any thoughts? UPDATE: When I open the Vista monitor properties window, I see my primary display and secondary display depicted. The primary one is portrayed as the regular blue box, but the secondary one is portrayed greyed-out. I have the option to "Extend desktop to this monitor", the only resolution is 800x600, and all of the advanced monitor properties are greyed out as well. If I opt to extend the desktop, the greyed-out box turns blue, when I then select Apply the screens flash as usual and I'm given the 15 second countdown to accept the new settings and when I do, everything returns to the previously broken state... secondary monitor is portrayed greyed-out again. At no point is the desktop shown on the secondary monitor.

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• Sparc Solaris 2.6 will not boot

  - by joshxdr

  I have a very old Sparc Solaris network that was working fine last week, but after a power outage none of the workstations will boot. The network looks like this: host A: solaris 2.6, shares /export/home to network by NFS host B: solaris 8, runs NIS server. Mounts /export/home/ by NFS. host C: RHEL5, shares /share to network by NFS. Mounts /export/home/ by NFS. I figured that the main problem was host A, since you need the home directories available for the other workstations to boot(?). Host A does not mount anything by NFS as far as I know. However, this workstation will NOT boot. The OBP bootup sequence looks like this: Boot device <blah> configuring network interface le0 Hostname <hostname> check file system <everything ok> check ufs filesystem <everything ok> NIS domainname is <name> starting router discovery starting rpc services: rpcbind keyserv ypbind done setting default interface for multicast: add net 224.0.0.0: gateway <hostname> <HANGS at this point> Is there some kind of debug mode so that I can get more detail as to why the workstation won't boot? Is my network structure inherently susceptible to power outage? Is there a way I can boot up to command line so I can at least turn off the NFS mounting?

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• Video card not detected in POST on initial boot.

  - by Jeff M

  I have a minor problem with my desktop computer after cleaning it out for dust. When I first boot up the computer, the video card does not get detected so I can't see anything. In POST, I'm getting the "can't detect video card" beeps. The boot sequence continues normally, just without video. However, if I restart it (using the restart button) anytime after POST, it would boot up normally. I have no reason to think that the motherboard, video card or PSU got damaged in the process. It was working fine before, works fine after resetting. Took all the necessary precautions while cleaning. On the initial boot, I can hear the video card's fan power up but immediately power down and try again one more time only to fail. After the beep, resetting gets everything running and sounding normally. I've reseated the card a couple of times and reset the BIOS but doesn't seem to help. I'm hoping I won't have to take it out and remove and reinstall everything again. Does anyone recognize these symptoms to know exactly what the problem is? My guess is that the video card isn't getting enough juice initially to be running stable to be detected. I just don't know what I did (or didn't do) to get it to be in this state. It's not a high priority thing for me at the moment, just means I have to always reset it after initially turning it on but will eventually remove everything and reinstall if it comes to that. I don't think the specs are relevant here but just in case, here's the relevant stuff: Motherboard: Gigabyte P35-DS3P Video: EVGA GeForce 8600 GTS PSU: Antec True Power Trio 650W Built ~2 years ago, still running well

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• Fresh 12.04 Install - mySQL not starting

  - by Lee Armstrong

  I have a freshly installed Ubuntu 12.04 x64 server and I installed Percona server from their official repositories. Trouble is it will not start! mysql-error.log shows nothing obvious. 121129 12:16:54 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql/ 121129 12:16:54 [Note] Plugin 'FEDERATED' is disabled. 121129 12:16:54 InnoDB: The InnoDB memory heap is disabled 121129 12:16:54 InnoDB: Mutexes and rw_locks use GCC atomic builtins 121129 12:16:54 InnoDB: Compressed tables use zlib 1.2.3 121129 12:16:54 InnoDB: Using Linux native AIO 121129 12:16:54 InnoDB: Initializing buffer pool, size = 12.0G 121129 12:16:54 InnoDB: Completed initialization of buffer pool 121129 12:16:54 InnoDB: highest supported file format is Barracuda. 121129 12:16:55 InnoDB: Waiting for the background threads to start 121129 12:16:56 Percona XtraDB (http://www.percona.com) 1.1.8-rel29.1 started; log sequence number 1598476 121129 12:16:56 [Note] Server hostname (bind-address): '0.0.0.0'; port: 3306 121129 12:16:56 [Note] - '0.0.0.0' resolves to '0.0.0.0'; 121129 12:16:56 [Note] Server socket created on IP: '0.0.0.0'. 121129 12:16:56 [Note] Event Scheduler: Loaded 0 events 121129 12:16:56 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.5.28-29.1-log' socket: '/var/run/mysqld/mysql.sock' port: 3306 Percona Server (GPL), Release 29.1 121129 12:16:56 [Note] Event Scheduler: scheduler thread started with id 1 And the syslog shows... Nov 29 12:17:07 V-PF-SQL1 /etc/init.d/mysql[2206]: 0 processes alive and '/usr/bin/mysqladmin --defaults-file=/etc/mysql/debian.cnf ping' resulted in Nov 29 12:17:07 V-PF-SQL1 /etc/init.d/mysql[2206]: #007/usr/bin/mysqladmin: connect to server at 'localhost' failed Nov 29 12:17:07 V-PF-SQL1 /etc/init.d/mysql[2206]: error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' Nov 29 12:17:07 V-PF-SQL1 /etc/init.d/mysql[2206]: Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists! Nov 29 12:17:07 V-PF-SQL1 /etc/init.d/mysql[2206]: The socket file is being created and I can access the server NOT using the socket using mysql -h 127.0.0.1 -P 3306 -u root --pPASSWORD

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• Dynamic DNS Updates with Wireless and Wired interfaces

  - by Phaedrus

  We have offices full of Windows & Mac users who obtain IP addresses from a Windows DHCP server, which in turn updates Dynamic DNS entries. We are noticing major inconsistencies with the entries, and have found that the problem is occurring more on Macs than on windows, and even more when users are frequently switching from wired to wireless adapter, which makes sense, as this sequence occurs: User enables wired adapter and registers Proper DNS User enables wireless adapter and registers 2nd proper DNS entry user switches off wireless manually and 2nd entry remains improperly until scavenge. Our help desk folks rely heavily (maybe more than they should) on the dynamic entries as part of their business process. For example, the user submits a help desk ticket, and the staff member expects to be able to remote desktop to their machine by hostname, which is hyperlinked in the helpdesk ticketing app. We have implemented multiple solutions & band-aids to different symptoms of the problems such as: Using DNS Reservations for Macintosh PCs Using DNS Scavenging to remove old records Switching from a Cisco DHCP server to the Windows DHCP Server But no matter what we do, it seems impossible to maintain perfect records. Has anyone encountered this problem before? What is industry best practice? Comments & Suggestions are much appreciated, /P

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• Port knocking via SSH tunnels

  - by j0ker

  I have a server running in my university's internal network. There is only one SSH daemon running which is secured by port knocking with knockd. Works fine if I try to connect from within the internal network. But since the server has no external IP, I have to tunnel into the internal network every time I want to access the server from outside. And since tunneling only works for a single port I cannot do the port knocking as easily as from an internal client. In fact, I don't get it to work at all. What I'm trying is opening tunnels for all the different ports that have to be knocked. Then I send TCP-SYN packets into the tunnels. But that doesn't work even for a single port. If I establish the tunnel on the first port in the knock sequence and send a packet through it, it doesn't reach the server. There is no entry in the log file of knockd, while there should be something like 123.45.67.89: openSSH: Stage 1 (as shown with internal knocks). So I guess, the problem doesn't exist within my knocking script but is a more general one. Are there any known problems with what I'm trying to do? Is it even possible or am I missing something? Thanks in advance!

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• When ran as a scheduled task, cannot save an Excel workbook when using Excel.Application COM object in PowerShell

  - by Daniel Richnak

  I'm having an issue where I've automated creating an Excel.Application COM object, add some data into a workbook, and then saving the document as an xlsx. This works fine if: I'm already in Powershell interactive host and either run each command in sequence, or execute as a ps1. I run it from cmd.exe, using the syntax: powershell.exe -command "c:\path\to\powershellscript.ps1" I create a scheduled task in Windows 7 / Server 2008 R2, use the above powershell.exe -command syntax, and use the mode "Run only when the user is logged on". It fails when I modify the same scheduled task, but set it to "run whether the user is logged on or not". Here's a sample script that illustrates the problem I'm having: $Excel = New-Object -Com Excel.Application $Excelworkbook = $Excel.Workbooks.Add() $excelworkbook.saveas("C:\temp\test.xlsx") $excelworkbook.close() I have a theory that the COM object fails somehow if my profile isn't loaded / if it's not performed in a command window. Any ideas on which options to choose when creating the scheduled task, or which options to use when creating the Excel object or using the SaveAs() function? Can anybody reproduce this? I've been able to see this behavior on both a Server 2008 R2 machine, and Windows 7. Haven't tried other platforms.

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• Building My First Computer And Suprise It Isn't Working

  - by BobbShots

  I've had many years of experience working on and around computers, but this was my first foray into building one completely from scratch. So far that foray has been a disaster. My rig is completely assembled, and on its maiden power-up plus many power cycles I noticed three things: There were a few beeps from the BIOS POST upon powering up the first time, but I wasn't paying attention completely to the sequence. However, every time after that there are 0 POST beeps, even after taking off all hardware except the CPU and MB. There was no video being sent to the monitor. I run a HDMI cable from my video card to the monitor. The video card was LOUD. My card is a Sapphire Radeon HD 5870 which is known for not only being a powerhouse, but being pretty quiet. A few times during my power cycles it ran a lot quieter, but most of the time it was just super loud. Can anyone provide help for any of these issues? My MB, CPU, and Video Card are: MB: ASUS P6X58D Premium LGA 1366 Intel X58 SATA 6Gb/s USB 3.0 ATX Intel Motherboard CPU: i7 920 Video Card: Sapphire Radeon HD 5870

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• System occasionally hangs boot process with SLES 11

  - by ThaMe90

  I have several (new) systems on which I had to install SLES11 on. However, after a few (though not every) reboots, the system hangs during the boot sequence. It will only continue after I physically press a key on the keyboard. From what I've found in the dmesg log from a failed boot is the following: [ 22.170276] sd 0:0:0:0: [sda] Mode Sense: b7 00 00 08 [ 22.171155] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 22.182760] sda: sda1 sda2 sda3 [ 22.383424] sd 0:0:0:0: [sda] Attached SCSI disk [ 22.545372] PM: Marking nosave pages: 000000000009a000 - 0000000000100000 [ 22.545377] PM: Marking nosave pages: 00000000bf780000 - 0000000100000000 [ 22.546217] PM: Basic memory bitmaps created [ 22.590380] PM: Basic memory bitmaps freed [ 22.596284] PM: Starting manual resume from disk [ 22.602319] PM: Resume from partition 8:1 [ 22.602321] PM: Checking hibernation image. [ 22.602479] PM: Error -22 checking image file [ 22.602481] PM: Resume from disk failed. [ 22.718727] kjournald starting. Commit interval 15 seconds [ 22.718960] EXT3-fs (sda3): using internal journal [ 22.718964] EXT3-fs (sda3): mounted filesystem with ordered data mode [ 1555.644404] udevd version 128 started [ 1555.697664] input: Power Button as /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0C:00/input/input0 [ 1555.707961] ACPI: Power Button [PWRB] I've looked around the internet for the PM: Resume from disk failed. message, but this seems to only be important when restoring the system after a hybernate, i.e. restore from the hdd. But this is not my situation. I only get this after a reboot, as I said before. The timestamp [ 1555.xxxxxx] is only the result of me pressing a key on the keyboard. Any suggestions on how to proceed? As I am getting stuck on this issue.

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• Wireshark WPA 4-way handshake

  - by cYrus

  From this wiki page: WPA and WPA2 use keys derived from an EAPOL handshake to encrypt traffic. Unless all four handshake packets are present for the session you're trying to decrypt, Wireshark won't be able to decrypt the traffic. You can use the display filter eapol to locate EAPOL packets in your capture. I've noticed that the decryption works with (1, 2, 4) too, but not with (1, 2, 3). As far as I know the first two packets are enough, at least for what concern unicast traffic. Can someone please explain exactly how does Wireshark deal with that, in other words why does only the former sequence work, given that the fourth packet is just an acknowledgement? Also, is it guaranteed that the (1, 2, 4) will always work when (1, 2, 3, 4) works? Test case This is the gzipped handshake (1, 2, 4) and an ecrypted ARP packet (SSID: SSID, password: password) in base64 encoding: H4sICEarjU8AA2hhbmRzaGFrZS5jYXAAu3J400ImBhYGGPj/n4GhHkhfXNHr37KQgWEqAwQzMAgx 6HkAKbFWzgUMhxgZGDiYrjIwKGUqcW5g4Ldd3rcFQn5IXbWKGaiso4+RmSH+H0MngwLUZMarj4Rn S8vInf5yfO7mgrMyr9g/Jpa9XVbRdaxH58v1fO3vDCQDkCNv7mFgWMsAwXBHMoEceQ3kSMZbDFDn ITk1gBnJkeX/GDkRjmyccfus4BKl75HC2cnW1eXrjExNf66uYz+VGLl+snrF7j2EnHQy3JjDKPb9 3fOd9zT0TmofYZC4K8YQ8IkR6JaAT0zIJMjxtWaMmCEMdvwNnI5PYEYJYSTHM5EegqhggYbFhgsJ 9gJXy42PMx9JzYKEcFkcG0MJULYE2ZEGrZwHIMnASwc1GSw4mmH1JCCNQYEF7C7tjasVT+0/J3LP gie59HFL+5RDIdmZ8rGMEldN5s668eb/tp8vQ+7OrT9jPj/B7425QIGJI3Pft72dLxav8BefvcGU 7+kfABxJX+SjAgAA Decode with: $ base64 -d | gunzip > handshake.cap Run tshark to see if it correctly decrypt the ARP packet: $ tshark -r handshake.cap -o wlan.enable_decryption:TRUE -o wlan.wep_key1:wpa-pwd:password:SSID It should print: 1 0.000000 D-Link_a7:8e:b4 - HonHaiPr_22:09:b0 EAPOL Key 2 0.006997 HonHaiPr_22:09:b0 - D-Link_a7:8e:b4 EAPOL Key 3 0.038137 HonHaiPr_22:09:b0 - D-Link_a7:8e:b4 EAPOL Key 4 0.376050 ZyxelCom_68:3a:e4 - HonHaiPr_22:09:b0 ARP 192.168.1.1 is at 00:a0:c5:68:3a:e4

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• sort utility on cyrillic text

  - by Anton

  I have to sort some lines of cyrillic characters and I want to use the sort utility (on MAC OS X 10.6). The problem is that result is incorrect. I take the text into clipboard, then run pbpaste | sort This is plaintext data, and I also tried passing a file to the sort command. My source data is ??????? ????? ???? ???? ?????? ??????? ???????? ?????? ? ????? ??????????????? ?????????? ???? ?????? And after sorting I get ???? ???? ???? ????? ?????? ?????? ?????? ? ????? ??????????????? ??????? ??????? ???????? ?????????? Theese lines aren’t even grouped by first letter. I tried option -d, but then I get an error sort: string comparison failed: Illegal byte sequence sort: Set LC_ALL='C' to work around the problem. sort: The strings compared were \320\321\321\321' and\320\320\320\321\321\320’. Exporting the variable as recommended doesn’t solve the problem. What can I do to use the sort utility for such a task? Any additional info is necessary?

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• Almost All Xenserver Logical Volumes Disappeared - Recovery?

  - by Alex

  We had a hard disc crash of one of two hard discs in a software raid with a LVM on top. The server is running Citrix xenserver. On the hard disk which is still intact, the volume group gets detected well, but only one LV is left. (some hashes replaced by "x") # lvdisplay --- Logical volume --- LV Name /dev/VG_XenStorage-x-x-x-x-408b91acdcae/MGT VG Name VG_XenStorage-x-x-x-x-408b91acdcae LV UUID x-x-x-x-x-x-vQmZ6C LV Write Access read/write LV Status available # open 0 LV Size 4.00 MiB Current LE 1 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 root@rescue ~ # vgdisplay --- Volume group --- VG Name VG_XenStorage-x-x-x-x-408b91acdcae System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 4 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 0 Max PV 0 Cur PV 1 Act PV 1 VG Size 698.62 GiB PE Size 4.00 MiB Total PE 178848 Alloc PE / Size 1 / 4.00 MiB Free PE / Size 178847 / 698.62 GiB VG UUID x-x-x-x-x-x-53w0kL I could understand if a full physical volume is lost - but why only the logical volumes? Is there any explanation for this? Is there any way to recover the logical volumes? EDIT We are here in a rescue system. The problem is that the whole server does not boot (GRUB error 22) What we are trying to do is to access the root filesystem. But everything was in the LVM. We have only this: (parted) print Model: ATA SAMSUNG HD753LJ (scsi) Disk /dev/sdb: 750GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 32.3kB 750GB 750GB primary boot, lvm And this 750GB LVM volume is exactly what we see on top. edit2 Output of vgcfgrestore, but from the rescue system, as there is no root to chroot to. # vgcfgrestore --list VG_XenStorage-x-b4b0-x-x-408b91acdcae File: /etc/lvm/archive/VG_XenStorage-x-x-x-x-408b91acdcae_00000.vg VG name: VG_XenStorage-x-x-x-x-408b91acdcae Description: Created *before* executing '/sbin/vgscan --ignorelockingfailure --mknodes' Backup Time: Fri Jun 28 23:53:20 2013 File: /etc/lvm/backup/VG_XenStorage-x-x-x-x-408b91acdcae VG name: VG_XenStorage-x-x-x-x-408b91acdcae Description: Created *after* executing '/sbin/vgscan --ignorelockingfailure --mknodes' Backup Time: Fri Jun 28 23:53:20 2013

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• Patterns for a tree of persistent data with multiple storage options?

  - by Robin Winslow

  I have a real-world problem which I'll try to abstract into an illustrative example. So imagine I have data objects in a tree, where parent objects can access children, and children can access parents: // Interfaces interface IParent<TChild> { List<TChild> Children; } interface IChild<TParent> { TParent Parent; } // Classes class Top : IParent<Middle> {} class Middle : IParent<Bottom>, IChild<Top> {} class Bottom : IChild<Middle> {} // Usage var top = new Top(); var middles = top.Children; // List<Middle> foreach (var middle in middles) { var bottoms = middle.Children; // List<Bottom> foreach (var bottom in bottoms) { var middle = bottom.Parent; // Access the parent var top = middle.Parent; // Access the grandparent } } All three data objects have properties that are persisted in two data stores (e.g. a database and a web service), and they need to reflect and synchronise with the stores. Some objects only request from the web service, some only write to it. Data Mapper My favourite pattern for data access is Data Mapper, because it completely separates the data objects themselves from the communication with the data store: class TopMapper { public Top FetchById(int id) { var top = new Top(DataStore.TopDataById(id)); top.Children = MiddleMapper.FetchForTop(Top); return Top; } } class MiddleMapper { public Middle FetchById(int id) { var middle = new Middle(DataStore.MiddleDataById(id)); middle.Parent = TopMapper.FetchForMiddle(middle); middle.Children = BottomMapper.FetchForMiddle(bottom); return middle; } } This way I can have one mapper per data store, and build the object from the mapper I want, and then save it back using the mapper I want. There is a circular reference here, but I guess that's not a problem because most languages can just store memory references to the objects, so there won't actually be infinite data. The problem with this is that every time I want to construct a new Top, Middle or Bottom, it needs to build the entire object tree within that object's Parent or Children property, with all the data store requests and memory usage that that entails. And in real life my tree is much bigger than the one represented here, so that's a problem. Requests in the object In this the objects request their Parents and Children themselves: class Middle { private List<Bottom> _children = null; // cache public List<Bottom> Children { get { _children = _children ?? BottomMapper.FetchForMiddle(this); return _children; } set { BottomMapper.UpdateForMiddle(this, value); _children = value; } } } I think this is an example of the repository pattern. Is that correct? This solution seems neat - the data only gets requested from the data store when you need it, and thereafter it's stored in the object if you want to request it again, avoiding a further request. However, I have two different data sources. There's a database, but there's also a web service, and I need to be able to create an object from the web service and save it back to the database and then request it again from the database and update the web service. This also makes me uneasy because the data objects themselves are no longer ignorant of the data source. We've introduced a new dependency, not to mention a circular dependency, making it harder to test. And the objects now mask their communication with the database. Other solutions Are there any other solutions which could take care of the multiple stores problem but also mean that I don't need to build / request all the data every time?

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• Emacs 24.1: How do I restore i-search Ctrl-Y behavior from older versions?

  - by Eric

  In emacs 24.1, when you do Ctrl-Y in an interactive search, it yanks the kill buffer into the search string ("it pastes the clipboard contents" in any-other-app's language) and tries to match it. In the last 20 versions or so, pressing Ctrl-Y matches the rest of the current line. I have two very common use cases: Match this line, revert the buffer, and search for the line (less often:) Where else is this text in the buffer? I tried modifying /lisp/isearch.el, switching the bindings for isearch-yank-line (which I want) and isearch-yank-kill (which I'm fine binding to the ridiculous \M-s\C-e key sequence). But I don't think this file even gets picked up. But I don't think this file even gets loaded. If I explicitly load it, I still get the 24.1 behavior. Here's my change: (add-hook 'isearch-mode-hook (lambda () (define-key isearch-mode-map "\C-y" 'isearch-yank-line) (define-key isearch-mode-map "\M-s\C-e" 'isearch-yank-kill) )) No change in the behavior. I even tried hacking isearch.el, still no change. This is on Windows btw, but I suspect it doesn't matter. Could someone tell me how I can restore the old binding?

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• PuTTY inserts random characters during a session

  - by Zachary Polikarpus

  I recently started renting space on a remote server so that I could work on a project. I found that a relatively painless way to access it on a windows machine is through PuTTY. However, there is one thing that has always irked me when using it: for seemingly no reason random characters are sometimes inserted at the cursor. Most of the time it is just a single tilde, but rarely it spits out what looks like some escape sequence ([[^8 or the like). It will only occur when I am focused on the window, whether I am typing or 20 feet away from the keyboard. If left for long enough, it will spit tildes at random intervals (average is about 1 minute). Finally, this behavior seems to be inconsistant when running programs such as nano or the mysql interface: in nano, instead of inserting tildes, it will set marks (ctrl-^); in mysql, lines will become un-editable. My question is this: Has anyone else experienced this sort of behavior in PuTTY? And if so, what can be done to prevent/correct this behavior?

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• What may the reason of slowness be (see details in message body)?

  - by Ivan

  I've got a really weird situation I'm beating to solve. A performance problem which looks really like an empty waiting sequence set in code (while it probably isn't so). I've got a pretty powerful dedicated server (10 GB RAM, eight Xeon cores, etc) running Ubuntu 10.04 with all the functionality services (except OpenVPN server used to provide secure access to clients) deployed in separate VirtualBox (vboxheadless) machines (one for the company e-mail server, one for web server and one for accounting/crm server (Firebird + proprietary app server working with Delphi-made clients)). CPU load (as "top" says) is almost always near zero. Host system RAM is close to 100% usage but not overloaded (as very little swapping gets used, and freed (by stopping one of VMs) memory doesn't get reused any quickly). Approximately 50% of guests RAM is used. iostat usually shows near zero %util. Network bandwidth seems to be underused. But the accounting/crm client (a Win32 Delphi application run on WinXP machines) software works hell-slow with this server (and works much better using an inside-LAN Windows server). I just can't imagine what can make it be slow if there are so plenty of CPU, RAM, HDD and bandwidth resources available on clients and on the server even in their hardest moments. Saying bandwidth is underused I not only know that clients and the server are connected to the Internet with a bigger channels than really used (which leaves the a chance they may have a bottleneck of a sort on the route between them), I've tested bandwidth between clients and the server by copying files among them.

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• Why is my new PC so slow at startup?

  - by rumtscho

  Bought a new PC this weekend, and it works really good. Only I have one big problem: startup time. Its BIOS needs 62 sec to load, then from Grub start to pw entering screen it's another 26 sec. I think this is a lot, because my old PC needs 34 sec for BIOS and another 8 sec to pw screen. After I enter the pw, the desktop is usable with practically no delay on both. The new PC is a core i7-930, running a Lucid Lynx 64 bit from a Intel Postville SSD (no internal HDs). The old PC is a Pentium 4 celeron (forgot the clock speed) running a Lucid Lynx 32 bit from an ATA 100 hard drive. Neither PC is overclocked. The new one has boot sequence 1.DVD ROM, 2.SSD (connected over SATA in AHCI mode), 3. removable drive. The old one boots from 1. DVD ROM, 2. HDD, 3. Floppy. Neither has a second OS installed. The new one has less software installed than the old one (I think), but the boot time difference was noticeable even before I made any installs. As far as I know, just the SSD should be enough to make a noticeable difference in boot time. I thought that having a good mainboard on the new PC as opposed to the basic office model on the old one would also mean a faster loading BIOS. If these assumptions are right, I guess I must have misconfigured something in the BIOS of the new PC. How should I configure it for a fast boot? It has an ASUS P6X58D board with an AMI BIOS, if you need the BIOS revision number I could post that too.

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• Extending partition on linux gparted but not more space in the vm

  - by Asken

  I have a vm test installation of a linux running a build server. Unfortunately I just pressed ok when adding the disk and ended up with an 8gb drive to play with. Well into the test the builds are consuming more and more space, of course. The vm drive was resized to 21gb and using gparted I expanded the drive partitions and that all worked fine but when I go back into the console and do df there's still only 8gb available. How can I claim the other 13gb I added? fdisk -l Disk /dev/sda: 21.0 GB, 20971520000 bytes 255 heads, 63 sectors/track, 2549 cylinders, total 40960000 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0006d284 Device Boot Start End Blocks Id System /dev/sda1 * 2048 499711 248832 83 Linux /dev/sda2 501758 40959999 20229121 5 Extended /dev/sda5 501760 40959999 20229120 8e Linux LVM vgdisplay --- Volume group --- VG Name ct System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 4 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size 19.29 GiB PE Size 4.00 MiB Total PE 4938 Alloc PE / Size 1977 / 7.72 GiB Free PE / Size 2961 / 11.57 GiB VG UUID MwiMAz-52e1-iGVf-eL4f-P5lq-FvRA-L73Sl3 lvdisplay --- Logical volume --- LV Name /dev/ct/root VG Name ct LV UUID Rfk9fh-kqdM-q7t5-ml6i-EjE8-nMtU-usBF0m LV Write Access read/write LV Status available # open 1 LV Size 5.73 GiB Current LE 1466 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 252:0 --- Logical volume --- LV Name /dev/ct/swap_1 VG Name ct LV UUID BLFaa6-1f5T-4MM0-5goV-1aur-nzl9-sNLXIs LV Write Access read/write LV Status available # open 2 LV Size 2.00 GiB Current LE 511 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 252:1

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• How to perform this Windows 7 permissions change on many files via GUI or command line

  - by hippietrail

  After using my external hard drive on another Windows 7 computer to tweak photos with Windows Live Photo Gallery then upload them to Facebook I found the modified images were now not visible on the original Windows 7 computer. I'm not sure if the things I tried to get it working subsequently changed anything, but I do know this is the sequence of actions that makes the permissions of the modified files match those of the unmodified files: Right click on broken image file, select "Properties" On the "Security" tab press the "Advanced" button In the "Permissions" tab press the "Continue" button with the shield icon on it Tick the box marked "Include inheritable permissions from this object's parent Click the "Remove" button to remove the only current entry "Type: Allow, Name: Administrators (XYZ\Administrators), Permission: Full control, Inherited From: OK on the "Permissions" tab. OK on the "Security" tab. Now this same procedure does not work at the folder level. It results in "access denied" dialogs. I'm looking for some way to perform this exact modification on all the images I edited on the other computer. I'm happy to use the Windows GUI in Explorer or any other included tools. I'm happy to use the Windows command line. I'd prefer not to use a third-party tool since I'd have to be satisfied it's not doing anything else. I'm not looking for a different way to change permissions to other settings to make an external drive full of photos editable on multiple computers. At least not in this question.

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