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• How to put 1000 lightweight server applications in the cloud

  - by Dan Bird

  The company I work for sells a commercial desktop/server app that runs on any non dedicated Windows PC or server and uses Tomcat for all interactions with the application. Customers are asking that we host their instance of the application so they don't have to run it locally on their own servers. The app is lightweight and an average server, in theory, could handle 25-50 instances before users would notice a slowdown. However only 1 instance can run per Windows instance (because the application writes to a common registry branch) so we'd need something like VMWare to create 25-50 Windows instances. We know we eventually need to reprogram to make it truly cloud-worthy but what would you recommend for a server farm or whatever for this? We don't have the setup to purchase our own servers so we must use a 3rd party. We have budgeted $500 - $1000 per year per customer for this service. Thanks in advance for your suggestions, experiences and guidance.

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• Why can't I open my Access application in design mode?

  - by mmyers

  I have been given an Access 2007 application (mainly VB code) that I need to modify. It has been locked down for production, so the toolbars and so forth are not visible. However, it is a .mdb file, not .mde, so in theory it should be possible to get into design mode by holding Shift while opening it. But that method has only worked a total of three times out of the (probably) 60 or 70 times I've tried. I realize now that I should have enabled the toolbars while I had it open, but unfortunately hindsight doesn't get me anywhere now. Does anyone know what might be causing the problem? Is it my own fault, or the application's, or Access's?

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• Asus EEE PC 1005HA (XP Home) refuses to connect to Virgin Mobile MiFi

  - by Dennis Wurster

  My client has an Asus EEE PC model 1005HA, and we're attempting to connect it to the WiFi network created by a VirginMobile MiFi unit. They also have a MacBook Pro with Snow Leopard that has absolutely no issue connecting to the MiFi. The specific symptom is that the netbook fails to lease an IP address from the MiFi unit. I supply the 12-digit numerical password (WPA) to the netbook, it throws a 'waiting for network' dialog with an indeterminate progress indicator, and then times out. Update: We've determined that this behavior has stopped when the EEE PC and the MiFi unit were taken out of the client's home, and to a different home that didn't have an existing wifi network. Similarly, when taken to a third location that didn't have wifi, the EEE PC and MiFi got along swimmingly. My current theory is that the existing wifi networks and the wifi leg of the MiFi unit are on the same channel and competing with one another. Perhaps the MacBook Pro has the capability to overcome this interference, while the EEE PC doesn't.

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• LVM, Soft RAID1, and Replication?

  - by mtkoan

  Hi all, I am practicing putting together a HA file server. It is a linux server with 2 1.5TB Hard drives. My plan is to use LVM to manage the physical volumes into logical volumes for /, /home, and /var. Then use md (soft RAID 1) to mirror the image onto the second HDD, THEN use DRDB to mirror the entire setup another server. Is this overkill? Would I just be okay with just md and DRDB? The system will serve user's homedirs (~100) and probably some groupware or other local intranet. On my own machines I've always separated root and /home partitions in case I break something, I can easily reinstall the OS. Should I follow that same theory here? If so I need LVM, because I really can't predict where we'll need more space, /var or /home.

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• Using video ports 'backwards'

  - by ACarter

  If I want to connect my laptop, which has a VGA output, to a monitor, I plug a VGA cable into both ends. The output being my laptop, and the input the monitor VGA output sockets are the same as VGA input sockets however, so what if I want to use my laptop as the monitor, with the video being outputted from somewhere else? As I said, VGA's output is the same as input, so in theory, I have the hardware in my laptop to do this. But presumably I need some software. So can I use the VGA port on a laptop as a video input? (And also, can this be done with HDMI?)

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• Anyone have any experience with bargain laptop batteries?

  - by chris

  I've got an oldish D820 that's got a 100% dead battery. I know that I could, in theory, take it apart and replace bad cells in the battery. I'm not really comfortable with doing that. I also know that there are various places that sell replacement batteries for 20% to 80% of the cost that Dell would charge. Does anyone have any experiences with buying more than a couple of these off-brand batteries? If a battery goes boom, it could be really ugly, so I'd rather not risk it, but at the same time, the dell batteries are really expensive... Any opinions on these ebay / off-brand battery vendors? Thanks!

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• installing SQLite3 gem on remote FreeBSD server using RVM - root permissions needed?

  - by atmosx

  I am trying to install ruby SQLite3 gem, on a remote freebsd server. I'm using RVM which in theory does not need 'root permission' to compile gems but I get a root error, here: [user ~]$ gem install sqlite3 -- --with-sqlite3-dir=/home/www/atma/opt/ [...] make install /usr/bin/install -c -o root -g wheel -m 0755 sqlite3_native.so /home/www/atma/.gems/gems/sqlite3-1.3.6/lib/sqlite3 install: /home/www/atma/.gems/gems/sqlite3-1.3.6/lib/sqlite3/sqlite3_native.so: chown/chgrp: Operation not permitted make: * [/home/www/atma/.gems/gems/sqlite3-1.3.6/lib/sqlite3/sqlite3_native.so] Error 71 Gem files will remain installed in /home/www/atma/.gems/gems/sqlite3-1.3.6 for inspection. Results logged to /home/www/atma/.gems/gems/sqlite3-1.3.6/ext/sqlite3/gem_make.out Any ideas how to approach this? Maybe re-installing RVM? best regards, PA

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• Script errors when run by launchd at startup, but not when run in Terminal

  - by Mechcozmo

  I'm attempting to create a RAM disk that loads the previous contents when the system starts up, and every six hours writes the contents to a disk image. Currently, when you run the script from the terminal ("sudo bash LogToRAM.sh") everything works fine. But when run from launchd during startup, it doesn't work. Here's the lines from the log; the first line just gives some idea as to where in the boot process we are: SecurityAgent[202] Showing Login Window com.mechcozmo.LogToRAM[51] + /Developer/usr/bin/SetFile -a V /Volumes/LogfileRAMdisk com.mechcozmo.LogToRAM[51] ERROR: File Not Found. (-43) on file: /Volumes/LogfileRAMdisk com.mechcozmo.LogToRAM[51] + /usr/sbin/asr -source '/Library/Application Support/LogToRAM/RAMdisk_store.dmg' -target /Volumes/LogfileRAMdisk/ -noverify Here is the script and plist file in question. Note that 'set -vx' is up at the top of the script; it give a lot of information about what is happening in the script. My current theory is that the /Volumes directory does not exist at this stage of the boot process, but that seems unlikely to be honest.

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• How do I disable microphone volume auto-adjusting?

  - by balpha

  My coworkers started yelling at me today because apparently I started screaming in their ears during a Google hangout. And sure enough, when I go to the Microphone settings dialog, I can see the level being auto-adjusted constantly; sometimes way too high. I don't think this has happened previously; at least nobody ever complained. Can I find out who is doing that auto-adjusting, and more importantly, can I turn it off? I couldn't find any related setting in the recording device settings. I'm using Windows 7 64bit, and (I'm mentioning this because the theory has come up that it may be related) I don't have Skype running.

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• Preferred apache permissions for www files with several authors

  - by user1316464

  I can't for the life of me figure out how to design my permissions scheme for my apache files. My requirements seem pretty simple: Apache should have standard permissions of RX for Directories and R for files Web authors should have RWX for Directories and RW for files Don't want to give any access to "other" Want new files/folders to inherit the proper permissions Here are the schemes I've tried 570 for directories and 460 for files Owner: Apache Group: Webdev The problem here is that new files created by users int the Webdev group are owned by user:Webdev and Apache can't read them. If Apache were in the group Webdev then it would also have the wrong permissions (ie it would have Write permissions to files) 750 for directories and 640 for files Owner: Webdev Group: Apache (Webdev is a member of Apache) The problem here is that there is only one webdev account and I have multiple people who need access to contribute. In theory this would work with only one developer if Webdev were also a member of the Apache group. Any ideas?

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• SSH: one user logs in, other don't

  - by Co Lega

  Some users can ssh correctly, others don't. I have an admin user, which is in wheel. I used vsftpd for allowing FTP. I created a nologin user for FTP. Call this user "ftpuser". Now I want to allow sftp. It allows me to connect using admin user. I remove the nologin, by giving the user a shell via usermod -s /bin/bash ftpuser. It still doesn't allow me to connect from the ftpuser via sftp. The content of /home/ftpuser/.ssh is just the known_hosts file which contains "localhost" entry only. User permissions are (in theory) ok: ls -la /home working (admin) : drwx------ 18 admin admin 4096 Feb 6 15:33 admin non-working(ftpuser): drwx------ 3 ftpuser ftp 4096 Mar 26 15:25 ftpuser I haven't configured anything special on openssh. Does the ftpuser need anything extra than shell to enter via ssh?

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• Cascading KVM switches

  - by einpoklum

  I have a not-so-small number of computers (say, 5) which I want to access with a single keyboard, USB and monitor. I can get an 8-port KVM switch, which is a pretty expensive piece of hardware; however, in theory, I should be able to cascade KVM switches: Have one 4-port KVM switch between 2 other KVMs (a 2-port and a 4-port). Is this doable (with typical off-the-shelf switches and cables)? Has anyone had experience doing this? Note: I'm interested in USB-only for the keyboard and mouse, and either VGA or DVI for the display. Audio and PS/2 connections are irrelevant for me..

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• Is visiting HTTPS websites on a public hotspot secure?

  - by Calmarius

  It's often said that HTTPS SSL/TLS connections are encrypted and said to be secure because the communication between the server and me is encrypted (also provides server authentication) so if someone sniffs my packets, they will need zillions of years to decrypt if using brute force in theory. Let's assume I'm on a public wifi and there is a malicious user on the same wifi who sniffs every packet. Now let's assume I'm trying to access my gmail account using this wifi. My browser does a SSL/TLS handshake with the server and gets the keys to use for encryption and decryption. If that malicious user sniffed all my incoming and outgoing packets. Can he calculate the same keys and read my encrypted traffic too or even send encrypted messages to the server in my name?

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• How can I measure TCP timeout limit on NAT firewall for setting keepalive interval?

  - by jmanning2k

  A new (NAT) firewall appliance was recently installed at $WORK. Since then, I'm getting many network timeouts and interruptions, especially for operations which would require the server to think for a bit without a response (svn update, rsync, etc.). Inbound SSH sessions over VPN also timeout frequently. That clearly suggests I need to adjust the TCP (and ssh) keepalive time on the servers in question in order to reduce these errors. But what is the appropriate value I should use? Assuming I have machines on both sides of the firewall between which I can make a connection, is there a way to measure what the time limit on TCP connections might be for this firewall? In theory, I would send a packet with gradually increasing intervals until the connection is lost. Any tools that might help (free or open source would be best, but I'm open to other suggestions)? The appliance is not under my control, so I can't just get the value, though I am attempting to ask what it currently is and if I can get it increased.

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• Could a DNSSEC at level n manipulate a zone at level n+2?

  - by jroith

  With some people wondering how DNSSEC could affect global censorship, I'd like to know if DNSSEC could protect a zone from being partially modified by a grandparent zone. (The point of this question is not to suggest that ICANN or it's members are not be trusted, but to figure out how DNSSEC affects the power they could exercise in theory.) For example: ICANN owns the root zone The .de zone is delegated to DENIC, Germany. Assume example.de is delegated to some 3rd party. Now, assuming DENIC does not remove example.de from their zone, would it be possible for them to redirect the subdomain abc.example.de elsewhere by returning signed records from the .de servers for abc.example.de ? Similarly, would it be possible for the DNS root to easily return signed fake records of a third-level domain xy.z while the second-level zone z is not participating in this and is not affected otherwise?

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• Beast / CRIME / Beach attack and stopping it

  - by user2143356

  I have read so much on all this but not entirely sure I understand what has gone on. Also, is this one, two or three problems? It looks to me like three, but it's all very confusing: Beast CRIME Beach It seems the solution may be to simply not use compression with HTTPS traffic (or is that just on one of them?) I use GZIP compression. Is that okay, or is that part of the problem? I also use Ubuntu 12.04 LTS Also, is non-HTTPS traffic okay? So after reading all the theory I just want the solution. I think this may be the solution, but can someone please confirm I have understood everything so I am not likely to suffer from this attack: SOLUTION: Use GZIP compression on HTTP traffic, but don't use any compression on HTTPS traffic

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• large RAID 10 vs small RAID1

  - by user116399

  The machine will store and serve millions of small files (<15Kb each), and all those files require a total storage space of 400G Considering the exact same SATA hard drives maker and models, on the exact same environment (OS, cpu, ram, raid controller, etc...) which one of the setups bellow would be faster? A) RAID 1 with 2 drives of 2T each, making up total storage of 2T B) RAID 10 with 4 drives of 2T each, making up total storage of 4T [EDIT]: I'm aware RAID10 is faster than RAID1. The larger the disk, at least in theory, the longer will take to do seeks/writes. So, will the performance gain of RAID10 will be outweighed by the "drag" caused the larger disk area when seek/write operations happened?

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• Directory "Bookmarking" in Linux

  - by Jason R. Mick

  Aside from aliasing and links, is there an easy way in Linux to tag commonly used directories and to navigate to a commonly used directory from the terminal. To be clear the disadvantages I see with alternative approaches, and why I want a bookmark/favorites like system: alias Cons: Too specific (every new favorite requires a new alias...although you could in theory make an alias that echo append your dir as a new alias, which would be sort of clever). Can't nest favorites in folders (can't think of a simple solution to this outside of heavy config scripting). links Cons: Clutter directory make ls a headache. pushd/popd Cons: Non-permanent (without shell config file scripting), can't nest favorites in directories, etc. Granted I have multiple ideas for making my own non-standard solution, but before I have at it I wanted to get some perspective on what's out there and if there is nothing, what is a recommended approach. Does anyone know of such a favorites/bookmark-like terminal solution?

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• Security considerations in providing VPN access to non-company issued computers [migrated]

  - by DKNUCKLES

  There have been a few people at my office that have requested the installation of DropBox on their computers to synchronize files so they can work on them at home. I have always been wary about cloud computing, mainly because we are a Canadian company and enjoy the privacy and being outside the reach of the Patriot Act. The policy before I started was that employees with company issued notebooks could be issued a VPN account, and everyone else had to have a remote desktop connection. The theory behind this logic (as I understand it) was that we had the potential to lock down the notebooks whereas the employees home computers were outside of our grasp. We had no ability to ensure they weren't running as administrator all the time / were running AV so they were a higher risk at being infected with malware and could compromise network security. With the increase in people wanting DropBox I'm curious as to whether or not this policy is too restrictive and overly paranoid. Is it generally safe to provide VPN access to an employee without knowing what their computing environment looks like?

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• Why is my Windows XP not allowing me to turn on sounds?

  - by Rookie

  This started to happen few weeks ago: Every time I start up Windows, the global sound volume is set to muted. I was able to just click the muted button to un-muted and that was fine, until now: Now I cant even click that unmute button! Every time I click the unmute button, I hear a split of a second the music I play, then it stops immediately. It is maybe 10 milliseconds until it mutes it again. In theory I could write a program to click that button continuously, but is there another solution to fix this? Or is this a broken hardware problem and Windows knows it and therefore doesn't allow me to enable sounds or my computer would break apart? Any ideas what could be causing this? A weird virus that's purpose is to piss me off? That weird this whole issue is, really, doesn't make any sense at all.

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• How to set up VLAN network

  - by Paddington

  I'm changing my network from having every device on flat network to using VLans. My problem is that we already have a lot of devices on this network(192.168.20.0/24). From theory, I read that each Vlan has to be a different subnet and then I need to configure virtual interfaces on my Cisco router to cater for inter vlan routing. 1) How can I segment this network with minimum down time on the devices already on the network? 2) Can I just create Vlans and leave all these Vlans in the same layer 3 network so that they can go out of the network (I am not too concerned about inter-Vlan routing) or I have to create subnets which means reconfiguring the existing devices (something I do not want).

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• Can I recover files on a disk With 5% of start of disk completely wiped (overwritten with 1s)

  - by ARA

  Recently a virus attacked my pc and cleared 5% of my hard disk which has one partition I viewed the disk in a hex viewer program like active undelete ,cleared the virus data and overwrote it with 1s I want to recover a large file that is about 10gb, but no recovery tools seem to be able to recover any files. I want to know ,in theory, is this file recoverable ? I think that files are fragmented, researched about NTFS File System and i understand cluster information are just saved in MFT File ? Is there any way to recover file without a MFT structure ?

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• What are the recognized ways to increase the size of the RAID array online/offline?

  - by user149509

  Is it possible, in theory, increase the size of the RAID-array of any level just by adding new drive(s)? Variant like "backup whole data - delete old array - add/replace disks - create new array - restore data" is obvious so what are the other options? Does it depend on the RAID-level only or on the implementation of RAID-controller only, or on both? Adding new disks to a striped array necessarily leads to a rebuilding of the array with the redistribution of the strips to the new drives? What steps should be done to increase size of RAID-array in online/offline scenarios? Especially interesting RAID-5 and RAID-10. I would like to see the big picture.

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• Running JBoss 6 with Runit / daemontools or other process supervision framework

  - by Alex Recarey

  I'm tying to use runit to daemonize JBoss. I use the /opt/jboss-6.1.0.Final/bin/run.sh script to start the server. When I do so from the comandline, JBoss does not detach (which is what we want), and will also shut down when CTRL+C is pressed. In theory a perfect candidate to use runit on. Everything works fine except when I try to get runit to shut down JBoss. When I issue the command sv stop jboss nothing happens. Runit thinks the process is stopped but jboss continues to run normally. I'm not doing anything special with the run script. This is my runit run script: #!/bin/sh exec 2>&1 exec /opt/jboss-6.1.0.Final/bin/run.sh -c standard -b 0.0.0.0 Looking at the jboss_init_redhat.sh script, the start section does mention ./bin/run.sh but the stop section has the following text: JBOSS_CMD_STOP=${JBOSS_CMD_STOP:-"java -classpath $JBOSSCP org.jboss.Shutdown --shutdown"} Any ideas of what I could try?

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• Why are special characters such as "carriage return" represented as "^M"?

  - by dotancohen

  Why is ^M used to represent a carriage return in VIM and other contexts? My guess is that M is the 13th letter of the Latin alphabet and a carriage return is \x0D or decimal 13. Is this the reason? Is this representation documented anywhere? I notice that Tab is represented by ^I, which is the ninth letter of the Latin alphabet. Conversely, Tab is \x09 or decimal 9, which supports my theory stated above. However, where might this be documented as fact?

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