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  • "Unable to open file", when the program tries to open file in /proc

    - by tristartom
    Hi, I try to read file /proc/'pid'/status, using c program. The code is as follows, and even I use sudo to run it, the prompt still keeps throwing "Unable to open file". Please let me know if you have any ideas on how to fix this. thanks Richard ... int main (int argc, char* argv[]) { string line; char* fileLoc; if(argc != 2) { cout << "a.out file_path" << endl; fileLoc = "/proc/net/dev"; } else { sprintf(fileLoc, "/proc/%d/status", atoi(argv[1])); } cout<< fileLoc << endl; ifstream myfile (fileLoc); if (myfile.is_open()) { while (! myfile.eof() ) { getline (myfile,line); cout << line << endl; } myfile.close(); } else cout << "Unable to open file"; return 0; }

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  • jQuery: get the file name selected from <input type="file" />

    - by ConNen
    This code should work in IE (don't even test it in Firefox), but it doesn't. What I want is to display the name of the attached file. Any help? <html> <head> <title>example</title> <script type="text/javascript" src="../js/jquery.js"></script> <script type="text/javascript"> $(document).ready( function(){ $("#attach").after("<input id='fakeAttach' type='button' value='attach a file' />"); $("#fakeAttach").click(function() { $("#attach").click(); $("#maxSize").after("<div id='temporary'><span id='attachedFile'></span><input id='remove' type='button' value='remove' /></div>"); $('#attach').change(function(){ $("#fakeAttach").attr("disabled","disabled"); $("#attachedFile").html($(this).val()); }); $("#remove").click(function(e){ e.preventDefault(); $("#attach").replaceWith($("#attach").clone()); $("#fakeAttach").attr("disabled",""); $("#temporary").remove(); }); }) }); </script> </head> <body> <input id="attach" type="file" /><span id="maxSize">(less than 1MB)</span> </body> </html>

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  • Tail the filename, not the file

    - by Craig Walker
    In UNIX (OS X BSD to be precise), I have a "tail -f" command on a log file. From time to time I want to delete this log file so I can more easily review it in my text editor. I delete the file, and then my program recreates it after new activity. However, my tail command (and anything else that was watching the old log file) doesn't update; it's still watching the old, deleted log file. I think I understand why this is (file names simply being pointers to blocks of file data). I'd like to know how I can work around this. Ideally, my tail command (and anything else I point to the file) would be able to read the data from the new file when the file name has been deleted and recreated. How would I do this?

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  • rsync to EC2: Identity file not accessible

    - by Richard
    I'm trying to rsync a file over to my EC2 instance: rsync -Paz --rsh "ssh -i ~/.ssh/myfile.pem" --rsync-path "sudo rsync" file.pdf [email protected]:/home/ubuntu/ This gives the following error message: Warning: Identity file ~/.ssh/myfile.pem not accessible: No such file or directory. [email protected]'s password: The pem file is definitely located at the path ~/.ssh/myfile.pem, though: vi ~/.ssh/myfile.pem shows me the file. If I remove the remote path from the very end of the rsync command: rsync -Paz --rsh "ssh -i ~/.ssh/myfile.pem" --rsync-path "sudo rsync" file.pdf [email protected] Then the command appears to work... building file list ... 1 file to consider file.pdf 41985 100% 8.79MB/s 0:00:00 (xfer#1, to-check=0/1) sent 41795 bytes received 42 bytes 83674.00 bytes/sec total size is 41985 speedup is 1.00 ...but when I go to the remote server, nothing has actually been transferred. What am I doing wrong?

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  • Viewing file: protocol requests made from a swf

    - by Erik Vold
    I've got a swf file in a index.html file, the swf is basically loading images, but it requests a xml file which details where the image/asset files are located. Now the index file (which is just html, js, and css) works (ie: the swf file is working) when used on this url: http://localhost:8500/core/index.html which I'm able to do with Coldfusion 8 single server development environment. But when I access the file directly with this url: file:///C:/ColdFusion8/wwwroot/core/index.html the swf file does not work. So I'm guessing that the swf is having trouble locating the files that it needs. The problem is I have no idea what file urls it is try to access atm, and both Firebug and Fiddler are not able to inform me what requests are made on the file: protocol. So is there another tool that I can use?

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  • Encrypted directory makes file operations for whole disk very slow

    - by user1566277
    I am running an arm GNU/Linux and I have a SD-Card with three partitions on it. On one of the Partition I create an encfs file and then mount it on a directory which is in another partition to make that directory encrypted. Works fine. But now the writing speed on all the partitions are reduced drastically. I can understand that it should be slow for encrypted directory but why the its reducing write speed for all the partitions. E.g., if do not mount the encrypted directory 20MB is transferred in 2 Sec. roughly but with the encrypted directory mounted its like 20 Seconds for same file. I am using LUKS and all the partitons are ext3 except for the directory where /dev/mapper/encfs is mounted as type ext2. Any hints?

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  • How can I make a permanently updated copy of a file in a different place to the original file?

    - by Mark
    I use two computers, a Linux one for coding and building and a Windows one which has the programming application to load the built program onto the hardware. Both computers have access to a network drive which I use to pass the files from Linux to Windows. My problem is, that every time I build I have to copy the files from where the are created to the network drive. How can I make some sort of file in the network drive on Ubuntu that always mirrors the file which is built in the different location, like a pointer? Thanks!

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  • Cannot access system after deleting passwd file

    - by joao rodrigo leao
    I was trying to change my user name and also my /home/username and my system started to crash. I deleted the passwd file but I had a backup named passwd_bkp. I tried to rename this passwd_bkp as passwd and it did not work. No commands were being executed... I was in a terminal window. I re-started my system and now I cannot login. The GRub loads two options: Linux and recovery mode. I tried to open a sessions as root but it says the file system is corrupted. I cannot access my files. Did I lose all my files?

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  • Run a .sql script file in C#

    - by SAMIR BHOGAYTA
    using System.Data.SqlClient; using System.IO; using Microsoft.SqlServer.Management.Common; using Microsoft.SqlServer.Management.Smo; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { string sqlConnectionString = "Data Source=(local);Initial Catalog=AdventureWorks;Integrated Security=True"; FileInfo file = new FileInfo("C:\\myscript.sql"); string script = file.OpenText().ReadToEnd(); SqlConnection conn = new SqlConnection(sqlConnectionString); Server server = new Server(new ServerConnection(conn)); server.ConnectionContext.ExecuteNonQuery(script); } } }

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  • Custom extensible file format for 2d tiled maps

    - by Christian Ivicevic
    I have implemented much of my game logic right now, but still create my maps with nasty for-loops on-the-fly to be able to work with something. Now I wanted to move on and to do some research on how to (un)serialize this data. (I do not search for a map editor - I am speaking of the map file itself) For now I am looking for suggestions and resources, how to implement a custom file format for my maps which should provide the following functionality (based on MoSCoW method): Must have Extensibility and backward compatibility Handling of different layers Metadata on whether a tile is solid or can be passed through Special serialization of entities/triggers with associated properties/metadata Could have Some kind of inclusion of the tileset to prevent having scattered files/tilesets I am developing with C++ (using SDL) and targetting only Windows. Any useful help, tips, suggestions, ... would be appreciated!

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  • Considerations when designing a file type

    - by AndyBursh
    I'm about to start writing a process for saving some data structure from code in to a file of some proprietary, as-yet-undefined type. However, I've never designed a file type or structure before. Are there any things, generally speaking, that I should consider before starting my design? Are there any accepted good practices here? Bad practices I should avoid? Any absolute do's and don'ts? Can anybody recommend any good reading on this topic?

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  • Upgrading MySQL causes errors

    - by user1032531
    I am running Centos 5.8 (Linux 2.6.18-308.13.1.el5 on x86_64), and wish to upgrade MySQL version 5.0.95. I am using a tutorial found at http://www.if-not-true-then-false.com/2010/install-mysql-on-fedora-centos-red-hat-rhel/. When I get to the following, I get the host of errors. Seems to have something to do with going from 386 to 86x64. Can anyone help? Thanks yum --enablerepo=remi,remi-test update mysql mysql-server Transaction Check Error: file /etc/my.cnf from install of mysql50-5.0.96-2.ius.el5.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/info/mysql.info.gz from install of mysql50-5.0.96-2.ius.el5.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysql.1.gz from install of mysql50-5.0.96-2.ius.el5.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqlaccess.1.gz from install of mysql50-5.0.96-2.ius.el5.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqladmin.1.gz from install of mysql50-5.0.96-2.ius.el5.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqldump.1.gz from install of mysql50-5.0.96-2.ius.el5.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqlshow.1.gz from install of mysql50-5.0.96-2.ius.el5.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /etc/my.cnf from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/charsets/Index.xml from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/charsets/cp1250.xml from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/charsets/cp1251.xml from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/czech/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/danish/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/dutch/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/english/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/estonian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/french/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/german/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/greek/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/hungarian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/italian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/japanese/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/korean/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/norwegian-ny/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/norwegian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/polish/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/portuguese/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/romanian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/russian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/serbian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/slovak/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/spanish/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/swedish/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/mysql/ukrainian/errmsg.sys from install of mysql-libs-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/bin/mysqlaccess from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/my_print_defaults.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysql.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysql_config.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysql_find_rows.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysql_waitpid.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqlaccess.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqladmin.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqldump.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386 file /usr/share/man/man1/mysqlshow.1.gz from install of mysql-5.5.28-1.el5.remi.x86_64 conflicts with file from package mysql-5.0.95-1.el5_7.1.i386

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  • System.IO.IOException: file used by another process

    - by Srodriguez
    Dear all, I've been working in this small piece of code that seems trivial but still i cannot really see where is the problem. My functions does a pretty simple thing. Opens a file, copy its contents, replace a string inside and copy it back to the original file (a simple search and replace inside a text file then). I didn't really know how to do that as I'm adding lines to the original file, so i just create a copy of the file, (file.temp) copy also a backup (file.temp) then delete the original file(file) and copy the file.temp to file. I get an exception while doing the delete of the file. Here is the sample code: private static bool modifyFile(FileInfo file, string extractedMethod, string modifiedMethod) { Boolean result = false; FileStream fs = new FileStream(file.FullName + ".tmp", FileMode.Create, FileAccess.Write); StreamWriter sw = new StreamWriter(fs); StreamReader streamreader = file.OpenText(); String originalPath = file.FullName; string input = streamreader.ReadToEnd(); Console.WriteLine("input : {0}", input); String tempString = input.Replace(extractedMethod, modifiedMethod); Console.WriteLine("replaced String {0}", tempString); try { sw.Write(tempString); sw.Flush(); sw.Close(); sw.Dispose(); fs.Close(); fs.Dispose(); streamreader.Close(); streamreader.Dispose(); File.Copy(originalPath, originalPath + ".old", true); FileInfo newFile = new FileInfo(originalPath + ".tmp"); File.Delete(originalPath); File.Copy(fs., originalPath, true); result = true; } catch (Exception ex) { Console.WriteLine(ex); } return result; }` And the related exception System.IO.IOException: The process cannot access the file 'E:\mypath\myFile.cs' because it is being used by another process. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.File.Delete(String path) at callingMethod.modifyFile(FileInfo file, String extractedMethod, String modifiedMethod) Normally these errors come from unclosed file streams, but I've taken care of that. I guess I've forgotten an important step but cannot figure out where. Thank you very much for your help,

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  • REST authentication S3 like hmac sha1 signature vs symetric data encryption.

    - by coulix
    Hello stackers, I was arguing about an S3 like aproach using authorization hash with a secret key as the seed and some data on the request as the message signed with hmac sha1 (Amazon S3 way) vs an other developer supporting symetric encryption of the data with a secret key known by the emiter and the server. What are the advantage of using signed data with hmac sha1 vs symetric key other than the fact that with the former, we do not need to encrypt the username or password. What would be the hardest to break ? symetric encryption or sha1 hashing at la S3 ? If all big players are using oauth and similar without symetric key it is sure that there are obvious advantages, what are those ?

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  • How to build this encryption system that allows multiple users/objects.

    - by Patrick
    Hello! I am trying to figure out how to create an optimal solution for my project. I made this simple picture in Photoshop to try to illustrate the problem and how i want it (if possible). Illustrative image Ill also try to explain it based on the picture. First off we have a couple of objects to the left, these objects all get encrypted with their own encryption key (EKey on the picture) and then stored in the database. On the other side we have different users placed into roles (one user can be in a lot of roles) and the roles are associated with different objects. So one person only has access the to the objects that the role provides. So for instance Role A might have access to Object A and B. Role B have access only to Object C and Role C have access to all objects. Nothing strange in that, right? Different roles have different objects that they can access. Now to the problem part. Each user has to login with his/her username/password and then he/she gets access to the objects that his/her roles provide. All the objects are encrypted so she needs to get a decryption key somehow. I don't want to store the encryption key as a text string on the server. It should be, if possible, decrypted using the users password (along with the role) or similar. That way you have to be a user on the server in order to decrypt an object an to work with it. I was thinking about making a public/private key encryption system, but i am kinda stuck on how to give the different users the decryption key to the objects. Since i need to be able to move users to and from roles, add new users, add new roles and create/delete objects. There will be one administrator that then adds some data to allow the users in that role to get the decryption key to decrypt the object. Nothing is static and i am trying to get a picture of how this can be built or if there is a far better solution. The only criteria are: -Encrypted objects. -Decryption key should not be stored as text. -Different users have access to different objects. -Does NOT have to have roles.

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  • Windows Server 2003 R2 Standard: Locks MS Office files, but not Adobe .AI and .PSD files?

    - by Bruce Garlock
    We have some shares setup on a Windows 2003 R2 server, and the MS Office files people save behave properly: The first person to open the file gets read/write, and the second person to open the file while the first person still has the file open, gets a read-only version. This is not true for the graphics files, like Adobe Illustrator .AI files, and Photoshop .PSD files. Anyone who goes to open these files has full read/write, even if someone else is already working on the file! This has lead to numerous file corruption issues, as well as other lost work, since it always saves the last changes to the file. How do we get Windows to properly lock these files so when someone is working on a file, and someone else wants to open one, they get read-only access? Many thanks, Bruce

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  • How do I encrypt but share a number of folders?

    - by d3vid
    I want to achieve the following functionality. Is it possible? Boot up computer (possibly via WakeOnLan or WakeOnPlan). Either be automatically logged in, or log in via login screen, or log in remotely. I change this behavior occasionally, so full disk encryption wouldn't work for me because it requires a password on bootup (which would it would prevent the remote bootup options, and the automatic login option). I am only interested in encrypting data, not the entire harddrive. Once logged in either: a launcher/tray icon is available to launch encryption app (preferred) run encryption app from the dash Prompted to unlock encrypted folder(s) individually. Unlocked folders are available to: me, apps I am running (e.g. editors, SpiderOak) Ideally, folders that I share with bindfs can be locked/unlocked by other users too. A key point is that once I have unlocked an encrypted folder, I don't want to have to think about it again. I currently achieve this via TrueCrypt (except for the last part). Unfortunately TrueCrypt isn't well integrated with Ubuntu (licensing issues prevent Debian from including it in their repo, the interface isn't quite integrated with Unity, setting it as a startup app doesn't quite work, sharing encrypted folders isn't really part of its design). Is there an alternative to TrueCrypt that is better integrated with the Ubuntu GUI and would suit this workflow?

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  • Deleted info in Boot folder

    - by user207984
    First off, I'm using Zorin 7 OS. So my Boot folder was too full to install any new updates, I used a tutorial I found somewhere on here to remove the unneeded linux-image files, and must of also deleted the latest one as well. Now when I attempt to boot I get error: no such partition. grub rescue> I used my MultiSystem USB to install (on a separate partition) a different Linux OS (Kali) and no longer get that error, however, it will ONLY give me the option to boot Kali Linux. Here's the biggest new problem though, I used the built in option of hard drive encryption for Zorin 7 when I initially installed it, so now when I attempt to explore it (to get all my saved data which is REALLY important to me), it asks me for password for encryption. However, the password says it in not recognized, and I know it's right, I had to type it in every single day. So I either need a way to restore my Zorin 7 boot files or GRUB or whatever, so I can boot it up... or I need to know how to fix my encryption problem to save all my info.

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  • Encrypt a file base upon a pregenerated "key" C#

    - by Anubis
    Hello everyone. I'm trying to determine the best course of action to implement a simple "licensing" system with a partner of mine. The concept is: Generate an encrypted value based upon several internal hardware components. Have the customer send this value to us which we will implement into our key generator. Once we have that, we add any other restrictions on the license (user, expires, etc.). From there we generate a file which we send to the customer they can add to their installation and voila, happy people about. I have the first part all done. My next part is trying to figure out which encryption methodology I would need to use. I already know Symmetric Encryption is pretty much the only route I can take. Most of the information I have found involves .NET already creating a key from its own internal methods. That's a bit of background, my question is: "Which encryption method could I use which would allow me to encrypt the restrictions based upon the "id" I was given from the customer's computer?" I'm writing this in C# by the way. Any ideas would be greatly appreciated! Take Care!

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  • How to encrypt/decrypt a file in Java?

    - by Petike
    Hello, I am writing a Java application which can "encrypt" and consequently "decrypt" whatever binary file. I am just a beginner in the "cryptography" area so I would like to write a very simple application for the beginning. For reading the original file, I would probably use the java.io.FileInputStream class to get the "array of bytes" byte originalBytes[] of the file. Then I would probably use some very simple cipher, for example "shift up every byte by 1" and then I would get the "encrypted" bytes byte encryptedBytes[] and let's say that I would also set a "password" for it, for example "123456789". Next, when somebody wants to "decrypt" that file, he has to enter the password ("123456789") first and after that the file could be decrypted (thus "shift down every byte by 1") and consequently saved to the output file via java.io.FileOutputStream I am just wondering how to "store" the password information to the encrypted file so that the decrypting application knows if the entered password and the "real" password equals? Probably it would be silly to add the password (for example the ASCII ordinal numbers of the password letters) to the beginning of the file (before the encrypted data). So my main question is how to store the password information to the encrypted file?

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  • Improving VPN performance - stronger encryption = more performance?

    - by Seth
    I have a site-to-site VPN set up with two SonicWall's (a TZ170 and a Pro1260). It was suggested to me that turning off encryption (so the VPN is tunneling only) would improve performance. (I'm not concerned with security, because the VPN is running over a trusted line.) Using FTP and HTTP transfers, I measured my baseline performance at about 130±10 kB/s. The Ipsec (Phase 2) Encryption was set to 3DES, so I set it to "none". However, the effect was opposite -- the performance dropped to 60±30 kB/s, and the transfers stall for about 25 seconds before any data comes down the line. I tried AES-128 and the throughput went UP to 160±5 kB/s. The rated speed of my line is 193 kB/s (it's a T1). Contrary to what I would think, stronger Ipsec encryption seems to improve throughput. Can anyone explain what might be going on here? Why would no encryption cause poor and highly variable performance, and cause transfers to stall? Why does AES-128 improve performance?

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  • Copying files between linux machines with strong authentication but without encryption

    - by Zizzencs
    I'm looking for a suitable program to copy files from one linux machine to another one. The program should be able to do authentication but it should not do encryption. The reason behind the latter is the lack of CPU power to do the encryption. I copy backups from ~70 machines to a single backup server simultaneously. The single server is an HP Proliant DL360 G7, with 10 Gbps ethernet connection and an FC storage backend that can do 4 Gbps. Through FTP I can write ~400MB/sec to the storage (that's about what I want) but through ssh with arcfour I can only do ~100MB/sec while having 100% CPU usage. That's why I want file transfers not to be encrypted. The alternatives that I found not really suitable: rcp: no authentication, forget it FTP: making the authentication "secure" (at least preventing plain-text password exchange) is possible but not really easy and I haven't found a method to force any FTP daemon to encrypt the control channel (for the authentication) and not to encrypt the data channel (for data transfers) SCP/SFTP: in farely recent ssh(d) implementations you can't turn off encryption. The best you can do is to use the arcfour cypher for the encryption but it sill uses too much CPU power for my needs. rsync over ssh: same problems as with SCP/SFTP. plain rsync: from the documentation of rsyncd: "The authentication protocol used in rsync is a 128 bit MD4 based challenge response system. This is fairly weak protection, though (with at least one brute-force hash-finding algorithm publicly available), so if you want really top-quality security, then I recommend that you run rsync over ssh." It's a no-go. Is there a protocol/program that can do exactly what I want? (A big plus would be if it could work on windows as well and/or if it would support rsync-stlye copying/synchronization (e.g. copy only the differences).)

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  • File locked / read-only

    - by oshirowanen
    On a networked computer, I have a file which is coming up as read-only because someone else has it open. This is not true. This is a file stored locally on the computer and it is not being used by anyone else. I can login to the same computer using a different user, and the file opens up fine. I just get the issue with a particular user account. Other than deleting theses account/profile and creating it again, how can I unlock this file? Double clicking on this file gives me a message saying The file is locked for editing by another user, or the file (or the folder in which it is located,) is marked as read-only, or you specified that you wanted to open this file read-only. I don't think the folder is locked, because I can use other files in that folder fine, it's just 1 particular file which is causing this issue. I know that only 1 user is using this file as the file is on his c: and the same file works fine if he logs off to allow another user to log in.

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  • Fragmented Log files could be slowing down your database

    - by Fatherjack
    Something that is sometimes forgotten by a lot of DBAs is the fact that database log files get fragmented in the same way that you get fragmentation in a data file. The cause is very different but the effect is the same – too much effort reading and writing data. Data files get fragmented as data is changed through normal system activity, INSERTs, UPDATEs and DELETEs cause fragmentation and most experienced DBAs are monitoring their indexes for fragmentation and dealing with it accordingly. However, you don’t hear about so many working on their log files. How can a log file get fragmented? I’m glad you asked. When you create a database there are at least two files created on the disk storage; an mdf for the data and an ldf for the log file (you can also have ndf files for extra data storage but that’s off topic for now). It is wholly possible to have more than one log file but in most cases there is little point in creating more than one as the log file is written to in a ‘wrap-around’ method (more on that later). When a log file is created at the time that a database is created the file is actually sub divided into a number of virtual log files (VLFs). The number and size of these VLFs depends on the size chosen for the log file. VLFs are also created in the space added to a log file when a log file growth event takes place. Do you have your log files set to auto grow? Then you have potentially been introducing many VLFs into your log file. Let’s get to see how many VLFs we have in a brand new database. USE master GO CREATE DATABASE VLF_Test ON ( NAME = VLF_Test, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test.mdf', SIZE = 100, MAXSIZE = 500, FILEGROWTH = 50 ) LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5MB, MAXSIZE = 250MB, FILEGROWTH = 5MB ); go USE VLF_Test go DBCC LOGINFO; The results of this are firstly a new database is created with specified files sizes and the the DBCC LOGINFO results are returned to the script editor. The DBCC LOGINFO results have plenty of interesting information in them but lets first note there are 4 rows of information, this relates to the fact that 4 VLFs have been created in the log file. The values in the FileSize column are the sizes of each VLF in bytes, you will see that the last one to be created is slightly larger than the others. So, a 5MB log file has 4 VLFs of roughly 1.25 MB. Lets alter the CREATE DATABASE script to create a log file that’s a bit bigger and see what happens. Alter the code above so that the log file details are replaced by LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 1GB, MAXSIZE = 25GB, FILEGROWTH = 1GB ); With a bigger log file specified we get more VLFs What if we make it bigger again? LOG ON ( NAME = VLF_Test_Log, FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL10.ROCK_2008\MSSQL\DATA\VLF_Test_log.ldf', SIZE = 5GB, MAXSIZE = 250GB, FILEGROWTH = 5GB ); This time we see more VLFs are created within our log file. We now have our 5GB log file comprised of 16 files of 320MB each. In fact these sizes fall into all the ranges that control the VLF creation criteria – what a coincidence! The rules that are followed when a log file is created or has it’s size increased are pretty basic. If the file growth is lower than 64MB then 4 VLFs are created If the growth is between 64MB and 1GB then 8 VLFs are created If the growth is greater than 1GB then 16 VLFs are created. Now the potential for chaos comes if the default values and settings for log file growth are used. By default a database log file gets a 1MB log file with unlimited growth in steps of 10%. The database we just created is 6 MB, let’s add some data and see what happens. USE vlf_test go -- we need somewhere to put the data so, a table is in order IF OBJECT_ID('A_Table') IS NOT NULL DROP TABLE A_Table go CREATE TABLE A_Table ( Col_A int IDENTITY, Col_B CHAR(8000) ) GO -- Let's check the state of the log file -- 4 VLFs found EXECUTE ('DBCC LOGINFO'); go -- We can go ahead and insert some data and then check the state of the log file again INSERT A_Table (col_b) SELECT TOP 500 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO -- insert 500 rows and we get 22 VLFs EXECUTE ('DBCC LOGINFO'); go -- Let's insert more rows INSERT A_Table (col_b) SELECT TOP 2000 REPLICATE('a',2000) FROM sys.columns AS sc, sys.columns AS sc2 GO 10 -- insert 2000 rows, in 10 batches and we suddenly have 107 VLFs EXECUTE ('DBCC LOGINFO'); Well, that escalated quickly! Our log file is split, internally, into 107 fragments after a few thousand inserts. The same happens with any logged transactions, I just chose to illustrate this with INSERTs. Having too many VLFs can cause performance degradation at times of database start up, log backup and log restore operations so it’s well worth keeping a check on this property. How do we prevent excessive VLF creation? Creating the database with larger files and also with larger growth steps and actively choosing to grow your databases rather than leaving it to the Auto Grow event can make sure that the growths are made with a size that is optimal. How do we resolve a situation of a database with too many VLFs? This process needs to be done when the database is under little or no stress so that you don’t affect system users. The steps are: BACKUP LOG YourDBName TO YourBackupDestinationOfChoice Shrink the log file to its smallest possible size DBCC SHRINKFILE(FileNameOfTLogHere, TRUNCATEONLY) * Re-size the log file to the size you want it to, taking in to account your expected needs for the coming months or year. ALTER DATABASE YourDBName MODIFY FILE ( NAME = FileNameOfTLogHere, SIZE = TheSizeYouWantItToBeIn_MB) * – If you don’t know the file name of your log file then run sp_helpfile while you are connected to the database that you want to work on and you will get the details you need. The resize step can take quite a while This is already detailed far better than I can explain it by Kimberley Tripp in her blog 8-Steps-to-better-Transaction-Log-throughput.aspx. The result of this will be a log file with a VLF count according to the bullet list above. Knowing when VLFs are being created By complete coincidence while I have been writing this blog (it’s been quite some time from it’s inception to going live) Jonathan Kehayias from SQLSkills.com has written a great article on how to track database file growth using Event Notifications and Service Broker. I strongly recommend taking a look at it as this is going to catch any sneaky auto grows that take place and let you know about them right away. Hassle free monitoring of VLFs If you are lucky or wise enough to be using SQL Monitor or another monitoring tool that let’s you write your own custom metrics then you can keep an eye on this very easily. There is a custom metric for VLFs (written by Stuart Ainsworth) already on the site and there are some others there are very useful so take a moment or two to look around while you are there. Resources MSDN – http://msdn.microsoft.com/en-us/library/ms179355(v=sql.105).aspx Kimberly Tripp from SQLSkills.com – http://www.sqlskills.com/BLOGS/KIMBERLY/post/8-Steps-to-better-Transaction-Log-throughput.aspx Thomas LaRock at Simple-Talk.com – http://www.simple-talk.com/sql/database-administration/monitoring-sql-server-virtual-log-file-fragmentation/ Disclosure I am a Friend of Red Gate. This means that I am more than likely to say good things about Red Gate DBA and Developer tools. No matter how awesome I make them sound, take the time to compare them with other products before you contact the Red Gate sales team to make your order.

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  • Intermittent bug - IE6 showing file as text in browser, rather than as file download

    - by Richard Ev
    In an ASP.NET WebForms 2.0 site we are encountering an intermittent bug in IE6 whereby a file download attempt results in the contents of the being shown directly in the browser as text, rather than the file save dialog being displayed. Our application allows the user to download both PDF and CSV files. The code we're using is: HttpResponse response = HttpContext.Current.Response; response.Clear(); response.AddHeader("Content-Disposition", "attachment;filename=\"theFilename.pdf\""); response.ContentType = "application/pdf"; response.BinaryWrite(MethodThatReturnsFileContents()); response.End(); This is called from the code-behind click event handler of a button server control. Where are we going wrong with this approach? Edit Following James' answer to this posting, the code I'm using now looks like this: HttpResponse response = HttpContext.Current.Response; response.ClearHeaders(); // Setting cache to NoCache was recommended, but doing so results in a security // warning in IE6 //response.Cache.SetCacheability(HttpCacheability.NoCache); response.AppendHeader("Content-Disposition", "attachment; filename=\"theFilename.pdf\""); response.ContentType = "application/pdf"; response.BinaryWrite(MethodThatReturnsFileContents()); response.Flush(); response.End(); However, I don't believe that any of the changes made will fix the issue.

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