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• Is it possible to put a form control on its own thread?

  - by BVernon

  I'm using a DataGridView and some operations that I do cause it to become unresponsive for periods of time. Normally I would put data processing in its own thread to make the form more responsive, but in this case it's the DataGridView itself that's taking so long. This leads me to wonder whether it's possible to have the main form on one thread and the DataGridView on another thread so it doesn't prevent the main form from responding. I completely understand that doing so is probably not 'safe' and likely opens up a can of worms that makes it hardly worth trying and I fully expect this post will be getting down votes for merely suggesting such a ridiculous idea. Is this possible? And if so how would you go about it?

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• Can we avoid multiple if''s(C#3.0)

  - by Newbie

  I tried my level best to write an improved version but failed. inFiles.ToList().ForEach(i => { filePath = inFolder + "\\" + i.Value; if (i.Key.Equals(replacementFile)) { replacementCollection = GetReplacementDataFromFile(filePath); } else if (i.Key.Equals(standardizationFile)) { standardizationCollection = GetStandardizationDataFromFile(filePath); } }); The problem is that I cannot use a switch case over here because the comparison variables are not constant. Kindly help to improve this code. I am using C#(3.0). Thanks

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• How to restore a slave from a mysql backup?

  - by robsf

  I'm running MySql 5.1. I have Master and a Slave on 2 machines and I set up replication. I do periodic backup on my slave server. I stop mysql, I copy all the files and I restart mysql. In case I lose the Master, I can set up a new one from the last backup. What If I lose the Slave? Can I restart the slave from the last backup? Am I supposed to keep track of the position of the replication every time I to a backup?

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• Find largest rectangle containing only zeros in an N&times;N binary matrix

  - by Rajendra

  Given an NxN binary matrix (containing only 0's or 1's), how can we go about finding largest rectangle containing all 0's? Example: I 0 0 0 0 1 0 0 0 1 0 0 1 II->0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 <--IV 0 0 1 0 0 0 IV is a 6×6 binary matrix; the return value in this case will be Cell 1: (2, 1) and Cell 2: (4, 4). The resulting sub-matrix can be square or rectangular. The return value can also be the size of the largest sub-matrix of all 0's, in this example 3 × 4.

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• Can I pass an array as arguments to a method with variable arguments in Java?

  - by user352382

  I'd like to be able to create a function like: class A { private String extraVar; public String myFormat(String format, Object ... args){ return String.format(format, extraVar, args); } } The problem here is that args is treated as Object[] in the method myFormat, and thus is a single argument to String.format, while I'd like every single Object in args to be passed as a new argument. Since String.format is also a method with variable arguments, this should be possible. If this is not possible, is there a method like String.format(String format, Object[] args)? In that case I could prepend extraVar to args using a new array and pass it to that method.

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• private virtual function in derived class

  - by user1706047

  class base { public: virtual void doSomething() = 0; }; class derived : public base { **private:** virtual void doSomething(){cout<<"Derived fn"<<endl;} }; now if i do the following: base *b=new child; b->doSomething(); //it calls the derived class fn even if that is private. Question: 1.its able to call the derived class fn even if that is private.How is it possible? Now if i change the inheritance access specifier from public to protected/private then i get compilation error as "'type cast' : conversion from 'Derived *' to 'base *' exists, but is inaccessible" Notes: I am aware on the concepts of the inheritance access specifiers.So in second case as its derived private/protected, its inaccessible. But here it confuses me for the first question. Any input will be highly appreciated

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• CSS: How to set remaining width as %, but having knowledge of only pixels

  - by Mega Matt

  Hi all, I've seen this question asked in a couple other contexts on SO, but I thought it would be worth asking again for my particular case. I'm trying to create some re-usable CSS classes for more consistency and less clutter on my site, and I'm stuck on trying to standardize one thing I use frequently. I have a container div that I don't want to set the height for (because it will vary depending on where on the site it is), and inside it is a header div, and then an unordered list of items, all with CSS applied to them. It looks a lot like this: I want the unordered list to take up the remaining room in the container div, knowing that the header div is 18px tall. I just don't know how to specify the list's height as "the result of 100% minus 18px". Does anyone have any advice in this situation? Thanks very much.

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• Why is it called NoSQL?

  - by beef jerky

  I've recently worked with MongoDB and learned about its schemaless design. However, I'm confused with the term NoSQL? Why is it called that? Doesn't it use SQL or SQL-like queries? I've also read from an article that the main difference lies in how data is stored. In the case of MongoDB, it's stored like JSON documents. Is this true? Also, I'm confused why I always see 'NoSQL vs relational databases'. Aren't NoSQL databases relational? I believe documents in MongoDB are still related/linked through some keys (please correct me if I'm wrong). So why is it labeled as non-relational? Thanks in advance!

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• JQuery mobile handling links (return false)

  - by shinax

  I'm planning on using JQM to make a simple mobile web app, and I'm having problems getting this simple functionality to work: when I click on some links (not all of them), I want to be able to first process some data, and then depending on that outcome, sometimes continue the link action (I like the whole transitions and ajax things), and sometimes don't. The important part is that I want to preserve the normal JQMobile transitions and stuff for the links, just sometimes prevent them (for example for validation and things like that). I've tried with: return false, preventDefault (and in combination with stopPropagation), and data-ajax="false", and none hav worked, they all redirect. Could somebody tell me the correct way to to this in JQMobile? Just in case it's important: I'm using anchor links, using this to test. Thank you in advance, Jennifer.

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• Module.new with class_eval

  - by dorelal

  This is a large commit. But I want you to concentrate on this change block. http://github.com/rails/rails/commit/d916c62cfc7c59ab6411407a05b946d3dd7535e9#L2L1304 Even without understanding the full context of the code I am not able to think of a scenario where I would use include Modue.new { class_eval <<-RUBY def foo puts 'foo' end RUBY } Then end result is that in the root context (self just before include Moduel.new) a method call foo has been added. If I take out the Module.new code and if I only leave class_eval in that case also I will have a method called foo in self. What am I missing.

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• Rotating a movieclip slowly (so it looks like it was animated) [on hold]

  - by user2537021

  Im trying to rotate an object X degrees, nut i want that when the rotation happends it isent all suden, i want that you can see the object spining all the way to the X degree. (im try ing to me more clear) (I'm pretty new at this so please be patient with me) switch (enemywalk) { case 1: colx = enemy.y; enemy.y -= 115; if ( enemy.hitTestObject (pared1) || enemy.hitTestObject (pared2) ) { enemy.y = colx; } enemy.rotation = enemyrotate; //random generated number break; }

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• Why can't I decrease the line-height of this text?

  - by daGUY

  http://jsfiddle.net/mJxn4/ This is very odd: I have a few lines of text wrapped in an <em> tag. No matter what I do, lowering the value for line-height below 17px has no effect. I can bump the line-height up to greater than 17px and it'll apply, but I can't get it lower than 17px. The CSS in question is: #others .item em { font-size: 13px; line-height: 17px; } Try adjusting the line height both higher and lower and run the updated fiddle after each change, and you'll see what I mean. Why would this be? No line-height is specified anywhere else in the CSS, so nothing is overriding it. That couldn't be the case anyway because I'm adjusting the line-height up and down within the same selector, so it doesn't make sense that a higher value would apply, but a lower value would get overridden.

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• PHP DateTime accept multiple formats?

  - by John Smith

  I'm trying to construct a DateTime object with multiple accepted formats. According to the DateTime::createFromFormat docs, the first parameter (format) must be a string. I was wondering if there was a way to createFromFormats. In my case, I want the year for my format to be optional: DateTime::createFromFormat('Y-m-d', $date); DateTime::createFromFormat('m-d', $date); so that a user can input just 'm-d' and the year would be assumed 2013. If I wanted multiple accepted formats, would I have to call createFromFormat each time? Shortest thing for my scenario is: DateTime::createFromFormat('m-d', $date) ?: DateTime::createFromFormat('Y-m-d', $date);

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• how to visualize (value, count) dataset with thousands data points

  - by user510040

  I have a file with 2 numeric columns: value and count. File may have 5000 rows. I do plot(value, count) to find the shape of distribution. But because there are too many data points the picture is not very clear. Do you know better visualization approach? Probably histograms or barplot with grouping close values on x axis will be the better way to look on data? I cannot figure out the syntax of using histogram or barplot for my case.

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• Android search list, String

  - by NightSky

  Hey guys what is the best way to search through my list of objects, they return a few strings, last name and first name for example. Here how i'm currently searching but my search needs to match the entire string which I don't want. The search needs it to match part of the string like our contacts list on our phone and ignore the case. if (searchQ.equalsIgnoreCase(child.first_name)) { addChildToList(child); } Ive tried contains and starts with for example, they did not work. Whats going on? Thanks! Cheers!

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• CSS center page on screen

  - by Kostronor

  //sorry for the bad formating, i am on my phone... When someone asks how to center a page, then the response is like: margin-left:50%; left:(-1/2 width); I used this code on a site with a width of 1000px,so it comes to screens, where this site does not fit. Now the site gets centered on the smaller screen and gets equaly pushet to left and right. So lets say, our screen is 600px wide: 200px are left 600px are on screen 200px are right You can scroll to the right, but the pixels on the left are unreachable... How can i solve this to control, how much of my site gets dragged to the left in case of smaller screens? This is especially important for mobile phones...

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• Why structs cannot be assigned directly?

  - by becko

  Suppose I have a fully defined struct with tag MyStruct, and suppose that x, y, ..., z are allowed values for its fields. Why is struct MyStruct q = {x,y,..,z}; allowed, but struct MyStruct q; q = {x,y,...,z}; is not allowed? I find this very annoying. In the second case, where I have previously declared q, I need to assign a value to each field, one by one: q.X = x; q.Y = y; ... q.Z = z; where X, Y, ..., Z are the fields of MyStruct. Is there a reason behind this?

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• Why does SQL Server consider N'????' and N'???' to be equal?

  - by Aidan Ryan

  We are testing our application for Unicode compatibility and have been selecting random characters outside the Latin character set for testing. On both Latin and Japanese-collated systems the following equality is true (U+3422): N'????' = N'???' but the following is not (U+30C1): N'????' = N'???' This was discovered when a test case using the first example (using U+3422) violated a unique index. Do we need to be more selective about the characters we use for testing? Obviously we don't know the semantic meaning of the above comparisons. Would this behavior be obvious to a native speaker?

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• What is the proper way to test is variable is empty in a batch file, If NOT "%1" == "" GOTO SomeLabe

  - by blak3r

  I need to test if a variable is set or not. I've tried several techniques but they seem to fail whenever %1 is surrounded by quotes such as the case when %1 = "c:\some path with spaces". IF NOT %1 GOTO MyLabel // This is invalid syntax IF "%1" == "" GOTO MyLabel // Works unless %1, otherwise fatally kills bat execution IF %1 == GOTO MyLabel // Gives an unexpected GOTO error. According to this site. These are the support IF syntax types. So, I don't see a way to do it. IF [NOT] ERRORLEVEL number command IF [NOT] string1==string2 command IF [NOT] EXIST filename command

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• nginx - redirection doesn't work as expected

  - by Luis

  I have a domain listening on both http and https. I want to redirect all the traffic to https except for two specific locations. It works, but only for mydomain.com, not for www.mydomain.com. Here the config: upstream mydomain_rails { server unix:/home/deploy/mydomain/shared/pids/unicorn.sock; } # blog.mydomain.com server { listen 80; server_name blog.mydomain.com; rewrite ^ http://www.mydomain.com/de/blog permanent; } # blog.mydomain.com.br server { listen 80; server_name blog.mydomain.com.br; rewrite ^ http://www.mydomain.com/br/blog permanent; } # www.mydomain.de server { listen 80; server_name mydomain.de www.mydomain.de; rewrite ^ https://www.mydomain.com/de permanent; } # www.mydomain.com.br server { listen 80; server_name mydomain.com.br www.mydomain.com.br; rewrite ^ https://www.mydomain.com/br permanent; } server { listen 80; server_name mydomain.com; rewrite ^ http://www.mydomain.com$request_uri permanent; } ## www.mydomain.com ## Redirect http to https, keep blogs on plain http server { listen 80; server_name www.mydomain.com; location / { # if ($host ~* ^(www\.mydomain\.com)$ ) { rewrite ^/(.*)$ https://www.mydomain.com/$1 permanent; # } # return 444; } # Matches any request starting with '/br/blog' and proxies to the upstream blog instance location ~* /br/blog { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; if (!-f $request_filename) { rewrite ^/br/blog$ /; rewrite ^/br/blog/(.*)$ /$1; proxy_pass http://mydomain_blog_br; break; } } # Matches any request starting with '/de/blog' and proxies to the upstream blog instance location ~* /de/blog { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; if (!-f $request_filename) { rewrite ^/de/blog$ /; rewrite ^/de/blog/(.*)$ /$1; proxy_pass http://mydomain_blog; break; } } } # www.mydomain.com server { add_header Cache-Control "public, must-revalidate"; server_name mydomain.com www.mydomain.com; listen 443; ssl on; ssl_certificate /etc/ssl/mydomain.com/sslchain.crt; ssl_certificate_key /etc/ssl/mydomain.com/privatekey.key; ## Strict Transport Security (ForceHTTPS), max-age 30d add_header Strict-Transport-Security "max-age=2592000; includeSubdomains"; ## Due SSL encryption, rather to increase the keepalive requests and timeout keepalive_requests 10; keepalive_timeout 60 60; root /home/deploy/mydomain/current/public/; error_log /home/deploy/mydomain/shared/log/nginx.error.log info; access_log /home/deploy/mydomain/shared/log/nginx.access.log main; ## Redirect from non-www to www if ($host = 'mydomain.com' ) { rewrite ^/(.*)$ https://www.mydomain.com/$1 permanent; } ## Caching images for 3 months location ~* \.(ico|css|js|gif|jpe?g|png)\?[0-9]+$ { expires 30d; break; } ## Deny illegal Host headers if ($host !~* ^(mydomain.com|www.mydomain.com)$ ) { return 444; } ## Deny certain User-Agents (case insensitive) if ($http_user_agent ~* (Baiduspider|webalta|Wget|WordPress|youdao|jakarta) ) { return 444; } ## Deny certain Referers (case insensitive) if ($http_referer ~* (dating|diamond|forsale|girl|jewelry|nudit|poker|porn|poweroversoftware|sex|teen|webcam|zippo|zongdo) ) { return 444; } ## Enable maintenance page. The page is copied in during capistrano deployment set $maintenance 0; if (-f $document_root/index.html) { set $maintenance 1; } if ($request_uri ~* (jpg|jpeg|gif|png|js|css)$) { set $maintenance 0; } if ($maintenance) { rewrite ^(.*)$ /index.html last; break; } location /uk { auth_basic "Restricted"; auth_basic_user_file /etc/nginx/htpasswd; root /home/deploy/mydomain/current/public/; try_files $uri @fallback; } # Matches any request starting with '/br/blog' and proxies to the upstream blog instance location ^~ /br/blog { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; if (!-f $request_filename) { rewrite ^/br/blog$ /; rewrite ^/br/blog/(.*)$ /$1; proxy_pass http://mydomain_blog_br; break; } } # Matches any request starting with '/de/blog' and proxies to the upstream blog instance location ^~ /de/blog { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; if (!-f $request_filename) { rewrite ^/de/blog$ /; rewrite ^/de/blog/(.*)$ /$1; proxy_pass http://mydomain_blog; break; }} # Matches any request starting with '/lp' and proxies to the upstream blog instance location /lp { proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; rewrite ^/lp(/?.*)$ /$1; proxy_pass http://mydomain_landingpage; break; } #Matches any request, and looks for static files before reverse proxying to the upstream app server socket location / { root /home/deploy/mydomain/current/public/; try_files $uri @fallback; } # Called after the above pattern, if no static file is found location @fallback { proxy_set_header X-Sendfile-Type X-Accel-Redirect; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header Host $http_host; proxy_redirect off; proxy_pass http://mydomain_rails; } ## All other errors get the generic error page error_page 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 495 496 497 500 501 502 503 504 505 506 507 /500.html; location /500.html { root /home/deploy/mydomain/current/public/; } } I defined the blog upstream. As said, it works properly for mydomain.com, but not for www.mydomain.com. Any idea?

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• Does anyone really understand how HFSC scheduling in Linux/BSD works?

  - by Mecki

  I read the original SIGCOMM '97 PostScript paper about HFSC, it is very technically, but I understand the basic concept. Instead of giving a linear service curve (as with pretty much every other scheduling algorithm), you can specify a convex or concave service curve and thus it is possible to decouple bandwidth and delay. However, even though this paper mentions to kind of scheduling algorithms being used (real-time and link-share), it always only mentions ONE curve per scheduling class (the decoupling is done by specifying this curve, only one curve is needed for that). Now HFSC has been implemented for BSD (OpenBSD, FreeBSD, etc.) using the ALTQ scheduling framework and it has been implemented Linux using the TC scheduling framework (part of iproute2). Both implementations added two additional service curves, that were NOT in the original paper! A real-time service curve and an upper-limit service curve. Again, please note that the original paper mentions two scheduling algorithms (real-time and link-share), but in that paper both work with one single service curve. There never have been two independent service curves for either one as you currently find in BSD and Linux. Even worse, some version of ALTQ seems to add an additional queue priority to HSFC (there is no such thing as priority in the original paper either). I found several BSD HowTo's mentioning this priority setting (even though the man page of the latest ALTQ release knows no such parameter for HSFC, so officially it does not even exist). This all makes the HFSC scheduling even more complex than the algorithm described in the original paper and there are tons of tutorials on the Internet that often contradict each other, one claiming the opposite of the other one. This is probably the main reason why nobody really seems to understand how HFSC scheduling really works. Before I can ask my questions, we need a sample setup of some kind. I'll use a very simple one as seen in the image below: Here are some questions I cannot answer because the tutorials contradict each other: What for do I need a real-time curve at all? Assuming A1, A2, B1, B2 are all 128 kbit/s link-share (no real-time curve for either one), then each of those will get 128 kbit/s if the root has 512 kbit/s to distribute (and A and B are both 256 kbit/s of course), right? Why would I additionally give A1 and B1 a real-time curve with 128 kbit/s? What would this be good for? To give those two a higher priority? According to original paper I can give them a higher priority by using a curve, that's what HFSC is all about after all. By giving both classes a curve of [256kbit/s 20ms 128kbit/s] both have twice the priority than A2 and B2 automatically (still only getting 128 kbit/s on average) Does the real-time bandwidth count towards the link-share bandwidth? E.g. if A1 and B1 both only have 64kbit/s real-time and 64kbit/s link-share bandwidth, does that mean once they are served 64kbit/s via real-time, their link-share requirement is satisfied as well (they might get excess bandwidth, but lets ignore that for a second) or does that mean they get another 64 kbit/s via link-share? So does each class has a bandwidth "requirement" of real-time plus link-share? Or does a class only have a higher requirement than the real-time curve if the link-share curve is higher than the real-time curve (current link-share requirement equals specified link-share requirement minus real-time bandwidth already provided to this class)? Is upper limit curve applied to real-time as well, only to link-share, or maybe to both? Some tutorials say one way, some say the other way. Some even claim upper-limit is the maximum for real-time bandwidth + link-share bandwidth? What is the truth? Assuming A2 and B2 are both 128 kbit/s, does it make any difference if A1 and B1 are 128 kbit/s link-share only, or 64 kbit/s real-time and 128 kbit/s link-share, and if so, what difference? If I use the seperate real-time curve to increase priorities of classes, why would I need "curves" at all? Why is not real-time a flat value and link-share also a flat value? Why are both curves? The need for curves is clear in the original paper, because there is only one attribute of that kind per class. But now, having three attributes (real-time, link-share, and upper-limit) what for do I still need curves on each one? Why would I want the curves shape (not average bandwidth, but their slopes) to be different for real-time and link-share traffic? According to the little documentation available, real-time curve values are totally ignored for inner classes (class A and B), they are only applied to leaf classes (A1, A2, B1, B2). If that is true, why does the ALTQ HFSC sample configuration (search for 3.3 Sample configuration) set real-time curves on inner classes and claims that those set the guaranteed rate of those inner classes? Isn't that completely pointless? (note: pshare sets the link-share curve in ALTQ and grate the real-time curve; you can see this in the paragraph above the sample configuration). Some tutorials say the sum of all real-time curves may not be higher than 80% of the line speed, others say it must not be higher than 70% of the line speed. Which one is right or are they maybe both wrong? One tutorial said you shall forget all the theory. No matter how things really work (schedulers and bandwidth distribution), imagine the three curves according to the following "simplified mind model": real-time is the guaranteed bandwidth that this class will always get. link-share is the bandwidth that this class wants to become fully satisfied, but satisfaction cannot be guaranteed. In case there is excess bandwidth, the class might even get offered more bandwidth than necessary to become satisfied, but it may never use more than upper-limit says. For all this to work, the sum of all real-time bandwidths may not be above xx% of the line speed (see question above, the percentage varies). Question: Is this more or less accurate or a total misunderstanding of HSFC? And if assumption above is really accurate, where is prioritization in that model? E.g. every class might have a real-time bandwidth (guaranteed), a link-share bandwidth (not guaranteed) and an maybe an upper-limit, but still some classes have higher priority needs than other classes. In that case I must still prioritize somehow, even among real-time traffic of those classes. Would I prioritize by the slope of the curves? And if so, which curve? The real-time curve? The link-share curve? The upper-limit curve? All of them? Would I give all of them the same slope or each a different one and how to find out the right slope? I still haven't lost hope that there exists at least a hand full of people in this world that really understood HFSC and are able to answer all these questions accurately. And doing so without contradicting each other in the answers would be really nice ;-)

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• Trouble connecting to vsftpd on ubuntu server

  - by littleK

  I have installed Ubuntu Server 10.10 and I am using it to host a domain that I have. I am trying to set up FTP for the server, but I am running into some problems. I have successfully installed vsFTPd and I have opened up ports 20, 21 on my firewall. In my vsFTPd configuration, I have enabled SSL. Every time I try to connect to my server via FTP, I receive a "Connection Refused" error. I have had a little more success with SSL disabled, however the connection process will time out after the LIST command (but it does accept my authentication). Here is my vsFTPd configuration, the SSL stuff is at the bottom: # Example config file /etc/vsftpd.conf # # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # # Run standalone? vsftpd can run either from an inetd or as a standalone # daemon started from an initscript. listen=YES # # Run standalone with IPv6? # Like the listen parameter, except vsftpd will listen on an IPv6 socket # instead of an IPv4 one. This parameter and the listen parameter are mutually # exclusive. #listen_ipv6=YES # # Allow anonymous FTP? (Disabled by default) anonymous_enable=NO # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) #local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. #anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. #anon_mkdir_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # If enabled, vsftpd will display directory listings with the time # in your local time zone. The default is to display GMT. The # times returned by the MDTM FTP command are also affected by this # option. use_localtime=YES # # Activate logging of uploads/downloads. xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # You may override where the log file goes if you like. The default is shown # below. #xferlog_file=/var/log/vsftpd.log # # If you want, you can have your log file in standard ftpd xferlog format. # Note that the default log file location is /var/log/xferlog in this case. #xferlog_std_format=YES # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. #ascii_upload_enable=YES #ascii_download_enable=YES # # You may fully customise the login banner string: #ftpd_banner=Welcome to blah FTP service. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd.banned_emails # # You may restrict local users to their home directories. See the FAQ for # the possible risks in this before using chroot_local_user or # chroot_list_enable below. #chroot_local_user=YES # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). #chroot_local_user=YES #chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd.chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. #ls_recurse_enable=YES # # Debian customization # # Some of vsftpd's settings don't fit the Debian filesystem layout by # default. These settings are more Debian-friendly. # # This option should be the name of a directory which is empty. Also, the # directory should not be writable by the ftp user. This directory is used # as a secure chroot() jail at times vsftpd does not require filesystem # access. secure_chroot_dir=/var/run/vsftpd/empty # # This string is the name of the PAM service vsftpd will use. pam_service_name=vsftpd # # This option specifies the location of the RSA certificate to use for SSL # encrypted connections. rsa_cert_file=/etc/ssl/private/vsftpd.pem # SSL ssl_enable=YES allow_anon_ssl=NO force_local_data_ssl=YES force_local_logins_ssl=YES ssl_tlsv1=YES ssl_sslv2=YES ssl_sslv3=YES Thanks!

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• Can't Get Virtual Users Setup in VSFTPD -Tried Everything

  - by N.T.

  Have Ubuntu 11.10 with vsftpd installed and working. Can not get virtual users setup at all? Vsftpd will allow main Ubuntu owner account to login, but nothing else? I've followed several tutorials on adding virtual users, but nothing works? I just need to add 2 virtual users and have them be able to upload files to vsftpd Ubuntu computer from other computers on my Lan network. Everywhere I've looked, people just point toward tutorials on adding virtual users, but that just is NOT working. I've been struggling with this for over a week now! PLEASE Help. Thanks. I'll even give a donation if someone can figure this out. here is the vsftpd.conf file I am using. I copied the original, and make a new one, every time I try a tutorial. So far, none have worked. Here is the vsftpd.conf file I'm using. (I hope this helps?) # Example config file /etc/vsftpd.conf # # The default compiled in settings are fairly paranoid. This sample file # loosens things up a bit, to make the ftp daemon more usable. # Please see vsftpd.conf.5 for all compiled in defaults. # # READ THIS: This example file is NOT an exhaustive list of vsftpd options. # Please read the vsftpd.conf.5 manual page to get a full idea of vsftpd's # capabilities. # # # Run standalone? vsftpd can run either from an inetd or as a standalone # daemon started from an initscript. listen=YES # # Run standalone with IPv6? # Like the listen parameter, except vsftpd will listen on an IPv6 socket # instead of an IPv4 one. This parameter and the listen parameter are mutually # exclusive. #listen_ipv6=YES # # Allow anonymous FTP? (Disabled by default) anonymous_enable=YES # # Uncomment this to allow local users to log in. local_enable=YES # # Uncomment this to enable any form of FTP write command. write_enable=YES # # Default umask for local users is 077. You may wish to change this to 022, # if your users expect that (022 is used by most other ftpd's) local_umask=022 # # Uncomment this to allow the anonymous FTP user to upload files. This only # has an effect if the above global write enable is activated. Also, you will # obviously need to create a directory writable by the FTP user. #anon_upload_enable=YES # # Uncomment this if you want the anonymous FTP user to be able to create # new directories. anon_mkdir_write_enable=YES # # Activate directory messages - messages given to remote users when they # go into a certain directory. dirmessage_enable=YES # # If enabled, vsftpd will display directory listings with the time # in your local time zone. The default is to display GMT. The # times returned by the MDTM FTP command are also affected by this # option. use_localtime=YES # # Activate logging of uploads/downloads. xferlog_enable=YES # # Make sure PORT transfer connections originate from port 20 (ftp-data). connect_from_port_20=YES # # If you want, you can arrange for uploaded anonymous files to be owned by # a different user. Note! Using "root" for uploaded files is not # recommended! #chown_uploads=YES #chown_username=whoever # # You may override where the log file goes if you like. The default is shown # below. #xferlog_file=/var/log/vsftpd.log # # If you want, you can have your log file in standard ftpd xferlog format. # Note that the default log file location is /var/log/xferlog in this case. xferlog_std_format=YES # # You may change the default value for timing out an idle session. #idle_session_timeout=600 # # You may change the default value for timing out a data connection. #data_connection_timeout=120 # # It is recommended that you define on your system a unique user which the # ftp server can use as a totally isolated and unprivileged user. #nopriv_user=ftpsecure # # Enable this and the server will recognise asynchronous ABOR requests. Not # recommended for security (the code is non-trivial). Not enabling it, # however, may confuse older FTP clients. #async_abor_enable=YES # # By default the server will pretend to allow ASCII mode but in fact ignore # the request. Turn on the below options to have the server actually do ASCII # mangling on files when in ASCII mode. # Beware that on some FTP servers, ASCII support allows a denial of service # attack (DoS) via the command "SIZE /big/file" in ASCII mode. vsftpd # predicted this attack and has always been safe, reporting the size of the # raw file. # ASCII mangling is a horrible feature of the protocol. #ascii_upload_enable=YES #ascii_download_enable=YES # # You may fully customise the login banner string: ftpd_banner=Welcome to Sage FTP service. # # You may specify a file of disallowed anonymous e-mail addresses. Apparently # useful for combatting certain DoS attacks. #deny_email_enable=YES # (default follows) #banned_email_file=/etc/vsftpd.banned_emails # # You may restrict local users to their home directories. See the FAQ for # the possible risks in this before using chroot_local_user or # chroot_list_enable below. chroot_local_user=YES # # You may specify an explicit list of local users to chroot() to their home # directory. If chroot_local_user is YES, then this list becomes a list of # users to NOT chroot(). #chroot_local_user=YES #chroot_list_enable=YES # (default follows) #chroot_list_file=/etc/vsftpd.chroot_list # # You may activate the "-R" option to the builtin ls. This is disabled by # default to avoid remote users being able to cause excessive I/O on large # sites. However, some broken FTP clients such as "ncftp" and "mirror" assume # the presence of the "-R" option, so there is a strong case for enabling it. #ls_recurse_enable=YES # # Debian customization # # Some of vsftpd's settings don't fit the Debian filesystem layout by # default. These settings are more Debian-friendly. # # This option should be the name of a directory which is empty. Also, the # directory should not be writable by the ftp user. This directory is used # as a secure chroot() jail at times vsftpd does not require filesystem # access. secure_chroot_dir=/var/run/vsftpd/empty # # This string is the name of the PAM service vsftpd will use. pam_service_name=vsftpd local_root=/media/FilesDrive # # This option specifies the location of the RSA certificate to use for SSL # encrypted connections. rsa_cert_file=/etc/ssl/private/vsftpd.pem

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• Does anyone really understand how HFSC scheduling in Linux/BSD works?

  - by Mecki

  I read the original SIGCOMM '97 PostScript paper about HFSC, it is very technically, but I understand the basic concept. Instead of giving a linear service curve (as with pretty much every other scheduling algorithm), you can specify a convex or concave service curve and thus it is possible to decouple bandwidth and delay. However, even though this paper mentions to kind of scheduling algorithms being used (real-time and link-share), it always only mentions ONE curve per scheduling class (the decoupling is done by specifying this curve, only one curve is needed for that). Now HFSC has been implemented for BSD (OpenBSD, FreeBSD, etc.) using the ALTQ scheduling framework and it has been implemented Linux using the TC scheduling framework (part of iproute2). Both implementations added two additional service curves, that were NOT in the original paper! A real-time service curve and an upper-limit service curve. Again, please note that the original paper mentions two scheduling algorithms (real-time and link-share), but in that paper both work with one single service curve. There never have been two independent service curves for either one as you currently find in BSD and Linux. Even worse, some version of ALTQ seems to add an additional queue priority to HSFC (there is no such thing as priority in the original paper either). I found several BSD HowTo's mentioning this priority setting (even though the man page of the latest ALTQ release knows no such parameter for HSFC, so officially it does not even exist). This all makes the HFSC scheduling even more complex than the algorithm described in the original paper and there are tons of tutorials on the Internet that often contradict each other, one claiming the opposite of the other one. This is probably the main reason why nobody really seems to understand how HFSC scheduling really works. Before I can ask my questions, we need a sample setup of some kind. I'll use a very simple one as seen in the image below: Here are some questions I cannot answer because the tutorials contradict each other: What for do I need a real-time curve at all? Assuming A1, A2, B1, B2 are all 128 kbit/s link-share (no real-time curve for either one), then each of those will get 128 kbit/s if the root has 512 kbit/s to distribute (and A and B are both 256 kbit/s of course), right? Why would I additionally give A1 and B1 a real-time curve with 128 kbit/s? What would this be good for? To give those two a higher priority? According to original paper I can give them a higher priority by using a curve, that's what HFSC is all about after all. By giving both classes a curve of [256kbit/s 20ms 128kbit/s] both have twice the priority than A2 and B2 automatically (still only getting 128 kbit/s on average) Does the real-time bandwidth count towards the link-share bandwidth? E.g. if A1 and B1 both only have 64kbit/s real-time and 64kbit/s link-share bandwidth, does that mean once they are served 64kbit/s via real-time, their link-share requirement is satisfied as well (they might get excess bandwidth, but lets ignore that for a second) or does that mean they get another 64 kbit/s via link-share? So does each class has a bandwidth "requirement" of real-time plus link-share? Or does a class only have a higher requirement than the real-time curve if the link-share curve is higher than the real-time curve (current link-share requirement equals specified link-share requirement minus real-time bandwidth already provided to this class)? Is upper limit curve applied to real-time as well, only to link-share, or maybe to both? Some tutorials say one way, some say the other way. Some even claim upper-limit is the maximum for real-time bandwidth + link-share bandwidth? What is the truth? Assuming A2 and B2 are both 128 kbit/s, does it make any difference if A1 and B1 are 128 kbit/s link-share only, or 64 kbit/s real-time and 128 kbit/s link-share, and if so, what difference? If I use the seperate real-time curve to increase priorities of classes, why would I need "curves" at all? Why is not real-time a flat value and link-share also a flat value? Why are both curves? The need for curves is clear in the original paper, because there is only one attribute of that kind per class. But now, having three attributes (real-time, link-share, and upper-limit) what for do I still need curves on each one? Why would I want the curves shape (not average bandwidth, but their slopes) to be different for real-time and link-share traffic? According to the little documentation available, real-time curve values are totally ignored for inner classes (class A and B), they are only applied to leaf classes (A1, A2, B1, B2). If that is true, why does the ALTQ HFSC sample configuration (search for 3.3 Sample configuration) set real-time curves on inner classes and claims that those set the guaranteed rate of those inner classes? Isn't that completely pointless? (note: pshare sets the link-share curve in ALTQ and grate the real-time curve; you can see this in the paragraph above the sample configuration). Some tutorials say the sum of all real-time curves may not be higher than 80% of the line speed, others say it must not be higher than 70% of the line speed. Which one is right or are they maybe both wrong? One tutorial said you shall forget all the theory. No matter how things really work (schedulers and bandwidth distribution), imagine the three curves according to the following "simplified mind model": real-time is the guaranteed bandwidth that this class will always get. link-share is the bandwidth that this class wants to become fully satisfied, but satisfaction cannot be guaranteed. In case there is excess bandwidth, the class might even get offered more bandwidth than necessary to become satisfied, but it may never use more than upper-limit says. For all this to work, the sum of all real-time bandwidths may not be above xx% of the line speed (see question above, the percentage varies). Question: Is this more or less accurate or a total misunderstanding of HSFC? And if assumption above is really accurate, where is prioritization in that model? E.g. every class might have a real-time bandwidth (guaranteed), a link-share bandwidth (not guaranteed) and an maybe an upper-limit, but still some classes have higher priority needs than other classes. In that case I must still prioritize somehow, even among real-time traffic of those classes. Would I prioritize by the slope of the curves? And if so, which curve? The real-time curve? The link-share curve? The upper-limit curve? All of them? Would I give all of them the same slope or each a different one and how to find out the right slope? I still haven't lost hope that there exists at least a hand full of people in this world that really understood HFSC and are able to answer all these questions accurately. And doing so without contradicting each other in the answers would be really nice ;-)

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• Why are my hard drives failing?

  - by WishCow

  I have a small Ubuntu server running at home, with 2 HDDs. There are two software raids (raid1) on the disks, managed by mdadm, which I believe is irrelevant, but mentioning it anyway. Both of the HDDs are Western Digital, and have been used for around 2 years, when one of them started making clicking noises, and died. I figured that maybe it's natural after 2 years, so I bought a new one, and resynced the raid arrays. After about a month, the other drive also died. I didn't get suspicious, since both drives have been bought at the same time, it's not that surprising to see both of them near each other, so I bought another one. So far, 2 old drives failed, and 2 brand new in the system. After one month, one of the new drives died. This is when it started getting suspicious. Since the PC was put together from some really old parts (think AthlonXP), I figured that maybe the motherboard's SATA controller is the culprit. Of course you can't switch parts easily in an old PC like this, so I bought a whole system, new MB, new CPU, new RAM. Took the just failed drive back, since it was under warranty, and got it replaced. So it is up to 2 failed drives from the old ones, and 1 failed drive from the new ones. No problems, for 1 month. After that errors were creeping up again in /var/log/messages, and mdadm was reporting raid array failures. I started tearing my hair out. Everything is new in the system, it's up to the third brand new HDD, it's simply not possible that all of the new drives that I bought were faulty. Let's see what is still common... the cables. Okay, long shot, let's replace the SATA cables. Take HDD back, smile to the guy at the counter and say that I'm really unlucky. He replaces the HDD. I come home, one month passes and one of HDDs fails, again. I'm not joking. Two of the brand new HDDs have failed. Maybe it's a bug in the OS. Let's see what the manufacturer's testing tool says. Download testing tool, burn it to a CD, reboot, leave HDD testing overnight. Test says that the drive is faulty, and I should back up everything, if I still can. I don't know what's happening, but it does not look like a software problem, something is definitely thrashing the HDDs. I should mention now, that the whole system is in a shoebox. Since there are a load of "build your own ikea case" stuff, I thought there shouldn't be any problems throwing the thing in a box, and stuffing it away somewhere. The box is well ventilated, but I thought that just maybe the drives were overheating. There is no other possible answer to this. So I took the HDD back, and got it replaced (for the 3rd time), and bought HDD coolers. And just now, I have heard the sound of doom. click click whizzzzzzzzz. SSH into the box: You have new mail! mail r 1 DegradedArrayEvent on /dev/md0 ... dmesg output: [47128.000051] ata3: lost interrupt (Status 0x50) [47128.000097] end_request: I/O error, dev sda, sector 58588863 [47128.000134] md: super_written gets error=-5, uptodate=0 [48043.976054] ata3: lost interrupt (Status 0x50) [48043.976086] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [48043.976132] ata3.00: cmd c8/00:18:bf:40:52/00:00:00:00:00/e1 tag 0 dma 12288 in [48043.976135] res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) [48043.976208] ata3.00: status: { DRDY } [48043.976241] ata3: soft resetting link [48044.148446] ata3.00: configured for UDMA/133 [48044.148457] ata3.00: device reported invalid CHS sector 0 [48044.148477] ata3: EH complete Recap: No possibility of overheating 6 drives have failed, 4 of those have been brand new. I'm not sure now that the original two have been faulty, or suffered the same thing that the new ones. There is nothing common in the system, apart from the OS which is Ubuntu Karmic now (started with Jaunty). New MB, new CPU, new RAM, new SATA cables. No, the little holes on the HDD are not covered I'm crying. Really. I don't have the face to return to the store now, it's not possible for 4 drives to fail under 4 months. A few ideas that I have been thinking: Is it possible that I fuck up something when I partition and resync the drives? Can it be so bad that it physicaly wrecks the drive? (since the vendor supplied tool says that the drive is damaged) I do the partitoning with fdisk, and use the same block size for the raid1 partitions (I check the exact block sizes with fdisk -lu) Is it possible that the linux kernel or mdadm, or something is not compatible with this exact brand of HDDs, and thrashes them? Is it possible that it may be the shoebox? Try placing it somewhere else? It's under a shelf now, so humidity is not a problem either. Is it possible that a normal PC case will solve my problem (I'm going to shoot myself then)? I will get a picture tomorrow. Am I just simply cursed? Any help or speculation is greatly appreciated. Edit: The power strip is guarded against overvoltage. Edit2: I have moved inbetween these 4 months, so the possibility of the cause being "dirty" electricity in both places, is very low. Edit3: I have checked the voltages in the BIOS (couldn't borrow a multimeter), and they are all seem correct, the biggest discrepancy is in the 12V, because it's supplying 11.3. Should I be worried about that? Edit4: I put my desktop PC's PSU into the server. The BIOS reported much more accurate voltage readings, and also it has successfully rebuilt the raid1 array, which took some 3-4 hours, so I feel a little positive now. Will get a new PSU tomorrow to test with that. Also, attaching the picture about the box: (disregard the 3rd drive)

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