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Closed 10 years ago.
I searched for working of an anti virus?
but could not got satisfactory answer .. except that
1) it goes through dictionary based approach in which any suspicious code matched with some entry in database is reported for an action to the use
or
2) it follows the harmful activities of a process eg.then terminates it if file deletes some critical files for the stability of the system
*when a pen drive is inserted to a computer then exactly how an antivirus detects a virus or a file infected by virus ? and at which layer antivirus scans the files ? *
Thanks in advance :D
In general, antivirus software scans files when they are written to disk.
Here is an example that compares two approaches to reading an email attachment:
If a user views an email and clicks to open an attachment, there will usually be a prompt to save the attachment, or to just open it right away without saving it. This is how many users get viruses on their machines. If they click to open the attachment without saving it, the antivirus doesn't have an opportunity to scan the file.
On the other hand, if the user saves the file first, then the
antivirus can scan it.
Some security software performs other checks besides just file saving. But this is basically how antivirus works.
In the case of the pen drive, the antivirus may not scan the files (unless the user directs it to do so), because the files have already been saved. However, some antivirus software will react to this event (attaching a new device) and catch the virus.
Related
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Closed 9 years ago.
Because there could possibly be so many windows open at different spots. Some windows are active some are not, how does the OS delegate the mouse event based on where the application window is? I'm a little lost.
The OS (or a dedicated program that comes as part of it) keeps track of the windows (their locations, sizes, depth w.r.t. other windows, state of "activeness") and the cursor position and can figure out which window is right below the mouse pointer. And that's all there is.
System call is made by software to OS, so OS returns response to software not to mouse, If windows are from same software it still applies. Softwares are managed in table in background.
id, path, request
1, c:\word.exe, 2
2, c:\word.exe, 3
so basicaly OS knows from where the request was made. "Operating System Concepts Essentials" covers questions like these.
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Closed 10 years ago.
I wanted to get some clear "real world" info on what kinda backend is required when running a newsstand app.
The app i intend to make should have the following features.
Issues, each issue with a bunch of articles.
An Issue can be "Free" or "Paid" depending on how its "Pushed"
Auto subscriptions
Push notifications
Data collection - getting some stats from the users.
I currently have no server, in this case, whats the server requirement? All i want is a print magazine kinda app, essentially a PDF. Is it possible to let Apple host the data with current issues.
Another question besides the server is, how are these Issues packaged? Forexample if its a text file or a pdf?
Any direction would be great
Taking your points in turn:
I currently have no server, in this case, whats the server requirement? All i want is a print magazine kinda app, essentially a PDF. Is it possible to let Apple host the data with current issues.
Apple does not provide hosting for newsstand content. You need your own server for this. It needs to hold the issues, and usually also respond to requests from your app about available and new issues.
Another question besides the server is, how are these Issues packaged? Forexample if its a text file or a pdf?
They are packaged however you like - you tell the newsstand framework which asset(s) need downloading for a particular issue (based on the response youve given about the issues above) Typically you'd bundle it all together in a zip file and unpack / process it on the device when the download is completed.
It's important to note that newsstand is not much more than a framework to enable backgrounded downloads and notifications, and to maintain a library of assets in your app's caches directory. The content and its display is entirely up to you, the developer.
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Closed 10 years ago.
I was looking through google for a software that would meet my needs and found very short, 12 lines with regular expressions (whatever this is), perl code. The person who posted it is claiming to say, to others, that this code does what I want. But since Im not programmer I don't know what to do with it? I might need to paste it into txt file and save it somehow but the code is supposted to use text files. I don't think I would be able to use text files inside another text. My purpose is to filter email addresses from giant messy txt files. Im trying to use this code (but don't know what to do with it): http://linuxconfig.org/extract-email-address-from-a-text-file
You run the program using perl. Instructions for getting perl are provided at: http://www.perl.org/get.html
Then see learn.perl.org for getting started instructions.
Assuming you are using a UNIX-like operating system (i.e. not Windows) the process is:
Put the code in a text file on a system with perl installed
Make it executable (chmod +x filename)
Run it as per the example under "Execution".
Save the content to a file named e.g.
extract.pl
And install per for windows: http://strawberryperl.com/ ; if you are on Unix, well done.
now you can execute the script by opening a console window, changing in the directory where the script is saved and execute
perl extract.pl < yourtextfile.txt
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Closed 11 years ago.
Let's say you need to rewrite a university website, the key feature being the ability to give certain users permission to edit certain parts of the site, and the editing would all have to happen in-browser.
I've been searching around, looking at various CMSs that fit the build here, but I'm wondering what your opinions are.
So, if you were to have to rewrite the system i described above, what CMS would you use? If none fit the build, would you suggest rolling your own instead?
My immediate reaction was: WordPress. It's currently at 3.1.2 and is a far cry from the simple blogging software it started as. Starting with V3 it took a strong step toward being a CMS. Its multisite feature supports multiple-sub-websites (e.g. for different departments), and it has reasonable support for role-based ACL. It has built-in WYSIWYG editing, and something over 12,000 extensions to had various types of functionality.
Something to remember is that many college sites are being supported by "whoever hasn't graduated yet." This makes long-term maintainability of the core code an important consideration. This is another check in the Win column for WP.
One word of warning: only consider themes that are strongly oriented toward V3+. Also note that themes are more than just a paint job -- they can add major chunks of task-specific functionality. Once you commit to using a theme you may find it challenging to switch to another without a certain amount of local customization.
WordPress is not perfect, but it may be everything you need. Check it out. It's free, extensible, and you clan play with it over a weekend and get a feel for how well it solves your problem.
Your stated requirement is surely available in almost any CMS you care to mention.
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Closed 12 years ago.
in Dropbox if a file is already present at their servers, the file is not uploaded. It syncs instantly..
Now, this check is done on a few things i think, probably the file size, file name, and of course the CRC (md5 hash or something...)
I was thinking.. if I know the file name, its size and its CRC, is it possible to create a fake file that produces that particular CRC (reverse hashing) so that dropbox actually syncs the true file?
It's just an experiment, it could be done for example with linux distribution images..
any idea on the topic?
Curious to see that someone is thinking about this also.
Problem 1:
Even if you were able to create a fake file with the same CRC, the client would just not upload the file again (but you would still keep your fake file in your computer).
You would just receive the desired file on the other computers associated with your dropbox account.
Problem 2:
Creating that fake file seems a bit impossible from my point of view. CRC's were developed to check file integrity so it seems a bit complex to create a file with the same CRC without a massive brute-force.
MY SUGGESTION:
I believe it would be much easier to modify the CRC routines in the Dropbox source code (if you have it) and allow the injection of your fake CRC values.
Final comment: I might not be very creative but I do not find a legal reason for the use of this scheme. Dropbox already provides a Public folder to share files (but traffic limits apply).