Verifying file integrity.

This post is all about the checksum, i have a read a lot about this topic in college days.Never had really hand experience how it can be used in daily life.

we download a lot of files from internet, copy files (movies ,songs .text and lot of other things) from friends place to our pen drive.Sometimes it may happen that , the file hasn't copied/downloaded properly :( .We realize this thing when we try to use the copied/downloaded content .
This is where our checksum comes into picture.Just to verify that the files are copied correctly Just use the "sum" Command in linux.
Just as an example:

Remote Host:
------------
$ sum vlc0.8.5test3win32.exe
20311 8132

After copying to pendrive or something.
---------------------------------------
[bash$pradeep@localhost]sum vlc0.8.5test3win32.exe
20311 8132

When you download a file , the checksum apart from verifying the file integrity helps us make sure that , the file we downloaded is not tampered by middle man.And it is virus free.

You can see many sites ,that provide some material to download has MD5/SHA1 signatures for the content they have kept for download.You can use this and verify that the piece of downloaded content is same as what is kept on the site and it is virus free.Sometimes it happens that , even though the content you downloaded works fine.But it is infected with virus.

This tool is very useful ("sum") to me in office .Very often i provide patches of our product to people .And provide them them the sum command output, to check whether the patch they had downloaded is fine. So that they wont come to me again saying , your patch is not proper . :)

All about autorun.inf

It is been long i thought of blogging about this topic, finally i am able to do this now.

What is this ?

I guess very few might have knowledge about this file, this is the file you most often see in the cd's(compact disc) home directory.You might have seen, when you insert cd into the drive , it gets auto started with some program,or it will open some default file , basically some sort of task is performed when cd is inserted.You might have wondered how this happened.Its all the magic of this autorun.inf file.

This is a some sort of script file ,which tells windows what to do upon the opening of folder in which it is located.which is type of initialization file ,which tells what actions to perform when the folder is opened.

We can do lot of things with it.You can make the windows set some background , when folder opens , and many more.This windows oses feature has made the viruses a way to spread themselves .Most often it is used by viruses ;).

Sometimes you might have seen , you try to open a drive/folder.It fails to
open.Its because of this autorun.inf.

How to locate and remove it ?
This file is always hidden in the folder.you can see this file in the root
folder of usb stick.You can use Dir /a to find that file from command line.Viruses make an entry in it , to run when the folder is opened.Just open that file from command line and see some malicious code has made an entry in it.If so you can safely delete this file.