Archive for 'Kernel'

Fork Bomb

Fork Bomb, Pretty much clear by name, anything which uses the "fork" operation and explodes like a bomb is known as Fork Bomb. It's a form of DOS (Denial Of Service) attack, using fork operation, in which a running process can create another running process. Fork bomb is sometimes referred as wabbit. In other words, Fork Bomb is a particular species of wabbit that can be written in one line of code.

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News: Kernel 3.4 Released

Linus torvalds has finally released Kernel 3.4.

"Sure, I always wish for the -rc's to calm down more quickly than they ever seem to do, but I think on the whole we didn't have any big disruptive events, which is just how I like it. Let's hope the 3.5 merge window is a calm one too," he wrote in his announcement.

The new Kernel includes substantial updates to the BTRFS file system and new support for graphics hardware from Nvidia, Intel and AMD, including AMD's Trinity and Radeon HD 7000-series, NVIDIA's Kepler stack. The release also includes the Yama security module, support for the x32 ABI, asymmetric multiprocessing support, the dm-verity device mapper target, and more.

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Zombie Process

It's a pretty much common question asked in most of the interviews related to Linux, and most of the time people got it confused with Orphan Process. But these two are totally different from each other. A Zombie Process is nearly the same thing which we see in lot of horror movies. Like the dead people which don't have any life force left, Zombie processes are the dead processes sitting in the process table and doing nothing.

To explain this in much better way, "Zombie process or defunct process is a process that have completed the execution, have released all the resources (CPU, memory) but still had an entry in the process table."

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Orphan Process

It's a pretty much common question asked in most of the interviews related to Linux, and most of the time people got it confused with Zombie Process. But these two are totally different from each other. An Orphan Process is nearly the same thing which we see in real world. Orphan means someone whose parents are dead. The same way Orphan process is a process, whose parents are dead, that means parents are either terminated, killed or exited but the child process is still alive.

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Upgrading the system is one of the very common tasks a Linux Administrator usually do. One can easily update the system with Yum or apt-get commands but the main problem which everyone faces is to reboot the system after a kernel upgrade. This comes out to be a big problem for small organizations, where one don't have High Availability setup and can't afford to reboot the system because of the upgrade.

Since reboots are disruptive, many system administrators delay the update of there patches and makes their system vulnerable to attacks. Below given is the frequency of reboots needed in the last year for respective flavors of linux.

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