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today's howtos

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HowTos
  • 20 ps Command Examples to Monitor Linux Processes
  • Where are the config files in GNOME

    When you install a new distribution, you end up with a generic desktop. GNOME, when you choose standard Ubuntu. This works but the great joy of running Linux is to have it all your way. So, get your own tweaks in there. How can you change your desktop? In GNOME, you have tools and files to change it. In this post you will learn where to find the files and use the tools.

  • Driftnet command tutorial and examples

    Sniffing consists of intercepting packets through a network to get their content. When we share a network, intercepting the traffic going through it is pretty easy with a sniffer, that’s why protocol encryption such as https is so important, when traffic is unencrypted even credentials go in plain text and can be intercepted by attackers.
    This tutorial focuses on intercepting media, specifically images using the Driftnet sniffer, as you will see it will be only possible to capture images going through unencrypted protocols like http rather than https, and even unprotected images within sites protected with SSL (insecure elements).

  • Top 48 Linux Interview Questions & Answers

    Are you preparing for a Linux interview? We have prepared some of the commonly asked Linux interview questions and their answers.

    If you are a beginner (with some knowledge of Linux or having certification) or with professional Linux administration experience, then following Q & A help for your interview preparation.

  • Configuring a Cisco switch from a Linux Terminal with Minicom

    As much as I like playing in the terminal, the jury is still out as to how much I like working with Cisco. To be as objective as possible, I need to tell myself that: 1, I am not familiar with the command set or how they like to do things so I must be open minded; 2, Relax, the command line is a happy place to be and 3, this is new territory, don?t get frustrated, just write it down and enjoy the learning process. Also, my brother in-law, whose career is in network administration just loves this Cisco business so it turned out to be quite educational. The scope of this article is not how to set up a router, just, this is how I was able to get going with it.

    The specific Cisco switch I configured was a Catalyst 3560 series PoE-48. I am sure these direction will work with other similar devices. Since I am an openSUSE user, the directions are tailored as such.

More in Tux Machines

Ubuntu-based Linux Lite 5.0 is here with massive changes

Ubuntu-based Linux Lite 5.0 is released with some massive changes across the operating system and it is immediately available for download. Read more

Python Is All You'll Ever Need In This Linux Distro

Choosing the perfect Linux distribution that satisfies your personal needs and likings can be an impossible task, and oftentimes requires a hint of Stockholm syndrome as compromise. In extreme cases, you might end up just rolling your own distro. But while frustration is always a great incentive for change, for [Josh Moore] it was rather curiosity and playful interest that led him to create snakeware, a Linux distribution where the entire user space not only runs on Python, but is Python. Imagine you would boot your Linux system, and instead of the shell of your choice, you would be greeted by an interactive Python interpreter, and everything you do on the system will be within the realms of that interpreter — that’s the gist of snakeware. Now, this might sound rather limiting at first, but keep in mind we’re talking about Python here, a language known for its versatility, with an abundance of packages that get things done quick and easy, which is exactly what [Josh] is aiming for. To get an idea of that, snakeware also includes snakewm, a graphical user interface written with pygame that bundles a couple of simple applications as demonstration, including a terminal to execute Python one-liners. Read more

Android Leftovers

Torvalds Blasts "Beyond Stupid" Flushing L1d On Context Switches - Reverts Code For Now

As part of the initial set of changes merged today for Linux 5.8 was the x86/mm material that included the controversial feature of opt-in flushing of the L1 data cache on context switching. Linus Torvalds ended up deciding to revert this functionality as for now at least he views it as crazy. While this feature is opt-in via new prctl options and not enabled by default and done in the name of helping those concerned about snoop assisted data sampling vulnerabilities or cache leakage via side channels and yet to be uncovered CPU vulnerabilities, for the time being Linux creator Linus Torvalds is not convinced. Read more Original:

  • Re: [GIT PULL] x86/mm changes for v5.8
    >  - Provide an opt-in (prctl driven) mechanism to flush the L1D cache on context switch.
    >    The goal is to allow tasks that are paranoid due to the recent snoop assisted data
    >    sampling vulnerabilites, to flush their L1D on being switched out.
    
    Am I mis-reading this?
    
    Because it looks to me like this basically exports cache flushing
    instructions to user space, and gives processes a way to just say
    "slow down anybody else I schedule with too".
    
    I don't see a way for a system admin to say "this is stupid, don't do it".
    
    In other words, from what I can tell, this takes the crazy "Intel
    ships buggy CPU's and it causes problems for virtualization" code
    (which I didn't much care about), and turns it into "anybody can opt
    in to this disease, and now it affects even people and CPU's that
    don't need it and configurations where it's completely pointless".
    
    To make matters worse, it has that SW flushing fallback that isn't
    even architectural from what I remember of the last time it was
    discussed, but most certainly will waste a lot of time going through
    the motions that may or may not flush the L1D after all.
    
    I don't want some application to go "Oh, I'm _soo_ special and pretty
    and such a delicate flower, that I want to flush the L1D on every task
    switch, regardless of what CPU I am on, and regardless of whether
    there are errata or not".
    
    Because that app isn't just slowing down itself, it's slowing down others too.
    
    I have a hard time following whether this might all end up being
    predicated on the STIBP static branch conditionals and might thus at
    least be limited only to CPU's that have the problem in the first
    place.
    
    But I ended up unpulling it because I can't figure that out, and the
    explanations in the commits don't clarify (and do imply that it's
    regardless of any other errata, since it's for "undiscovered future
    errata").
    
    Because I don't want a random "I can make the kernel do stupid things"
    flag for people to opt into. I think it needs a double opt-in.
    
    At a _minimum_, SMT being enabled should disable this kind of crazy
    pseudo-security entirely, since it is completely pointless in that
    situation. Scheduling simply isn't a synchronization point with SMT
    on, so saying "sure, I'll flush the L1 at context switch" is beyond
    stupid.
    
    I do not want the kernel to do things that seem to be "beyond stupid".
    
    Because I really think this is just PR and pseudo-security, and I
    think there's a real cost in making people think "oh, I'm so special
    that I should enable this".
    
    I'm more than happy to be educated on why I'm wrong, but for now I'm
    unpulling it for lack of data.
    
    Maybe it never happens on SMT because of all those subtle static
    branch rules, but I'd really like to that to be explained.
    
                        Linus