Language Selection

English French German Italian Portuguese Spanish

today's leftovers

Filed under
Misc
  • Fedora 34 Looking To Tweak Default zRAM Configuration

    ast year with Fedora 33 zRAM was switched on by default. The setup was that using a compressed zRAM drive for swap space leads to better performance and in turn a better user experience. Some spins of Fedora have been using swap-on-zRAM by default going back many releases while since F33 it's been used for all spins. Now with Fedora 34 the configuration is being further refined.

    With Fedora 33, the zRAM configuration was limited to a 0.5 fraction of RAM or 4GB, whichever is smaller, while for Fedora 34 the zram-fraction will be 1.0 and the maximum zRAM size set to 8GiB.

    [...]

    This in particular should help the Fedora 34 experience for systems with minimal amounts of RAM.

  • A Zoological guide to kernel data structures

    Recently I was working on a BPF feature which aimed to provide a mechanism to display any kernel data structure for debugging purposes. As part of that effort, I wondered what the limits are. How big is the biggest kernel data structure? What's the typical kernel data structure size?

    [...]

    A lot of the articles we read about the Linux kernel talk about size, but in the context of numbers of lines of code, files, commits and so on. These are interesting metrics, but here we're going to focus on data structures, and we're going to use two fantastic tools in our investigation...

    [...]

    Zooming out again, what's interesting about the pattern of structure size frequency is that it seems to reflect the inherent cost of large data structures; they pay a tax in terms of memory utilization, so while we see many small data structures, and the falloff as we approach larger sizes is considerable.

    This pattern is observed elsewhere, bringing us back to the zoological title of this post. If we look at the frequency of animal species grouped by their size, we see a similar pattern of exponential decay as we move from smaller to larger species sizes. For more info see https://en.wikipedia.org/wiki/Body_size_and_species_richness. If metabolic cost is a factor in determining this pattern in nature, we can observe a similar "metabolic cost" in memory utilization for larger data structures in the Linux kernel also. A related observation - that smaller species (such as insects) exist in much larger numbers than larger species in nature - would be interesting to investigate for the Linux kernel, but that would require observing data structure utilization in running systems, which is a job for another day!

  • Destination Linux 208: Mythbusting Linux Misconceptions

    This week on Destination Linux, we’re going to bust some myths as we talk about some Linux Misconceptions. Then we’re going to review some information on openSUSE and review the interesting facts revealed in it’s most recent community poll. We’ve also got our famous tips, tricks and software picks. All of this and so much more this week on Destination Linux.

  • Software Is Eating Every Layer Of The Datacenter

    Software may be eating the world, as Marc Andreessen correctly asserted nearly a decade ago, but some parts of the world are crunchier than others and take some time for the hardware to be smashed open and for software to flow in and out of it.

    We have been watching with great interest since around 2008 or so as merchant silicon came to switching and routing and how control of hardware was broken free from control of software, much as the X86 platform emerged as a common computing substrate a decade earlier. Initial attempts at creating portable and compatible operating systems for switching and routing had their issues, but a second wave network operating systems are emerging and, we think, will eventually become the way that networking is done in the datacenter, breaking the hegemony of proprietary operating systems as happened in compute in the past. A decade of open systems Unix platforms on dozens of chip architectures really just helped create the conditions that allowed Linux on X86 to become the dominate platform in the datacenter. And, ironically, now that Linux dominates, now different hardware, now including various kinds of accelerators as well as new CPUs, can now be slipped easily in and out of compute in the datacenter without huge disruption to Linux.

    The same thing is starting to happen with network operating systems, including the SONiC/SAI effort championed by Microsoft, the ArcOS platform from Arrcus, whatever Nvidia ultimately cooks up through the combination of Mellanox Technology and Cumulus Networks. Cisco Systems is now a supplier of merchant silicon with its Silicon One router chips, which debuted in December 2019 and which were augmented with switch chips last October. Every switch ASIC vendor has created some form of programmability for its packet processing engines, with P4 as advanced by Barefoot Networks (now part of Intel) being the darling but by no means the only way to achieve programmability, and now we see the industry rallying behind the concept of the Data Processing Unit, or DPU, which among other things manages network and storage virtualization and increasingly runs the compute hypervisor, offloading these functions from the CPUs in host systems.

  • The Fridge: Ubuntu Weekly Newsletter Issue 665

    Welcome to the Ubuntu Weekly Newsletter, Issue 665 for the week of January 3 – 9, 2021.

  • The 2020 CC Global Summit Keynotes Are Here!

    In addition to the 170+ sessions hosted at last year’s virtual event, we hosted three keynotes that helped us think through how to connect the events of 2020 with our work—and find a path forward in hope and optimism. We’re excited to share these recordings of the keynotes with you today!

  • Wikipedia’s future lies in poorer countries

    The number of people actively editing Wikipedia articles in English, its most-used language, peaked in 2007 at 53,000, before starting a decade-long decline. That trend spawned fears that the site would atrophy into irrelevance. Fortunately for Wikipedia’s millions of readers, the bleeding has stopped: since 2015 there have been around 32,000 active English-language editors. This stabilising trend is similar for other languages of European origin.

    Meanwhile, as more people in poorer countries gain [Internet] access, Wikipedia is becoming a truly global resource. The encyclopedia’s sub-sites are organised by language, not by nationality. However, you can estimate the typical wealth of speakers of each language by averaging the GDP per head of the countries they live in, weighted by the number of speakers in each country. (For Portuguese, this would be 80% Brazil, 5% Portugal and 15% other countries; for Icelandic, it is almost entirely Iceland.)

More in Tux Machines

JingOS arrives as China’s first Linux Distro, offers iPadOS-like features and functions

JingOS was built with the idea of improving the functionality and productivity of a tablet overall. So, the team behind the new operating system took inspiration from the Cupertino based giant’s iPadOS platform to offer a simple/clean, yet productive and efficient UI design that can ensure that your tablets are a mini computer that one can work on, on the go. JingOS is not only a tablet OS but a full function Linux distro. Read more

9to5Linux Weekly Roundup: January 17th, 2021

Thank you everyone for following 9to5Linux on social media; we’re nearing 6K followers on Twitter and that’s only possible thanks to you guys! Thank you again to everyone who donated so far to help me keep this website alive for as long as possible. This week has been quite interesting despite the fact that no major releases were planned. We saw the launch of a new PinePhone Linux phone edition, the release of the Flatpak 1.10 and Wine 6.0 software, and much more. Read more

Security Leftovers

  • New coalition aims to combat growing wave of ransomware attacks [iophk: Windows TCO]

    The California-based nonprofit aims to produce recommendations that will help governments and the private sector tackle the scourge of ransomware attacks.

    [Attackers] have increasingly used these types of attacks -- which involve accessing and encrypting the victim’s network and demanding payment to allow access again -- to hit major targets, with city governments in Atlanta, Baltimore and New Orleans severely impaired by ransomware attacks over the past two years.

    More recently, hospitals have become a target during the COVID-19 pandemic, with cyber criminals seeing vulnerable hospitals as easy targets more likely to pay a quick ransom as health care systems struggle to keep up with coronavirus cases. In some instances, the cyberattacks have been blamed for deaths due to delayed care.

  • This tiny shortcut can completely crash your Windows 10 device

    A zero-day exploit has been discovered that can crash your Windows 10 device – and, even more worrying, can be delivered inside a seemingly harmless shortcut file. The vulnerability can corrupt any NTFS-formatted hard drive and even be exploited by standard and low privilege user accounts.

    Security researcher Jonas Lykkegaard referenced the vulnerability on Twitter last week and had previously drawn attention to the issue on two previous occasions last year. Despite this, the NTFS vulnerability remains unpatched.

    There are various ways to trigger the vulnerability that involve trying to access the $i30 NTFS attribute on a folder in a particular way. One such exploit involves the creation of a Windows shortcut file that has its icon location set to C:\:$i30:$bitmap. Bleeping Computer found that this triggered the vulnerability even if users did not attempt to click on the file in question. Windows Explorer’s attempts to access the icon path in the background would be enough to corrupt the NTFS hard drive.

  • This Easily-Exploitable Windows 10 NTFS Bug Can Instantly Corrupt Your Hard Drives

    Jonas says that this Windows 10 bug isn't new and has been around since the release of Windows 10 April 2018 Update, and remains exploitable on the latest versions, as well. BleepingComputer shared that the problematic command includes $i30 string, a Windows NTFS Index Attribute associated with directories.

    [...]

    After running the command, Windows 10 will start displaying prompts to restart the device and repair the corrupted drive. Apparently, the issue also impacts some Windows XP versions and similar NTFS bugs have been known for years but are yet to be addressed by the Windows maker.

  • Nidhi Razdan, Phishing, And Three Hard Lessons

    Nidhi Razdan, a career journalist, became a victim of an elaborate phishing attack that made her quit her 21-year-old job and part with many of her personal details.

  • Windows Finger command abused by phishing to download malware

    Attackers are using the normally harmless Windows Finger command to download and install a malicious backdoor on victims' devices. The 'Finger' command is a utility that originated in Linux/Unix operating systems that allows a local user to retrieve a list of users on a remote machine or information about a particular remote user. In addition to Linux, Windows includes a finger.exe command that performs the same functionality.

Security Auditing Tools For Ubuntu

Malware, where aren’t thou found? Well, even our wonderful Ubuntu can be infected. So what can we do about it? Hope and pray we keep our system safe and better yet, audit our systems regularly for malwares and rootkits. There are 4 system auditors for Ubuntu that we will review - lynis, rkhunter, chkrootkit, and clamav. [...] Oddly enough, there aren’t many tools to scan for malware out there for Linux. Why? I’m not sure. However, these 4 tools are more than enough to detect malwares, rootkits, and viruses. Read more Also: Windows Finger command abused by phishing to download malware