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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘Linux’ Category

Chromium/Chrome on opensuse Tumbleweed ARM notes

Posted by jpluimers on 2020/07/27

Somehow Firefox is available on ARM by default, but the crash recovery isn’t that awesome.

On my list of things to try is Chrome or Chromium. These links should help me find out if this is possible at all:

On Firefox crash recovery:

–jeroen

Posted in *nix, Chrome, Google, Linux, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

Eject USB drives / eject command – Unix & Linux Stack Exchange

Posted by jpluimers on 2020/07/20

I always thought than an umount /dev/sdX# for all partitions on /dev/sdX was enough for USB devices to be ejected, but there are three commands that (on most systems) actually power down USB drives (or USB to SD card adapters):

  • udisks --detach /dev/sdX (requires the udisks package which is obsolete)
  • eject /dev/sdX seems not to be enough on some systems; it is part of the util-linux package
  • udisksctl power-off -b /dev/sdX is equivalent to the udisks command; it is part of the udisks2 package.

These will ensure that the disk is not part of the fdisk --list output any more.

The opposite of these is sg_start, which is from the sg3_utils package.

Source: [WayBack] Eject USB drives / eject command – Unix & Linux Stack Exchange

On MacOS, you can use  diskutil eject /Volumes/<LABEL> (source: answer by efesaid on [WayBack] Eject USB drives / eject command – Unix & Linux Stack Exchange)

–jeroen

Posted in *nix, *nix-tools, Linux, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

openSUSE forums tips

Posted by jpluimers on 2020/07/17

A few tips from posting to the openSUSE forums, learned from banging my head to the wall too often.

  • They are at https://forums.opensuse.org/forum.php
  • The forum software can be very slow at times taking ~tens of seconds for loading a post:
    • loading multiple posts or pages of posts you are interested in multiple tabs speeds up your reading a lot
  • Answers on the post often are along the form “has been answered before” without pointing to the actual link, even if the post is marked with a read icon, for instance in [WayBack] No option to “keep me logged in on this device” with Novell/openSUSE login?
  • Your email is not your username, so do not use it during logon: [WayBack] Lousy log in
  • The search function in the forum is horrible.
  • The forum software is proprietary (vBulletin – Wikipedia) and has a
  • When writing/replying to posts:
    1. Edit your answer off-line, because
      • you will automatically be logged off even if the forum indicates you are still logged on (there is no count down of the activity timer), see
      • when you re-logon, your carefully edited text has been lost from the cache
    2. Never use formatting, either auto-introduced, or introduced while pasting, avoid BB-code
      1. Reasoning
      2. Though the forum supports BB code, NNTP news readers do not, and the added formatting gives quite a mess
      3. Use the text (“Source mode”) version of the editor, by first clicking the left most button: “Source”

        • After this, the third and fourth button get greyed out:
      4. Remove formatting button is the second from the left (in both text and WYSIWIG mode): “Remove format”
      5. If you are in WYSIWIG mode, then always paste using the third button from the left that strips formatting: “Paste as plain text”
      6. NEVER EVER paste with formatting with the fourth button from the left: “Paste from Word”

–jeroen

Posted in *nix, Linux, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

GitHub – gamelinux/passivedns: A network sniffer that logs all DNS server replies for use in a passive DNS setup

Posted by jpluimers on 2020/07/15

Cool tool: [WayBackGitHub – gamelinux/passivedns: A network sniffer that logs all DNS server replies for use in a passive DNS setup via [WayBack] How to log all my DNS queries? – Unix & Linux Stack Exchange (thanks mxmlnkn!).

It listens on port 53 for DNS requests then logs them to a file on regular intervals aggregating similar requests.

Usage is simple:

# passivedns -i ens32 -l /var/log/passivedns.log

[*] PassiveDNS 1.2.0
[*] By Edward Bjarte Fjellskål <edward.fjellskaal@gmail.com>
[*] Using libpcap version 1.8.1
[*] Using ldns version 1.7.0
[*] Device: ens32
[*] Sniffing...

There are more options in the docs (it can do a lot including export to databases for querying), but this simple one allows you to just grep over abusive hosts like [WayBack] Nice when someone in Dallas using 69.162.119.78 is querying your DNS infrastructure for many permutations of domains… · GitHub

Originating in 2013 ([WayBack] PassiveDNS version 1.0 | GameLinux), it still is being maintained.

It uses libpcap for sniffing and I ran it on separate machine hooked to a vSwitch configured in promiscuous mode so it sees all network traffic from that particular network segment.

There is a not fully up-to-date package available for various OpenSuSE releases (including Tumbleweed) [WayBack] Install package home:mnhauke:security / passivedns. It is x86_64 only, so if you want to run it on ARM, or want a more recent version then you need to build it yourself, for instance by using this as a template: [WayBack] Show home:mnhauke:security / passivedns – openSUSE Build Service.

Next tool on my list to try: [WayBack] dnstracer(8) – Linux man page.

–jeroen

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Posted in *nix, *nix-tools, Development, DevOps, Infrastructure, Linux, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

Marrying U-Boot, uEFI and grub2 – Alexander Graf – openSUSE…

Posted by jpluimers on 2020/07/13

A very insightful talk: “Marrying U-Boot, uEFI and grub2 – Alexander Graf – openSUSE…”

Booting is hard. Booting in the ARM world is even harder. State of the art are a dozen different boot loaders that may or may not deserve that name. Each gets configured differently and each has its own pros and cons.

As a distribution this is a nightmare. Configuring each and every one of them complicates code that really should be very simple.

To solve the problem, we can just add another layer of abstraction (grub2) on top of another layer of abstraction (uEFI) on top of another layer of abstraction (u-boot). Follow me on a journey on how all those layers can make life easier for the distribution and how much fun uEFI really is.

After this talk, you will know how ARM systems boot, what uEFI really means, how uEFI binaries interact with firmware and how we are going to move to uEFI based boot on openSUSE for ARM.

Usually known as agraf on-line, [WayBack] Alexander Graf – Open IoT & ELC 2017 is an impressive guy:

Alexander Graf

SUSE
KVM Wizard
Nürnberg Area, Germany
Alexander started working for SUSE about 9 years ago. Since then he worked on fancy things like SUSE Studio, QEMU, KVM and openSUSE on ARM. Whenever something really useful comes to his mind, he tends to implement it. Among others he did Mac OS X virtualization using KVM, nested SVM, KVM on PowerPC and a lot of work in QEMU for openSUSE on ARM. He is the upstream maintainer of KVM for PowerPC, QEMU for PowerPC and QEMU for S390x.

Slides: [WayBack] Marrying U-Boot, UEFI and grub.pdf

There are 2 videos on YouTube (view them below):

A few things I learned

Boot sequence:

  1. Raspberry Pi has a tiny boot ROM
  2. It loads the firmware in the GPU (for Raspberry this is a Raspberry Foundation provided binary)
  3. The firmware loads U-Boot
  4. U-Boot loads grub2
  5. grub2 can have many modules (like file system drivers) and loads the kernel

Alexander pushed the U-Boot stuff up stream, but the FreeBSD team was the first to actually boot a full OS from it.

Relations:

  • uEFI/EFI is a set of specs that define the API
  • U-Boot is the firmware implementing uEFI, so your machine behaves as a PC making booting a lot more standardised, starting at handing off to a regular grub2 boot process
  • U-Boot loads grub2

U-boot:

–jeroen

References:

Images

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Posted in *nix, *nix-tools, openSuSE, Power User, SuSE Linux, Tumbleweed | Leave a Comment »

 
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