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9 July 2026

8 July 2026

  • 13:4513:45, 8 July 2026 Linux network analysis with traceroute (hist | edit) [6,963 bytes] Aranzinger (talk | contribs) (Created page with "The Linux tool '''traceroute''' provides a lot of possibilities to trace the path of network packets through a network or the Internet to a specific host. This article provides an overview of the function of [http://de.wikipedia.org/wiki/Traceroute traceroute]. Furthermore, we present interesting option parameters for traceroute. In addition to traceroute, mtr is also interesting. It combines the functionality of traceroute and ping....")
  • 10:0310:03, 8 July 2026 How to set up VLAN in OPNsense (hist | edit) [3,582 bytes] Aranzinger (talk | contribs) (Created page with "'''Virtual Local Area Networks''' - VLANs - are an important tool for the network infrastructure, particularly in environments with firewall solutions such as OPNsense. They allow to divide a physical network into multiple logical networks, which improves security and organization. This article describes how to set up VLANs in OPNsense 25.1. == Assign VLAN == First, a '''VLAN-ID between 1 and 4094''' is assigned to an interface. The ID 4095 is reser...")
  • 08:0708:07, 8 July 2026 Network configuration Ubuntu - Netplan (hist | edit) [2,213 bytes] Aranzinger (talk | contribs) (Created page with "In the current version of Ubuntu Server, Ubuntu 18.04 (Bionic Beaver), the network configuration can no longer be set in the file <code>/etc/network/interfaces</code> in a default installation. Since Ubuntu 17.10, there is [http://manpages.ubuntu.com/manpages/bionic/man5/netplan.5.html Netplan], which is a new option to configure network interfaces. The network configuration is stored in .yaml-files. In addition to changes to the configuration of the network interfac...")

7 July 2026

  • 13:0713:07, 7 July 2026 NVMe-CLI (hist | edit) [21,620 bytes] Aranzinger (talk | contribs) (Created page with "The '''NVMe Command Line Interface''' ('''NVMe-CLI''') provides multiple '''functions on querying and configuring NVMe SSDs''' on Linux and FreeBSD. In this article, we explain how to install NVMe-CLI and which funtions NVMe-CLI offers. == Version information == In the Linux distributions, the following versions of NVMe-CLI are included: {| class="wikitable" |+ ! colspan="2" |Linux distribution !NVMe-CLI version |- | rowspan="3" |Debian GNU/Linux |1...")

3 July 2026

  • 07:2807:28, 3 July 2026 EFI shell USB drive (hist | edit) [1,257 bytes] Aranzinger (talk | contribs) (Created page with "The '''EFI shell''' allows to run EFI applications, such as tools for updating the BIOS or the firmware of network cards or RAID controllers. In a lot of systems, an EFI shell is already included in the BIOS. If an integrated EFI shell is missing, an USB drive with EFI shell can be used as an alternative. == Create USB stick with EFI shell == The following steps must be performed, to create an USB drive with EFI shell: # Format USB stick with '''FAT32''' # Create '''/...")

1 July 2026

  • 11:2711:27, 1 July 2026 Grafana installation and configuration on Ubuntu server 18.04 LTS (hist | edit) [4,476 bytes] Aranzinger (talk | contribs) (Created page with "'''Grafana''' is a webbased open source frontend for virtualizing metrics and for alerting when thresholds are exceeded. Grafana '''supports numerous data sources''', for example Time Series databases such as InfluxDB, Graphite or Prometheus, log files via Elasticsearch and SQL data bases. Pre-defined dashboards are available through a marketplace.<ref>[https://grafana.com/grafana/dashboards Grafana Dashboards] (grafana.com)</ref> This aticle explains the '''installa...")
  • 07:3007:30, 1 July 2026 Upload own Ubuntu packages to reprepro repository (hist | edit) [5,956 bytes] Aranzinger (talk | contribs) (Created page with "In the following article, it is explained '''how to upload''' your own Ubuntu packages to a '''reprepro''' repository. The packages are transferred in a folder on the repository server with '''dupload''' via scp and processed there via an inoticoming job from reprepro. In the examples shown, the client is running Ubuntu 12.10, and the server is running '''Ubuntu 12.04.2''' with kernel 3.2.0-38-generic. In the article Create Own apt repository using reprepro on Ubuntu...")

30 June 2026

  • 12:3712:37, 30 June 2026 Linux file systems (hist | edit) [3,206 bytes] Aranzinger (talk | contribs) (Created page with "There are numerous '''file systems''' for different application purposes. This article includes excerpts highlighting particularly relevant file systems that are also included in the Linux Storage Stack Diagram. Further file systems are mentioned in the documentation of the Linux kernel.<ref>[https://www.kernel.org/doc/html/latest/filesystems/ Filesystems in the Linux kernel] (www.kernel.org)</ref> == File systems for storing data == ==...")
  • 10:1410:14, 30 June 2026 FSCK Best Practices (hist | edit) [9,798 bytes] Aranzinger (talk | contribs) (Created page with "File system checks (FSCK) verify the consistency of '''file systems'''. Generally, a check of journaling file systems such as Ext3, Ext4, or XFS is performed quickly, since the metadata journal ensures consistency. Nevertheless, there may be situations in which a file system becomes corrupted and must be '''fixed'''. A '''regular FSCK''' is '''recommended''' on server systems to prevent file system problems. == Periodic check on Ubuntu == Ubuntu has deactivated...")
  • 07:3707:37, 30 June 2026 VMware Contract ID (hist | edit) [819 bytes] Aranzinger (talk | contribs) (Created page with "For the renewal of an existing or soon-to-expire VMware support & subscription contract, the '''Support Contract ID''' of the product is required. This information can be found in your [https://support.broadcom.com/ Broadcom Support Portal] in '''MyEntitlements.''' <gallery width="1024" height="820" showcarousel="false" slideinfozoneopacity="0.95"> file:Vmware support id 1.png|Select '''My Entitlements''' file:Vmware support id 2.png|Select your '''Site ID''' , then ''...")

29 June 2026

  • 13:5213:52, 29 June 2026 Upgrade Linux Mint Debian Edition (hist | edit) [1,209 bytes] Aranzinger (talk | contribs) (Created page with "An installation of '''Linux Mint Debian Edition''' (LMDE) can be updated to a newer version once it is released. In this example, we present the upgrade from LMDE 6 to LMDE 7. == Preparation == To prepare, the updatetool mintupgrade must be installed:<ref>[https://blog.linuxmint.com/?p=4923 How to upgrade to LMDE 7] (blog.linuxmint.com, 14.10.2025)</ref> apt update apt install mintupgrade '''Important note - create backup:''' Before you continue, we recommend t...")

19 June 2026

  • 08:1008:10, 19 June 2026 Installation of N8n (hist | edit) [8,378 bytes] Aranzinger (talk | contribs) (Created page with "'''n8n''' is a performant open-source platform for automatizing workflows. In contrast to cloud services such as Zapier or Make.com, n8n enables self-hostet operation, which allows you to maintain full control over your data, workflows, and costs. This article describes four different self-contained methods ("paths") to install n8n on a local Linux server. Select the path that fits best to your use case and follow the steps from beginning to end. == Requirements ==...")

18 June 2026

  • 12:1212:12, 18 June 2026 Creation of Proxmox HA cluster (hist | edit) [5,573 bytes] Aranzinger (talk | contribs) (Created page with "This article describes the configuration of a '''High Availability Cluster''' or '''HA Cluster''' using three servers with '''Proxmox''' '''VE''' 8.2.2. In this example, Ceph is configured within the cluster as the data storage. ==Requirements for High Availability== Before configuring the HA cluster, it must be verified if all requirements are fulfilled: *3 server systems identical in design * all nodes must be located in the same system * date and time must be sy...")
  • 09:0909:09, 18 June 2026 LVM basic configuration (hist | edit) [9,041 bytes] Aranzinger (talk | contribs) (Created page with "In the following article, the '''basic configuration''' of LVs is explained. The used system is a '''Ubuntu Server 10.4''' with the 2.6.32-24 kernel and the LVM-version 2.02.54(1) (2009-10-26). In the following, it is explained how to create '''partitions''' of '''''Physical Volumes''''' (PVs), a '''''Volume Group''''' (VG) and the '''''Logical Volumes''''' (LVs) built on top of them. ==Creating partitions== First, the partitions for the PVs are created. The following...")

17 June 2026

  • 15:1715:17, 17 June 2026 Linux performance analysis in 60 seconds (hist | edit) [1,548 bytes] Aranzinger (talk | contribs) (Created page with "When a critical '''performance issue''' arises on a Linux server, there is often little time to analyze the problem in detail. Brendan Gregg, computer performance analyst and kernel engineer, describes in a blog posting and in a video, '''which Linux commands he uses for the performance analysis in the first 60 seconds'''. == Commands for performance analysis == The following commands are recommended by Brendan Gregg:<ref>[http://techblog.netflix.com/2015/11/linux-...")
  • 14:1714:17, 17 June 2026 Docker basics - the most important terms (hist | edit) [1,331 bytes] Aranzinger (talk | contribs) (Created page with "This article provides an introduction in Docker and shows useful terms, which can be useful when using Docker and Docker containers: <pre> # Start container docker container run <IMAGENAME> starts a container based on an image (Example: checkmk/check-mk-raw:2.2.0-latest) # List containers (active) docker ps displays a list of all containers that are currently active # List containers (all) docker ps -all displays all containers on the system including those that ha...")
  • 10:4410:44, 17 June 2026 Measuring TCP and UDP Network Performance with iperf (hist | edit) [4,338 bytes] Aranzinger (talk | contribs) (Created page with "'''iperf''', the open-source tool, allows to measure the maximum TCP and UDP network bandwidth. It is an alternative for netperf<ref>[http://www.netperf.org/ Netperf] (www.netperf.org)</ref>. == Installation == Iperf is already included in the Debian and Ubuntu repository, which means that an installation is easy possible via <code>apt-get install iperf</code>. For RHEL and CentOS, the package is available in the EPEL<ref>[http://dl.fedoraproject.org/pub/epel/6/x86_64...")
  • 07:4007:40, 17 June 2026 Permanently Change the Root Data Directory in Docker (hist | edit) [2,589 bytes] Aranzinger (talk | contribs) (Created page with "This article explains how to permanently switch the default root data directory <code>/var/lib/docker/</code> to a different directory. == Background information == The <code>/var/lib/docker</code> directory stores all images, volumes from Docker and can grow significantly depending on how many containers are used. The directory is structured as follows:<pre> root@js-checkmk-02:/var/lib/docker# ls buildkit containers engine-id image network overlay2 plugins runt...")

16 June 2026

11 June 2026

  • 12:0812:08, 11 June 2026 Secure SSH login with 2 factor authentication (hist | edit) [5,104 bytes] Aranzinger (talk | contribs) (Created page with "A SSH shell belongs to the essential management tools on Linux based servers. This shell is already well covered by using certificate based login methods only and by deactivating root logins. Furthermore, an additional registration step can be added, for example a one-time password, with a second factor. This further enhances security, as a successful login now relies on something you have (the certificate) and something you know (the one-time password). This article sho...")
  • 09:5609:56, 11 June 2026 Restrict executable SSH-commands via authorized keys (hist | edit) [4,790 bytes] Aranzinger (talk | contribs) (Created page with " The '''OpenSSH''' secure shell server allows a secure and encrypted remote access on Linux and Unix systems. On the server side, the '''authorized_keys''' file in the ''.ssh'' folder is primarily used for configuring a SSH public key authentication under Ubuntu. Normally, a user is granted '''full access''' on the system, on which the authentication was set up. In some cases, such as automatized backup processes, it is useful that the access is restricted to just a...")
  • 08:2508:25, 11 June 2026 OpenSSH public key authentication fails (hist | edit) [2,634 bytes] Aranzinger (talk | contribs) (Created page with "This article describes how to resolve issues with SSH authentication using public key authentication. In the article SSH key login, it is explained how to set up public key authentication in general. == Server-side problems == In most cases, the reason why public key authentication is not working can be found in the file and directory permissions. The home directory on the server as well as the sub-directory .ssh is not allowed to have writing right...")

10 June 2026

  • 14:1614:16, 10 June 2026 AMD Security Vulnerabilities - June 2026 (hist | edit) [4,195 bytes] Aranzinger (talk | contribs) (Created page with "On '''June 9th, 2026''', AMD published the security bulletins '''AMD-SB-3039'''<ref>[https://www.amd.com/en/resources/product-security/bulletin/amd-sb-3039.html ASP non-Coherent Memory Access – June 2026] (www.amd.com/en/resources/product-security)</ref> and '''AMD-SB-9025'''<ref>[https://www.amd.com/en/resources/product-security/bulletin/amd-sb-9025.html AMD uProf Vulnerabilities – June 2026] (www.amd.com/en/resources/product-security)</ref> for security vulnerabili...")
  • 10:5210:52, 10 June 2026 Slow SSH login due to DNS timeout (hist | edit) [4,529 bytes] Aranzinger (talk | contribs) (Created page with "This article describes solutions for when an '''SSH login is slow'''. ==Problem== It takes approximately 10 seconds when you log in to a Linux system via SSH until the password prompt appears. After this, the SSH session functions completely normal. ==Background== The SSH server tries to make a reverse DNS lookup for the IP from which the SSH connection is established. If there is no functioning configured DNS (for example a wrong registered IP for the DNS server in /...")
  • 08:3008:30, 10 June 2026 OpenSSH configuration (hist | edit) [2,372 bytes] Aranzinger (talk | contribs) (Created page with "The following configuration describes advanced OpenSSH configurations that can be expaned as needed. If you have more interesting contents, kindly send us a message. An overview of all server-side SSH configuration options can be found in the manpage of sshd_config. man sshd_config === Conditional configuration with "Match" === "Match", the configuration option, allows a global configuration (for example in <code>/etc/ssh/sshd_config</code>) to ove...")

9 June 2026

  • 13:3513:35, 9 June 2026 Samba-server basics (hist | edit) [6,372 bytes] Aranzinger (talk | contribs) (Created page with "A '''Samba-Server''' helps with the integration of '''Windows- and Unix/Linux computers'''.<ref>[http://www.oreilly.de/german/freebooks/samba2ger/ch01.html#936841 Samba, 2. Auflage] www.oreilly.de</ref> '''Files''' can be, for example, exchanged or '''printers''' can be shared. The name Samba comes from the SMB protocol ('''''Server Message Block'''''), which is used for network-based data exchange on Windows. These days, people are increasingly referring to the "'''''Co...")
  • 07:3007:30, 9 June 2026 Supermicro BMC Security Advisories June 2026 (hist | edit) [1,664 bytes] Aranzinger (talk | contribs) (Created page with "In '''June 2026''', Supermicro published security advisories for the BMC-firmware of its mainboards. This security vulnerability requires a '''firmware update'''. In this article, you will find information on this security advisory and where to find updates on Thomas-Krenn products. == Security advisories == {| class="wikitable" |- style="background-color: #EFEFEF; font-weight: bold;" ! align="center" |CVE ! align="center" |Risk potential: ! align="center" |Title |-...")

8 June 2026

5 June 2026

  • 10:2610:26, 5 June 2026 Secure SSH login on Debian with fail2ban (hist | edit) [4,196 bytes] Aranzinger (talk | contribs) (Created page with "'''fail2ban''', which is a tool written in Python, pursues the target to secure server services against DoS attacks. It verifies log files according to predefined patterns and temporarily blocks the relevant IP addresses if access attempts fail repeatedly. This article explains how to secure a Debian based server with fail2ban. The used version from fail2ban is '''1.0.2-2''' on '''Debian 12'''. ==Problem== When executing the command "journalctl -u ssh", multiple failed...")
  • 07:2507:25, 5 June 2026 Prohibit SSH root login on Debian (hist | edit) [2,002 bytes] Aranzinger (talk | contribs) (Created page with "If you want to prohibit the direct SSH root login on Debian, you will need at least one additional user to the root user, who is authorized to log in to the server. With this user, you can switch to the root account. '''ATTENTION:''' If you did not create any other users, you will log yourself out of the system! == PermitRootLogin no == Edit the /etc/ssh/sshd_config file and set PermitRootLogin yes on PermitRootLogin no After this, restart the SSH service /etc...")

3 June 2026

  • 14:4114:41, 3 June 2026 Raspi-firmware: missing /boot/firmware, did you forget to mount it (hist | edit) [2,468 bytes] Aranzinger (talk | contribs) (Created page with "When installing Debian 12.0 using the live image, the raspi-firmware package will be also installed. However, this is not required on x86 systems and should therefore be deinstalled. If raspi-firmware is present, however, it causes the following error when installing a kernel update: '''raspi-firmware: missing /boot/firmware, did you forget to mount it?'''. == Problem == Debian 12.0 was installed via live image. When attempting to install updates using '''sudo apt d...")

29 May 2026

  • 08:2408:24, 29 May 2026 Setup Postfix in Debian (hist | edit) [11,334 bytes] Aranzinger (talk | contribs) (Created page with "'''Postfix''' is a widely used mail server, or more specifically, an MTA ([http://de.wikipedia.org/wiki/Mail_Transfer_Agent Mail Transfer Agent]). In this article, we describe how to install Postfix on Debian Lenny 5.0. In this example, we use a test server (lists.wefi.net). Replace this name with the name of your server. == Install package == The Postfix installation must be started on the command line as follows: apt-get install postfix Debian provides a note that...")

28 May 2026

  • 13:5413:54, 28 May 2026 Creating mailing lists in Mailman (hist | edit) [4,128 bytes] Aranzinger (talk | contribs) (Created page with "In this article, we explain how to '''create a new mailing list in Debian'''. We also present important configuration parameters. Information on installing Mailman can be found in the article Setup Mailman in Debian. == Create mailing list == A new mailing list can be created with the '''newlist''' command. Next, enter your email address. Mailman will use this address to send you email notifications in the future (for example, when new subscribers join the mailing...")

22 May 2026

  • 10:1010:10, 22 May 2026 Setup of Mailman in Debian (hist | edit) [14,354 bytes] Aranzinger (talk | contribs) (Created page with "'''GNU Mailman''' is a software for administrating mailing lists for free. In this article, we describe how to setup Mailman on Debian Lenny (Debian 5.0). At Thomas-Krenn, we use Mailman for mailing lists of the IPMI Sensor Monitoring Plugin. == Install MTA == For the operation of mailing lists with Mailman, the MTA (Mail Transfer Agent) is required. During the subsequent installation of Postfix, select '''Internet Site''' as the 'General type of mail configuration...")
  • 07:0107:01, 22 May 2026 Setting up password authentication with Active Directory on Debian (hist | edit) [6,975 bytes] Aranzinger (talk | contribs) (Created page with "Central directory services such as OpenLDAP or Active Directory (AD) simplify the '''password management''' for administrator and user. With regard to Linux server, the aspect of the SSH '''authentication''' via AD is interesting. From an IT security perspective, this solution also has its advantages: * Administrators do not have to choose and administrate different passwords for every server. You can log in to the servers with the AD password. * The password change or d...")

21 May 2026

  • 13:1613:16, 21 May 2026 PCIe link lost (hist | edit) [10,734 bytes] Aranzinger (talk | contribs) (Created page with "On Linux systems, when using Intel I350 network chips, messages such as '''PCIe link lost''' may appear, followed by '''igb 0000:82:00.0 enp130s0f0: malformed Tx packet detected and dropped, LVMMC:0xffffffff'''. Therefore, the affected network interface does not work. As a solution, the Linux kernel parameter '''pcie_aspm.policy=performance''' or an updated BIOS with deactivated ASPM can be used. == Affected hardware and software == We have encountered this issue i...")
  • 09:0909:09, 21 May 2026 MegaRAID 9341-4i Debian 11 DMAR DRHD handling fault status reg 3 (hist | edit) [5,244 bytes] Aranzinger (talk | contribs) (Created page with "After installing Debian 11 on a system with MegaRAID 9341-4i RAID controller, messages such as '''AVAGO EFI SAS Driver is Unhealthy''' may appear during the boot process and '''DMAR: DRHD: handling fault status reg 3''' in the system log. In this article, we explain how to solve this problem by using the kernel parameter '''intel_iommu=on iommu=pt'''. == Description of problem == After installing Debian 11, the following problems appear on a system with MegaRAI...")
  • 07:5607:56, 21 May 2026 Debian 11 installation with DMAR DRHD handling fault status reg 3 error message (hist | edit) [4,446 bytes] Aranzinger (talk | contribs) (Created page with "When installing Debian 11 on systems with a MegaRAID 9341-4i RAID controller, it may come to error messages such as '''AVAGO EFI SAS Driver is Unhealthy''' during the starting process and '''DMAR: DRHD: handling fault status reg 3 '' when starting the operating system. In this article, we show how to install Debian 11 by using the kernel parameters '''intel_iommu=on''' and '''iommu=pt'''. == Error message in the BIOS, during boot process and installation == In this ca...")

20 May 2026

  • 09:3909:39, 20 May 2026 Security advisories on Intel products 2026.2 IPU (hist | edit) [2,700 bytes] Aranzinger (talk | contribs) (Created page with "In '''2026''', Intel published new security advisories as part of the IPU 2026.2 on different Intel products. Some of these security advisories require '''firmware updates'''. In this article, you will find an excerpt and hints on these security advisories as well as information on where to find updates for Thomas-Krenn products. == Affected systems == * Intel Xeon processors * Intel Core processors * Intel Atom processors * Intel Pentium processors * Intel Celeron...")
  • 07:5307:53, 20 May 2026 AMD Security Vulnerabilities - May 2026 (hist | edit) [8,768 bytes] Aranzinger (talk | contribs) (Created page with "On '''May 12th, 2026''', AMD published the security bulletins '''AMD-SB-3030''' <ref>[https://www.amd.com/en/resources/product-security/bulletin/amd-sb-3030.html AMD EPYC and AMD EPYC Embedded Series Processor Vulnerabilities – May 2026] (www.amd.com/en/resources/product-security)</ref>, '''AMD-SB-4017'''<ref>[https://www.amd.com/en/resources/product-security/bulletin/amd-sb-4017.html AMD Athlon, AMD Ryzen, and AMD Ryzen Embedded Series Processor Vulnerabilities – Ma...")

15 May 2026

  • 10:2510:25, 15 May 2026 NIC bonding on Debian (hist | edit) [2,149 bytes] Aranzinger (talk | contribs) (Created page with "==Different kinds of bonding== * mode=0 (balance-rr) * mode=1 (active-backup) * mode=2 (balance-xor) * mode=3 (broadcast) * mode=4 (802.3ad) (see also Link Aggregation and LACP basics) * mode=5 (balance-tlb) * mode=6 (balance-alb) == Install packages == apt-get install ifenslave-2.6 == Configuration Debian 5.0 Lenny and newer == In this example, we explain a configuration with mode 4 (802.3ad). For the link aggregation, we use: * eth0 and * eth1 <code>/etc...")
  • 07:4207:42, 15 May 2026 Reset IPMI password (hist | edit) [3,669 bytes] Aranzinger (talk | contribs) (Created page with "This article describes how to reset the '''password''' of an '''IPMI module'''. Please note that on Supermicro systems, the maximum password length is effectively 19 characters when setting a new password (The array length is 20 characters and the string is NULL-terminated, leaving 19 characters available). <ref>[https://www.supermicro.com/support/faqs/faq.cfm?faq=16778 What is the maximum password length for IPMI?] (Supermicro FAQ 16778)</ref> ==Resetting the password...")

11 May 2026

6 May 2026

29 April 2026

  • 11:1711:17, 29 April 2026 Internet-Speed-Test with LibreSpeed (hist | edit) [4,558 bytes] Aranzinger (talk | contribs) (Created page with "There are websites for testing the own '''internet speed''' offered by a lot of providers. The most services of this kind collect '''multiple local data''' in such tests, which is why they are '''not without risk from a data protection perspective'''. The open source alternative '''LibreSpeed''' offers a data-efficient alternative. == Data collection of conventional speedtest-alternatives == Traditional providers of internet speed testing services collect a large amoun...")
  • 09:2809:28, 29 April 2026 TKMI Settings (hist | edit) [4,880 bytes] Aranzinger (talk | contribs) (Created page with "== Menu == {| class="wikitable" style="width:100%;" | style="width:240px; text-align:center;" | 220px|overview | '''Overview'''<br> Overview of the settings available in the TKMI. |} == System and basic configuration == {| class="wikitable" style="width:100%;" | style="width:240px; text-align:center;" | 220px|configure date and time | '''Date & Time'''<br> The '''date, time and time synchronizat...")
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