Archive for the ‘Virtual Machines’ Category

How to install and use WSL 2 Windows native Linux emulation Debian and Ubuntu Linux on Windows 10 / Windows 11

Thursday, October 31st, 2024

WSL (Windows Subsystem for Linux) is perhaps relatively rarely known to the old school sys admins rats who usually use stuff like QEMU / KVM for Windows or Virtualbox / VMWare for Host machine.
However most people most lileky heard but never used or heard about the native (container like) virtualization WSL which was introduced in Windows 10 and Windows 11 as an attempt from Microsoft to improve the interoperability between Windows and Linux.
WSL version 1 and ver 2 allows Microsoft Windows for using a Linux environment without the need for a separate virtual machine.

In Windows 10, it is existing in Windows 10 Professional version can be installed either by joining the Windows Insider program or manually via Microsoft Store or Winget.
Hence perhaps you don't know that WSL virtualization can be used by those who want to mix Linux and Windows or for example get an advantages against dual-boot (installing Linux and Windows on the same computer).
Even better most significant WSL pros is you can literally running both systems at the same time without the need to run or stop every software that’s running and reboot to another system.

Procedure to set up a WSL is simple and similar to setting up a real Linux OS, therefore this guide can also be used as a reference to Linux setup.The specifications of WSL setup procedure are mainly in Install WSL and then setup any packages you would like to use for example if you want to be able to access remotely the WSL emulated Debian / Ubuntu or other of the installable distros via OpenSSH server.

1. Requirements to install and use WSL Linux emulation

To have the wsl subsystem used on Windows 10 or Windows 11 requirements:

You must be running Windows 10 version 2004 and higher (Build 19041 and higher) or Windows 11 to use the commands below. If you are on earlier versions please see the manual install page.

2. List available installable Linux distributions

WSL subsystem has ported only a certain set of Linux distributions, so if you need a very specific and unique Linux distribution, you would perhaps need to use Hyper-V virtualization or Virtualbox / VMWare.
However for people like me who are mainly using Debian GNU / Linux on daily basis as well as some OracleLinux admins / SUSE it is a perfect solution.

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl –list –online
The following is a list of valid distributions that can be installed.
Install using 'wsl.exe –install <Distro>'.

NAME FRIENDLY NAME
Ubuntu Ubuntu
Debian Debian GNU/Linux
kali-linux Kali Linux Rolling
Ubuntu-18.04 Ubuntu 18.04 LTS
Ubuntu-20.04 Ubuntu 20.04 LTS
Ubuntu-22.04 Ubuntu 22.04 LTS
Ubuntu-24.04 Ubuntu 24.04 LTS
OracleLinux_7_9 Oracle Linux 7.9
OracleLinux_8_7 Oracle Linux 8.7
OracleLinux_9_1 Oracle Linux 9.1
openSUSE-Leap-15.6 openSUSE Leap 15.6
SUSE-Linux-Enterprise-15-SP5 SUSE Linux Enterprise 15 SP5
SUSE-Linux-Enterprise-15-SP6 SUSE Linux Enterprise 15 SP6
openSUSE-Tumbleweed openSUSE Tumbleweed

3. Install Linux distribution for a first time

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl –install

The default Linux distribution that will get installed inside WLS Virtlualization is Ubuntu.

4. Install Debian GNU / Linux distribution as a second distro

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl –install Debian

That second installed distro would make Debian now the default one to boot by WSL.

To run the fresh installed Debian GNU / Linux distribution, run only wsl command with no arguments.

# wsl

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl –set-version Debian 2
For information on key differences with WSL 2 please visit https://aka.ms/wsl2
Conversion in progress, this may take a few minutes.
The distribution is already the requested version.
Error code: Wsl/Service/WSL_E_VM_MODE_INVALID_STATE
PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl –set-version 2
There is no distribution with the supplied name.
Error code: Wsl/Service/WSL_E_DISTRO_NOT_FOUND
PS C:\Windows\System32\WindowsPowerShell\v1.0>

Simply pressting CTRL + D from the actively running WSL emulated Linux (that is pretty much like a native Windows docker container if we have to compare to Linux) would stop the VM.

5. List runnable / installed VM Linux distributions

To list the available runnable Linux VMs on your Windows status on Windows Subsystem for Linux:

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl –list –verbose
NAME STATE VERSION
* Debian Stopped 2
Ubuntu Stopped 2
PS C:\Windows\System32\WindowsPowerShell\v1.0>

6. Run and check recent installed Linux distribution version

wsl2-windows-virtualization-install-virtual-machine-debian4

To run the newly install Debian Virtualized Linux (which as you can see is the default set distribution to run by WSL virtualization) simply type

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl

hipo@PC2LP3:/mnt/c/Windows/System32/WindowsPowerShell/v1.0$hipo@WL-2SLPWL3:/mnt/c/Windows/System32/WindowsPowerShell/v1.0$ cd ~
hipo@PC2LP3:~$

hipo@PC2LP3:~$ cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 12 (bookworm)"
NAME="Debian GNU/Linux"
VERSION_ID="12"
VERSION="12 (bookworm)"
VERSION_CODENAME=bookworm
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"
hipo@WL-2SLPWL3:~$

7. Update the Debian distribuion packages to latest available

hipo@PC2LP3:~$ sudo su – root
hipo@PC2LP3:~# apt update –fix-missing

8. Install openssh server to be able to connect to the WSL hosted Virtual Machine

hipo@PC2LP3:/home/hipo# apt install openssh-server –yes
…

windows-wsl-linux-emulation

root@PC2LP3:/home/hipo# systemctl start openssh-server telnet
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down
root@WL-2SLPWL3:/home/hipo# /etc/init.d/ssh start
Starting OpenBSD Secure Shell server: sshd.
root@WL-2SLPWL3:/home/hipo# ps -ef|grep -i ssh
root 30 9 0 18:19 ? 00:00:00 sshd: /usr/sbin/sshd [listener] 0 of 10-100 startups
root 32 15 0 18:20 pts/1 00:00:00 grep -i ssh

windows-wsl-linux-emulation

By default a fresh new installed VM would have a process list like below:

root@PC2LP3:/home/hipo# ps axuwef

wsl2-windows-virtualization-install-virtual-machine-debian7

To be able to have ifconfig and a number of other network tools it is useful to install net-tools package

root@PC2LP3:/home/hipo# apt install net-tools –yes
…

root@PC2LP3:/home/hipo# /sbin/ifconfig
…

Once the WSL VM and OpenSSHD is run you can try to telnet or ssh to the VM locally or remotely.

root@PC2LP3:/home/hipo# telnet localhost 22
Trying 127.0.0.1…
Connected to localhost.
Escape character is '^]'.
SSH-2.0-OpenSSH_9.2p1 Debian-2+deb12u3

9. Run commands directly from Windows command line or Powershell

You can also use the powershell to run commands via the virtualized Linux environment using simple syntax

# wsl [cmd-to-run]

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl ls /
bin dev home lib lost+found mnt proc run srv tmp var
boot etc init lib64 media opt root sbin sys usr
PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl ps -ef
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 18:07 hvc0 00:00:00 /init
root 5 1 0 18:07 hvc0 00:00:00 plan9 –control-socket 5 –log-level 4 –server-fd 6 –pipe-fd 8 –log-t
root 8 1 0 18:07 ? 00:00:00 /init
root 9 8 0 18:07 ? 00:00:00 /init
hipo 10 9 0 18:07 pts/0 00:00:00 ps -ef
PS C:\Windows\System32\WindowsPowerShell\v1.0>

10. Enable systemd on Linux distribution in WSL 2

Once you boot into the WSL installed distro shell edit /etc/wsl.conf:

$ vim /etc/wsl.conf

[boot]
systemd=true

11. Setting extra useful variables to boot the WSL emulated Linux VM

root@debian-wsl:/home/hipo# cat /etc/wsl.conf
[boot]
systemd=true

# Automatically mount Windows drive when the distribution is launched
[automount]

# Set to true will automount fixed drives (C:/ or D:/) with DrvFs under the root directory set above. Set to false means drives won't be mounted automatically, but need to be mounted manually or with fstab.
enabled = true

# Sets the directory where fixed drives will be automatically mounted. This example changes the mount location, so your C-drive would be /c, rather than the default /mnt/c.
root = /

# DrvFs-specific options can be specified.
options = "metadata,uid=1003,gid=1003,umask=077,fmask=11,case=off"

# Sets the `/etc/fstab` file to be processed when a WSL distribution is launched.
mountFsTab = true

# Network host settings that enable the DNS server used by WSL 2. This example changes the hostname, sets generateHosts to false, preventing WSL from the default behavior of auto-generating /etc/hosts, and sets generateResolvConf to false, preventing WSL from auto-generating /etc/resolv.conf, so that you can create your own (ie. nameserver 1.1.1.1).
[network]
hostname = debian-wsl
generateHosts = true
generateResolvConf = true

# Set whether WSL supports interop processes like launching Windows apps and adding path variables. Setting these to false will block the launch of Windows processes and block adding $PATH environment variables.
[interop]
enabled = false
appendWindowsPath = false

# Set the user when launching a distribution with WSL.
[user]
default = hipo

# Set a command to run when a new WSL instance launches. This example starts the Docker container service.
#[boot]
#command = service docker start
root@debian-wsl:/home/hipo#

To learn about on Advanced settings configuration in WSL check out official Microsoft documentation here

12. Shutting down a running emulated Linux VM

If you have run a WSL VM and you want to shut it down do:

# wsl shutdown

If you at a point want to delete / uninstall the installed distribution you can do

# wsl –terminate Distro_Name
# wsl –uninstall Distro_Name

Or you if you want to do a cleanup of the stored files inside the installed distribution (if you have stored files), do:

# wsl –unregister Distro_Name

For more in depth details check out the manual

PS C:\Windows\System32\WindowsPowerShell\v1.0> wsl –help
Copyright (c) Microsoft Corporation. All rights reserved.
For privacy information about this product please visit https://aka.ms/privacy.

Usage: wsl.exe [Argument] [Options…] [CommandLine]

Arguments for running Linux binaries:

If no command line is provided, wsl.exe launches the default shell.

–exec, -e <CommandLine>
Execute the specified command without using the default Linux shell.

–shell-type <standard|login|none>
Execute the specified command with the provided shell type.

—
Pass the remaining command line as-is.

Options:
–cd <Directory>
Sets the specified directory as the current working directory.
If ~ is used the Linux user's home path will be used. If the path begins
with a / character, it will be interpreted as an absolute Linux path.
Otherwise, the value must be an absolute Windows path.

–distribution, -d <Distro>
Run the specified distribution.

–user, -u <UserName>
Run as the specified user.

–system
Launches a shell for the system distribution.

Arguments for managing Windows Subsystem for Linux:

–help
Display usage information.

–debug-shell
Open a WSL2 debug shell for diagnostics purposes.

–install [Distro] [Options…]
Install a Windows Subsystem for Linux distribution.
For a list of valid distributions, use 'wsl.exe –list –online'.

Options:
–no-launch, -n
Do not launch the distribution after install.

–web-download
Download the distribution from the internet instead of the Microsoft Store.

–no-distribution
Only install the required optional components, does not install a distribution.

–enable-wsl1
Enable WSL1 support.

–manage <Distro> <Options…>
Changes distro specific options.

Options:
–move <Location>
Move the distribution to a new location.

–set-sparse, -s <true|false>
Set the vhdx of distro to be sparse, allowing disk space to be automatically reclaimed.

–mount <Disk>
Attaches and mounts a physical or virtual disk in all WSL 2 distributions.

Options:
–vhd
Specifies that <Disk> refers to a virtual hard disk.

–bare
Attach the disk to WSL2, but don't mount it.

–name <Name>
Mount the disk using a custom name for the mountpoint.

–type <Type>
Filesystem to use when mounting a disk, if not specified defaults to ext4.

–options <Options>
Additional mount options.

–partition <Index>
Index of the partition to mount, if not specified defaults to the whole disk.

–set-default-version <Version>
Changes the default install version for new distributions.

–shutdown
Immediately terminates all running distributions and the WSL 2
lightweight utility virtual machine.

–status
Show the status of Windows Subsystem for Linux.

–unmount [Disk]
Unmounts and detaches a disk from all WSL2 distributions.
Unmounts and detaches all disks if called without argument.

–uninstall
Uninstalls the Windows Subsystem for Linux package from this machine.

–update
Update the Windows Subsystem for Linux package.

Options:
–pre-release
Download a pre-release version if available.

–version, -v
Display version information.

Arguments for managing distributions in Windows Subsystem for Linux:

–export <Distro> <FileName> [Options]
Exports the distribution to a tar file.
The filename can be – for stdout.

Options:
–vhd
Specifies that the distribution should be exported as a .vhdx file.

–import <Distro> <InstallLocation> <FileName> [Options]
Imports the specified tar file as a new distribution.
The filename can be – for stdin.

Options:
–version <Version>
Specifies the version to use for the new distribution.

–vhd
Specifies that the provided file is a .vhdx file, not a tar file.
This operation makes a copy of the .vhdx file at the specified install location.

–import-in-place <Distro> <FileName>
Imports the specified .vhdx file as a new distribution.
This virtual hard disk must be formatted with the ext4 filesystem type.

–list, -l [Options]
Lists distributions.

Options:
–all
List all distributions, including distributions that are
currently being installed or uninstalled.

–running
List only distributions that are currently running.

–quiet, -q
Only show distribution names.

–verbose, -v
Show detailed information about all distributions.

–online, -o
Displays a list of available distributions for install with 'wsl.exe –install'.

–set-default, -s <Distro>
Sets the distribution as the default.

–set-version <Distro> <Version>
Changes the version of the specified distribution.

–terminate, -t <Distro>
Terminates the specified distribution.

–unregister <Distro>
Unregisters the distribution and deletes the root filesystem.
PS C:\Windows\System32\WindowsPowerShell\v1.0>

Once wsl is installed you can run it directly from Windows start menu, by searching for the name of the distribution you would like to run for example to run my Debian WSL running emulator::

Sum it up

What was shown up is how to run in parallel virtualized Linux distribution on Windows 10 and Windows 11 and how to install update to latest and run opensshd server to be able to ssh into the WSL Linux virtual machine remotely.
.Also i've shown you, How to test ssh is reachable and how to stop / start or destroy and cleanup any stored files for VM if necessery, as well as how to apply some extra advanced configurations to boot VM for.

Using WSL is not the best virtualization ever but anyways it is an alternative for people employed in Domain attached Windows PCs part of Big Corporations, where VirtualBox use is blocked / prohibited and you still need to experiment or develop Shell scripts or software on Python / Perl / Ruby on Linux before you do stuff on the PreProd or Production Linux host.

That's all folks, Enjoy ! 🙂

Tags: about, access, Admins, com, Connected, Debian Ubuntu, Debian Virtualized Linux, distributions, emulator, Failed, How to, linux?, Lists, procedure, reference, running, setting, use, Windows, WSL
Posted in Debian, Educational, Linux, Various, Virtual Machines, Windows | 1 Comment »

KVM Creating LIVE and offline VM snapshot backup of Virtual Machines. Restore KVM VM from backup. Delete old KVM backups

Tuesday, January 16th, 2024

For those who have to manage Kernel-Based Virtual Machines it is a must to create periodic backups of VMs. The backup is usually created as a procedure part of the Update plan (schedule) of the server either after shut down the machine completely or live.

Since KVM is open source the very logical question for starters, whether KVM supports Live backups. The simple answer is Yes it does.

virsh command as most people know is the default command to manage VMs on KVM running Hypervisor servers to manage the guest domains.

KVM is flexible and could restore a VM based on its XML configuration and the VM data (either a static VM single file) or a filesystem laying on LVM filesystem etc.

To create a snapshot out of the KVM HV, list all VMs and create the backup:

# export VM-NAME=fedora;
# export SNAPSHOT-NAME=fedora-backup;
# virsh list –all
…

It is useful to check out the snapshot-create-as sub arguments

# virsh help snapshot-create-as
…

OPTIONS
[–domain] <string> domain name, id or uuid
–name <string> name of snapshot
–description <string> description of snapshot
–print-xml print XML document rather than create
–no-metadata take snapshot but create no metadata
–halt halt domain after snapshot is created
–disk-only capture disk state but not vm state
–reuse-external reuse any existing external files
–quiesce quiesce guest's file systems
–atomic require atomic operation
–live take a live snapshot
–memspec <string> memory attributes: [file=]name[,snapshot=type]
[–diskspec] disk attributes: disk[,snapshot=type][,driver=type][,file=name]

# virsh shutdown $VM_NAME
# virsh snapshot-create-as –domain $VM-NAME –name "$SNAPSHOT-NAME"

1. Creating a KVM VM LIVE (running machine) backup

# virsh snapshot-create-as –domain debian \
–name "debian-snapshot-2024" \
–description "VM Snapshot before upgrading to latest Debian" \
–live

On successful execution of KVM Virtual Machine live backup, should get something like:

Domain snapshot debian-snapshot-2024 created

2. Listing backed-up snapshot content of KVM machine

# virsh snapshot-list –domain debian

a. To get more extended info about a previous snapshot backup

# virsh snapshot-info –domain debian –snapshotname debian-snapshot-2024

b. Listing info for multiple attached storage qcow partition to a VM

# virsh domblklist linux-guest-vm1 –details

Sample Output would be like:

Type Device Target Source
——————————————————————-
file disk vda /kvm/linux-host/linux-guest-vm1_root.qcow2
file disk vdb /kvm/linux-host/linux-guest-vm1_attached_storage.qcow2
file disk vdc /kvm/linux-host/guest01_logging_partition.qcow2
file cdrom sda –
file cdrom sdb

3. Backup KVM only Virtual Machine data files (but not VM state) Live

# virsh snapshot-create-as –name "mint-snapshot-2024" \
–description "Mint Linux snapshot" \
–disk-only \
–live
–domain mint-home-desktop

4. KVM restore snapshot (backup)

To revert backup VM state to older backup snapshot:

# virsh shutdown –domain manjaro
# virsh snapshot-revert –domain manjaro –snapshotname manjaro-linux-back-2024 –running

5. Delete old unnecessery KVM VM backup

# virsh snapshot-delete –domain dragonflybsd –snapshotname dragonfly-freebsd

Tags: backups, cdrom, command, created, Creating, Delete, domain name, filesystem, kvm, Listing, logical question, snapshot, virsh
Posted in Linux, System Administration, Virtual Machines | No Comments »

Simple bash shell Script to easy and quickly automate deploy RHEL Linux Virtual Machines on KVM Virtualization

Friday, November 3rd, 2023

Earlier I've blogged in about howto build KVM Virtual Machine RHEL 8.3 Linux install on Redhat 8.3 Linux Hypervisor with custom tailored kickstart.cfg as one of the Projects i was involved in my work duty as system administrator, we had the task to build
a KVM virtual machines and build a High Availability Linux PCS Corosync / Pacemaker / haproxy cluster on it to save some money for the company from purchasing VMWare licenses.

The setup of the KVM Virtual machine on a first glimpse is relatively simple and I thought, this can be done just for 2 / 3 days but it turned out to take up 2 weeks or so to properly prepare the kickstarter file and learn a bit about basic virt-install KVM options and experiment with them until
we can produce a noral working Virtual machines.

The original developed simple script that I used to bring up a new KVM virtual machines in a bit easier way virt-install-kvm.sh looked like so:

#!/bin/sh
# Script to build a new VM based on a kickstart.cfg file template
# with virt-install
# Author Georgi Georgiev hip0
# hipo@Pc-freak.net

KS_FILE='kickstart.cfg';
VM_NAME='RHEL8_3-VirtualMachine';
VM_DESCR='CentOS 8.3 Virtual Machine';
RAM='8192';
CPUS='8';
# size is in Gigabytes
VM_IMG_SIZE='70';
ISO_LOCATION='/vmprivate/rhel-server-8.3-x86_64-dvd.iso';
VM_IMG_FILE_LOC='/vmprivate/RHEL8_3-VirtualMachine.img';

virt-install -n "$VMNAME" –description "$VM_DESCR" –os-type=Linux –os-variant=rhel8.3 –ram=8192 –vcpus=8 –location="$ISO_LOCATION" –disk path=$VM_IMG_FILE,bus=virtio,size=$IMG_VM_SIZE –graphics none –initrd-inject=/root/$KS_FILE –extra-args "console=ttyS0 ks=file:/$KS_FILE"

The script basicly did what it was aimed for but modifying the kickstarter ks.cfg every time with multiple additional parameters, like network configurations as well some additional modifications to ks.cfg for VM parameters was annoying.

Recently as we had to repeat the same task again in order to migrate old customer containing a Linux OpenVZ Virtual machines to a newer OS installed RHEL versionb with KVM virtual machines, i've took some hours and scripted a small script that would easiy our task to build new KVM Virtual Machines
from scratch relatively easy, if we have to repeat the Linux OS build operation again and again.

Before proceeding to use the script of course one has to use LVM and setup the partitions on the Host which will be the Hypervisor where the KVM VMs will be installed as well you need to download an ISO image of Redhat Enterprise Linux / CentOS / Fedora or whatever kind of RPM based Linux
you would like to setup as well as do the basic configurations regarding the emulated Hardware node "Power" of the new Virtual Machine (CPU / Memory / Disk Partition) as well as choose a proper meaningful VM name (preferrably following some good meaningful crafted naming convention, that will talk a bit about what is inside the KVM VM container).

The script that automates a bit the KVM VM installation which you find below you can also download from here virt-install.sh

#!/bin/bash
virt_install_path=$(which virt-install);
vm_host='vmname01';
boot_iso='/vmprivate/rhel-8.7-x86_64-dvd.iso';
os_version='rhel8.7';
vm_cpus_count='4';
vm_ram='6144';
vm_img_location='/vmprivate/NAME-of-VM.img';
vm_machine_description='Name Production system';
ks_file_location_template='/root/ks.cfg.templ';
ks_file_location='/root/ks.cfg';
ks_vm_read_loc=$(echo $ks_file_location |sed -e 's#root/##g');
vm_main_ip='192.168.23.52';
vm_netmask='255.255.255.192';
vm_gateway='192.168.23.33';
vm_nameserver='172.30.50.2';
#–ip=192.168.233.52 –netmask=255.255.255.192 –gateway=192.168.233.33 –nameserver=172.20.88.2

echo "Checking if defined $vm_host image $vm_img_location is not already present";
if [ ! -f $vm_img_location ]; then
echo
else
echo 'Exiting $vm_img_location is present';
echo "To destroy exiting VM image $vm_img_location run manually cmds:";
echo 'virsh list; virsh destroy $vm_host; virsh undefine $vm_host –remove-all-storage';
exit 1;
fi

alias cp='cp -f';
/usr/bin/cp -rpf $ks_file_location_template $ks_file_location;

echo "Setting VM Main IP: $vm_main_ip";
echo "Setting VM netmask: $vm_netmask";
echo "Setting VM Gateway: $vm_gateway";
echo "Setting VM Nameserver $vm_nameserver";
/usr/bin/perl -pi -e "s/ip=a1.a2.a3.a4/ip=$vm_main_ip/" $ks_file_location
/usr/bin/perl -pi -e "s/netmask=b1.b2.b3.b4/netmask=$vm_netmask/" $ks_file_location
/usr/bin/perl -pi -e "s/gateway=c1.c2.c3.c4/nameserver=$vm_nameserver/" $ks_file_location
/usr/bin/perl -pi -e "s/nameserver=d1.d2.d3.d4/gateway=$vm_gateway/" $ks_file_location
/usr/bin/perl -pi -e "s/vm-hostname/$vm_host/" $ks_file_location

echo "Running VM install:";
echo $virt_install_path -n $vm_host –description "$vm_machine_description" –os-type=Linux –os-variant=$os_version –ram=$vm_ram –vcpus=$vm_cpus_count –location=$boot_iso –disk path=$vm_img_location,bus=virtio,size=90 –graphics none –initrd-inject=$ks_file_location –extra-args "console=ttyS0 ks=file:$ks_vm_read_loc"

$virt_install_path -n $vm_host –description "$vm_machine_description" –os-type=Linux –os-variant=$os_version –ram=$vm_ram –vcpus=$vm_cpus_count –location=$boot_iso –disk path=$vm_img_location,bus=virtio,size=90 –graphics none –initrd-inject=$ks_file_location –extra-args "console=ttyS0 ks=file:$ks_vm_read_loc"

Modify the script to insert the required parameters of the new VM in the script header session, you will have to provide below options.

vm_host='vmname01';
boot_iso='/vmprivate/rhel-8.7-x86_64-dvd.iso';
os_version='rhel8.7';
vm_cpus_count='4';
vm_ram='6144';
vm_img_location='/vmprivate/NAME-of-VM.img';
vm_machine_description='Name Production system';
ks_file_location_template='/root/ks.cfg.templ';
ks_file_location='/root/ks.cfg';
ks_vm_read_loc=$(echo $ks_file_location |sed -e 's#root/##g');
vm_main_ip='192.168.23.52';
vm_netmask='255.255.255.192';
vm_gateway='192.168.23.33';
vm_nameserver='172.30.50.2';

The automatic Build virtual machine script is tested and works with Redhat Enterprise Linux and of course is pretty primitive as there is so much available online that would do similar, but still I like it because it works for me 🙂

You will need also the ks.cfg.templ file which has the basic kickstarter configuration that will bring up the Virtual machines according to predefined configurations.
Here is the ks.cfg.templ and ks.cfg files as well, you will have to place them under /root/ or some other directory.
Of course this script is just a basic one, it can be easily updated to accept its variable options as arguments if you need to bring up a multitude of virtual machines relatively quickly with few minor modifications.

Hope the script is helpful to some sysadmin out there. If so don't forget to donate me for a beer in my Patreon account found in the widgets section 🙂

Tags: automate, bit, cfg, cmds, exit 1, file, LVM, network, root, script header, usr bin
Posted in Bash Scripting, Linux, System Administration, Virtual Machines | No Comments »

How to make 27 inch monitor to work on 2560×1440 with Virtualbox Linux

Wednesday, October 4th, 2023

make-virtualbox-with-linux-work-on-2k-2560x1440-howto

I've bought a new "second hand" refurbished EIZO Flexscan Monitor EV2760 S1 K1 awesome monitor re from Kvant Serviz a company reseller of Second Hand electronics that is located on the territy of Bulgarian Academy of Sciences (BAN / BAS) and was created by BAS people originally for the BAS people and am pretty happy with it for doing my daily job as system administrator, especially as the monitor has been used on very short screen time for only 256 use hours (which is less than a year of full-use time), whether EIZO does guarantee their monitors to be able to serve up to 5 Full years monitor use time.

For those who deals with Graphics such as Designers and people into art working with Computers knows EIZO brand Monitors for quite some time now and it seems as much of those people are using Windows or Macintoshes, these monitors have been mainly created to work optimally with Windows / Mac computers on a higher resolution.
My work PC that is Dell Latitude 5510 with its HDMI cable has been running perfect with The EIZO with Windows 10, however as I'm using a Virtualbox virutal machines with CentOS Linux, the VM does not automatically detected the highest resolution 2K that this monitors supports 2560×1440 at 60 Hz is the best one can use to get more things fit into the screen and hopefully also good for the Eyes, the Ecoview shoulk also be a good idea for the eyes, as the Ecoview by EIZO tries to adjust the monitor brightness to lower levels according to the light in the room to try to minimize the eye strain on the eyes. The Ecoview mode is a little bit I guess like the famous BENQ's monitors Eye care.
I'm talking about all this Displays specifics as I spend quite a lot of time to learn the very basics about monitors as my old old 24 Inch EIZO Monitor Flexscan model 2436W started to wear off with time and doesn't support HDMI cable input, so I had to use a special. cable connector that modifies the signal from HDMI to DVI (and I'm not sure how this really effects the eyes), plus the DVI quality is said to be a little bit worse than HDMI as far as I read a bit on the topic online.

Well anyways currently I'm a happy owner of the EIZO EV2760 Monitor which has a full set of inputs of:

27" In-Plane Switching (IPS) Panel
DisplayPort | HDMI | DVI-D | 3.5mm Audio
2560 x 1440 Native Resolution
1000:1 Typical Contrast Ratio

I've tried to make the monitor work with Linux and my first assumption from what I've read was that I have to reinstall the Guess Addition Tools on the Virtualbox with additing the Guest Addition Tools via the Vbox GUI interface:

Devices -> Insert Guest Additions CD Image

virtualbox-resolutions-screenshot

But got an error that the Guest additions tools iso is missing
So eventually resolved it by remounting and reinstalling the guest addition tools with the following set of commands:

[root@localhost test]# yum install perl gcc dkms kernel-devel kernel-headers make bzip2
[root@localhost test]# cd /mnt/cdrom/
[root@localhost cdrom]# ls
AUTORUN.INF runasroot.sh VBoxSolarisAdditions.pkg
autorun.sh TRANS.TBL VBoxWindowsAdditions-amd64.exe
cert VBoxDarwinAdditions.pkg VBoxWindowsAdditions.exe
NT3x VBoxDarwinAdditionsUninstall.tool VBoxWindowsAdditions-x86.exe
OS2 VBoxLinuxAdditions.run

[root@localhost cdrom]# ./VBoxLinuxAdditions.run

Verifying archive integrity… All good.
Uncompressing VirtualBox 6.1.34 Guest Additions for Linux……..
VirtualBox Guest Additions installer
Removing installed version 6.1.34 of VirtualBox Guest Additions…
Copying additional installer modules …
Installing additional modules …
VirtualBox Guest Additions: Starting.
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel
modules. This may take a while.
VirtualBox Guest Additions: To build modules for other installed kernels, run
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup <version>
VirtualBox Guest Additions: or
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup all
VirtualBox Guest Additions: Building the modules for kernel
3.10.0-1160.80.1.el7.x86_64.
ERROR: Can't map '//etc/selinux/targeted/policy/policy.31': Invalid argument

ERROR: Unable to open policy //etc/selinux/targeted/policy/policy.31.
libsemanage.semanage_read_policydb: Error while reading kernel policy from /etc/selinux/targeted/active/policy.kern. (No such file or directory).
OSError: No such file or directory
VirtualBox Guest Additions: Running kernel modules will not be replaced until
the system is restarted

The solution to that was to reinstal the security policy-target was necessery

[root@localhost test]# yum install selinux-policy-targeted –reinstall

And of course rerun the reinstall of Guest addition tools up to the latest

[root@localhost cdrom]# ./VBoxLinuxAdditions.run

Unfortunately that doesn't make it resolve it and even shutting down the VM machine and reloading it again with Raised Video Memory for the simulated hardware from settings from 16 MB to 128MB for the VM does not give the option from the Virtualbox interface to set the resolution from

View -> Virtual Screen 1 (Resize to 1920×1200)

to any higher than that.

After a bit of googling I found some newer monitors doesn't seem to be seen by xrandr command and few extra commands with xrandr need to be run to make the 2K resolution 2560×1440@60 Herzes work under the Linux virtual machine.

These are the extra xranrd command that make it happen

# xrandr –newmode "2560x1440_60.00" 311.83 2560 2744 3024 3488 1440 1441 1444 1490 -HSync +Vsync
# xrandr –addmode Virtual1 2560x1440_60.00
# xrandr –output Virtual1 –mode "2560x1440_60.00"

As this kind of settings needs to be rerun on next time the Virtual Machine runs it is a good idea to place the commands in a tiny shell script:

[test@localhost ~]$ cat xrandr-set-resolution-to-2560×1440.sh
#!/bin/bash
xrandr –newmode "2560x1440_60.00" 311.83 2560 2744 3024 3488 1440 1441 1444 1490 -HSync +Vsync
xrandr –addmode Virtual1 2560x1440_60.00
xrandr –output Virtual1 –mode "2560x1440_60.00"

You can Download the xrandr-set-resolution-to-2560×1440.sh script from here

Once the commands are run, to make it affect the Virtualbox, you can simply put it in FullScreen mode via

View -> Full-Screen Mode (can be teriggered from keyboard by pressing Right CTRL + F) together

[test@localhost ~]$ xrandr –addmode Virtual1 2560x1440_60.00
[test@localhost ~]$ xrandr –output Virtual1 –mode "2560x1440_60.00"
[test@localhost ~]$ xrandr
Screen 0: minimum 1 x 1, current 2560 x 1440, maximum 8192 x 8192
Virtual1 connected primary 2560×1440+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
1920×1200 60.00 + 59.88
2560×1600 59.99
1920×1440 60.00
1856×1392 60.00
1792×1344 60.00
1600×1200 60.00
1680×1050 59.95
1400×1050 59.98
1280×1024 60.02
1440×900 59.89
1280×960 60.00
1360×768 60.02
1280×800 59.81
1152×864 75.00
1280×768 59.87
1024×768 60.00
800×600 60.32
640×480 59.94
2560x1440_60.00 60.00*
Virtual2 disconnected (normal left inverted right x axis y axis)
Virtual3 disconnected (normal left inverted right x axis y axis)
Virtual4 disconnected (normal left inverted right x axis y axis)
Virtual5 disconnected (normal left inverted right x axis y axis)
Virtual6 disconnected (normal left inverted right x axis y axis)
Virtual7 disconnected (normal left inverted right x axis y axis)
Virtual8 disconnected (normal left inverted right x axis y axis)

Tadadadam ! That's all folks, enjoy having your 27 Inch monitor running at 2560×1440 @ 60 Hz 🙂

Tags: ERROR, How to, inch, installed version, Installing, left, make, monitor, Monitors, necessery, right, system administrator, Virtualbox Linux, work
Posted in CentOS, Linux, Linux and FreeBSD Desktop, System Administration, Virtual Machines | No Comments »

Howto convert KVM QCOW2 format Virtual Machine to Vmdk to migrate to VMware ESXi

Thursday, November 17th, 2022

Why you would want to convert qcow2 to vmdk?

When managing the heterogeneous virtual environment or changing the virtualization solutions that become so common nowadays, you might need to migrate qcow2 from a Linux based KVM virtualization solution to VMWare's proprietary vmdk – the file format in which a VMWare does keep stored it's VMs, especially if you have a small business or work in a small start-up company where you cannot afford to buy something professional as VMware vCenter Converter Standalone or Microsoft virtual machine converter (MVMC)- usually used to to migrate VMware hosts to Hyper-V hosts, but also capable to migrate .qcow2 to .vmdk. The reason is that your old datacenter based on Linux OS custom KVM virtual machines might be moved to VMWare ESX to guarantee better and more systemized management (which though is very questionable, since most of my experiences with VMWare was that though the software was a great one, the people who manage it was not very much specialists in managing it).

Another common reason is that running a separate Linux virtual machine, costs you more than a well organized VMWare farm because you need more qualified Linux specialists to manage the KVMs thus KVM to VMWare management as in most big corporations nowadays’s main target is to cut the costs.
Even with successful migrations like that, though you might often expect a drop in the quality of the service when your VM ends in the VMWare farm.

Nomatter what’s the reason to migrate qcow2 to VMDK So lets proceed with how the .QCOW2 to .VMDK can be easily done.

1. Get information about the VM you would like to migrate to VMDK

In QEMU-KVM environment, the popular image format is qcow2, which outperforms the first generation of qcow format and raw format. You can find the files of virtual disks by checking the information of virtual machine by virsh command:

[root@hypervisor-machine ~]# virsh dominfo virtual-machine-name

INFO
ID: {e59ae416-9314-4e4b-af07-21c31d91b3fb}
EnvID: 1704649750
Name: CentOS7minimal
Description:
Type: VM
State: stopped
OS: centos7
Template: no
Uptime: 00:00:00 (since 2019-04-25 13:04:11)
Home: /vz/vmprivate/e39ae416-9314-4e4b-af05-21c31d91b3fb/
Owner: root@.
GuestTools: state=not_installed
GuestTools autoupdate: on
Autostart: off
Autostop: shutdown
Autocompact: off
Boot order: hdd0 cdrom0
EFI boot: off
Allow select boot device: off
External boot device:
On guest crash: restart
Remote display: mode=manual port=6903 address=0.0.0.0
Remote display state: stopped
Hardware:
cpu sockets=1 cpus=2 cores=2 VT-x accl=high mode=64 ioprio=4 iolimit='0'
memory 2048Mb
video 32Mb 3d acceleration=off vertical sync=yes
memory_guarantee auto
hdd0 (+) scsi:0 image='/vz/vmprivate/e59ae415-9314-4e4b-af05-21c31d91b3fb/harddisk.hdd' type='expanded' 5120Mb subtype=virtio-scsi
cdrom0 (+) scsi:1 image='/home/CentOS-7-x86_64-Minimal-1611.iso' state=disconnected subtype=virtio-scsi
usb (+)
net0 (+) dev='vme42bef5f3' network='Bridged' mac=001C42BEF5F3 card=virtio ips='10.50.50.27/255.255.255.192 ' gw='10.50.50.1'
SmartMount: (-)
Disabled Windows logo: on
Nested virtualization: off
Offline management: (-)
Hostname: kvmhost.fqdn.com

2. Convert the harddrive to VMDK

[root@hypervisor-machine e59ae415-9314-4e4b-af05-21c31d91b3fb]# ls -lsah

1.3G -rw-r—– 1 root root 1.3G Apr 25 14:43 harddisk.hdd

a. Converstion with qemu:

You can use qemu-img tool that is installable via cmds:

yum install quemu-img / apt install qemu-img / zipper install qemu-img (depending on the distribution RedHat / Debian / SuSE Linux)

-f: format of the source image

-O: format of the target image

[root@hypervisor-machine ~]# qemu-img convert -f qcow2 -O vmdk \-o adapter_type=lsilogic,subformat=streamOptimized,compat6 harddisk.hdd harddisklsilogic.vmdk

[root@ hypervisor-machine e59ae415-9314-4e4b-af05-21c31d91b3fb]# ls -lsah

1.3G -rw-r—– 1 root root 1.3G Apr 25 14:43 harddisk.hdd

536M -rw-r–r– 1 root root 536M Apr 26 14:52 harddisklsilogic.vmdk

3. Upload the new harddrive to the ESXi Hypervisor and adapt it to ESX

This vmdk might not be able to used on ESXi, but you can use it on VMware Workstation. To let it work on ESXi, you need to use vmkfstools to convert it again.

a. Adapt the filesystem to ESXi

[root@hypervisor-machine ~]# vmkfstools -i harddisklsilogic.vmdk -d thin harddisk.vmdk

4. Create a VM and add the converted harddrive to the machine.

Futher

Recreate the initramfs

But of course this won’t work directly as it often happens with Linux 🙂 !!.
We need to make adjustments to the virtual machine as well with few manual interventions:

1. Start the machine from the VMWare interface

2. Grub CentOS Linux rescue will appear from the prompt

3. Run command

dracut –regenerate-all –force

to Recreate the initramfs.

Note that You might also have to edit your network configuration since your network device usually get’s a different name.

Finally reboot the host:

[root@hypervisor-machine ~]# reboot

And voila you’re ready to play the VM inside the ESX after some testing, you might switch off the KVM Hypervisor hosted VM and reroute the network to point to the ESX Cluster.

Tags: command, Convert, External, MVMC, Offline, qemu, Remote, shutdown, Start, video
Posted in Linux, Migration, System Administration, Virtual Machines | No Comments »

How to RPM update Hypervisors and Virtual Machines running Haproxy High Availability cluster on KVM, Virtuozzo without a downtime on RHEL / CentOS Linux

Friday, May 20th, 2022

Here is the scenario, lets say you have on your daily task list two Hypervisor (HV) hosts running CentOS or RHEL Linux with KVM or Virutozzo technology and inside the HV hosts you have configured at least 2 pairs of virtual machines one residing on HV Host 1 and one residing on HV Host 2 and you need to constantly keep the hosts to the latest distribution major release security patchset.

The Virtual Machines has been running another set of Redhat Linux or CentOS configured to work in a High Availability Cluster running Haproxy / Apache / Postfix or any other kind of HA solution on top of corosync / keepalived or whatever application cluster scripts Free or Open Source technology that supports a switch between clustered Application nodes.

The logical question comes how to keep up the CentOS / RHEL Machines uptodate without interfering with the operations of the Applications running on the cluster?

Assuming that the 2 or more machines are configured to run in Active / Passive App member mode, e.g. one machine is Active at any time and the other is always Passive, a switch is possible between the Active and Passive node.

HAProxy--Load-Balancer-cluster-2-nodes-your-Servers

In this article I'll give a simple step by step tested example on how you I succeeded to update (for security reasons) up to the latest available Distribution major release patchset on one by one first the Clustered App on Virtual Machines 1 and VM2 on Linux Hypervisor Host 1. Then the App cluster VM 1 / VM 2 on Hypervisor Host 2.
And finally update the Hypervisor1 (after moving the Active resources from it to Hypervisor2) and updating the Hypervisor2 after moving the App running resources back on HV1.
I know the procedure is a bit monotonic but it tries to go through everything step by step to try to mitigate any possible problems. In case of failure of some rpm dependencies during yum / dnf tool updates you can always revert to backups so in anyways don't forget to have a fully functional backup of each of the HV hosts and the VMs somewhere on a separate machine before proceeding further, any possible failures due to following my aritcle literally is your responsibility 🙂

0. Check situation before the update on HVs / get VM IDs etc.

Check the virsion of each of the machines to be updated both Hypervisor and Hosted VMs, on each machine run:

# cat /etc/redhat-release
CentOS Linux release 7.9.2009 (Core)

The machine setup I'll be dealing with is as follows:

hypervisor-host1 -> hypervisor-host1.fqdn.com
• virt-mach-centos1
• virt-machine-zabbix-proxy-centos (zabbix proxy)

hypervisor-host2 -> hypervisor-host2.fqdn.com
• virt-mach-centos2
• virt-machine-zabbix2-proxy-centos (zabbix proxy)

To check what is yours check out with virsh cmd –if on KVM or with prlctl if using Virutozzo, you should get something like:

[root@hypervisor-host2 ~]# virsh list
Id Name State
—————————————————-
1 vm-host1 running
2 virt-mach-centos2 running

# virsh list –all

[root@hypervisor-host1 ~]# virsh list
Id Name State
—————————————————-
1 vm-host2 running
3 virt-mach-centos1 running

[root@hypervisor-host1 ~]# prlctl list
UUID STATUS IP_ADDR T NAME
{dc37c201-08c9-589d-aa20-9386d63ce3f3} running – VM virt-mach-centos1
{76e8a5f8-caa8-5442-830e-aa4bfe8d42d9} running – VM vm-host2
[root@hypervisor-host1 ~]#

If you have stopped VMs with Virtuozzo to list the stopped ones as well.

# prlctl list -a

[root@hypervisor-host2 74a7bbe8-9245-5385-ac0d-d10299100789]# vzlist -a
CTID NPROC STATUS IP_ADDR HOSTNAME
[root@hypervisor-host2 74a7bbe8-9245-5385-ac0d-d10299100789]# prlctl list
UUID STATUS IP_ADDR T NAME
{92075803-a4ce-5ec0-a3d8-9ee83d85fc76} running – VM virt-mach-centos2
{74a7bbe8-9245-5385-ac0d-d10299100789} running – VM vm-host1

# prlctl list -a

If due to Virtuozzo version above command does not return you can manually check in the VM located folder, VM ID etc.

[root@hypervisor-host2 vmprivate]# ls
74a7bbe8-9245-4385-ac0d-d10299100789 92075803-a4ce-4ec0-a3d8-9ee83d85fc76
[root@hypervisor-host2 vmprivate]# pwd
/vz/vmprivate
[root@hypervisor-host2 vmprivate]#

[root@hypervisor-host1 ~]# ls -al /vz/vmprivate/
total 20
drwxr-x—. 5 root root 4096 Feb 14 2019 .
drwxr-xr-x. 7 root root 4096 Feb 13 2019 ..
drwxr-x–x. 4 root root 4096 Feb 18 2019 1c863dfc-1deb-493c-820f-3005a0457627
drwxr-x–x. 4 root root 4096 Feb 14 2019 76e8a5f8-caa8-4442-830e-aa4bfe8d42d9
drwxr-x–x. 4 root root 4096 Feb 14 2019 dc37c201-08c9-489d-aa20-9386d63ce3f3
[root@hypervisor-host1 ~]#

Before doing anything with the VMs, also don't forget to check the Hypervisor hosts has enough space, otherwise you'll get in big troubles !

[root@hypervisor-host2 vmprivate]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos_hypervisor-host2-root 20G 1.8G 17G 10% /
devtmpfs 20G 0 20G 0% /dev
tmpfs 20G 0 20G 0% /dev/shm
tmpfs 20G 2.0G 18G 11% /run
tmpfs 20G 0 20G 0% /sys/fs/cgroup
/dev/sda1 992M 159M 766M 18% /boot
/dev/mapper/centos_hypervisor-host2-home 9.8G 37M 9.2G 1% /home
/dev/mapper/centos_hypervisor-host2-var 9.8G 355M 8.9G 4% /var
/dev/mapper/centos_hypervisor-host2-vz 755G 25G 692G 4% /vz

[root@hypervisor-host1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 50G 1.8G 45G 4% /
devtmpfs 20G 0 20G 0% /dev
tmpfs 20G 0 20G 0% /dev/shm
tmpfs 20G 2.1G 18G 11% /run
tmpfs 20G 0 20G 0% /sys/fs/cgroup
/dev/sda2 992M 153M 772M 17% /boot
/dev/mapper/centos-home 9.8G 37M 9.2G 1% /home
/dev/mapper/centos-var 9.8G 406M 8.9G 5% /var
/dev/mapper/centos-vz 689G 12G 643G 2% /vz

Another thing to do before proceeding with update is to check and tune if needed the amount of CentOS repositories used, before doing anything with yum.

[root@hypervisor-host2 yum.repos.d]# ls -al
total 68
drwxr-xr-x. 2 root root 4096 Oct 6 13:13 .
drwxr-xr-x. 110 root root 12288 Oct 7 11:13 ..
-rw-r–r–. 1 root root 4382 Mar 14 2019 CentOS7.repo
-rw-r–r–. 1 root root 1664 Sep 5 2019 CentOS-Base.repo
-rw-r–r–. 1 root root 1309 Sep 5 2019 CentOS-CR.repo
-rw-r–r–. 1 root root 649 Sep 5 2019 CentOS-Debuginfo.repo
-rw-r–r–. 1 root root 314 Sep 5 2019 CentOS-fasttrack.repo
-rw-r–r–. 1 root root 630 Sep 5 2019 CentOS-Media.repo
-rw-r–r–. 1 root root 1331 Sep 5 2019 CentOS-Sources.repo
-rw-r–r–. 1 root root 6639 Sep 5 2019 CentOS-Vault.repo
-rw-r–r–. 1 root root 1303 Mar 14 2019 factory.repo
-rw-r–r–. 1 root root 666 Sep 8 10:13 openvz.repo
[root@hypervisor-host2 yum.repos.d]#

[root@hypervisor-host1 yum.repos.d]# ls -al
total 68
drwxr-xr-x. 2 root root 4096 Oct 6 13:13 .
drwxr-xr-x. 112 root root 12288 Oct 7 11:09 ..
-rw-r–r–. 1 root root 1664 Sep 5 2019 CentOS-Base.repo
-rw-r–r–. 1 root root 1309 Sep 5 2019 CentOS-CR.repo
-rw-r–r–. 1 root root 649 Sep 5 2019 CentOS-Debuginfo.repo
-rw-r–r–. 1 root root 314 Sep 5 2019 CentOS-fasttrack.repo
-rw-r–r–. 1 root root 630 Sep 5 2019 CentOS-Media.repo
-rw-r–r–. 1 root root 1331 Sep 5 2019 CentOS-Sources.repo
-rw-r–r–. 1 root root 6639 Sep 5 2019 CentOS-Vault.repo
-rw-r–r–. 1 root root 1303 Mar 14 2019 factory.repo
-rw-r–r–. 1 root root 300 Mar 14 2019 obsoleted_tmpls.repo
-rw-r–r–. 1 root root 666 Sep 8 10:13 openvz.repo

1. Dump VM definition XMs (to have it in case if it gets wiped during update)

There is always a possibility that something will fail during the update and you might be unable to restore back to the old version of the Virtual Machine due to some config misconfigurations or whatever thus a very good idea, before proceeding to modify the working VMs is to use KVM's virsh and dump the exact set of XML configuration that makes the VM roll properly.

To do so:
Check a little bit up in the article how we have listed the IDs that are part of the directory containing the VM.

[root@hypervisor-host1 ]# virsh dumpxml (Id of VM virt-mach-centos1 ) > /root/virt-mach-centos1_config_bak.xml
[root@hypervisor-host2 ]# virsh dumpxml (Id of VM virt-mach-centos2) > /root/virt-mach-centos2_config_bak.xml

2. Set on standby virt-mach-centos1 (virt-mach-centos1)

As I'm upgrading two machines that are configured to run an haproxy corosync cluster, before proceeding to update the active host, we have to switch off
the proxied traffic from node1 to node2, – e.g. standby the active node, so the cluster can move up the traffic to other available node.

[root@virt-mach-centos1 ~]# pcs cluster standby virt-mach-centos1

3. Stop VM virt-mach-centos1 & backup on Hypervisor host (hypervisor-host1) for VM1

Another prevention step to make sure you don't get into damaged VM or broken haproxy cluster after the upgrade is to of course backup

[root@hypervisor-host1 ]# prlctl backup virt-mach-centos1

[root@hypervisor-host1 ]# prlctl stop virt-mach-centos1
[root@hypervisor-host1 ]# cp -rpf /vz/vmprivate/dc37c201-08c9-489d-aa20-9386d63ce3f3 /vz/vmprivate/dc37c201-08c9-489d-aa20-9386d63ce3f3-bak
[root@hypervisor-host1 ]# tar -czvf virt-mach-centos1_vm_virt-mach-centos1.tar.gz /vz/vmprivate/dc37c201-08c9-489d-aa20-9386d63ce3f3

[root@hypervisor-host1 ]# prlctl start virt-mach-centos1

4. Remove package version locks on all hosts

If you're using package locking to prevent some other colleague to not accidently upgrade the machine (if multiple sysadmins are managing the host), you might use the RPM package locking meachanism, if that is used check RPM packs that are locked and release the locking.

+ List actual list of locked packages

[root@hypervisor-host1 ]# yum versionlock list
…
…..
0:libtalloc-2.1.16-1.el7.*
0:libedit-3.0-12.20121213cvs.el7.*
0:p11-kit-trust-0.23.5-3.el7.*
1:quota-nls-4.01-19.el7.*
0:perl-Exporter-5.68-3.el7.*
0:sudo-1.8.23-9.el7.*
0:libxslt-1.1.28-5.el7.*
versionlock list done

+ Clear the locking

# yum versionlock clear

+ List actual list / == clear all entries

[root@virt-mach-centos2 ]# yum versionlock list; yum versionlock clear
[root@virt-mach-centos1 ]# yum versionlock list; yum versionlock clear
[root@hypervisor-host1 ~]# yum versionlock list; yum versionlock clear
[root@hypervisor-host2 ~]# yum versionlock list; yum versionlock clear

5. Do yum update virt-mach-centos1

For some clarity if something goes wrong, it is really a good idea to make a dump of the basic packages installed before the RPM package update is initiated,
The exact versoin of RHEL or CentOS as well as the list of locked packages, if locking is used.

Enter virt-mach-centos1 (ssh virt-mach-centos1) and run following cmds:

# cat /etc/redhat-release > /root/logs/redhat-release-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# cat /etc/grub.d/30_os-prober > /root/logs/grub2-efi-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

+ Only if needed!!

# yum versionlock clear
# yum versionlock list

Clear any previous RPM packages – careful with that as you might want to keep the old RPMs, if unsure comment out below line

# yum clean all |tee /root/logs/yumcleanall-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

Proceed with the update and monitor closely the output of commands and log out everything inside files using a small script that you should place under /root/status the script is given at the end of the aritcle.:

yum check-update |tee /root/logs/yumcheckupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
yum check-update | wc -l
yum update |tee /root/logs/yumupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
sh /root/status |tee /root/logs/status-before-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

6. Check if everything is running fine after upgrade

Reboot VM

# shutdown -r now

7. Stop VM virt-mach-centos2 & backup on Hypervisor host (hypervisor-host2)

Same backup step as prior

# prlctl backup virt-mach-centos2

# prlctl stop virt-mach-centos2
# cp -rpf /vz/vmprivate/92075803-a4ce-4ec0-a3d8-9ee83d85fc76 /vz/vmprivate/92075803-a4ce-4ec0-a3d8-9ee83d85fc76-bak
## tar -czvf virt-mach-centos2_vm_virt-mach-centos2.tar.gz /vz/vmprivate/92075803-a4ce-4ec0-a3d8-9ee83d85fc76

# prctl start virt-mach-centos2

8. Do yum update on virt-mach-centos2

Log system state, before the update

# cat /etc/redhat-release > /root/logs/redhat-release-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# cat /etc/grub.d/30_os-prober > /root/logs/grub2-efi-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# yum versionlock clear == if needed!!
# yum versionlock list

+ Clean old install update / packages if required

# yum clean all |tee /root/logs/yumcleanall-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

Initiate the update

# yum check-update |tee /root/logs/yumcheckupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out 2>&1
# yum check-update | wc -l
# yum update |tee /root/logs/yumupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out 2>&1
# sh /root/status |tee /root/logs/status-before-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

9. Check if everything is running fine after upgrade

Reboot VM

# shutdown -r now

10. Stop VM vm-host2 & backup

# prlctl backup vm-host2

# prlctl stop vm-host2

Or copy the actual directory containig the Virtozzo VM (use the correct ID)

# cp -rpf /vz/vmprivate/76e8a5f8-caa8-5442-830e-aa4bfe8d42d9 /vz/vmprivate/76e8a5f8-caa8-5442-830e-aa4bfe8d42d9-bak
## tar -czvf vm-host2.tar.gz /vz/vmprivate/76e8a5f8-caa8-4442-830e-aa5bfe8d42d9

# prctl start vm-host2

11. Do yum update vm-host2

# cat /etc/redhat-release > /root/logs/redhat-release-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# cat /etc/grub.d/30_os-prober > /root/logs/grub2-efi-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

Clear only if needed

# yum versionlock clear
# yum versionlock list
# yum clean all |tee /root/logs/yumcleanall-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

Do the rpm upgrade

# yum check-update |tee /root/logs/yumcheckupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# yum check-update | wc -l
# yum update |tee /root/logs/yumupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# sh /root/status |tee /root/logs/status-before-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

12. Check if everything is running fine after upgrade

Reboot VM

# shutdown -r now

13. Do yum update hypervisor-host2

# cat /etc/redhat-release > /root/logs/redhat-release-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# cat /etc/grub.d/30_os-prober > /root/logs/grub2-efi-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

Clear lock if needed

# yum versionlock clear
# yum versionlock list
# yum clean all |tee /root/logs/yumcleanall-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

Update rpms

# yum check-update |tee /root/logs/yumcheckupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out 2>&1
# yum check-update | wc -l
# yum update |tee /root/logs/yumupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out 2>&1
# sh /root/status |tee /root/logs/status-before-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

14. Stop VM vm-host1 & backup

Some as ealier

# prlctl backup vm-host1

# prlctl stop vm-host1

# cp -rpf /vz/vmprivate/74a7bbe8-9245-4385-ac0d-d10299100789 /vz/vmprivate/74a7bbe8-9245-4385-ac0d-d10299100789-bak
# tar -czvf vm-host1.tar.gz /vz/vmprivate/74a7bbe8-9245-4385-ac0d-d10299100789

# prctl start vm-host1

15. Do yum update vm-host2

# cat /etc/redhat-release > /root/logs/redhat-release-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# cat /etc/grub.d/30_os-prober > /root/logs/grub2-efi-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# yum versionlock clear == if needed!!
# yum versionlock list
# yum clean all |tee /root/logs/yumcleanall-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# yum check-update |tee /root/logs/yumcheckupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# yum check-update | wc -l
# yum update |tee /root/logs/yumupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# sh /root/status |tee /root/logs/status-before-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

16. Check if everything is running fine after upgrade

+ Reboot VM

# shutdown -r now

17. Do yum update hypervisor-host1

Same procedure for HV host 1

# cat /etc/redhat-release > /root/logs/redhat-release-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# cat /etc/grub.d/30_os-prober > /root/logs/grub2-efi-vorher-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

Clear lock

# yum versionlock clear
# yum versionlock list
# yum clean all |tee /root/logs/yumcleanall-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

# yum check-update |tee /root/logs/yumcheckupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# yum check-update | wc -l
# yum update |tee /root/logs/yumupdate-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out
# sh /root/status |tee /root/logs/status-before-$(hostname)-$(date '+%Y-%m-%d_%H-%M-%S').out

18. Check if everything is running fine after upgrade

Reboot VM

# shutdown -r now

Check hypervisor-host1 all VMs run as expected

19. Check if everything is running fine after upgrade

Reboot VM

# shutdown -r now

Check hypervisor-host2 all VMs run as expected afterwards

20. Check once more VMs and haproxy or any other contained services in VMs run as expected

21. Haproxy Unstandby virt-mach-centos1

Assuming that the virt-mach-centos1 and virt-mach-centos2 are running a Haproxy / corosync cluster you can try to standby node1 and check the result
hopefully all should be fine and traffic should come to host node2.

[root@virt-mach-centos1 ~]# pcs cluster unstandby virt-mach-centos1

Monitor logs and make sure HAproxy works fine on virt-mach-centos1

22. If necessery to redefine VMs (in case they disappear from virsh) or virtuosso is not working

[root@virt-mach-centos1 ]# virsh define /root/virt-mach-centos1_config_bak.xml
[root@virt-mach-centos1 ]# virsh define /root/virt-mach-centos2_config_bak.xml

23. Set versionlock to RPMs to prevent accident updates and check OS version release

[root@virt-mach-centos2 ]# yum versionlock \*
[root@virt-mach-centos1 ]# yum versionlock \*
[root@hypervisor-host1 ~]# yum versionlock \*
[root@hypervisor-host2 ~]# yum versionlock \*

[root@hypervisor-host2 ~]# cat /etc/redhat-release
CentOS Linux release 7.8.2003 (Core)

Other useful hints

[root@hypervisor-host1 ~]# virsh console dc37c201-08c9-489d-aa20-9386d63ce3f3
Connected to domain virt-mach-centos1
..

! Compare packages count before the upgrade on each of the supposable identical VMs and HVs – if there is difference in package count review what kind of packages are different and try to make the machines to look as identical as possible !

Packages to update on hypervisor-host1 Count: XXX
Packages to update on hypervisor-host2 Count: XXX
Packages to update virt-mach-centos1 Count: – 254
Packages to update virt-mach-centos2 Count: – 249

The /root/status script

+++

#!/bin/sh
echo '======================================================= '
echo '= Systemctl list-unit-files –type=service | grep enabled '
echo '======================================================= '
systemctl list-unit-files –type=service | grep enabled

echo '======================================================= '
echo '= systemctl | grep ".service" | grep "running" '
echo '======================================================= '
systemctl | grep ".service" | grep "running"

echo '======================================================= '
echo '= chkconfig –list '
echo '======================================================= '
chkconfig –list

echo '======================================================= '
echo '= netstat -tulpn '
echo '======================================================= '
netstat -tulpn

echo '======================================================= '
echo '= netstat -r '
echo '======================================================= '
netstat -r

+++

That's all folks, once going through the article, after some 2 hours of efforts or so you should have an up2date machines.
Any problems faced or feedback is mostly welcome as this might help others who have the same setup.

Thanks for reading me 🙂

Tags: backups, check, cmds, Connected, downtime, echo, Linux Hypervisor Host, list, logs, repo, root root, rpm, Set, setup, updates, virtual machines, yum versionlock
Posted in CentOS, Linux, Linux Package Management, System Administration, Virtual Machines | 1 Comment »

Disable VNC on KVM Virtual Machine without VM restart / How to Change VNC listen address

Monday, February 28th, 2022

disable-vnc-port-listener-on-a-KVM-ran-virtual-machine-virsh-libvirt-libvirt-architecture-design

Say you have recently run a new KVM Virtual machine, have connected via VNC on lets say the default tcp port 5900
installed a brand new Linux OS using a VNC client to connect, such as:
TightVNC / RealVNC if connecting from Windows Client machine or Vncviewer / Remmina if connecting from Linux / BSD and now
you want to turn off the VNC VM listener server either for security reasons to make sure some script kiddie random scanner did not manage to connect and take control over your VM or just because, you will be only further using the new configured VM only via SSH console sessions as they call it in modern times to make a buziness buzz out of it a headless UNIX server (server machines connected a network without a Physical monitor attached to it).

The question comes then how can be the KVM VNC listener on TCP port 5900 be completely disabled?

One way of course is to filter out with a firewall 5900 completely either on a Switch Level (lets say on a Cisco equipment catalist in front of the machine) or the worst solution to locally filter directly on the server with firewalld or iptables chain rules.

1. Disable KVM VNC Port listener via VIRSH VM XML edit

The better way of course is to completely disable the VNC using KVM, that is possible through the virsh command interface.
By editing the XML Virtual Machine configuration and finding the line about vnc confiuguration with:

root@server:/kvm/disk# virsh edit pcfreakweb
Domain pcfreakweb XML configuration not changed.

like:

<graphics type='vnc' port='5900' autoport='yes' listen='0.0.0.0'>
<listen type='address' address='0.0.0.0'/>

and set value to undefined:

port='-1'

virsh-KVM-disable-VNC-port-listener-virsh-xml-edit-screenshot

Modifying the XML however will require you to reboot the Virtual Machine for which XML was editted. This might be not possible
if you have a running production server already configured with Apache / Proxy / PostgreSQL / Mail or any other Internet public service.

2. Disable VNC KVM TCP port 5900 to a dynamic running VM without a machine reboot

Thus if you want to remove the KVM VNC Port Listener on 5900 without a VM shutdown / reboot you can do it via KVM's virsh client interface.

root@server:/kvm/disk# virsh
Welcome to virsh, the virtualization interactive terminal.

Type: 'help' for help with commands
'quit' to quit

virsh # qemu-monitor-command pcfreakweb –hmp change vnc none

The virsh management user interface client, can do pretty much more of real time VM changes, it is really useful to use it if you have KVM Hypervisor hosts with 10+ Virtual machines and it if you have to deal with KVM machines on daily, do specific changes to the VMs on how VM networks are configured, information on HV hardware, configure / reconfigure storage volumes to VMs etc, take some time to play with it 🙂

Tags: address, apache2, domain, help, kvm, machines, none, port, root, root server, tcp, terminal, user interface, virsh, Vncviewer Remmina, welcome, Windows Client, xml
Posted in Curious Facts, Linux, Virtual Machines | No Comments »

How to filter dhcp traffic between two networks running separate DHCP servers to prevent IP assignment issues and MAC duplicate addresses

Tuesday, February 8th, 2022

Tracking the Problem of MAC duplicates on Linux routers

If you have two networks that see each other and they're not separated in VLANs but see each other sharing a common netmask lets say 255.255.254.0 or 255.255.252.0, it might happend that there are 2 dhcp servers for example (isc-dhcp-server running on 192.168.1.1 and dhcpd running on 192.168.0.1 can broadcast their services to both LANs 192.168.1.0.1/24 (netmask 255.255.255.0) and Local Net LAN 192.168.1.1/24. The result out of this is that some devices might pick up their IP address via DHCP from the wrong dhcp server.

Normally if you have a fully controlled little or middle class home or office network (10 – 15 electronic devices nodes) connecting to the LAN in a mixed moth some are connected via one of the Networks via connected Wifi to 192.168.1.0/22 others are LANned and using static IP adddresses and traffic is routed among two ISPs and each network can see the other network, there is always a possibility of things to go wrong. This is what happened to me so this is how this post was born.

The best practice from my experience so far is to define each and every computer / phone / laptop host joining the network and hence later easily monitor what is going on the network with something like iptraf-ng / nethogs / iperf – described in prior how to check internet spepeed from console and in check server internet connectivity speed with speedtest-cli) iftop / nload or for more complex stuff wireshark or even a simple tcpdump. No matter the tools network monitoring is only part on solving network issues. A very must have thing in a controlled network infrastructure is defining every machine part of it to easily monitor later with the monitoring tools. Defining each and every host on the Hybrid computer networks makes administering the network much easier task and tracking irregularities on time is much more likely.

Since I have such a hybrid network here hosting a couple of XEN virtual machines with Linux, Windows 7 and Windows 10, together with Mac OS X laptops as well as MacBook Air notebooks, I have followed this route and tried to define each and every host based on its MAC address to pick it up from the correct DHCP1 server 192.168.1.1 (that is distributing IPs for Internet Provider 1 (ISP 1), that is mostly few computers attached UTP LAN cables via LiteWave LS105G Gigabit Switch as well from DHCP2 – used only to assigns IPs to servers and a a single Wi-Fi Access point configured to route incoming clients via 192.168.0.1 Linux NAT gateway server.

To filter out the unwanted IPs from the DHCPD not to propagate I've so far used a little trick to Deny DHCP MAC Address for unwanted clients and not send IP offer for them.

To give you more understanding, I have to clear it up I don't want to have automatic IP assignments from DHCP2 / LAN2 to DHCP1 / LAN1 because (i don't want machines on DHCP1 to end up with IP like 192.168.0.50 or DHCP2 (to have 192.168.1.80), as such a wrong IP delegation could potentially lead to MAC duplicates IP conflicts. MAC Duplicate IP wrong assignments for those older or who have been part of administrating large ISP network infrastructures makes the network communication unstable for no apparent reason and nodes partially unreachable at times or full time …

However it seems in the 21-st century which is the century of strangeness / computer madness in the 2022, technology advanced so much that it has massively started to break up some good old well known sysadmin standards well documented in the RFCs I know of my youth, such as that every electronic equipment manufactured Vendor should have a Vendor Assigned Hardware MAC Address binded to it that will never change (after all that was the idea of MAC addresses wasn't it !).
Many mobile devices nowadays however, in the developers attempts to make more sophisticated software and Increase Anonimity on the Net and Security, use a technique called MAC Address randomization (mostly used by hackers / script kiddies of the early days of computers) for their Wi-Fi Net Adapter OS / driver controlled interfaces for the sake of increased security (the so called Private WiFi Addresses). If a sysadmin 10-15 years ago has seen that he might probably resign his profession and turn to farming or agriculture plant growing, but in the age of digitalization and "cloud computing", this break up of common developed network standards starts to become the 'new normal' standard.

I did not suspected there might be a MAC address oddities, since I spare very little time on administering the the network. This was so till recently when I accidently checked the arp table with:

Hypervisor:~# arp -an
192.168.1.99 5c:89:b5:f2:e8:d8 (Unknown)
192.168.1.99 00:15:3e:d3:8f:76 (Unknown)

..

and consequently did a network MAC Address ARP Scan with arp-scan (if you never used this little nifty hacker tool I warmly recommend it !!!)
If you don't have it installed it is available in debian based linuces from default repos to install

Hypervisor:~# apt-get install –yes arp-scan
…

It is also available on CentOS / Fedora / Redhat and other RPM distros via:

Hypervisor:~# yum install -y arp-scan
…

Hypervisor:~# arp-scan –interface=eth1 192.168.1.0/24
…

192.168.1.19 00:16:3e:0f:48:05 Xensource, Inc.
192.168.1.22 00:16:3e:04:11:1c Xensource, Inc.
192.168.1.31 00:15:3e:bb:45:45 Xensource, Inc.
192.168.1.38 00:15:3e:59:96:8e Xensource, Inc.
192.168.1.34 00:15:3e:d3:8f:77 Xensource, Inc.
192.168.1.60 8c:89:b5:f2:e8:d8 Micro-Star INT'L CO., LTD
192.168.1.99 5c:89:b5:f2:e8:d8 (Unknown)
192.168.1.99   00:15:3e:d3:8f:76 (Unknown)
192.168.x.91     02:a0:xx:xx:d6:64        (Unknown)
192.168.x.91     02:a0:xx:xx:d6:64        (Unknown) (DUP: 2)
…

N.B. !. I found it helpful to check all available interfaces on my Linux NAT router host.

As you see the scan revealed, a whole bunch of MAC address mess duplicated MAC hanging around, destroying my network topology every now and then
So far so good, the MAC duplicates and strangely hanging around MAC addresses issue, was solved relatively easily with enabling below set of systctl kernel variables.

1. Fixing Linux ARP common well known Problems through disabling arp_announce / arp_ignore / send_redirects kernel variables disablement

Linux answers ARP requests on wrong and unassociated interfaces per default. This leads to the following two problems:

ARP requests for the loopback alias address are answered on the HW interfaces (even if NOARP on lo0:1 is set). Since loopback aliases are required for DSR (Direct Server Return) setups this problem is very common (but easy to fix fortunately).

If the machine is connected twice to the same switch (e.g. with eth0 and eth1) eth2 may answer ARP requests for the address on eth1 and vice versa in a race condition manner (confusing almost everything).

This can be prevented by specific arp kernel settings. Take a look here for additional information about the nature of the problem (and other solutions): ARP flux.

To fix that generally (and reboot safe) we include the following lines into

Hypervisor:~# cp -rpf /etc/sysctl.conf /etc/sysctl.conf_bak_07-feb-2022
Hypervisor:~# cat >> /etc/sysctl.conf

# LVS tuning
net.ipv4.conf.lo.arp_ignore=1
net.ipv4.conf.lo.arp_announce=2
net.ipv4.conf.all.arp_ignore=1
net.ipv4.conf.all.arp_announce=2

net.ipv4.conf.all.send_redirects=0
net.ipv4.conf.eth0.send_redirects=0
net.ipv4.conf.eth1.send_redirects=0
net.ipv4.conf.default.send_redirects=0

Press CTRL + D simultaneusly to Write out up-pasted vars.

2. Digging further the IP conflict / dulicate MAC Problems

Even after this arp tunings (because I do have my Hypervisor 2 LAN interfaces connected to 1 switch) did not resolved the issues and still my Wireless Connected devices via network 192.168.1.1/24 (ISP2) were randomly assigned the wrong range IPs 192.168.0.XXX/24 as well as the wrong gateway 192.168.0.1 (ISP1).
After thinking thoroughfully for hours and checking the network status with various tools and thanks to the fact that my wife has a MacBook Air that was always complaining that the IP it tried to assign from the DHCP was already taken, i"ve realized, something is wrong with DHCP assignment.
Since she owns a IPhone 10 with iOS and this two devices are from the same vendor e.g. Apple Inc. And Apple's products have been having strange DHCP assignment issues from my experience for quite some time, I've thought initially problems are caused by software on Apple's devices.
I turned to be partially right after expecting the logs of DHCP server on the Linux host (ISP1) finding that the phone of my wife takes IP in 192.168.0.XXX, insetad of IP from 192.168.1.1 (which has is a combined Nokia Router with 2.4Ghz and 5Ghz Wi-Fi and LAN router provided by ISP2 in that case Vivacom). That was really puzzling since for me it was completely logical thta the iDevices must check for DHCP address directly on the Network of the router to whom, they're connecting. Guess my suprise when I realized that instead of that the iDevices does listen to the network on a wide network range scan for any DHCPs reachable baesd on the advertised (i assume via broadcast) address traffic and try to connect and take the IP to the IP of the DHCP which responds faster !!!! Of course the Vivacom Chineese produced Nokia router responded DHCP requests and advertised much slower, than my Linux NAT gateway on ISP1 and because of that the Iphone and iOS and even freshest versions of Android devices do take the IP from the DHCP that responds faster, even if that router is not on a C class network (that's invasive isn't it??). What was even more puzzling was the automatic MAC Randomization of Wifi devices trying to connect to my ISP1 configured DHCPD and this of course trespassed any static MAC addresses filtering, I already had established there.

Anyways there was also a good think out of tthat intermixed exercise 🙂 While playing around with the Gigabit network router of vivacom I found a cozy feature SCHEDULEDING TURNING OFF and ON the WIFI ACCESS POINT – a very useful feature to adopt, to stop wasting extra energy and lower a bit of radiation is to set a swtich off WIFI AP from 12:30 – 06:30 which are the common sleeping hours or something like that.

3. What is MAC Randomization and where and how it is configured across different main operating systems as of year 2022?

Depending on the operating system of your device, MAC randomization will be available either by default on most modern mobile OSes or with possibility to have it switched on:

Android Q: Enabled by default
Android P: Available as a developer option, disabled by default
iOS 14: Available as a user option, disabled by default
Windows 10: Available as an option in two ways – random for all networks or random for a specific network

Lately I don't have much time to play around with mobile devices, and I do not my own a luxury mobile phone so, the fact this ne Androids have this MAC randomization was unknown to me just until I ended a small mess, based on my poor configured networks due to my tight time constrains nowadays.

Finding out about the new security feature of MAC Randomization, on all Android based phones (my mother's Nokia smartphone and my dad's phone, disabled the feature ASAP:

4. Disable MAC Wi-Fi Ethernet device Randomization on Android

MAC Randomization creates a random MAC address when joining a Wi-Fi network for the first time or after “forgetting” and rejoining a Wi-Fi network. It Generates a new random MAC address after 24 hours of last connection.

Disabling MAC Randomization on your devices. It is done on a per SSID basis so you can turn off the randomization, but allow it to function for hotspots outside of your home.

Open the Settings app
Select Network and Internet
Select WiFi
Connect to your home wireless network
Tap the gear icon next to the current WiFi connection
Select Advanced
Select Privacy
Select "Use device MAC"

5. Disabling MAC Randomization on MAC iOS, iPhone, iPad, iPod

To Disable MAC Randomization on iOS Devices:

Open the Settings on your iPhone, iPad, or iPod, then tap Wi-Fi or WLAN

Tap the information button next to your network
Turn off Private Address
Re-join the network

Of course next I've collected their phone Wi-Fi adapters and made sure the included dhcp MAC deny rules in /etc/dhcp/dhcpd.conf are at place.

The effect of the MAC Randomization for my Network was terrible constant and strange issues with my routings and networks, which I always thought are caused by the openxen hypervisor Virtualization VM bugs etc.

That continued for some months now, and the weird thing was the issues always started when I tried to update my Operating system to the latest packetset, do a reboot to load up the new piece of software / libraries etc. and plus it happened very occasionally and their was no obvious reason for it.

6. How to completely filter dhcp traffic between two network router hosts
IP 192.168.0.1 / 192.168.1.1 to stop 2 or more configured DHCP servers
on separate networks see each other

To prevent IP mess at DHCP2 server side (which btw is ISC DHCP server, taking care for IP assignment only for the Servers on the network running on Debian 11 Linux), further on I had to filter out any DHCP UDP traffic with iptables completely.
To prevent incorrect route assignments assuming that you have 2 networks and 2 routers that are configurred to do Network Address Translation (NAT)-ing Router 1: 192.168.0.1, Router 2: 192.168.1.1.

You have to filter out UDP Protocol data on Port 67 and 68 from the respective source and destination addresses.

In firewall rules configuration files on your Linux you need to have some rules as:

# filter outgoing dhcp traffic from 192.168.1.1 to 192.168.0.1
-A INPUT -p udp -m udp –dport 67:68 -s 192.168.1.1 -d 192.168.0.1 -j DROP
-A OUTPUT -p udp -m udp –dport 67:68 -s 192.168.1.1 -d 192.168.0.1 -j DROP
-A FORWARD -p udp -m udp –dport 67:68 -s 192.168.1.1 -d 192.168.0.1 -j DROP

-A INPUT -p udp -m udp –dport 67:68 -s 192.168.0.1 -d 192.168.1.1 -j DROP
-A OUTPUT -p udp -m udp –dport 67:68 -s 192.168.0.1 -d 192.168.1.1 -j DROP
-A FORWARD -p udp -m udp –dport 67:68 -s 192.168.0.1 -d 192.168.1.1 -j DROP

-A INPUT -p udp -m udp –sport 67:68 -s 192.168.1.1 -d 192.168.0.1 -j DROP
-A OUTPUT -p udp -m udp –sport 67:68 -s 192.168.1.1 -d 192.168.0.1 -j DROP
-A FORWARD -p udp -m udp –sport 67:68 -s 192.168.1.1 -d 192.168.0.1 -j DROP

You can download also filter_dhcp_traffic.sh with above rules from here

Applying this rules, any traffic of DHCP between 2 routers is prohibited and devices from Net: 192.168.1.1-255 will no longer wrongly get assinged IP addresses from Network range: 192.168.0.1-255 as it happened to me.

7. Filter out DHCP traffic based on MAC completely on Linux with arptables

If even after disabling MAC randomization on all devices on the network, and you know physically all the connecting devices on the Network, if you still see some weird MAC addresses, originating from a wrongly configured ISP traffic router host or whatever, then it is time to just filter them out with arptables.

## drop traffic prevent mac duplicates due to vivacom and bergon placed in same network – 255.255.255.252
dchp1-server:~# arptables -A INPUT –source-mac 70:e2:83:12:44:11 -j DROP

To list arptables configured on Linux host

dchp1-server:~# arptables –list -n

If you want to be paranoid sysadmin you can implement a MAC address protection with arptables by only allowing a single set of MAC Addr / IPs and dropping the rest.

dchp1-server:~# arptables -A INPUT –source-mac 70:e2:84:13:45:11 -j ACCEPT
dchp1-server:~# arptables -A INPUT –source-mac 70:e2:84:13:45:12 -j ACCEPT

dchp1-server:~# arptables -L –line-numbers
Chain INPUT (policy ACCEPT)
1 -j DROP –src-mac 70:e2:84:13:45:11
2 -j DROP –src-mac 70:e2:84:13:45:12
3

Once MACs you like are accepted you can set the INPUT chain policy to DROP as so:

dchp1-server:~# arptables -P INPUT DROP

If you later need to temporary, clean up the rules inside arptables on any filtered hosts flush all rules inside INPUT chain, like that

dchp1-server:~# arptables -t INPUT -F

Tags: android, Anyways, apple, apt-get, arp, arp-scan, asap, based, connection, default, DHCP, eth0, eth1, filter, How to, hybrid network, iftop, ios, ip arptables, ipv4, key, linux?, lvs, MAC, mac duplicate, mac os, machines, mess, Monitoring, network, Networking, Open, router, something, sysctl, traffic, two, UDP, variables, Vivacom Chineese, WiFi, Windows, WLAN, wrong, yum
Posted in Debian, Linux, Networking, System Administration, Virtual Machines | No Comments »

CentOS 8 / Redhat 8 insert additional guests additions to VM to enable Fullscreen, Copy / Paste and Shared Folder from host OS

Monday, January 10th, 2022

My experience with enabling virtualbox additions guest tools on many of the separate Linux distributions throughout time is pretty bad as it always is a pain in the ass to enable fully functional full screen and copy paste for Virtualbox…

For those who installed it for a first time vbox guest addition tools for Virtualbox are additional software components added so the Emulated Operating system
could allow better screen resolution and better mouse integration support.

So far I've installed virtualbox additions tools to CentOS 7 and Debian Linux various releases and faced complications there as well.
Few days ago my colleague Georgi Stoyanov have installed CentOS 8.3 with current version of VirtualBox 6.1 (vesrsion from beginning of 2022) and he has also shared had issues with enabling the CentOS 8.3 Linux to work with guestadditions but eventually found a resolution.

Thus he has shared with me the solution and I share it with you, so hopefully someone else could enable Guesttools on his CentOS 8.3 with less digging online.
The error received is:

# ./VBoxLinuxAdditions.run

Trying to install Guest Additions in RHEL 8.3.

VirtualBox Guest Additions: Starting.
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel
modules. This may take a while.
VirtualBox Guest Additions: To build modules for other installed kernels, run
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup
VirtualBox Guest Additions: or
VirtualBox Guest Additions: /sbin/rcvboxadd quicksetup all
VirtualBox Guest Additions: Building the modules for kernel
4.18.0-193.el8.x86_64.

VirtualBox Guest Additions: Look at /var/log/vboxadd-setup.log to find out what
went wrong
ValueError: File context for /opt/VBoxGuestAdditions-6.0.20/other/mount.vboxsf already defined
VirtualBox Guest Additions: Running kernel modules will not be replaced until
the system is restarted
Press Return to close this window…

No idea what to do next. Been trying for sometime.

To enable guestaddtions in CentOS 8.3, e.g. get arount the error you have to:

1. Install all necessery dependncies RPMs required by GuestAddition tools

# dnf install tar bzip2 kernel-devel-$(uname -r) kernel-headers perl gcc make elfutils-libelf-devel

# dnf -y install gcc automake make kernel-headers dkms bzip2 libxcrypt-compat kernel-devel perl

2. Run below semanage and restorecon commands

# semanage fcontext -d /opt/VBoxGuestAdditions-/other/mount.vboxsf
# restorecon /opt/VBoxGuestAdditions-/other/mount.vboxsf

3. Insert Virtualbox guest additions ISO and Run it

Devices -> Insert Guest Additions CD Image

Click Run button to exec Vbox_GAs_6.0.18 script or run it manually

or mount it manually with mount command and execute the VBoxLinuxAdditions.run to do so:

$ cd /run/media/`whoami`/VB*
$ su
# ./VBoxLinuxAdditions.run
Installing additional modules …
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel modules. This may take a while.
VirtualBox Guest Additions: Running kernel modules will not be replaced until the system is restarted
VirtualBox Guest Additions: Starting.

4. Reboot the VM

# reboot

5. Check and Confirm Virtualbox guest additions are properly installed and running

# lsmod | grep vbox
…

6. Enable Copy / Paste from to Virttual Machine e.g. Shared Clipboard / Shared Folder etc.

The three options most useful besides the support for FullScreen OS emulation by Virtualbox to enable right after
guesttools is on are:

1. Devices -> Shared Clipboard -> Bidirectional
2. Devices -> Drag and Drop -> Bidirectional
3. Devices -> Shared Folders -> Shared Folder Settings

Tags: additions, CentOS, copy paste, enable, fullscreen, installed, Installing, log, mount, org, Reboot, Redhat, resolution, sudo, support, vm
Posted in Linux, Various, Virtual Machines | No Comments »

KVM Virtual Machine RHEL 8.3 Linux install on Redhat 8.3 Linux Hypervisor with custom tailored kickstart.cfg

Friday, January 22nd, 2021

If you don't have tried it yet Redhat and CentOS and other RPM based Linux operationg systems that use anaconda installer is generating a kickstart file after being installed under /root/{anaconda-ks.cfg,initial-setup- ks.cfg,original-ks.cfg} immediately after the OS installation completes. Using this Kickstart file template you can automate installation of Redhat installation with exactly the same configuration as many times as you like by directly loading your /root/original-ks.cfg file in RHEL installer.

Here is the official description of Kickstart files from Redhat:

"The Red Hat Enterprise Linux installation process automatically writes a Kickstart file that contains the settings for the installed system. This file is always saved as /root/anaconda-ks.cfg. You may use this file to repeat the installation with identical settings, or modify copies to specify settings for other systems."

Kickstart files contain answers to all questions normally asked by the text / graphical installation program, such as what time zone you want the system to use, how the drives should be partitioned, or which packages should be installed. Providing a prepared Kickstart file when the installation begins therefore allows you to perform the installation automatically, without need for any intervention from the user. This is especially useful when deploying Redhat based distro (RHEL / CentOS / Fedora …) on a large number of systems at once and in general pretty useful if you're into the field of so called "DevOps" system administration and you need to provision a certain set of OS to a multitude of physical servers or create or recreate easily virtual machines with a certain set of configuration.

1. Create /vmprivate storage directory where Virtual machines will reside

First step on the Hypervisor host which will hold the future created virtual machines is to create location where it will be created:

[root@redhat ~]# lvcreate –size 140G –name vmprivate vg00
[root@redhat ~]# mkfs.ext4 -j -b 4096 /dev/mapper/vg00-vmprivate
[root@redhat ~]# mount /dev/mapper/vg00-vmprivate /vmprivate

To view what is the situation with Logical Volumes and VG group names:

[root@redhat ~]# vgdisplay -v|grep -i vmprivate -A7 -B7
Segments 1
Allocation inherit
Read ahead sectors auto
– currently set to 8192
Block device 253:0

— Logical volume —
LV Path /dev/vg00/vmprivate
LV Name vmprivate
VG Name vg00
LV UUID VVUgsf-FXq2-TsMJ-QPLw-7lGb-Dq5m-3J9XJJ
LV Write Access read/write
LV Creation host, time main.hostname.com, 2021-01-20 17:26:11 +0100
LV Status available
# open 1
LV Size 150.00 GiB

Note that you'll need to have the size physically available on a SAS / SSD Hard Drive physically connected to Hypervisor Host.

To make the changes Virtual Machines storage location directory permanently mounted add to /etc/fstab

/dev/mapper/vg00-vmprivate /vmprivate ext4 defaults,nodev,nosuid 1 2

[root@redhat ~]# echo '/dev/mapper/vg00-vmprivate /vmprivate ext4 defaults,nodev,nosuid 1 2' >> /etc/fstab

2. Second we need to install the following set of RPM packages on the Hypervisor Hardware host

[root@redhat ~]# yum install qemu-kvm qemu-img libvirt virt-install libvirt-client virt-manager libguestfs-tools virt-install virt-top -y

3. Enable libvirtd on the host

[root@redhat ~]# lsmod | grep -i kvm
[root@redhat ~]# systemctl enable libvirtd

4. Configure network bridging br0 interface on Hypervisor

In /etc/sysconfig/network-scripts/ifcfg-eth0 you need to include:

NM_CONTROLED=NO

Next use nmcli redhat configurator to create the bridge (you can use ip command instead) but since the tool is the redhat way to do it lets do it their way ..

[root@redhat ~]# nmcli connection delete eno3
[root@redhat ~]# nmcli connection add type bridge autoconnect yes con-name br0 ifname br0
[root@redhat ~]# nmcli connection modify br0 ipv4.addresses 10.80.51.16/26 ipv4.method manual
[root@redhat ~]# nmcli connection modify br0 ipv4.gateway 10.80.51.1
[root@redhat ~]# nmcli connection modify br0 ipv4.dns 172.20.88.2
[root@redhat ~]# nmcli connection add type bridge-slave autoconnect yes con-name eno3 ifname eno3 master br0
[root@redhat ~]# nmcli connection up br0

5. Prepare a working kickstart.cfg file for VM

Below is a sample kickstart file I've used to build a working fully functional Virtual Machine with Red Hat Enterprise Linux 8.3 (Ootpa) .

#version=RHEL8
#install
# Run the Setup Agent on first boot
firstboot --enable
ignoredisk --only-use=vda
# Use network installation
#url --url=http://hostname.com/rhel/8/BaseOS
##url --url=http://171.23.8.65/rhel/8/os/BaseOS
# Use text mode install
text
#graphical
# System language
#lang en_US.UTF-8
keyboard --vckeymap=us --xlayouts='us'
# Keyboard layouts
##keyboard us
lang en_US.UTF-8
# Root password
rootpw $6$gTiUCif4$YdKxeewgwYCLS4uRc/XOeKSitvDJNHFycxWVHi.RYGkgKctTMCAiY2TErua5Yh7flw2lUijooOClQQhlbstZ81 --iscrypted
# network-stuff
# place ip=your_VM_IP, netmask, gateway, nameserver hostname 
network --bootproto=static --ip=10.80.21.19 --netmask=255.255.255.192 --gateway=10.80.21.1 --nameserver=172.30.85.2 --device=eth0 --noipv6 --hostname=FQDN.VMhost.com --onboot=yes
# if you need just localhost initially configured uncomment and comment above
##network В --device=lo --hostname=localhost.localdomain
# System authorization information
authconfig --enableshadow --passalgo=sha512 --enablefingerprint
# skipx
skipx
# Firewall configuration
firewall --disabled
# System timezone
timezone Europe/Berlin
# Clear the Master Boot Record
##zerombr
# Repositories
## Add RPM repositories from KS file if necessery
#repo --name=appstream --baseurl=http://hostname.com/rhel/8/AppStream
#repo --name=baseos --baseurl=http://hostname.com/rhel/8/BaseOS
#repo --name=inst.stage2 --baseurl=http://hostname.com ff=/dev/vg0/vmprivate
##repo --name=rhsm-baseos В  В --baseurl=http://172.54.8.65/rhel/8/rhsm/x86_64/BaseOS/
##repo --name=rhsm-appstream --baseurl=http://172.54.8.65/rhel/8/rhsm/x86_64/AppStream/
##repo --name=os-baseos В  В  В --baseurl=http://172.54.9.65/rhel/8/os/BaseOS/
##repo --name=os-appstream В  --baseurl=http://172.54.8.65/rhel/8/os/AppStream/
#repo --name=inst.stage2 --baseurl=http://172.54.8.65/rhel/8/BaseOS
# Disk partitioning information set proper disk sizing
##bootloader --location=mbr --boot-drive=vda
bootloader --append=" crashkernel=auto tsc=reliable divider=10 plymouth.enable=0 console=ttyS0 " --location=mbr --boot-drive=vda
# partition plan
zerombr
clearpart --all --drives=vda --initlabel
part /boot --size=1024 --fstype=ext4 --asprimary
part swap --size=1024
part pv.01 --size=30000 --grow --ondisk=vda
##part pv.0 --size=80000 --fstype=lvmpv
#part pv.0 --size=61440 --fstype=lvmpv
volgroup s pv.01
logvol / --vgname=s --size=15360 --name=root --fstype=ext4
logvol /var/cache/ --vgname=s --size=5120 --name=cache --fstype=ext4 --fsoptions="defaults,nodev,nosuid"
logvol /var/log --vgname=s --size=7680 --name=log --fstype=ext4 --fsoptions="defaults,nodev,noexec,nosuid"
logvol /tmp --vgname=s --size=5120 --name=tmp --fstype=ext4 --fsoptions="defaults,nodev,nosuid"
logvol /home --vgname=s --size=5120 --name=home --fstype=ext4 --fsoptions="defaults,nodev,nosuid"
logvol /opt --vgname=s --size=2048 --name=opt --fstype=ext4 --fsoptions="defaults,nodev,nosuid"
logvol /var/log/audit --vgname=s --size=3072 --name=audit --fstype=ext4 --fsoptions="defaults,nodev,nosuid"
logvol /var/spool --vgname=s --size=2048 --name=spool --fstype=ext4 --fsoptions="defaults,nodev,nosuid"
logvol /var --vgname=s --size=7680 --name=var --fstype=ext4 --fsoptions="defaults,nodev,nosuid"
# SELinux configuration
selinux --disabled
# Installation logging level
logging --level=debug
# reboot automatically
reboot
###
%packages
@standard
python3
pam_ssh_agent_auth
-nmap-ncat
#-plymouth
#-bpftool
-cockpit
#-cryptsetup
-usbutils
#-kmod-kvdo
#-ledmon
#-libstoragemgmt
#-lvm2
#-mdadm
-rsync
#-smartmontools
-sos
-subscription-manager-cockpit
# Tune Linux vm.dirty_background_bytes (IMAGE-439)
# The following tuning causes dirty data to begin to be background flushed at
# 100 Mbytes, so that it writes earlier and more often to avoid a large build
# up and improving overall throughput.
echo "vm.dirty_background_bytes=100000000" >> /etc/sysctl.conf
# Disable kdump
systemctl disable kdump.service
%end

Important note to make here is the MD5 set root password string in (rootpw) line this string can be generated with openssl or mkpasswd commands :

Method 1: use openssl cmd to generate (md5, sha256, sha512) encrypted pass string

[root@redhat ~]# openssl passwd -6 -salt xyz test
$6$xyz$rjarwc/BNZWcH6B31aAXWo1942.i7rCX5AT/oxALL5gCznYVGKh6nycQVZiHDVbnbu0BsQyPfBgqYveKcCgOE0

Note: passing -1 will generate an MD5 password, -5 a SHA256 encryption and -6 SHA512 encrypted string (logically recommended for better security)

Method 2: (md5, sha256, sha512)

[root@redhat ~]# mkpasswd –method=SHA-512 –stdin

The option –method accepts md5, sha-256 and sha-512
Theoretically there is also a kickstart file generator web interface on Redhat's site here however I never used it myself but instead use above kickstart.cfg

6. Install the new VM with virt-install cmd

Roll the new preconfigured VM based on above ks template file use some kind of one liner command line like below:

[root@redhat ~]# virt-install -n RHEL8_3-VirtualMachine –description "CentOS 8.3 Virtual Machine" –os-type=Linux –os-variant=rhel8.3 –ram=8192 –vcpus=8 –location=/vmprivate/rhel-server-8.3-x86_64-dvd.iso –disk path=/vmprivate/RHEL8_3-VirtualMachine.img,bus=virtio,size=70 –graphics none –initrd-inject=/root/kickstart.cfg –extra-args "console=ttyS0 ks=file:/kickstart.cfg"

7. Use a tiny shell script to automate VM creation

For some clarity and better automation in case you plan to repeat VM creation you can prepare a tiny bash shell script:

#!/bin/sh
KS_FILE='kickstart.cfg';
VM_NAME='RHEL8_3-VirtualMachine';
VM_DESCR='CentOS 8.3 Virtual Machine';
RAM='8192';
CPUS='8';
# size is in Gigabytes
VM_IMG_SIZE='140';
ISO_LOCATION='/vmprivate/rhel-server-8.3-x86_64-dvd.iso';
VM_IMG_FILE_LOC='/vmprivate/RHEL8_3-VirtualMachine.img';

virt-install -n "$VMNAME" –description "$VM_DESCR" –os-type=Linux –os-variant=rhel8.3 –ram=8192 –vcpus=8 –location="$ISO_LOCATION" –disk path=$VM_IMG_FILE,bus=virtio,size=$IMG_VM_SIZE –graphics none –initrd-inject=/root/$KS_FILE –extra-args "console=ttyS0 ks=file:/$KS_FILE"

A copy of virt-install.sh script can be downloaded here

Wait for the installation to finish it should be visualized and if all installation is smooth you should get a login prompt use the password generated with openssl tool and test to login, then disconnect from the machine by pressing CTRL + ] and try to login via TTY with

[root@redhat ~]# virst list –all
Id Name State
—————————
2 RHEL8_3-VirtualMachine running

…

[root@redhat ~]# virsh console RHEL8_3-VirtualMachine

redhat8-login-prompt

One last thing I recommend you check the official documentation on Kickstart2 from CentOS official website

In case if you later need to destroy the VM and the respective created Image file you can do it with:

[root@redhat ~]# virsh destroy RHEL8_3-VirtualMachine
[root@redhat ~]# virsh undefine RHEL8_3-VirtualMachine

Don't forget to celebreate the success and give this nice article a credit by sharing this nice tutorial with a friend or by placing a link to it from your blog 🙂

Enjoy !

Tags: access, addresses, Administration, after, ALL, allows, and, Below, better security, cfg, connection, custom, file, installation, mount dev, need, Redhat, use, virtual machines, vm
Posted in Everyday Life, Linux, System Administration, Various, Virtual Machines | 2 Comments »

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Archive for the ‘Virtual Machines’ Category

1. Requirements to install and use WSL Linux emulation

2. List available installable Linux distributions

4. Install Debian GNU / Linux distribution as a second distro

5. List runnable / installed VM Linux distributions

6. Run and check recent installed Linux distribution version

7. Update the Debian distribuion packages to latest available

8. Install openssh server to be able to connect to the WSL hosted Virtual Machine

10. Enable systemd on Linux distribution in WSL 2

11. Setting extra useful variables to boot the WSL emulated Linux VM

12. Shutting down a running emulated Linux VM

Sum it up

1. Creating a KVM VM LIVE (running machine) backup

2. Listing backed-up snapshot content of KVM machine

3. Backup KVM only Virtual Machine data files (but not VM state) Live

4. KVM restore snapshot (backup)

5. Delete old unnecessery KVM VM backup

Devices -> Insert Guest Additions CD Image

1. Get information about the VM you would like to migrate to VMDK

2. Convert the harddrive to VMDK

3. Upload the new harddrive to the ESXi Hypervisor and adapt it to ESX

4. Create a VM and add the converted harddrive to the machine.

0. Check situation before the update on HVs / get VM IDs etc.

1. Dump VM definition XMs (to have it in case if it gets wiped during update)

2. Set on standby virt-mach-centos1 (virt-mach-centos1)

3. Stop VM virt-mach-centos1 & backup on Hypervisor host (hypervisor-host1) for VM1

4. Remove package version locks on all hosts

5. Do yum update virt-mach-centos1

6. Check if everything is running fine after upgrade

7. Stop VM virt-mach-centos2 & backup on Hypervisor host (hypervisor-host2)

8. Do yum update on virt-mach-centos2

9. Check if everything is running fine after upgrade

10. Stop VM vm-host2 & backup

11. Do yum update vm-host2

12. Check if everything is running fine after upgrade

13. Do yum update hypervisor-host2

14. Stop VM vm-host1 & backup

15. Do yum update vm-host2

16. Check if everything is running fine after upgrade

17. Do yum update hypervisor-host1

18. Check if everything is running fine after upgrade

19. Check if everything is running fine after upgrade

20. Check once more VMs and haproxy or any other contained services in VMs run as expected

21. Haproxy Unstandby virt-mach-centos1

22. If necessery to redefine VMs (in case they disappear from virsh) or virtuosso is not working

23. Set versionlock to RPMs to prevent accident updates and check OS version release

Other useful hints

The question comes then how can be the KVM VNC listener on TCP port 5900 be completely disabled?

1. Disable KVM VNC Port listener via VIRSH VM XML edit

2. Disable VNC KVM TCP port 5900 to a dynamic running VM without a machine reboot

Tracking the Problem of MAC duplicates on Linux routers

1. Fixing Linux ARP common well known Problems through disabling arp_announce / arp_ignore / send_redirects kernel variables disablement

2. Digging further the IP conflict / dulicate MAC Problems

3. What is MAC Randomization and where and how it is configured across different main operating systems as of year 2022?

4. Disable MAC Wi-Fi Ethernet device Randomization on Android

5. Disabling MAC Randomization on MAC iOS, iPhone, iPad, iPod

6. How to completely filter dhcp traffic between two network router hosts IP 192.168.0.1 / 192.168.1.1 to stop 2 or more configured DHCP servers on separate networks see each other

7. Filter out DHCP traffic based on MAC completely on Linux with arptables

1. Install all necessery dependncies RPMs required by GuestAddition tools

2. Run below semanage and restorecon commands

3. Insert Virtualbox guest additions ISO and Run it