OS

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Understanding basic nmcli in Rocky Linux 9

In Rocky Linux 9, the nmcli command-line tool (Network Manager Command Line) replaces the traditional ifcfg files that we have been using since Rocky Linux 8. If you can Google “Why nmcli is replacing the ifcfg”, you will find a comprehensive list of key reasons why the transition took place. One thing that I like best is this particular answer

nmcli commands are designed to be easily automated and scripted (e.g., using Ansible), offering better control and error checking (syntax validation) compared to generating flat text files through scripts.

Usage 1a: List the NetworkManager connection profiles

# nmcli con
NAME   UUID                                  TYPE      DEVICE 
ens33  xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx  ethernet  ens33  
lo     yyyyyyyy-yyyy-yyyy-yyyy-yyyyyyyyyyyy  loopback  lo

Usage 1b: List the Network Devices and their status

# nmcli dev
DEVICE  TYPE      STATE                   CONNECTION 
ens33   ethernet  connected               ens33      
lo      loopback  connected (externally)  lo        

Usage 2a: Disable the connection of ens33

# nmcli con down ens33
Connection 'ens33' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)

Usage 2b: Enable the connection of ens33

# nmcli con up ens33
Connection 'ens33' successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)

Usage 2c: Show Connection Details

# nmcli con show ens33
[root@hpc-wfly-rl9 ~]# nmcli con show ens33
connection.id:                          ens33
connection.uuid:                        817c4ac5-49f4-3752-9a16-9d7460bed1c9
connection.stable-id:                   --
connection.type:                        802-3-ethernet
connection.interface-name:              ens33
connection.autoconnect:                 yes
connection.autoconnect-priority:        -999
connection.autoconnect-retries:         -1 (default)
connection.multi-connect:               0 (default)
connection.auth-retries:                -1
connection.timestamp:                   1763952141
connection.permissions:                 --
connection.zone:                        --
connection.controller:                  --
connection.master:                      --
connection.slave-type:                  --
connection.port-type:                   --
connection.autoconnect-slaves:          -1 (default)
connection.autoconnect-ports:           -1 (default)
connection.down-on-poweroff:            -1 (default)
connection.secondaries:                 --
connection.gateway-ping-timeout:        0
connection.ip-ping-timeout:             0
connection.ip-ping-addresses:           --
connection.ip-ping-addresses-require-all:-1 (default)
connection.metered:                     unknown
connection.lldp:                        default
.....
.....

Usage 3: Set the static IP Address of the Ethernet Connection

# nmcli con mod ens33 ipv4.method manual ipv4.address 10.10.1.2/24 ipv4.gateway 10.10.1.1
# nmcli con up ens33

Usage 4a: Using conn to update DNS (replace manual scripting of /etc/resolv.conf)

# nmcli con mod ens33 ipv4.dns '8.8.8.8,8.8.8.4' 
# nmcli con show |grep dns
# nmcli con up ens33

At /etc/resolv.conf, you will notice

# Generated by NetworkManager
search myown.domain.com
nameserver 8.8.8.8
nameserver 8.8.8.4

Usage 4b: Using nmcli to update domain search (replace manual scripting of /etc/resolv.conf)

# nmcli con mod ens33 ipv4.dns-search 'myown.domain.com'
# nmcli con up ens33

Usage 5a: Disable IPv6 

# nmcli con mod ens33 ipv6.method "disabled"
# nmcli con up ens33
.....
....
ipv6.method:                            disabled
ipv6.dns:                               --
ipv6.dns-search:                        --
ipv6.dns-options:                       --
ipv6.dns-priority:                      0
ipv6.addresses:                         --
....
.....

Display the IP settings of the device. If there is no inet6 entry is displayed, IPv6 is disabled on the device.

# ip address show ens33
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
altname enp2s1
inet 192.168.x.x/19 brd 192.168.x.x scope global noprefixroute ens33
    valid_lft forever preferred_lft forever

References:

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Could not resolve host: mirrorlist.centos.org for CentOS-7

Issues:

If you need to install something for your EOL CentOS-7. For example to install CentOS_lm_sensors

Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=stock error was
14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"
http://mirror.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] curl#6 - "Could not resolve host: mirror.centos.org; Unknown error"
Trying other mirror.

Solutions:

Create a directory and save the original repo files before editing

# cd /etc/yum.repos.d
# mkdir original_repos
# copy -v *.repo original_repos

You will need to update the repofiles to point to vault.centos.org

sed -i s/mirror.centos.org/vault.centos.org/g /etc/yum.repos.d/*.repo
sed -i s/^#.*baseurl=http/baseurl=http/g /etc/yum.repos.d/*.repo
sed -i s/^mirrorlist=http/#mirrorlist=http/g /etc/yum.repos.d/*.repo
sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

Clean the old cache

# yum clean all

Let’s try installing lm_sensors using yum.

# yum install lm_sensors
# yum install lm_sensors-sensord
# sensors-detect
# watch -d sensors
# service sensord start
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Issues when Installing Dockers on Rocky Linux 8.10

I was installing dockers on Rocky Linux 8.10. These were my steps:

dnf config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
dnf install docker-ce docker-ce-cli containerd.io

I immediately got this error…..

Error: 
 Problem 1: problem with installed package podman-4:4.9.4-1.module+el8.10.0+1815+5fe7415e.x86_64
  - package podman-4:4.9.4-1.module+el8.10.0+1815+5fe7415e.x86_64 from @System requires runc >= 1.0.0-57, but none of the providers can be installed
  - package podman-4:4.9.4-1.module+el8.10.0+1815+5fe7415e.x86_64 from appstream requires runc >= 1.0.0-57, but none of the providers can be installed
  - package podman-4:4.9.4-1.module+el8.10.0+1825+623b0c20.x86_64 from appstream requires runc >= 1.0.0-57, but none of the providers can be installed
  - package podman-4:4.9.4-12.module+el8.10.0+1843+6892ab28.x86_64 from appstream requires runc >= 1.0.0-57, but none of the providers can be installed
  - package podman-4:4.9.4-13.module+el8.10.0+1871+e6fa1069.x86_64 from appstream requires runc >= 1.0.0-57, but none of the providers can be installed
  - package podman-4:4.9.4-13.module+el8.10.0+1874+ce489889.x86_64 from appstream requires runc >= 1.0.0-57, but none of the providers can be installed

To resolve the issues, do add the --allowerasing flag,

dnf install docker-ce docker-ce-cli containerd.io --allowerasing
================================================================================
 Package                   Arch   Version                Repository        Size
================================================================================
Installing:
 containerd.io             x86_64 1.6.32-3.1.el8         docker-ce-stable  35 M
     replacing  runc.x86_64 1:1.1.12-1.module+el8.10.0+1815+5fe7415e
 docker-ce                 x86_64 3:26.1.3-1.el8         docker-ce-stable  27 M
 docker-ce-cli             x86_64 1:26.1.3-1.el8         docker-ce-stable 7.8 M
Installing dependencies:
 libcgroup                 x86_64 0.41-19.el8            baseos            69 k
Installing weak dependencies:
 docker-buildx-plugin      x86_64 0.14.0-1.el8           docker-ce-stable  14 M
 docker-ce-rootless-extras x86_64 26.1.3-1.el8           docker-ce-stable 5.0 M
 docker-compose-plugin     x86_64 2.27.0-1.el8           docker-ce-stable  13 M
Removing dependent packages:
 buildah                   x86_64 1:1.34.0-1.module+el8.10.0+1815+5fe7415e
                                                         @AppStream        31 M
 cockpit-podman            noarch 84.1-1.module+el8.10.0+1815+5fe7415e
                                                         @AppStream       682 k
 containers-common         x86_64 2:1-81.module+el8.10.0+1815+5fe7415e
                                                         @AppStream       580 k
 podman                    x86_64 4:4.9.4-1.module+el8.10.0+1815+5fe7415e
                                                         @AppStream        52 M
 podman-catatonit          x86_64 4:4.9.4-1.module+el8.10.0+1815+5fe7415e
                                                         @AppStream       794 k

Transaction Summary
================================================================================
Install  7 Packages
Remove   5 Packages

Total download size: 102 M
Is this ok [y/N]: y

References:

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Using grubby to configure bootloader menu for Rocky Linux 8

grubby is a command line tool to configure bootloader menu entries for Linux. Here are some commands which you may find useful

List Kernels

# grubby --info=ALL | grep ^kernel
kernel="/boot/vmlinuz-4.18.0-553.16.1.el8_10.x86_64"
kernel="/boot/vmlinuz-4.18.0-513.18.1.el8_9.x86_64"
kernel="/boot/vmlinuz-4.18.0-425.3.1.el8.x86_64"
kernel="/boot/vmlinuz-0-rescue-1fd272f10209466d81c89276e275d210"

Check Defaults Loading 

# grubby --default-kernel
/boot/vmlinuz-4.18.0-553.16.1.el8_10.x86_64
# grubby --default-index
0

Change Default Loading

# grubby --set-default="/boot/vmlinuz-4.18.0-513.18.1.el8_9.x86_64"

Verify Default Loading

# grubby --default-kernel
/boot/vmlinuz-4.18.0-513.18.1.el8_9.x86_64
# grubby --default-index
1
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Troubleshooting Intel VMD Driver Boot Issue on Supermicro Server with Rocky Linux 8.7

I was installing Rocky Linux 8.7 on a Supermicro Server with Intel VirtualRAID. I could not boot to Rocky Linux 8.7, the Install Screen could not be presented. Instead, there are repeated errors like the one below on the screen.

“DMAR: [INTR-REMAP] Request device [bc:00.5] fault index 0x8000 [fault reason 0x25] Blocked a compatibility format interrupt request”

The Issue was explained in the Article from Intel “Unable to Boot RHEL* 8.7/9.0 if Intel® VMD Is Enabled for Intel® Virtual RAID on CPU (Intel® VROC) RAID Management”

Resolution
A problem with the inbox Intel®️ VMD driver included in RHEL 8.7 and 9.0 was identified, and it is necessary to add the boot parameter intremap=off to the kernel command line while installing the operating system. This will prevent the operating system from encountering any problems.

This particular issue has been fixed via a kernel update and has been implemented in RHEL 9.1.

it is necessary to add the boot parameter intremap=off to the kernel command line while installing the operating system

I tried Rocky Linux 8.9 and the issue was fixed.

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Enterprise Container Management Solutions – SuSE Rancher

What is SuSE Rancher?

Website: https://www.rancher.com/ (by SuSE)

Rancher Labs builds innovative, open source container management solutions for enterprises leveraging containers to accelerate software development and improve IT operations. The flagship product, Rancher, is a complete container management platform that makes it easy to manage all aspects of running containers in development and production environments, on any infrastructure. RancherOS is a minimalist Linux distribution which is perfect for running Docker containers at scale.

View on-demand recordings of past Rancher demos, online meetups, and Kubernetes tutorials at Rancher Youtube Channel. ( Rancher Labs )

This guide walks you through the process of adopting an enterprise container management platform (Dummies e-copy).

This guide will help security teams understand the attack surface for Kubernetes deployments and how attackers can exploit vulnerabilities. Get the e-copy of the Ultimate Guide to Kubernetes Security

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Red Hat has decided to stop making the source code of RHEL available to the public.

Important News: for All RedHat Derivative Users

Red Hat has decided to stop making the source code of RHEL available to the public. From now on it will only be available to customers — who can’t legally share it.

A superficially modest blog post from a senior Hatter announces that going forward, the company will only publish the source code of its CentOS Stream product to the world. In other words, only paying customers will be able to obtain the source code to Red Hat Enterprise Linux… And under the terms of their contracts with the Hat, that means that they can’t publish it.

The Register Red Hat strikes a crushing blow against RHEL downstreams