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How to keep your Linux server Healthy for Years: Hard learned lessons

Friday, November 28th, 2025

how-to-keep-your-linux-servers-healthy-every-year-doctor_tux

I’ve been running Linux servers long enough to watch hardware die, kernels panic, filesystems fill up at midnight hours, and network cards slowly burn out like old light bulbs.

Over time, you learn that keeping a server alive is less about “perfect architecture” and more about steady discipline – the small habits built to manage the machines, helps prevent big disasters.

Here are some practical, battle-tested lessons that keep my boxes running for years with minimal downtime. Most of them were learned the hard way.

1. Monitor Before You Fix – and Fix Before It Breaks

Most Linux disasters come from things we should have noticed earlier. The lack of monitoring, there is modern day saying that should become your favourite if you are a sysadmin or Dev Ops engineer.

"Monitoring everything !"

The disk that was at 89% yesterday will be at 100% tonight.
The log file that grew by 500 MB last week will explode this week.
The swap usage creeping from 1% → 5% → 20% means your next heavy task will choke.
The unseen failing BIOS CMOS battery
The RAID disks degradation etc.

You don’t need enterprise monitoring to prevent this. And even simple tools like monit or a simple zabbix-agent -> zabbix-server or any other simplistic scripted monitoring gives you a basic issues pre-warning.

Even a simple cronjob shell one liner can save you hours of further sh!t :

#!/bin/bash

df -h / | awk 'NR==2 { if($5+0 > 85) print "Disk Alert: / is at " $5 }' \
| mail -s "Disk Warning on $(hostname)" admin@example.com

2. Treat /etc directory as Sacred – Treat It Like an expensive gem

Every sysadmin eventually faces the nightmare of a broken config overwritten by a package update or a hasty command at 2 AM.

To avoid crying later, archive /etc automatically:

# tar czf /root/etc-$(date +%Y-%m-%d).tar.gz /etc

If you prefer the backup to be more sophisticated you can use my clone of the dirs_backup.sh (an old script I wrote for easifying backup of specific directories on the filesystem ) the etc_backup.sh you can get here.
Run it weekly via cron.
This little trick has saved me more times than I can count — especially when migrating between Debian releases or recovering from accidental edits.

3. Automate everything what you have to repeatevely do

If you find yourself doing something manually more than twice, script it and forget it.

Examples:

rotating logs for misbehaving apps
restarting services that occasionally get “stuck”
syncing backups between machines
cleaning temp directories

Here’s a small example I still use today:

#!/bin/bash

# Kill zombie PHP-FPM children that keep leaking memory

ps aux | grep php-fpm | awk '{if($6 > 300000) print $2}' | xargs -r kill -9

Dirty way to get rid of misfunctioning php-fpm ?
Yes. But it works.

4. Backups Don’t Exist Unless You Test Them

It’s easy to feel proud when you write a backup script.
It’s harder – and far more important – to test the restore.

Once a month or at least once in a few months, try restore a random backup to a dummy VM.
Sometimes backup might fails, or you might get something different from what you originally expected and by doing so
you can guarantee you will not cry later helplessly.

A broken backup doesn’t fail quietly – it fails on the day you need it most.

5. Don’t Ignore Hardware – It Ages like Everything Else

Linux might run forever, but hardware doesn’t.

Signs of impending doom:

dmesg spam with I/O errors
slow SSD response
increasing SMART reallocated sectors
random freezes without logs
sudden network flakiness

Run this monthly:

6. Document Everything (Future You Will Thank Past You)

There are moments when you ask yourself:

“Why did I configure this machine like this?”

If you don’t document your decisions, you’ll have no idea one year later.

A simple markdown file inside /root/notes.txt or /root/README.md is enough.

Document:

installed software
custom scripts
non-standard configs
firewall rules
weird hacks you probably forgot already

This turns chaos into something you can actually maintain.

7. Keep Things Simple – Complexity Is the Enemy of Uptime

The longer I work with servers, the more I strip away:

fewer moving parts
fewer services
fewer custom patches
fewer “temporary” hacks that become permanent

A simple system is a reliable system.
A complex one dies at the worst possible moment.

8. Accept That Failure Will Still Happen

No matter how careful you are, servers will surely:

crash
corrupt filesystems
lose network connectivity
inexplicably freeze
reboot after a kernel panic

Don’t aim for perfection.Aim for resilience.

If you can restore the machine in under an hour, you're winning and in the white.

Final Thoughts

Linux is powerful – but it rewards those who treat it with respect and perseverance.
Over many years, I’ve realized that maintaining servers is less about brilliance and more about humble, consistent care and hard work persistence.

I hope this article helps some sysamdmin to rethink and rebundle servers maintenance strategy in a way that will avoid a server meltdown at night hours like 3 AM.

Cheers !

Tags: doesn, doom, hardware, How to, machines, need, restore, running, scripts, servers, services, simple, something, today, years
Posted in Linux, System Administration, Various | No Comments »

Migrating Server environments to Docker Containers a brief step-by-step guide

Wednesday, November 12th, 2025

migrating-server--applications-environment-to-docker-containers

In modern IT environments, containerization has become an essential strategy for improving application portability, scalability, and consistency. Docker, as a containerization platform, allows you to package applications and their dependencies into isolated containers that can be easily deployed across different environments. Migrating an existing server environment into Docker containers is a common scenario, and this guide will walk you through the key steps of doing so.

Why Migrate to Docker?

Before we dive into the specifics, let’s briefly understand why you might want to migrate your server environment to Docker:

Portability: Containers encapsulate applications and all their dependencies, making them portable across any system running Docker.
Scalability: Containers are lightweight and can be scaled up or down easily, offering flexibility to handle varying loads.
Consistency: With Docker, you can ensure that your application behaves the same in development, testing, and production.
Isolation: Docker containers run in isolation from the host system, minimizing the risk of configuration conflicts.

Steps to Migrate a Server Environment into Docker

Migrating an environment of servers into Docker typically involves several steps: evaluating the current setup, containerizing applications, managing dependencies, and orchestrating deployment. Here’s a breakdown:

1. Evaluate the Existing Server Environment

Before migrating, it's essential to inventory the current server environment to understand the following:

The applications running on the servers
Dependencies (e.g., databases, third-party services, libraries, etc.)
Networking setup (e.g., exposed ports, communication between services)
Storage requirements (e.g., persistent data, volumes)
Security concerns (e.g., user permissions, firewalls)

For example, if you're running a web server with a backend database and some caching layers, you'll need to break down these services into their constituent parts so they can be containerized.

2. Containerize the Application

The next step is to convert the services running on your server into Docker containers. Docker containers require a Dockerfile, which is a blueprint for how to build and run the container. Let's walk through an example of containerizing a simple web application.

Example: Migrating a Simple Node.js Web Application

Assume you have a Node.js application running on your server. To containerize it, you need to:

Create a Dockerfile
Build the Docker image
Run the containerized application

2.1. Write a Dockerfile

A Dockerfile defines how your application will be built within a Docker container. Here’s an example for a Node.js application:

# Step 1: Use the official Node.js image as a base image FROM node:16

# Step 2: Set the working directory inside the container WORKDIR /usr/src/app # Step 3: Copy package.json and package-lock.json to the container COPY package*.json ./

# Step 4: Install dependencies inside the container RUN npm install

# Step 5: Copy the rest of the application code to the container COPY . .

# Step 6: Expose the port that the application will listen on EXPOSE 3000

# Step 7: Start the application CMD ["npm", "start"]

This Dockerfile:

Uses the official node:16 image as a base.
Sets the working directory inside the container to /usr/src/app.
Copies the package.json and package-lock.json files to the container and runs npm install to install dependencies.
Copies the rest of the application code into the container.
Exposes port 3000 (assuming that’s the port your app runs on).
Defines the command to start the application.

2.2: Build the Docker Image

Once the Dockerfile is ready, build the Docker image using the following command:

# docker build -t my-node-app .

This command tells Docker to build the image using the current directory (.) and tag it as my-node-app.

2.3: Run the Docker Container

After building the image, you can run the application as a Docker container:

# docker run -p 3000:3000 -d my-node-app

This command:

Maps port 3000 from the container to port 3000 on the host machine.
Runs the container in detached mode (-d).

3. Handling Dependencies and Services

If your server environment includes multiple services (e.g., a database, caching layer, or message queue), you'll need to containerize those as well. Docker Compose can help you define and run multi-container applications.

Example: Dockerizing a Node.js Application with MongoDB

To run both the Node.js application and a MongoDB database, you’ll need a docker-compose.yml file.

Create a docker-compose.yml file in your project directory:

version: '3'

services:
web:
build: .
ports:
– "3000:3000"
depends_on:
– db
db:
image: mongo:latest
volumes:
– db-data:/data/db
networks:
– app-network

volumes:
db-data:

networks:
app-network:
driver: bridge

This docker-compose.yml file:

Defines two services: web (the Node.js app) and db (the MongoDB container).
The depends_on directive ensures the database service starts before the web application.
Uses a named volume (db-data) for persistent data storage for MongoDB.
Defines a custom network (app-network) for communication between the two containers.

3.1. Start Services with Docker Compose

To start the services defined in docker-compose.yml, use the following command:

# docker-compose up -d

This command will build the web service (Node.js app), pull the MongoDB image, create the necessary containers, and run them in the background.

4. Manage Data Persistence

Containers are ephemeral by design, meaning data stored inside a container is lost when it stops or is removed. To persist data across container restarts, you’ll need to use volumes.

In the example above, the MongoDB service uses a named volume (db-data) to persist the database data. Docker volumes allow you to:

Persist data on the host machine outside of the container.
Share data between containers.

To check if the volume is created and inspect its usage, use:

# docker volume ls # docker volume inspect db-data

5. Networking Between Containers

In Docker, containers communicate with each other over a network. By default, Docker Compose creates a network for each application defined in a docker-compose.yml file. Containers within the same network can communicate with each other using container names as hostnames.

For example, in the docker-compose.yml above:

The web container can access the db container using db:27017 as the database URL (MongoDB's default port).

6. Scaling and Orchestrating with Docker Swarm or Kubernetes

If you need to scale your application to multiple instances or require orchestration, Docker Swarm and Kubernetes are the two most popular container orchestration platforms.

Docker Swarm:

Built into Docker, Swarm allows you to easily manage a cluster of Docker nodes and scale your containers across multiple machines. To initialize a swarm:

# docker swarm init

Kubernetes:

Kubernetes is a powerful container orchestration tool that provides high availability, automatic scaling, and management of containerized applications. If you’re migrating a more complex server environment, Kubernetes will offer additional features like rolling updates, automatic recovery, and more sophisticated networking options.

7. Security and Permissions

When migrating to Docker, it's important to pay attention to security best practices, such as:

Running containers with the least privileges (using the USER directive in the Dockerfile).
Using multi-stage builds to keep the image size small and reduce the attack surface.
Regularly scanning Docker images for known vulnerabilities using tools like Anchore, Trivy, or Clair.
Configuring network isolation for sensitive services.

Conclusion

Migrating a server environment into Docker containers involves more than just running an application in isolation. It requires thoughtful planning around dependencies, data persistence, networking, scaling, and security. By containerizing services with Docker, you can create portable, scalable, and consistent environments that streamline both development and production workflows.

By following the steps outlined in this guide—writing Dockerfiles, using Docker Compose for multi-container applications, and ensuring data persistence—you can successfully migrate your existing server environment into a Dockerized architecture. For larger-scale environments, consider leveraging orchestration tools like Docker Swarm or Kubernetes to manage multiple containerized services across a cluster.

Tags: applications, Configuring, created, dependencies, Docker Containers, inside, js, Maps, Migrating Server, need, Networking, running, services, using
Posted in Docker, Linux, System Administration, System Optimization | No Comments »

Unlocking the Power of lnav: Logfile Navigator – ncurses text based tool guide to mutiple Logs on multiple servers easy analysis on Linux

Saturday, September 13th, 2025

If you've ever found yourself buried under a mountain of log files, tailing multiple outputs, or grepping through endless lines trying to spot an error, it's time to meet your new best friend: lnav, the Logfile Navigator.

Lightweight, terminal-based, and surprisingly powerful, lnav is one of the most underrated tools for developers, sysadmins, and anyone who regularly digs into logs. It turns your chaotic logs into something that’s not only readable—but genuinely useful.

What is lnav and why use it ?

lnav (Logfile Navigator) is a command-line tool for viewing and analyzing log files. It goes beyond tail, less, or grep by:

Automatically detecting and merging log formats.
Highlighting timestamps, log levels, and errors.
Providing SQL-like queries over your logs.
Offering interactive navigation with a UI inside the terminal.

And yes, all of that without needing to set up a database or a server.

1. Installing lnav on Linux

Installation is straightforward. On most systems, you can install it via package managers:

On Ubuntu/Debian:

# apt install lnav

On Fedora:

# dnf install lnav

On Arch Linux:

# pacman -S lnav

Or build from source via GitHub if you want the latest version.

2. Use lnav Instead of Tail / Grep why?

Traditional tools are powerful, but they require manual work to chain together functionality. lnav gives you:

Automatic multi-log parsing: Drop multiple logs in, and it merges them chronologically.
Syntax highlighting: Errors and warnings stand out.
SQL querying: Run queries like SELECT * FROM syslog_log WHERE log_level = 'error';
Filtering and searching: Use intuitive filters and bookmarks to highlight specific entries.

3. Basic tool Usage is simple

Let’s say you want to inspect a system log:

# lnav /var/log/syslog

You'll immediately get:

Color-coded output (timestamps, levels, messages).
Scrollable view (arrow keys, PgUp, PgDn).
Real-time updates (like tail -f).
Search with /, filter with :filter-in, and even SQL queries.

Lets say you need to analyze Apache webserver logs recursively including the logs already rotated and gunzipped with *.gz extension on CentOS / Fedora / RHEL, you can do it with:

# lnav -r /var/log/httpd

You can parse the log file and get additional information about requests as well as you can print overall summary of log file.

Choose the line you want to parse. The selected line is always the one at the top of the window. Then press 'p' and you should see the following result:

Now, if you want to see a summary view of the logs by date and time, simply press 'i'.

To quit a screen you have chosen press 'q'.

4. LNAV helpful options and hotkeys

Once you've opened a log file/s for analyze you can use few hotkeys that will allow us to move through the output of lnav and the available views more easily:

e or E to jump to the next / previous error message.
w or W to jump to the next / previous warning message.
b or Backspace to move to the previous page.
Space to move to the next page.
g or G to move to the top / bottom of the current view.

To take a closer look at the way lnav operates, use -d option, the debug information is to be spit inside a .txt file:

# lnav /var/log/httpd -d lnav.txt

In this example, the debug information that is generated when lnav starts will be written to a file named lnav.txt inside the current working directory.

5. Real-World Use Cases

a. Troubleshooting application or system process Crashes

Open all relevant logs in one go:

# lnav /var/log/*.log

Errors are highlighted, and you can jump between them with n / N kbd keys.

b. Combining Multiple Logs

Working with an app that logs to different files and you need to combine:

# lnav /var/log/nginx/access.log /var/log/nginx/error.log

Or lets say you want to combine Apache Webserver with Haproxy log and get log summaries or filter out stuff:

# lnav /var/log/apache2/access.log /var/log/haproxy.log

Now you will get a single, chronological timeline of events.

If you want to Search for a concrete occurance of Error / Warning or IP address inside a bunch of loaded combined logs you can do it with the same command like in simple vim by pressing / (slash) from kbd and type out what you want to filter out to get shown.

c. Analyze SQL Queries Logs

Yes, you can actually do this by passing it query in its command prompt :

:.schema
:SELECT log_time, log_level, log_message FROM syslog_log WHERE log_level = 'error';

You get a table of filtered logs, sortable by columns.

6. lnav more usage command tips

:help — Opens the help menu.
:filter-in <string> — Show only lines matching <string>.
:filter-out <string> — Hide lines matching <string>.
:export-to <filename> — Export current view to a file.
:tag <tagname> — Tag lines for later reference.
q — Quit (but why would you want to?).

7. Using lnav as a pager for systemd-journald

# journalctl | lnav
# journalctl -f | lnav
# journalctl -u ssh.service | lnav

8. Use lnav to review remote ssh logs

Newer versions after 0.10 supports ssh protocol as well and theoretically should work:

# lnav user@server-name-here:/var/log/file.log

To read all logs inside /var/log

# lnav root@server-name-here:/var/log/
# lnav root@server-name-here:/var/log/*.err

9. Using lnav to view docker container logs

# docker logs 811ab84aa95l | lnav
# docker logs -f application | lnav

The latest version of lnav supports even the following simplified docker:// URL syntax:

# lnav docker://{container_id_or_name}/dir_path/to/log/file
# lnav docker://{container_id_or_name}/var/dir_path/log
# lnav docker://application/var/log/
# lnav docker://applcation/var/log/nginx/nginx.app.log

10. Monitoring compilation and command output useful for developers

Compilation from archived tar balls with ./configure && make etc. generate lot of outputs and logs while working.
Here is where the tool can come handy.
For example, here is how to watch the output of make command when compiling something:

# lnav -e './configure && make'

11. Learning lnav tool through online ssh service availability via lnav.org

f you're lazy to install it and want to test it anyways:

# Start The Basic Tutorial:
ssh -o PubkeyAuthentication=no -o PreferredAuthentications=password tutorial1@demo.lnav.org

# Playground:
ssh -o PubkeyAuthentication=no -o PreferredAuthentications=password playground@demo.lnav.org

Closure

While tools like Kibana, Grafana, and ELK stacks are powerful, they can be overkill for many use cases—especially when you're SSHed into a box and just need to get answers fast. That’s where lnav shines as it is fast, lightweight, visual and can be used offline.

If you’re a developer, sysadmin, SRE (Site Reliability Engineer), or just someone who cares about logs, give lnav a spin. It might just become among your favorite sysadm tools on Linux and safe you pretty much of time if you have to do log reading and analyzing on daily basis (for example if you're admining 20+ or more Linux servers.

Tags: about, access, command, help menu, Installing, linux?, log files, Logfile Navigator, Monitoring, move, need, nginx, Open, org, Search, servers, Space, use, var, view
Posted in Linux, Monitoring, System Administration, Various | No Comments »

How To Install ChatGPT on Debian Linux with snap

Tuesday, August 19th, 2025

chatgpt-desktop-linux-screenshot

To install ChatGPT (official desktop app) on Debian Linux using Snap, do the following:
You need as

Prerequisites

Debian-based system (e.g., Debian, Ubuntu, Mint whatever deb based Linux).
Snap package manager installed.

1. Install Snap (if not installed)

Run these commands in your terminal:

# apt update sudo apt install snapd

Enable and start the Snap daemon:

# systemctl enable snapd sudo systemctl start snapd

Create a symbolic link to ensure

snap

is accessible:

# ln -s /var/lib/snapd/snap /snap

2. Find ChatGPT Snap Package

The official ChatGPT desktop app (by OpenAI) is not available as a Snap package directly from OpenAI, but a third-party Snap package or wrapper may exist.

You can search with:

# snap find chatgpt

As of now, you might see unofficial community packages (e.g.,

chatgpt-desktop

chatgpt-wrapper

, etc.).

3. Install ChatGPT Snap Package

If you find a package (e.g., chatgpt-desktop), install it like this:

# snap install chatgpt-desktop

Note: Be cautious about third-party Snap packages—review the publisher and permissions.

4.Launch ChatGPT

Once installed, launch it from your app menu or run:

/snap/bin/chatgpt-desktop-client

Alternative (if no Snap available)

If no Snap package is available or you're uncomfortable with third-party sources:

Option: Use the Official .deb Installer

OpenAI released an official desktop app for Linux in

.deb

format:

To use the native deb;

Download from: https://openai.com/chat
Install with:

# apt install ./chatgpt_*.deb

Tags: about, alternative, and, available, based, bin, Chat, com, Commands, community, create, daemon, deb, Debian, debian linux, Desktop, download, enable, find, format, how, How to, installed, need, official, packages, sudo, systemctl, update
Posted in AI on Linux, Linux, Various | No Comments »

How to RIP audio CD and convert to MP3 format on Linux

Thursday, April 11th, 2024

I've been given a very tedious task to Copy music from Audio CD Drive to MP3 / MP4 file format and then copy the content to external Flash drive.
Doing so is pretty trivial, you just need to have a CD / DVD rom on your computer something that becomes rare nowadays and then you need to have installed a bunch of software, if you don't already have it as i've pointed in my previous article Howto craete Music Audio CD from MP3 files, create playable WAV format audio CD Albums from MP3s.

Creating a Audio CD from an MP3 collection is exactly the opposite to what is aim't now (to copy the content of a CD to a computer and prepare it for A Car MP3 player).

1. RIPing audio CDs to WAV and Conver to MP3 from terminal

On Linux there is many ways to do it and many tools that can do it for your both graphical and command line.
But as I prefer command line to do stuff, in this article I'll mention the quickest and most elementary one which is done in 2 steps.

1. Use a tool to dump the CD Audio music to Tracks in WAV format
2. Convert the WAV to MP3 format

We'll need cdparanoia tool installed as well as ffmpeg.

If you don't have them installed do:

# apt-get install –yes cdparanoia dvd+rw-tools cdw cdrdao audiotools cdlabelgen dvd+rw-tools wodim ffmpeg lame normalize-audio libavcodec58

Next create the directory where you want to dump the .wav files.

# mkdir /home/hipo/audiorip/cd1
# cd /home/hipo/audiorip/cd1

Next assumng the Audio CD is plugged in the CD reader, dump its full content into track*.WAV files with cmd:

# paranoia -B

This will produce you the dumped songs into .wav files.

hipo@noah:~/audiorip/cd1$ ls -al *.wav
-rw-r–r– 1 root root 10278284 мар 25 22:49 track01.cdda.wav
-rw-r–r– 1 root root 21666668 мар 25 22:50 track02.cdda.wav
-rw-r–r– 1 root root 88334108 мар 25 22:53 track03.cdda.wav
-rw-r–r– 1 root root 53453948 мар 25 22:55 track04.cdda.wav
-rw-r–r– 1 root root 100846748 мар 25 22:58 track05.cdda.wav
-rw-r–r– 1 root root 41058908 мар 25 22:59 track06.cdda.wav
-rw-r–r– 1 root root 105952940 мар 25 23:02 track07.cdda.wav
-rw-r–r– 1 root root 50074124 мар 25 23:03 track08.cdda.wav
-rw-r–r– 1 root root 92555948 мар 25 23:06 track09.cdda.wav
-rw-r–r– 1 root root 61939964 мар 25 23:07 track10.cdda.wav
-rw-r–r– 1 root root 8521340 мар 25 23:07 track11.cdda.wav

Then you can use a simple for loop with ffmpeg command to conver the .wav files to .mp3s.

hipo@noah:~/audiorip/cd1$ for i in $( ls -1 *); do ffmpeg -i $i $i.wav.mp3; done

ffmpeg version 1.2.12 Copyright (c) 2000-2015 the FFmpeg developers
built on Feb 12 2015 18:03:16 with gcc 4.7 (Debian 4.7.2-5)
configuration: –prefix=/usr –extra-cflags='-g -O2 -fstack-protector –param=ssp-buffer-size=4 -Wformat -Werror=format-security ' –extra-ldflags='-Wl,-z,relro' –cc='ccache cc' –enable-shared –enable-libmp3lame –enable-gpl –enable-nonfree –enable-libvorbis –enable-pthreads –enable-libfaac –enable-libxvid –enable-postproc –enable-x11grab –enable-libgsm –enable-libtheora –enable-libopencore-amrnb –enable-libopencore-amrwb –enable-libx264 –enable-libspeex –enable-nonfree –disable-stripping –enable-libvpx –enable-libschroedinger –disable-encoder=libschroedinger –enable-version3 –enable-libopenjpeg –enable-librtmp –enable-avfilter –enable-libfreetype –enable-libvo-aacenc –disable-decoder=amrnb –enable-libvo-amrwbenc –enable-libaacplus –libdir=/usr/lib/x86_64-linux-gnu –disable-vda –enable-libbluray –enable-libcdio –enable-gnutls –enable-frei0r –enable-openssl –enable-libass –enable-libopus –enable-fontconfig –enable-libpulse –disable-mips32r2 –disable-mipsdspr1 –dis libavutil      52. 18.100 / 52. 18.100
libavcodec     54. 92.100 / 54. 92.100
libavformat    54. 63.104 / 54. 63.104
libavdevice    54. 3.103 / 54. 3.103
libavfilter     3. 42.103 / 3. 42.103
libswscale      2. 2.100 / 2. 2.100
libswresample   0. 17.102 / 0. 17.102
libpostproc    52. 2.100 / 52. 2.100
[wav @ 0x66c900] max_analyze_duration 5000000 reached at 5015510 microseconds
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'track01.cdda.wav':
Duration: 00:00:23.19, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s
Output #0, mp3, to 'track01.cdda.wav.wav.mp3':
Metadata:
    TSSE            : Lavf54.63.104
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s16le -> libmp3lame)
Press [q] to stop, [?] for help
size=     363kB time=00:00:23.19 bitrate= 128.2kbits/s
video:0kB audio:363kB subtitle:0 global headers:0kB muxing overhead 0.058402%
ffmpeg version 1.2.12 Copyright (c) 2000-2015 the FFmpeg developers
built on Feb 12 2015 18:03:16 with gcc 4.7 (Debian 4.7.2-5)
configuration: –prefix=/usr –extra-cflags='-g -O2 -fstack-protector –param=ssp-buffer-size=4 -Wformat -Werror=format-security ' –extra-ldflags='-Wl,-z,relro' –cc='ccache cc' –enable-shared –enable-libmp3lame –enable-gpl –enable-nonfree –enable-libvorbis –enable-pthreads –enable-libfaac –enable-libxvid –enable-postproc –enable-x11grab –enable-libgsm –enable-libtheora –enable-libopencore-amrnb –enable-libopencore-amrwb –enable-libx264 –enable-libspeex –enable-nonfree –disable-stripping –enable-libvpx –enable-libschroedinger –disable-encoder=libschroedinger –enable-version3 –enable-libopenjpeg –enable-librtmp –enable-avfilter –enable-libfreetype –enable-libvo-aacenc –disable-decoder=amrnb –enable-libvo-amrwbenc –enable-libaacplus –libdir=/usr/lib/x86_64-linux-gnu –disable-vda –enable-libbluray –enable-libcdio –enable-gnutls –enable-frei0r –enable-openssl –enable-libass –enable-libopus –enable-fontconfig –enable-libpulse –disable-mips32r2 –disable-mipsdspr1 –dis libavutil      52. 18.100 / 52. 18.100
libavcodec     54. 92.100 / 54. 92.100
libavformat    54. 63.104 / 54. 63.104
libavdevice    54. 3.103 / 54. 3.103
libavfilter     3. 42.103 / 3. 42.103
libswscale      2. 2.100 / 2. 2.100
libswresample   0. 17.102 / 0. 17.102
libpostproc    52. 2.100 / 52. 2.100
[mp3 @ 0x66c900] max_analyze_duration 5000000 reached at 5015510 microseconds
Input #0, mp3, from 'track01.cdda.wav.mp3':
Metadata:
    encoder         : Lavf54.63.104
Duration: 00:00:23.22, start: 0.000000, bitrate: 128 kb/s
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 128 kb/s
File 'track01.cdda.wav.mp3.wav.mp3' already exists. Overwrite ? [y/N] y
Output #0, mp3, to 'track01.cdda.wav.mp3.wav.mp3':
Metadata:
    TSSE            : Lavf54.63.104
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p
Stream mapping:
Stream #0:0 -> #0:0 (mp3 -> libmp3lame)
Press [q] to stop, [?] for help
Trying to remove 1152 samples, but the queue is emptys
size=     363kB time=00:00:23.24 bitrate= 128.1kbits/s
video:0kB audio:363kB subtitle:0 global headers:0kB muxing overhead 0.058336%
ffmpeg version 1.2.12 Copyright (c) 2000-2015 the FFmpeg developers
built on Feb 12 2015 18:03:16 with gcc 4.7 (Debian 4.7.2-5)
configuration: –prefix=/usr –extra-cflags='-g -O2 -fstack-protector –param=ssp-buffer-size=4 -Wformat -Werror=format-security ' –extra-ldflags='-Wl,-z,relro' –cc='ccache cc' –enable-shared –enable-libmp3lame –enable-gpl –enable-nonfree –enable-libvorbis –enable-pthreads –enable-libfaac –enable-libxvid –enable-postproc –enable-x11grab –enable-libgsm –enable-libtheora –enable-libopencore-amrnb –enable-libopencore-amrwb –enable-libx264 –enable-libspeex –enable-nonfree –disable-stripping –enable-libvpx –enable-libschroedinger –disable-encoder=libschroedinger –enable-version3 –enable-libopenjpeg –enable-librtmp –enable-avfilter –enable-libfreetype –enable-libvo-aacenc –disable-decoder=amrnb –enable-libvo-amrwbenc –enable-libaacplus –libdir=/usr/lib/x86_64-linux-gnu –disable-vda –enable-libbluray –enable-libcdio –enable-gnutls –enable-frei0r –enable-openssl –enable-libass –enable-libopus –enable-fontconfig –enable-libpulse –disable-mips32r2 –disable-mipsdspr1 –dis libavutil      52. 18.100 / 52. 18.100
libavcodec     54. 92.100 / 54. 92.100
libavformat    54. 63.104 / 54. 63.104
libavdevice    54. 3.103 / 54. 3.103
libavfilter     3. 42.103 / 3. 42.103
libswscale      2. 2.100 / 2. 2.100
libswresample   0. 17.102 / 0. 17.102
libpostproc    52. 2.100 / 52. 2.100
[mp3 @ 0x66c900] max_analyze_duration 5000000 reached at 5015510 microseconds
Input #0, mp3, from 'track01.cdda.wav.mp3.wav.mp3':
Metadata:
    encoder         : Lavf54.63.104
Duration: 00:00:23.25, start: 0.000000, bitrate: 128 kb/s
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p, 128 kb/s
Output #0, mp3, to 'track01.cdda.wav.mp3.wav.mp3.wav.mp3':
Metadata:
    TSSE            : Lavf54.63.104
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p
Stream mapping:
Stream #0:0 -> #0:0 (mp3 -> libmp3lame)
Press [q] to stop, [?] for help
Trying to remove 1152 samples, but the queue is emptys
size=     364kB time=00:00:23.27 bitrate= 128.1kbits/s
video:0kB audio:364kB subtitle:0 global headers:0kB muxing overhead 0.058271%
ffmpeg version 1.2.12 Copyright (c) 2000-2015 the FFmpeg developers
built on Feb 12 2015 18:03:16 with gcc 4.7 (Debian 4.7.2-5)
configuration: –prefix=/usr –extra-cflags='-g -O2 -fstack-protector –param=ssp-buffer-size=4 -Wformat -Werror=format-security ' –extra-ldflags='-Wl,-z,relro' –cc='ccache cc' –enable-shared –enable-libmp3lame –enable-gpl –enable-nonfree –enable-libvorbis –enable-pthreads –enable-libfaac –enable-libxvid –enable-postproc –enable-x11grab –enable-libgsm –enable-libtheora –enable-libopencore-amrnb –enable-libopencore-amrwb –enable-libx264 –enable-libspeex –enable-nonfree –disable-stripping –enable-libvpx –enable-libschroedinger –disable-encoder=libschroedinger –enable-version3 –enable-libopenjpeg –enable-librtmp –enable-avfilter –enable-libfreetype –enable-libvo-aacenc –disable-decoder=amrnb –enable-libvo-amrwbenc –enable-libaacplus –libdir=/usr/lib/x86_64-linux-gnu –disable-vda –enable-libbluray –enable-libcdio –enable-gnutls –enable-frei0r –enable-openssl –enable-libass –enable-libopus –enable-fontconfig –enable-libpulse –disable-mips32r2 –disable-mipsdspr1 –dis libavutil      52. 18.100 / 52. 18.100
libavcodec     54. 92.100 / 54. 92.100
libavformat    54. 63.104 / 54. 63.104
libavdevice    54. 3.103 / 54. 3.103
libavfilter     3. 42.103 / 3. 42.103
libswscale      2. 2.100 / 2. 2.100
libswresample   0. 17.102 / 0. 17.102
libpostproc    52. 2.100 / 52. 2.100
[wav @ 0x66c900] max_analyze_duration 5000000 reached at 5015510 microseconds
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, wav, from 'track02.cdda.wav':
Duration: 00:02:21.28, bitrate: 1411 kb/s
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s
Output #0, mp3, to 'track02.cdda.wav.wav.mp3':
Metadata:
    TSSE            : Lavf54.63.104
    Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16p
Stream mapping:
Stream #0:0 -> #0:0 (pcm_s16le -> libmp3lame)
Press [q] to stop, [?] for help
…

Finally remove the old unneded .wav files and enjoy the mp3s with vlc / mplayer / mpg123 or whatever player you like.

hipo@noah:~/audiorip/cd1$ rm -f *.wav

Now mount the flash drive and copy th files into it.

# mkdir /media/usb-drive
# mount /dev/sdc1 /media/usb-drive/
# mkdir -p /media/usb-drive/cd1
# fdisk -l |grep -i sdc1
/dev/sdc1 on /media/usb-drive type vfat (rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=utf8,shortname=mixed,errors=remount-ro

# cp -rpf ~/audiorip/cd1*.mp3 /mnt/usb-drive/cd1
# umount /dev/sdc1

2. RIPping audio CD on Linux with rip-audio-cds-linux.sh script

#!/bin/bash
# A simple shell script to rip audio cd and create mp3 using lame
# and cdparanoia utilities.
# —————————————————————————-
# Written by Vivek Gite <http://www.cyberciti.biz/>
# (c) 2006 nixCraft under GNU GPL v2.0+
# —————————————————————————-
read -p "Starting in 5 seconds ( to abort press CTRL + C ) " -t 5
cdparanoia -B
for i in *.wav
do
lame –vbr-new -b 360 "$i" "${i%%.cdda.wav}.mp3"
rm -f "$i"
done

If you need to automate the task of dumping the audio CDs to WAV and convert them to MP3s you can do it via a small shell script like the one provided by cyberciti.biz that uses paranoia and lame commands in a shell script loop. Script rip-audio-cds-linux.sh is here

3. Dump Audio CD to MP3 with Graphical program ( ripperx )

By default most modern Linux distributions including the Debian GNU / Linux based ones has the ripperx in the default repositories, as well as the tool is downloadable and compilable from source from sourceforge.net

ripping-audio-cds-linux-graphical-program-ripperx-tool

# apt-cache show ripperx|grep -i descript -A3 -B3
Architecture: amd64
Depends: cdparanoia, vorbis-tools (>= 1.0beta3), libatk1.0-0 (>= 1.12.4), libc6 (>= 2.14), libcairo2 (>= 1.2.4), libfontconfig1 (>= 2.12.6), libfreetype6 (>= 2.2.1), libgcc1 (>= 1:3.0), libgdk-pixbuf2.0-0 (>= 2.22.0), libglib2.0-0 (>= 2.16.0), libgtk2.0-0 (>= 2.8.0), libpango-1.0-0 (>= 1.14.0), libpangocairo-1.0-0 (>= 1.14.0), libpangoft2-1.0-0 (>= 1.14.0), libstdc++6 (>= 5.2), libtag1v5 (>= 1.9.1-2.2~)
Suggests: sox, cdtool, mpg321, flac, toolame
Description-en: GTK-based audio CD ripper/encoder
ripperX is a graphical interface for ripping CD audio tracks (using
cdparanoia) and then encoding them into the Ogg, FLAC, or MP2/3
formats using the vorbis tools, FLAC, toolame or other available
MP3 encoders.
.
It includes support for CDDB lookups and ID3v2 tags.
Description-md5: cdeabf4ef72c33d57aecc4b4e2fd5952
Homepage: http://sourceforge.net/projects/ripperx/
Tag: hardware::storage, hardware::storage:cd, interface::graphical,
interface::x11, role::program, scope::application, uitoolkit::gtk,

# apt install –yes ripperx

That's all folks.
Enjoy !

Tags: Audio, audio cd, ccache, cdda, cmd, Convert, ffmpeg, gcc, graphical interface, help, hipo, linux?, need, Press, RIP, root root, shell script
Posted in Educational, File Convert Tools, Linux, Linux and FreeBSD Desktop, Linux Audio & Video | No Comments »

How to do a port redirect to localhost service with socat or ncat commands to open temporary access to service not seen on the network

Friday, February 23rd, 2024

You know sometimes it is necessery to easily and temporary redirect network TCP ports to be able to be accessible from Internal DMZ-ed Network via some Local Network IP connection or if the computer system is Internet based and has an external "'real" Internet Class A / B address to be reachable directly from the internet via lets say a modern Internet browser such as Mozilla Firefox / Google Chrome Browser etc.

Such things are easy to be done with iptables if you need to do the IP redirect permanent with Firewall rule changes on Linux router with iptables.
One way to create a TCP port redirect using firewall would include few iptable rules like for example:

1. Redirect port traffic from external TCP port source to internal one

# iptables -t nat -I PREROUTING -p tcp –dport 10000 -j REDIRECT –to-ports 80
# iptables -t nat -I OUTPUT -p tcp -o lo –dport 10000 -j REDIRECT –to-ports 80
# iptables -t nat -A OUTPUT -o lo -d 127.0.0.1 -p tcp –dport 80 -j DNAT –to-destination 192.168.0.50:10000
# iptables -t nat -I OUTPUT –source 0/0 –destination 0/0 -p tcp –dport 80 -j REDIRECT –to-ports 10000

Then you will have 192.168.00.50:10000 listener (assuming that the IP is already configured on some of the host network interface, plugged in to the network).

But as messing up with the firewall is not the best thing to do especially, if you need to just temporary redirect external listener port to a service configured on the server to only run on TCP port on loopback address 127.0.0.1, you can do it instead with another script or command for simplicy.

One simple way to do a port redirect on the fly on GNU / Linux or FreeBSD / OpenBSD is with socat command.

Lets say you have a running statistics of a web server Apache / Nginx / Haproxy frontend / backend statistics or whatever kind of web TCP service on port 80 on your server and this interface is on purpose configured to be reachable only on localhost interface port 80, so you can either access it by creating an ssh tunnel towards the service on 127.0.0.1 or by accessing it by redirecting the traffic towards another external TCP port, lets say 10000.

Here is how you can achieve

2. Redirect Local network accessible IP on all configured Server network interfaces port 10000 to 127.0.0.1 TCP 80 with socat

# socat tcp-l:10000,fork,reuseaddr tcp:127.0.0.1:80

If you need to access later the redirected port in a Browser, pick up the machine first configured IP and open it in a browser (assuming there is no firewall filter prohibiting access to redirected port).

root@pcfreak:~# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 109.104.212.130 netmask 255.255.255.0 broadcast 109.104.212.255
ether 91:f8:51:03:75:e5 txqueuelen 1000 (Ethernet)
RX packets 652945510 bytes 598369753019 (557.2 GiB)
RX errors 0 dropped 10541 overruns 0 frame 0
TX packets 619726615 bytes 630209829226 (586.9 GiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

Then in a browser open http://102.104.212.130 or https://102.104.212.130 (depending on if remote service has SSL encryption enabled or not) and you're done, the configured listener Server service should pop-up on the screen.

3. Redirect IP Traffic from External IP to Localhost loopback interface with netcat ( ncat ) swiss army knife hackers and sysadmins tool

If you need to redirect lets say TCP / IP port 8000 to Port a server local binded service on TCP 80 with ncat, instead of socat (if lets say socat is not pre-installed on the machine), you can do it by simply running those two commands:

[root@server ~]# mkfifo svr1_to_svr2
[root@server ~]# ncat -vk -l 8000 < svr1_to_svr2 | ncat 127.0.0.1 80 > svr1_to_svr2
Ncat: Version 7.92 ( https://nmap.org/ncat )
Ncat: Listening on 0.0.0.0:10000
Ncat: Connection from 10.10.258.39.
Ncat: Connection from 10.10.258.39:51813.
Ncat: Connection from 10.10.258.39.
Ncat: Connection from 10.10.258.39:23179.

I you don't care to log what is going on the background of connection and you simply want to background the process with a one liner command you can achive that with:

[root@server /tmp]# cd tmp; mkfifo svr1_to_svr2; (ncat -vk -l 8000 < svr1_to_svr2 | ncat 127.0.0.1 80 > svr1_to_svr2 &)

Then you can open the Internal Machine Port 80 TCP service on 8000 in a browser as usual.

For those who want a bit of more sophisticated proxy like script I would suggest you take a look at using netcat and a few lines of shell script loop, that can simulate a raw and very primitive proxy with netcat this is exampled in my previous article Create simple proxy server with netcat ( nc ) based utility.

Hope this article is helpful to anyone, there is plenty of other ways to do a port redirect with lets say perl, python and perhaps other micro tools. If you know of one liners or small scripts, that do it please share in comments, so we can learn from each other !

Enjoy ! 🙂

Tags: configured, How to, ifconfig eth0, Internal Machine Port, Mozilla Firefox Google Chrome Browser, Ncat Connection, need, network interface, port, proxy server, say, shell script, swiss army knife, tcp
Posted in Educational, Linux, Linux and FreeBSD Desktop, Networking | No Comments »

Megaraid SAS software installation on CentOS Linux

Saturday, October 20th, 2012

With a standard el5 on a new Dell server, it may be necessary to install the Dell Raid driver, otherwise the OMSA always reports an error and hardware monitoring is therefore obsolete:

Previously, the megaraid_sys package was now called mptlinux

For this we need the following packages in advance:

# yum install gcc kernel-devel
Now the driver stuff:

# yum install dkms mptlinux
That should have built the new module, better test it:

# modinfo mptsas

# dkms status
After a kernel update it may be necessary to build the driver for the new version:

# dkms build -m mptlinux -v 4.00.38.02

# dkms install -m mptlinux -v 4.00.38.02

Tags: based, better, called, Dell Raid, Display, Enable X11, gcc, Getting X11, installation, list, need, packages, somehost, ssh, standard, tell, update, working, xauth, yum
Posted in Linux, Linux and FreeBSD Desktop | 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 »

OpenVZ enable or disable auto start on Linux Hypervisor host boot for Virtual Machine containers

Wednesday, July 7th, 2021

To make OpenVZ / Virtuozzo Hypervisor servers and you are not sure whether your configured container virtual machines are configured to automatically boot on Linux Physical OS host boot in case of restart after patch update set or after unexpected shutdown due to Kernel / OS bug a hang or due to some electricity Power outage.

To check what is your current configuration for Virtual Environment on CentOS Linux you need to check inside /etc/sysconfig/vz-scripts/VEID.conf
You need to check the value for inside the file

ONBOOT=""

To get the exact ID of "VEID.conf of the current openvz guest VM containers exec:

[root@openvz vz-scripts]# vzlist -a
CTID NPROC STATUS IP_ADDR HOSTNAME
300 23 running 10.10.10.1 VirtualMachine1
301 25 running 10.10.10.2 VirtualMachine2

[root@openvz ~]# cd /etc/sysconfig/vz-scripts
[root@gbapp2 vz-scripts]# pwd
/etc/sysconfig/vz-scripts

[root@openvz vz-scripts]# grep -i ONBOOT 300.conf 301.conf
300.conf:ONBOOT="yes"
301.conf:ONBOOT="yes"

If you happen to have configured ONBOOT="no" you will need to the change to respective VEID.conf:

vi /etc/sysconfig/vz-scripts/VEID.conf

search for

ONBOOT=”no”

and change to

ONBOOT=”yes”

OpenVZ_virtuozzo-standard-process-tree-landscape

OpenVZ server process tree. The colors of the virtual severs are indicated by colors.

OpenVZ Quick cheat sheet commands

This change will auto-start the VPS container next time the host Hypervisor node is rebooted.
If you happen to have daily work with OpenVZ legacy systems like I do you might find also useful the following OpenVZ Cheatsheet pdf document.

A miniature quick cheatsheet for OpenVZ Virtualion, in case if you are like me and you have to use various virtualization technologies and tend to forget is as below:

vzlist # List running instances
vzlist -a # List all instances

vzctl stop <instance>
vzctl start <instance>
vzctl status <instance>

vzctl exec <instance> <command> # Run a command

vzctl enter <instance> # Get console

vzyum <instance> install <package> # Install a package

# Change properties
vzctl set <instance> –hostname <hostname> –save
vzctl set <instance> –ipadd <IP> –save
vzctl set <instance> –userpasswd root:<password> –save

If need to get more insight on how OpenVZ Virtualization does work on a low level and stretch out its possibilities, an old but useful document you might want to check is OpenVZ-Users-Guide PDF.

If you need it to hava e copy of it openvz_cheat_sheet.txt.

Tags: auto start, check, configured, disable, Linux Hypervisor, need, ONBOOT, root password, sysconfig, virtual machines
Posted in Linux, System Administration, Virtual Machines | No Comments »

Configure rsyslog buffering on Linux to avoid message lost to Central Logging server

Wednesday, January 13th, 2021

1. Rsyslog Buffering

One of the best practice about logs management is to send syslog to a central server. However, a logging system should be capable of avoiding message loss in situations where the server is not reachable. To do so, unsent data needs to be buffered at the client when central server is not available. You might have recently noticed that many servers forwarding logs messages to a central server do not have buffering functionalities activated. Thus I strongly advise you to have look to this documentation to know how to check your configuration: http://www.rsyslog.com/doc/rsyslog_reliable_forwarding.html

Rsyslog buffering with TCP/UDP configured

In rsyslog, every action runs on its own queue and each queue can be set to buffer data if the action is not ready. Of course, you must be able to detect that "the action is not ready", which means the remote server is offline. This can be detected with plain TCP syslog and RELP, but not with UDP. So you need to use either of the two. In this howto, we use plain TCP syslog.

– Version requirement

Please note that we are using rsyslog-specific features. The are required on the client, but not on the server. So the client system must run rsyslog (at least version 3.12.0), while on the server another syslogd may be running, as long as it supports plain tcp syslog.

How To Setup rsyslog buffering on Linux

First, you need to create a working directory for rsyslog. This is where it stores its queue files (should need arise). You may use any location on your local system. Next, you need to do is instruct rsyslog to use a disk queue and then configure your action. There is nothing else to do. With the following simple config file, you forward anything you receive to a remote server and have buffering applied automatically when it goes down. This must be done on the client machine.

# Example:
# $ModLoad imuxsock             # local message reception
# $WorkDirectory /rsyslog/work # default location for work (spool) files
# $ActionQueueType LinkedList   # use asynchronous processing
# $ActionQueueFileName srvrfwd # set file name, also enables disk mode
# $ActionResumeRetryCount -1    # infinite retries on insert failure
# $ActionQueueSaveOnShutdown on # save in-memory data if rsyslog shuts down
# *.*       @@server:port

Tags: action, central server, client, default location, linux?, need, queue, system, use, working
Posted in System Administration | No Comments »

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