Server Reinstall: OS Reinstall Step-by-Step Guide

Server reinstallation (OS reinstall) is the process of installing the operating system from scratch, returning the server to a clean state. This is used to resolve serious system issues, switch to a different operating system, or bring the server to a clean starting point. This guide covers when to reinstall, how to prepare, and the steps through the REXE control panel.

When is Reinstallation Necessary?

Consider reinstallation in these situations:

Mandatory Cases

Server was hacked: Malware or rootkit detected
Critical system files corrupted: System won't boot or keeps crashing
Unrecoverable configuration error: System became inaccessible
Ransomware attack: Files were encrypted

Preferred Cases

You want to switch to a different Linux distribution
You're handing the server over to someone else (clean handover)
You want to clean up long-accumulated issues
You want to reset a test environment

Reinstallation deletes ALL data on the disk. This action cannot be undone. Always take a backup before proceeding.

Pre-Reinstall Backup Checklist

Before starting reinstallation, back up the following data:

1. Website and Application Files

hljs bash

# Backup web files
tar -czf /tmp/www-backup-$(date +%Y%m%d).tar.gz /var/www/

# Backup application directory
tar -czf /tmp/app-backup-$(date +%Y%m%d).tar.gz /opt/myapp/

# Transfer backups to remote server
rsync -avz /tmp/*-backup-*.tar.gz user@backup-server:/backup/

2. Database Backups

hljs bash

# MySQL/MariaDB all databases
mysqldump --all-databases -u root -p > /tmp/all-databases-$(date +%Y%m%d).sql

# Specific database
mysqldump -u root -p mydb > /tmp/mydb-$(date +%Y%m%d).sql

# PostgreSQL
pg_dumpall -U postgres > /tmp/postgres-all-$(date +%Y%m%d).sql

# Compress backups
gzip /tmp/*.sql

3. Configuration Files

hljs bash

# Nginx configuration
tar -czf /tmp/nginx-config-$(date +%Y%m%d).tar.gz /etc/nginx/

# Apache configuration
tar -czf /tmp/apache-config-$(date +%Y%m%d).tar.gz /etc/apache2/

# SSH configuration and keys
tar -czf /tmp/ssh-config-$(date +%Y%m%d).tar.gz /etc/ssh/ /root/.ssh/

# Crontab
crontab -l > /tmp/crontab-backup-$(date +%Y%m%d).txt

# Full /etc directory
tar -czf /tmp/etc-backup-$(date +%Y%m%d).tar.gz /etc/

4. SSL Certificates

hljs bash

# Let's Encrypt certificates
tar -czf /tmp/letsencrypt-$(date +%Y%m%d).tar.gz /etc/letsencrypt/

# Custom certificates
tar -czf /tmp/ssl-certs-$(date +%Y%m%d).tar.gz /etc/ssl/

5. User Data and Home Directories

hljs bash

# All user home directories
tar -czf /tmp/home-backup-$(date +%Y%m%d).tar.gz /home/

# User list
cat /etc/passwd > /tmp/users-list.txt
cat /etc/group > /tmp/groups-list.txt

6. Installed Package List

hljs bash

# Ubuntu/Debian
dpkg --get-selections > /tmp/installed-packages.txt

# RHEL/CentOS/AlmaLinux
rpm -qa > /tmp/installed-packages.txt

Backup Verification

hljs bash

# List backup files and check sizes
ls -lh /tmp/*-backup-*.tar.gz

# Verify archive contents
tar -tzf /tmp/www-backup-*.tar.gz | head -20

# Verify backups reached remote server
rsync -avz --dry-run /tmp/*-backup-*.tar.gz user@backup-server:/backup/

OS Reinstall via REXE Control Panel

Step 1: Log into Control Panel

Go to panel.rexe.tr
Log in with your username and password
Navigate to My Servers in the left menu
Select the server you want to reinstall

Step 2: Initiate Reinstall

On the server detail page, click the Actions or Management tab
Find the Reinstall Operating System (OS Reinstall) option
Read the warning message and confirm

Step 3: Select Operating System

Available options typically include:

Ubuntu 22.04 LTS (recommended)
Ubuntu 20.04 LTS
Debian 12
Debian 11
AlmaLinux 9
CentOS Stream 9
Windows Server (if available)

Step 4: Installation Parameters

- Operating System: Ubuntu 22.04 LTS
- Hostname: server-name.domain.com
- Root Password: [set a strong password]
- SSH Key: [add if available]

The reinstall process typically takes 5-15 minutes. The server will be inaccessible during this time. You'll receive an email notification when complete.

Step 5: Confirm Installation

Review all parameters
Click Confirm and Start
The process begins and progress is shown in the panel

Post-Installation Configuration Checklist

After the server is reinstalled:

1. First Connection and Security

hljs bash

# Connect via SSH
ssh root@server-ip

# Update the system
apt update && apt upgrade -y

# Create a new user (don't work as root)
adduser newuser
usermod -aG sudo newuser

# Secure SSH configuration
nano /etc/ssh/sshd_config
# PermitRootLogin no
# PasswordAuthentication no (if using SSH keys)

systemctl restart sshd

2. Firewall Configuration

hljs bash

# Install and configure UFW
apt install ufw -y
ufw default deny incoming
ufw default allow outgoing
ufw allow ssh
ufw allow 80/tcp
ufw allow 443/tcp
ufw enable

3. Install Essential Software

hljs bash

# Essential tools
apt install -y curl wget git vim htop net-tools unzip

# Set timezone
timedatectl set-timezone UTC

# Enable NTP
timedatectl set-ntp true

4. Restore from Backups

hljs bash

# Transfer backups to server
rsync -avz user@backup-server:/backup/ /tmp/restore/

# Restore web files
tar -xzf /tmp/restore/www-backup-*.tar.gz -C /

# Restore database
mysql -u root -p < /tmp/restore/all-databases-*.sql

# Restore Nginx configuration
tar -xzf /tmp/restore/nginx-config-*.tar.gz -C /
nginx -t && systemctl restart nginx

# Restore SSL certificates
tar -xzf /tmp/restore/letsencrypt-*.tar.gz -C /

5. Service Verification

hljs bash

# Check all service statuses
systemctl list-units --type=service --state=running

# Web server
curl -I http://localhost

# Database
mysql -u root -p -e "SHOW DATABASES;"

# Firewall
ufw status verbose

Within the first 24 hours after installation, verify all services are working correctly. Especially check SSL certificate validity and auto-renewal settings.

Conclusion

Server reinstallation is a smooth process when properly prepared. With comprehensive backups, careful installation parameter selection, and systematic post-installation configuration, you can quickly restore your server to its previous state. The REXE control panel makes this process achievable in just a few clicks.

Server Reinstall: OS Reinstall Step-by-Step Guide

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