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Linux Firewall Basics: ufw vs firewalld (Quick Start)

<p><img alt="Linux ufw firewall status showing allowed SSH and web ports" src="https://blog.gnomeitsolutions.com/wp-content/uploads/2026/08/blogger-firewall-ufw.png" style="max-width:100%;height:auto;border-radius:6px;"/></p><p>Every Linux server needs a firewall. On Debian/Ubuntu you usually see <strong>ufw</strong>; on RHEL/CentOS/Rocky it's <strong>firewalld</strong>. Both wrap iptables/nftables—pick one and stay consistent.</p><h2>ufw (Ubuntu / Debian)</h2><pre><code>sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow 22/tcp comment 'SSH'
sudo ufw allow 80,443/tcp comment 'Web'
sudo ufw enable
sudo ufw status numbered</code></pre><h2>firewalld (RHEL family)</h2><pre><code>sudo systemctl enable --now firewalld
sudo firewall-cmd --permanent --add-service=ssh
sudo firewall-cmd --permanent --add-service=http
sudo firewall-cmd --permanent --add-service=https
sudo firewall-cmd --reload
sudo firewall-cmd --list-all</code></pre><h2>Before you lock yourself out</h2><ul><li>Keep an active SSH session open while testing rules</li><li>Allow SSH <em>before</em> enabling the firewall</li><li>Use a cloud console (VNC/serial) as backup access</li></ul>

Linux Firewall Basics: ufw vs firewalld (Quick Start)

Every Linux server needs a firewall. On Debian/Ubuntu you usually see ufw ; on RHEL/CentOS/Rocky it's firewalld . Both wrap iptables/nft...

Detect SSH Brute-Force Attacks on Linux (auth.log + fail2ban)

<p><img alt="fail2ban SSH jail status on Linux server terminal" src="https://blog.gnomeitsolutions.com/wp-content/uploads/2026/08/blogger-ssh-fail2ban-2.png" style="max-width:100%;height:auto;border-radius:6px;"/></p><p>SSH is the front door to most Linux servers. Attackers scan the internet 24/7 looking for weak passwords and open port 22. This guide shows how to spot brute-force attempts quickly and block repeat offenders with <strong>fail2ban</strong>.</p><h2>1. Check auth.log for failed logins</h2><pre><code>sudo grep 'Failed password' /var/log/auth.log | tail -20
sudo grep 'Invalid user' /var/log/auth.log | awk '{print $10}' | sort | uniq -c | sort -rn | head</code></pre><p>The second command lists usernames attackers tried most often (root, admin, ubuntu, etc.).</p><h2>2. Count attempts by source IP</h2><pre><code>sudo grep 'Failed password' /var/log/auth.log \
  | awk '{print $(NF-3)}' | sort | uniq -c | sort -rn | head -15</code></pre><p>Any IP with hundreds of failures in a short window is almost certainly a bot.</p><h2>3. Install and enable fail2ban</h2><pre><code>sudo apt update && sudo apt install -y fail2ban
sudo systemctl enable --now fail2ban
sudo fail2ban-client status sshd</code></pre><h2>4. Harden sshd (do this first)</h2><ul><li>Disable password login: <code>PasswordAuthentication no</code></li><li>Disable root login: <code>PermitRootLogin no</code></li><li>Use a non-default port or restrict with firewall</li><li>Allow only your admin IP if possible</li></ul><p>After editing <code>/etc/ssh/sshd_config</code>, run <code>sudo sshd -t && sudo systemctl reload sshd</code>.</p><h2>5. Monitor bans</h2><pre><code>sudo fail2ban-client status sshd
sudo zgrep 'Ban' /var/log/fail2ban.log | tail -10</code></pre><p>Review banned IPs weekly. Legitimate users behind NAT can trigger bans if they mistype passwords—adjust <code>maxretry</code> and <code>bantime</code> in <code>/etc/fail2ban/jail.local</code>.</p>

Detect SSH Brute-Force Attacks on Linux (auth.log + fail2ban)

SSH is the front door to most Linux servers. Attackers scan the internet 24/7 looking for weak passwords and open port 22. This guide shows ...

Deploy WordPress with Docker Compose on Linux (Nginx + MySQL Stack)

<p>Deploy <strong>WordPress with Docker Compose</strong> on Linux — Nginx, PHP, MySQL, and persistent volumes in one stack file.</p>
<h2>Prerequisites</h2>
<ul>
<li>Docker and Docker Compose installed</li>
<li>Linux server with 2GB+ RAM</li>
<li>Domain pointed to server (optional for SSL)</li>
</ul>
<h2>Step 1: Create project directory</h2>
<pre><code>mkdir -p ~/wordpress-docker && cd ~/wordpress-docker</code></pre>
<h2>Step 2: docker-compose.yml</h2>
<div class="gnome-script-box" style="max-height:420px;overflow:auto;margin:1.75rem 0;border-radius:14px;box-shadow:0 12px 32px rgba(15,23,42,0.18);border:1px solid #30363d;background:#0d1117;">
<pre style="margin:0;padding:1.25rem;color:#e6edf3;font-family:Consolas,monospace;font-size:13px;line-height:1.55;"><code>services:
  db:
    image: mysql:8.0
    volumes:
      - db_data:/var/lib/mysql
    environment:
      MYSQL_ROOT_PASSWORD: changeme
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wpuser
      MYSQL_PASSWORD: changeme
    restart: always

wordpress:
    depends_on:
      - db
    image: wordpress:latest
    ports:
      - "8080:80"
    volumes:
      - wp_data:/var/www/html
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: wpuser
      WORDPRESS_DB_PASSWORD: changeme
      WORDPRESS_DB_NAME: wordpress
    restart: always

volumes:
  db_data:
  wp_data:</code></pre>
</div>
<h2>Step 3: Start the stack</h2>
<pre><code>docker compose up -d
docker compose ps</code></pre>
<p>Open <code>http://your-server-ip:8080</code> to complete WordPress setup.</p>
<figure class="wp-block-image size-large"><img alt="Docker Compose WordPress stack on Linux" decoding="async" src="https://blog.gnomeitsolutions.com/wp-content/uploads/2026/08/linux-docker-basic-1.png" /><figcaption>Docker Compose WordPress deployment on Linux</figcaption></figure>
<h2>Step 4: Useful commands</h2>
<pre><code>docker compose logs -f wordpress
docker compose down
docker compose pull && docker compose up -d</code></pre>
<h2>Related tutorials</h2>
<ul>
<li><a href="https://blog.gnomeitsolutions.com/install-docker-almalinux-ubuntu/">Install Docker on AlmaLinux & Ubuntu</a></li>
<li><a href="https://blog.gnomeitsolutions.com/wordpress-backup-shell-script-linux/">WordPress Backup Shell Script</a></li>
<li><a href="https://blog.gnomeitsolutions.com/docker-cleanup-shell-script-linux/">Docker Cleanup Shell Script</a></li>
</ul>
<hr><p><strong>Read the full version with scripts and images:</strong> <a href="https://blog.gnomeitsolutions.com/docker-compose-wordpress-nginx-linux/" rel="canonical">Deploy WordPress with Docker Compose on Linux (Nginx + MySQL Stack)</a></p>

Deploy WordPress with Docker Compose on Linux (Nginx + MySQL Stack)

Deploy WordPress with Docker Compose on Linux — Nginx, PHP, MySQL, and persistent volumes in one stack file. Prerequisites Docker and Do...