Ravindra BagaleCourses & study guides

8. Hosting a Static Website and Changing the Configuration

8.7 Changing the Port

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Kadhi kadhi admin panel kiwa dusri site vegalya port var chalvavi lagte, udaharanartha 8081.

# Nginx: /etc/nginx/conf.d/admin.conf   (Ubuntu: sites-available + symlink)
server {
    listen 8081;
    server_name _;
    root /var/www/admin;
    index index.html;
}

# Apache (AL2023/CentOS): add to /etc/httpd/conf.d/admin.conf
Listen 8081
<VirtualHost *:8081>
    DocumentRoot /var/www/admin
    <Directory /var/www/admin>
        Require all granted
    </Directory>
</VirtualHost>

On Ubuntu Apache, put Listen 8081 in /etc/apache2/ports.conf (not in the vhost file). Then:

  1. Test and reload the web server.
  2. Check that it listens: sudo ss -tlnp | grep 8081.
  3. Security group: add an inbound rule Custom TCP 8081 (from My IP for admin pages).
  4. CentOS Stream 9: open firewalld if active (sudo firewall-cmd --permanent --add-port=8081/tcp && sudo firewall-cmd --reload) and allow the port in SELinux:
sudo semanage port -l | grep -w http_port_t              # ports web servers may bind to
sudo semanage port -a -t http_port_t -p tcp 8081          # add 8081 if not listed

Without the SELinux step, the service fails to start with bind() to 0.0.0.0:8081 failed (13: Permission denied).

Why this matters for security

Moving a service to a non-standard port is not security – Nmap finds port 8081 in seconds. Real protection is the security group source rule (My IP only for admin ports), authentication and HTTPS. Every extra open port is extra attack surface.

Ravindra Bagale's Tip

Port badalla, config barobar, service chalu – tarihi site ughadat nahi. Karan security group madhe navin port allow kela nahi! Khup students hi step visartat. Server var ss -tlnp aani AWS madhe inbound rule – donhi check kara.

Lab

Serve /var/www/admin on port 8081 with Nginx. Allow 8081 only from My IP in the security group and confirm it opens from your laptop but not from your phone's mobile data.