Lab Information
The Nautilus system admins team has rolled out a web UI application for their backup utility on the Nautilus backup server within the Stratos Datacenter. This application operates on port 5003, and firewalld is active on the server. To meet operational needs, the following requirements have been identified:
Allow all incoming connections on port 5003/tcp. Ensure the zone is set to public.
Lab Solutions
🧭 Part 1: Lab Step-by-Step Guidelines
🔹 Step 1: Log in to Jump Host
ssh thor@jump_host.stratos.xfusioncorp.com
Password:
mjolnir123
🔹 Step 2: SSH into Backup Server
ssh clint@stbkp01.stratos.xfusioncorp.com
Password:
H@wk3y3
🔹 Step 3: Switch to root
sudo -i
🔥 Configure firewalld
🔹 Step 4: Ensure default zone is public
firewall-cmd --set-default-zone=public
🔹 Step 5: Allow port 5003/tcp permanently
firewall-cmd --zone=public --add-port=5003/tcp --permanent
🔹 Step 6: Reload firewall to apply changes
firewall-cmd --reload
🔹 Step 7: Verify port is open
firewall-cmd --zone=public --list-ports
🔹 Step 8: Verify active zone
firewall-cmd --get-default-zone
Expected output:
[root@stbkp01 ~]# firewall-cmd --set-default-zone=public
Warning: ZONE_ALREADY_SET: public
success
[root@stbkp01 ~]# firewall-cmd --zone=public --add-port=5003/tcp --permanent
success
[root@stbkp01 ~]# firewall-cmd --reload
success
[root@stbkp01 ~]# firewall-cmd --zone=public --list-ports
5003/tcp
[root@stbkp01 ~]# firewall-cmd --get-default-zone
public
✅ Final Checklist
✔ Default zone set to public
✔ Port 5003/tcp added permanently
✔ Firewall reloaded
✔ Port verified open
✔ Completed on Backup Server only
🧠 Part 2: Simple Step-by-Step Explanation (Beginner Friendly)
🔹 What is happening?
A backup web UI runs on:
port 5003
But firewalld blocks incoming traffic by default.
We must allow traffic to that port.
🔹 What is a zone?
Firewalld uses zones like:
public
internal
trusted
The lab requires the zone to be:
public
🔹 Why use --permanent?
Without --permanent, changes disappear after reboot.
The lab expects persistent configuration.
🔹 Why reload?
After adding permanent rules:
firewall-cmd --reload
applies them immediately.
🔐 Real-World Context
Opening specific ports is common when:
Deploying web apps
Exposing APIs
Enabling monitoring dashboards
Only required ports should be opened — never open all traffic.
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