How to Open Ports 80 and 443 on Oracle Cloud Infrastructure (OCI) Ubuntu Instances

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Step 1: OCI Console Ingress Security Rules

First, we need to instruct Oracle's network firewall to allow incoming traffic on web ports.
1. Log into your Oracle Cloud Console.
2. Go to Compute > Instances and click on your instance.
3. Under instance details, click on your Primary VNIC's Subnet link.
4. Click on the Security List for the subnet (usually "Default Security List").
5. Click Add Ingress Rules and add rules with Source CIDR 0.0.0.0/0, IP Protocol TCP, and Destination Port Range 80,443.

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Step 2: Configure Local OS Firewall (Ubuntu/Debian)

Oracle's Ubuntu images contain iptables rules that block incoming traffic even if OCI security rules are open. Connect to your instance via SSH and run the following commands to open ports 80 and 443:

sudo iptables -I INPUT 6 -p tcp --dport 80 -j ACCEPT
sudo iptables -I INPUT 6 -p tcp --dport 443 -j ACCEPT
sudo netfilter-persistent save
sudo netfilter-persistent reload

Step 3: Verification

Once both steps are complete, check if your web server responds by running curl -I http://localhost locally, and then trying to visit your server's public IP address in a web browser. If it loads the default welcome page, your ports are successfully open!

Frequently Asked Questions

Why does Oracle Cloud block ports by default? Oracle Cloud Infrastructure (OCI) uses a "security-first" design. By default, all incoming traffic is blocked to protect your Virtual Machines from unauthorized access and potential exploits. You must explicitly declare which ports (like port 80 for HTTP and port 443 for HTTPS) are allowed to receive traffic.

What is the difference between OCI Ingress Rules and the OS Firewall? Think of OCI Ingress Rules as the security gate at the entrance of a building (the cloud network layer), and the local OS firewall (like iptables or ufw) as the locked door to your specific apartment (the Virtual Machine). To allow visitors in, both the security gate and the apartment door must be open. If either is closed, the connection will time out.

Why does iptables block traffic even if UFW is disabled? Oracle's default Ubuntu images come preloaded with raw iptables rules that take precedence over user-friendly tools like UFW. Even if you turn off UFW, the active iptables rules in the Ubuntu image will continue to block port 80 and 443 until you insert the rules manually using iptables -I INPUT ....

My rules disappear after I reboot my Oracle instance. How do I fix this? This happens when you do not save the new firewall state. Running sudo netfilter-persistent save writes your current active rules to a persistent configuration file. On reboot, the netfilter-persistent service automatically loads these saved rules back into iptables