Can't access Oracle Cloud Always Free Compute http port

Question

Yesterday, I was set up my first always free compute VM. I installed ubuntu 18.04 minimal on my VM. For my web service need, I installed Nginx. I'm confused because when I tried to access my public IP via a web browser, the Nginx welcome page didn't load. I think that is because port 80 didn't open. So, I tried to open that with set Ingress Rules in Security List Details menu as the picture below. Ingress Rule for port 80

But now, I still can't access the web server in my VM. May be there more experienced people in Oracle Cloud who can help me to solve this. Thank you

Answer 1

I wasted a lot of time on this. I wish I had found this first: https://docs.cloud.oracle.com/en-us/iaas/developer-tutorials/tutorials/apache-on-ubuntu/01oci-ubuntu-apache-summary.htm

1. configure ingress route for port 80

2. install ubuntu.

3. install apache/nginx

4. curl localhost should bring back webpage in text format, however fails over internet.

5. forget ufw firewall - this may cause issues with the Oracle firewall

6. use

$ sudo iptables -I INPUT 6 -m state --state NEW -p tcp --dport 80 -j ACCEPT
$ sudo netfilter-persistent save

g) test your web page over internet

Answer 2

This is how I did it without directly meddling with iptables.

First create an Ingress Rule in Oracle Cloud vps's dashboard/Networking/Virtual Cloud Networks, for example, for port range 23-90

Next, install firewalld in ubuntu (firewalld is available in centos I think)

sudo apt-get install firewalld
sudo systemctl enable firewalld
sudo systemctl start firewalld

You only need to do this one time. It will still be there after a reboot.

Then, to open port 80:

sudo firewall-cmd --zone=public --add-port=80/tcp --permanent  #  or --add-service=http 
sudo firewall-cmd --reload

To verify:

sudo firewall-cmd --list-all

Output:

public
  target: default
  icmp-block-inversion: no
  interfaces:
  sources:
  services: dhcpv6-client ssh
  ports: 80/tcp
  ...

The same applies to opening other port(s). You can easily remove the port (--remove-port=80/tcp + a --reload), refer to firewalld docs.

To test from a remote computer

1. run a web server at port 80 in Oracle Cloud vps if one is not already running, for example:

   python3 -m http.server 80
   

2. In a remote computer

   curl ip-of-oc-vps:80
   

I also wasted a lot of time on Oracle Cloud Always Free vps' firewall. I hope this can save other people some time.