How to Open Port on Oracle Cloud Ubuntu Server

Oracle Cloud Ubuntu virtual machines are not compatible with UFW firewall. This is because oracle cloud needs some iptables rules to communicate with storage devices.

To open a port in Oracle cloud Ubuntu Virtual Machine, edit file

vi /etc/iptables/rules.v4

Find the line

-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT

This is the rule for opening port 22 (SSH). To open another port, duplicate this line, replace 22 with the port you need to open.

For example, to open ports 80 and 443, add these 2 lines below.

-A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 443 -j ACCEPT

IMPORTANT: Do not remove the entry for port 22. If you remove this line, you won’t be able to SSH into the server.

To activate the firewall rules, run the command

sudo iptables-restore < /etc/iptables/rules.v4

To see the INPUT rules, run the command

root@oc1-serverok-in:~# iptables -L INPUT
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     udp  --  anywhere             anywhere             udp spt:ntp
ACCEPT     tcp  --  anywhere             anywhere             state NEW tcp dpt:ssh
ACCEPT     tcp  --  anywhere             anywhere             state NEW tcp dpt:http
ACCEPT     tcp  --  anywhere             anywhere             state NEW tcp dpt:https
REJECT     all  --  anywhere             anywhere             reject-with icmp-host-prohibited

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