I set it to a port other than the default port used by SSH, MariaDB, PostgreSQL and MongoDB. To connect these daemons, firewall(NOT ufw BUT iptables) must be configured in OCI(ubuntu 22). Besides these ports should be added to public subnet’s security list in OCI. Followings is only about firewall.

OCI’s default user is ubuntu. To add a new user and to delete an user, follow the step below.

OCI’s memory is only 1GB and Swapping is needed. Followings is example of configuration 2GB swapping.