If you want to allow connection from the public to the private subnet by RDP and Oracle Net, then port 33 must be added in the security list for the private subnet. Reminder: In OCI only SSH port 22 is open in the subnet security lists as per default when the VCN is created by the VCN Wizard.
This gives me the flexibility, to connect to running OCI instances on different ways like Putty, MobaXterm, Windows Subsystem for Linux, WinSCP etc.
id_rsa_oci.pub – Public key generated by ssh-keygen.id_rsa_oci – Private key generated by ssh-keygen.For working with these machines, I use these three types of SSH keys: Oracle Cloud Infrastructure Linux based offerings like compute instances and virtual machines for databases are accessible by SSH key as per default. This blog post shows you the different methods to connect to an Oracle Cloud Infrastructure private/public network by using a bastion host. If your bastion host is compromitted, your SSH keys are lost!In one of the last trainings, some participants had problems with. For security reasons, I never put any SSH keys on a bastion host to connect from there to the target instances. For this case, we use an Oracle Linux based bastion host which acts as a jump host. In our Trivadis Oracle Cloud Infrastructure training environments, we never use direct access to an application or database server by a public IP address.