I created an Ubuntu instance on Oracle Cloud Infrastructure (OCI). I am able to connect to this instance with SSH (TCP 22). I created some services on this instance, like daytime (TCP 13), mail (TCP 25), http (TCP 80), dns (TCP/UDP 53). I added similar rules to the Default Security List on the OCI management web page of this instance similar to the default SSH rule. However, when I try to connect to any of these services from Internet I get
No route to host error. The only exception is the SSH service which works with no problem.
Once I had installed
ufw to this instance; however, later I disabled and removed
ufw. After that, I removed
iptables package also. So, now there is no Linux firewall at all. However, I still have this problem.
This seems to be an OCI-related problem. I had done similar configurations in other cloud platforms (AWS, GCP, etc.) with no problem.
Where else can I look to isolate this problem?
Update: Removing iptables and rebooting solved the problem. Now I will try to re-install iptables.