When Oracle Cloud's Ubuntu instance doesn't accept connections to ports other than 22
Thanks to the free trial periods, I’m testing this and that on Oracle Clouds.
While running a Ubuntu instance, I was stuck with a weird problem that made me pull out hairs for hours.
My problem was this:
I added several ingress rules in my default security list,
but the instance didn’t accept any connection to ports other than 22, the SSH port.
I looked into nearly every network setting in the Oracle Cloud console and searched for similar problems on the web,
but nothing worked.
After some time and more tests, I began to suspect that a firewall or something was blocking connections.
When SSH server on port 22 was down, it said connection was refused.
But when I tried connecting to other ports, it said no route to host.
Hmmmm… interesting, something was blocking connections.
I searched for any configuration for iptables
.
There were two files in /etc/iptables/
, and gotcha!
I found rules that were rejecting connections in /etc/iptables/rules.v4
file:
Because of these things, changes in the console would never have effects.
Amazon AWS’s Ubuntu images don’t have such configurations by default, so it maybe due to Oracle’s security policy.
I didn’t want to take Oracle’s default security policy down, so I just added following lines:
By both adding ingress rules on the console and inserting lines in /etc/iptables/rules.v4
,
I could finally connect through other ports without any problem!
Oracle is a relatively new runner in the cloud race.
It needs some more work on it, but I think the new Always Free
service is a really attractive starter for developers like me.