05 Disable Firewall

Overview

Even though I thought I had deployed the agent correctly to GORDON, the agent had not completed configuration.

The problem was that the firewall was still active on GORDON and was preventing the proper handshaking between the agent (GORDON) and the server (CRONULLA).

References

• Michael Kerrisk - man7.org
  • systemctl

Procedure

I had two (2) options to fix the firewall stopping the agent communicating with the server:

1. Set up the firewall rules
2. Disable the firewall

I would have preferred to go with option #1, but I could not get firewall-config working with legible text. The errors were:

** (firewall-config:8373): WARNING **: Couldn't connect to accessibility bus: Failed to connect to socket /tmp/dbus-wkFdUchAdk: Connection refused (firewall-config:8373): Pango-WARNING **: failed to choose a font, expect ugly output. engine-type='PangoRenderFc', script='common' (firewall-config:8373): Pango-WARNING **: failed to choose a font, expect ugly output. engine-type='PangoRenderFc', script='latin' GLib-GIO-Message: Using the 'memory' GSettings backend. Your settings will not be saved or shared with other applications.

In the end, I went with option #2.

Disable Firewall Daemon on GORDON

On GORDON, the firewall daemon is disabled:

systemctl disable firewalld

The output was:

Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service. Removed symlink /etc/systemd/system/basic.target.wants/firewalld.service.

Stop Firewall Daemon on GORDON

On GORDON, the firewall daemon is stopped and the status is onfirmed:

systemctl stop firewalld systemctl status firewalld

The output was:

• firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled) Active: inactive (dead) Sep 09 16:52:49 gordon.yaocm.id.au systemd[1]: Starting firewalld - dynamic firewall daemon... Sep 09 16:52:55 gordon.yaocm.id.au systemd[1]: Started firewalld - dynamic firewall daemon. Sep 09 20:23:03 gordon.yaocm.id.au systemd[1]: Stopping firewalld - dynamic firewall daemon... Sep 09 20:23:04 gordon.yaocm.id.au systemd[1]: Stopped firewalld - dynamic firewall daemon.

Remove Agent on CRONULLA

Even with the firewall disabled on GORDON, the agent could not finish the set-up on the server. I had to decommission the agent as follows:

Then I removed the agent home as follows:

/opt/app/oracle/agent/12.1.0.4/agent_inst/bin/emctl stop agent rm -fR /opt/app/oracle/agent/12.1.0.4

And re-install the agent again. Now everything seems to be okay.