Chapter 5. Troubleshooting remote host configuration issues


System logs are a useful source of information when troubleshooting a remote host configuration issue. In addition, it is helpful to be aware of any known issues.

5.1. TCP ports and destinations

The complete remote host configuration solution currently relies on existing clients; your system will be communicating with Red Hat in different ways.

5.1.1. Subscription manager

For subscription-manager, the system must be able to reach the following destination and TCP ports:

  • subscription.rhn.redhat.com:443 (https)
  • subscription.rhsm.redhat.com:443 (https)
  • cdn.redhat.com:443 (https)
  • *.akamaiedge.net:443 (https)
  • *.akamaitechnologies.com:443 (https)

5.1.2. Insights client

For Red Hat Insights for Red Hat Enterprise Linux data collection to work correctly, the system must be able to reach the following destination and TCP ports:

  • api.access.redhat.com:443 (https)
  • cert-api.access.redhat.com:443 (https)

5.1.3. RHC client daemon

For the rhc daemon, rhcd, to communicate with the MQTT message broker, the system must be able to reach the following:

  • connect.cloud.redhat.com:443 (https)

5.1.4. Adding a proxy for RHC to use for the connection

Use the following commands to add a proxy for rhc to use to connect to Red Hat.

# mkdir -p /etc/systemd/system/rhcd.service.d
# cat /etc/systemd/system/rhcd.service.d/proxy.conf
[Service]
Environment=HTTPS_PROXY=http://proxy.corp.com:8888
# systemctl daemon-reload
# systemctl restart rhcd
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5.2. RHC client communication

The communication technology behind the rhc daemon, rhcd, is MQTT. The client establishes a connection to the Red Hat message broker and waits for new messages. The new messages are then read and converted into playbook execution. While the messages are consumed almost instantaneously, the communication is always established by the client. There is no communication initiated from the Red Hat services to your environment.

5.3. Consulting and interpreting log files

Troubleshooting an issue often starts by looking at the logs to see what happened during a given event.

  • Use the following command to consult logs:
# journalctl -u rhcd
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  • Use -f, --follow, to show only the most recent journal entries, and continuously print new entries as they are appended to the journal:
# journalctl -u rhcd -f
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