Doing remote server upgrades is risky and usually requires a reboot of the system to load the new kernel, modules and binaries. To lower the risk of downtime due to a misconfigured firewall or mount settings, I would usually follow the following routine:
- Login to local PDU
 - Turn on IP KVM port
 - Reboot server
 - Wait until server becomes reachable
 - Login to local PDU
 - Turn off IP KVM port
 
3.6 – not great, not terrible. Usually being the key word above – sometimes I would simply forget to turn on the IP KVM or vice versa… However, we can automate all of that with Systemd and its support for dependency management:
Provided Systemd scripts will do the following:
- Turn on the remote PDU outlet for IP KVM just before the server shuts down / reboots
 - Turn off the remote PDU outlet for IP KVM 3 hours after system boots up
 
For the completeness of this topic, I also have the PDU setup to automatically turn on the IP KVM outlet on resume of power outage / cold boot.
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