System Administration tips for Ubuntu

Use dropbear to remotely unlock a fully encrypted disk via ssh

If you've enabled full disk encryption, you will need to enter a password to unlock the disk at reboot time.  If you want to be able to unlock the disk remotely via ssh, here are the steps

1. http://blog.netpacket.co.uk/2016/12/05/unlocking-ubuntu-server-16-encrypted-luks-using-dropbear-ssh/
2. After following the above steps, I create an entry called "unlock" in my ~/.ssh/config file on my Mac laptop.  So after I boot my Ubuntu 16.04 LTS Desktop VM (using the VirtualBox CLI), then I type 'ssh unlock', and type 'unlock' when presented with the busybox prompt.  I am prompted to enter a password to unlock the encrypted disk.  After that, the system will boot up, then I can ssh in remotely.
   

   Host unlock
     Hostname 192.168.56.101
     User root
     IdentityFile /Users/ksa/.ssh/id_rsa_ubuntu_unlock
     StrictHostKeyChecking no

List all software repositories

You can look at the /etc/apt/sources.list file, and in the /etc/apt/sources.list.d/ directory, but here is a single command line which can list all the sources

1. apt-cache policy

Use Landscape or Cockpit to centrally manage and monitor Ubuntu machines

If you have a group of 10 or fewer Ubuntu hosts you administer, you can install Landscape (on premises version) in a VM to manage those hosts for free.

1. https://landscape.canonical.com/set-up-on-prem

In addition to Landscape (or an alternative) is Cockpit which you can use to centrally manage CentOS, RedHat, Fedora, and Ubuntu hosts:

1. http://www.configserverfirewall.com/ubuntu-linux/install-cockpit-ubuntu-16-04/

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