Ubuntu Linux Tweaks

DHCP Reservations

By default, Ubuntu 18 and up will use the machine ID found in /etc/machine-id instead of the MAC address for DHCP leases. MAC based DHCP leasing can be enabled by doing one of two things. See below

Method 1

Edit the yaml file in /etc/netplan/ to look something like this:

network:
  ethernets:
    eth0:
      dhcp4: true
      dhcp-identifier: mac
  version: 2

Then apply the changes

sudo netplan apply

Method 2

Delete the yaml file in /etc/netplan/ and define the default behavior in /etc/systemd/network/99-default.network like so:

[Match]
Name=*

[Network]
DHCP=ipv4
LinkLocalAddressing=ipv6

[DHCP]
ClientIdentifier=mac
UseMTU=true

Then apply the empty netplan configuration and run dhclient or reboot the computer

sudo netplan apply
sudo dhclient <your_interface_here>

Certificate Authority Certificate Installation

Export certificate authority certificates to a base64 format without the full certificate chain, move them to /usr/local/share/ca-certificates/, then update the certificate store

sudo update-ca-certificates

This will add the certificate information to /etc/ssl/certs/ca-certificates.crt and create symlinks to /etc/ssl/certs/