Linux un-numbered interfaces for Packet Capture

allow-hotplug ens6f1
iface ens6f1 inet manual
up ifconfig $IFACE -arp up
up ip link set $IFACE promisc on
down ip link set $IFACE promisc off
down ifconfig $IFACE down
post-up for i in rx tx sg tso ufo gso gro lro; do ethtool -K $IFACE $i off; done

Nicely lifted from https://github.com/Security-Onion-Solutions/security-onion/wiki/NetworkConfiguration

you can also configure to start tcpdump in post-up

</p>
<p>post-up for i in rx tx sg tso ufo gso gro lro; do ethtool -K $IFACE $i off; done; tcpdump -n -i $IFACE -w /var/tmp/trace -C100 -W 999

Update:

WIth netplan you can have an interface brought up without an address by adding it with an empty configuration: {}

# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd
  ethernets:
    ens160:
      dhcp4: yes
    ens192: {}