Similar to what I wrote for Ubuntu 18.04, here is how to setup an LXC container on Debian forky.

Installing the required packages

Start by installing the necessary packages on the host:

apt install lxc libvirt-clients debootstrap

Network setup

Ensure the veth kernel module is loaded by adding the following to /etc/modules-load.d/lxc-local.conf:

veth

and then loading it manually for now:

modprobe veth

Enable IPv4 forwarding by putting this in /etc/sysctl.d/lxc-local.conf:

net.ipv4.ip_forward=1

and applying it:

sysctl -p /etc/sysctl.d/lxc-local.conf

Restart the LXC network bridge:

systemctl restart lxc-net.service

Ensure that container traffic is not blocked by the host firewall, for example by adding the following to /etc/network/iptables.up.rules:

-A FORWARD -d 10.0.3.0/24 -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -s 10.0.3.0/24 -j ACCEPT
-A INPUT -d 224.0.0.251 -s 10.0.3.1 -j ACCEPT
-A INPUT -d 239.255.255.250 -s 10.0.3.1 -j ACCEPT
-A INPUT -d 10.0.3.255 -s 10.0.3.1 -j ACCEPT
-A INPUT -d 10.0.3.1 -s 10.0.3.0/24 -j ACCEPT

and applying the rules:

iptables-apply

Creating a container

To see all available images, run:

lxc-create -n foo --template=download -- --list

and then create a Debian forky container using:

lxc-create -n forky -t download -- -d debian -r forky -a amd64

Start and stop the container like this:

lxc-start -n forky
lxc-stop -n forky

Connecting to the container

Attach to the running container's console:

lxc-attach -n forky

Inside the container, you can change the root password by typing:

passwd

and install some essential packages:

apt install openssh-server vim

To find the container's IP address (for example, so that you can ssh to it from the host):

lxc-ls --fancy