Test scripts for setting up bridge/ipforward/vlan/802.1q/802.1ad/pppoe

script-downstream.sh

#!/bin/bash

intf="eth1"
o="$1"

echo 1 >/proc/sys/net/ipv4/ip_forward
echo 1 >/proc/sys/net/ipv4/conf/$intf/forwarding

ip link set $intf up

while kill -9 $(cat /run/ppp0.pid) 1>/dev/null 2>/dev/null; do sleep 0.1; done
ip link set $intf down
ip link set dev $intf mtu 1500
ip addr del 192.168.22.2/24 dev $intf  2> /dev/null
ip addr del 192.168.1.8/24 dev $intf   2> /dev/null
ip route del default                   2> /dev/null
ip link del ${intf}.10                 2> /dev/null
ip link del ${intf}.20                 2> /dev/null
ip link del ${intf}.10.20              2> /dev/null
ip link set $intf up

orig=$intf
proto=""
[[ "$o" == "qq" || "$o" == "ad" ]] && mtu="mtu 1504" || mtu="mtu 1500"
[ -z "$o" ] && o="b"

if [[ "$o" == "ad" ]]; then
  proto="protocol 802.1ad"
  o="qq"
fi
if [[ "$o" == "qq" ]]; then
  ip link add link $intf name ${intf}.10 type vlan $proto id 10
  intf="${intf}.10"
  ip link set $intf up
  o="q"
fi
if [[ "$o" == "q" || "$o" == "qp" ]]; then
  ip link add link $intf name ${intf}.20 type vlan id 20
  intf="${intf}.20"
  ip link set $intf up
  [[ "$o" == "qp" ]] && o="p" || o="i"
fi

if [[ "$o" == "i" ]]; then
  echo "SETUP: ipforward"
  echo "define wan = $intf" > /etc/systemd/network/eth1.nft
  systemctl start nftables
  ip link set $intf up
  ip link set dev $orig $mtu
  ip addr add 192.168.22.2/24 broadcast 192.168.22.255 dev $intf
  ip route add default via 192.168.22.1 dev $intf
  ip a show dev $intf; ip r
elif [[ "$o" == "b" ]]; then
  echo "SETUP: bridged"
  echo "define wan = $intf" > /etc/systemd/network/eth1.nft
  systemctl start nftables
  ip link set $intf up
  ip addr add 192.168.1.8/24 broadcast 192.168.1.255 dev $intf
  ip route add default via 192.168.1.1 dev $intf
  ip a show dev $intf; ip r
elif [[ "$o" == "p" ]]; then
  echo "SETUP: pppoe"
  if [ -z "$(cat /etc/ppp/chap-secrets | grep eric)" ]; then
      echo -e '\n"eric"          *       "1234"                  *' >>/etc/ppp/chap-secrets 
  fi
  echo "define wan = ppp0" > /etc/systemd/network/eth1.nft
  systemctl start nftables
  arguments=(
	plugin /usr/lib/rp-pppoe/rp-pppoe.so nic-$intf
	persist
	holdoff 0
	noauth
	remotename myisp
	name eric
	defaultroute
	noipdefault
	#nodetach
	noaccomp
	nodeflate
	noproxyarp
	nopcomp
	novj
	novjccomp
	lcp-echo-interval 10
  )
  pppd "${arguments[@]}"
fi

script-upstream.sh

#!/bin/bash

intf="lan2"
o="$1"

echo 1 > /proc/sys/net/ipv4/ip_forward
echo 1 > /proc/sys/net/ipv4/conf/brlan/forwarding
echo 1 > /proc/sys/net/ipv4/conf/$intf/forwarding

ip link set $intf up

while kill -9 $(cat /run/pppoe-server.pid) 1>/dev/null 2>/dev/null; do sleep 0.1; done
ip link set $intf down
ip link set dev $intf mtu 1500
ip link set dev $intf nomaster         2> /dev/null
ip route del 192.168.22.0/24 dev $intf 2> /dev/null
ip route del 192.168.22.0/24 dev $intf.10  2> /dev/null
ip route del 192.168.22.0/24 dev $intf.10.20  2> /dev/null
ip addr del 192.168.22.1/24 dev $intf  2> /dev/null
ip link del ${intf}.10                 2> /dev/null
ip link del ${intf}.20                 2> /dev/null
ip link del ${intf}.10.20              2> /dev/null
ip link set $intf up

orig=$intf
proto=""
[[ "$o" == "qq" || "$o" == "ad" ]] && mtu="mtu 1504" || mtu="mtu 1500"
[ -z "$o" ] && o="b"

if [[ "$o" == "ad" ]]; then
  proto="protocol 802.1ad"
  o="qq"
fi
if [[ "$o" == "qq" ]]; then
  ip link add link $intf name ${intf}.10 type vlan $proto id 10
  intf="${intf}.10"
  ip link set $intf up
  o="q"
fi
if [[ "$o" == "q" || "$o" == "qp" ]]; then
  ip link add link $intf name ${intf}.20 type vlan id 20
  intf="${intf}.20"
  ip link set $intf up
  [[ "$o" == "qp" ]] && o="p" || o="i"
fi

if [[ "$o" == "i" ]]; then
  echo "SETUP: ipforward"
  ip link set $intf up
  ip link set dev $orig $mtu
  ip addr add 192.168.22.1/24 broadcast 192.168.22.255 dev $intf
  ip route add 192.168.22.0/24 dev $intf
  ip a show dev $intf; ip r
elif [[ "$o" == "b" ]]; then
  echo "SETUP: bridged"
  ip link set dev $intf master brlan
  bridge vlan add vid 2 dev $intf pvid untagged
  ip link set $intf up
elif [[ "$o" == "p" ]]; then
  echo "SETUP: pppoe"
  if [ -z "$(cat /etc/ppp/chap-secrets | grep eric)" ]; then
      echo -e '\n"eric"          *       "1234"                  *' >>/etc/ppp/chap-secrets 
  fi
  cat <<-EOF >/run/pppoe-server-options
	require-chap
	auth
	lcp-echo-interval 10
	lcp-echo-failure 2
	ms-dns 192.168.1.1
	netmask 255.255.255.0
	defaultroute
	noipdefault
	EOF
  pppoe-server -k -C isp -L 192.168.22.1 -R 192.168.22.2 -N 9 -I $intf \
      -X /run/pppoe-server.pid -O /run/pppoe-server-options
fi

For anyone interested, I've posted my test-setup scripts for testing all different kinds of network connections:

One script on a host that is most near to the internet connection, upstream.
One script for a host that is connected to the first host, down-stream.

The scripts assume that the selected interface $intf is not managed by NetworkManager, systemd-networkd or any other

Start both scripts with the same argument, see script for argument options.

no argument = b
b = bridge (on upstream host)
i = ipforwarded (on upstream host)
p = pppoe setup
q = 802.1q single vlan
qq = 802.1q QinQ double vlan
ad = 802.1ad double vlan
qp = vlan and pppoe combined

Not all very difficult to setup, but easy pppoe setup was not documented very well, so maybe this info can help more testers.

One may need to change some ip numbers, I published this more as an example then ready to go scripts.