Run OpenWrt on QEMU virtual machines with LAN and WAN network.

host-network-setup.sh

#
# The following script will
#   - Create Linux bridge $BR_WAN, $BR_LAN
#   - Install IP addresses and basic routes
#   - Enable proxy_arp on $BR_WAN
#   - Enable ip_forward
#   - Enable MASQUERADE on $IF_INET

# - $BR_LAN, $BR_WAN has to be allowed in ~/.usr/etc/qemu/bridge.conf
#
#	Sample content:
#
#		allow br-lan
#		allow br-wan
#
#	See qemu-bridge-helper.c of QEMU source code for details (`allow all`, `deny all`, `include xxx` can also be used).
#
# config variables
BR_WAN="br-wan"
BR_LAN="br-lan"
IF_INET="eth0"

# - qemu-bridge-help has to be root setuid program.
HELPER="$HOME/.usr/libexec/qemu-bridge-helper"
mac_rand() {
	hexdump -n 3 -e '"52:54:00:" 2/1 "%02x:" 1/1 "%02x"' /dev/urandom
}

# setup bridge for LAN network
sudo ip link add dev "$BR_LAN" type bridge
sudo ip link set dev "$BR_LAN" up
sudo ip addr add 192.168.1.3 dev "$BR_LAN"
sudo ip route add 192.168.1.0/24 dev "$BR_LAN"

# setup bridge for WAN network
sudo ip link add dev "$BR_WAN" type bridge
sudo ip link set dev "$BR_WAN" up
sudo ip addr add 192.168.7.1 dev "$BR_WAN"
#sudo ip link set dev tap0 master "$BR_WAN"
sudo ip route add 192.168.7.0/24 dev "$BR_WAN"

# Internet access setup
sudo sysctl -w net.ipv4.ip_forward=1
sudo sysctl -w net.ipv4.conf."$BR_WAN".proxy_arp=1
sudo iptables -t nat -A POSTROUTING -o "$IF_INET" -j MASQUERADE

openwrt-wan-setup.sh

openwrt_wan_static() {
  # Run this within OpenWrt
  uci batch <<EOF
  delete network.wan
  set network.wan=interface
  set network.wan.ifname=eth1
  set network.wan.proto=static
  set network.wan.ipaddr=192.168.7.2
  set network.wan.netmask=255.255.255.0
  set network.wan.gateway=192.168.7.1
  add_list network.wan.dns=208.67.222.222
  add_list network.wan.dns=208.67.220.220
  commit
  EOF
  /etc/init.d/network reload
}

host_dnsmasq_br_wan() {
  # Run this within host machine
  #
  #sudo apt-get install dnsmasq
  #sudo vi /etc/dnsmasq.conf
  #
  # Minimal conf.  The netmask is needed as br-wan is a bridge otherwise dnsmasq would complain "no address range available for DHCP request via br-wan"
  #
  #   interface=br-wan
  #   dhcp-range=192.168.7.50,192.168.7.150,255.255.255.0,30m
}

qemustart.sh

#!/bin/sh

BR_WAN="br-wan"
BR_LAN="br-lan"
IF_INET="eth1"

# qemu-bridge-helper needs to be root setuid program.
HELPER="$HOME/.usr/libexec/qemu-bridge-helper"


SELF="$0"

usage() {
	cat >&2 <<EOF
usage: $SELF <target> [<subtarget> [<extra-qemu-options>]] [--qga]
       $SELF [-h|--help]

<subtarget> will default to "generic" and it must be explicitly specified if <extra-qemu-options> are to be used

Examples

  $SELF x86 64
  $SELF x86 64 --qga
  $SELF x86 64 --qga --incoming tcp:0:4444
  $SELF x86 64-glibc
  $SELF malta be
  $SELF malta le64
  $SELF malta be-glibc
EOF
}

__errmsg() {
	echo "$*" >&2
}

mac_rand() {
	hexdump -n 3 -e '"52:54:00:" 2/1 "%02x:" 1/1 "%02x"' /dev/urandom
}


OPT_MEM=256
while [ "$#" -gt 0 ]; do
	case "$1" in
		--qga)
			if [ -z "$OPT_QGA" ]; then
				OPT_QGA=" -device virtio-serial"
				OPT_QGA="$OPT_QGA -chardev socket,path=/tmp/qga.sock,server,nowait,id=qga0"
				OPT_QGA="$OPT_QGA -device virtserialport,chardev=qga0,name=org.qemu.guest_agent.0"
				shift
			fi
			;;
		-m)
			OPT_MEM="$2"
			shift 2
			;;
		--help|\
			-h)
			usage
			exit 0
			;;
		*)
			if [ -z "$TARGET" ]; then
				TARGET="$1"
			elif [ -z "$SUBTARGET" ]; then
				SUBTARGET="$1"
			else
				OPT_QEMU_EXTRA="$OPT_QEMU_EXTRA $1"
			fi
			shift
			;;
	esac
done

if [ -z "$TARGET" ]; then
	usage
	exit 1
fi
if [ -z "$SUBTARGET" ]; then
	SUBTARGET="generic"
fi

OPT_QEMU_EXTRA="$OPT_QEMU_EXTRA $OPT_QGA"

MAC_LAN="$(mac_rand)"
MAC_WAN="$(mac_rand)"

case "$TARGET" in
	malta)
		# SUBTARGET can be le, be, le64, be64, le-glibc, le64-glibc, etc..
		is64="$(echo $SUBTARGET | grep -o 64)"
		if [ "$(echo "$SUBTARGET" | grep -o '^..')" = "le" ]; then
			isel="el"
		fi
		IMG="bin/targets/$TARGET/$SUBTARGET/lede-malta-${SUBTARGET%-*}-vmlinux-initramfs.elf"
		"qemu-system-mips$is64$isel" -M malta -kernel "$IMG" -m "$OPT_MEM" -nographic \
			-netdev bridge,id=wan,br="$BR_WAN,helper=$HELPER" -device pcnet,netdev=wan,mac="$MAC_WAN" \
			-netdev bridge,id=lan,br="$BR_LAN,helper=$HELPER" -device pcnet,netdev=lan,mac="$MAC_LAN" \
			$OPT_QEMU_EXTRA

		;;
	x86)
		IMG="bin/targets/$TARGET/$SUBTARGET/lede-$TARGET-${SUBTARGET%-*}-combined-ext4.img"
		if [ -s "$IMG.gz" ]; then
			gunzip "$IMG.gz"
		fi
		#
		# generic: 32-bit, pentium4 (CONFIG_MPENTIUM4), kvm guest, virtio
		# legacy: 32-bit, i486 (CONFIG_M486)
		# 64: 64-bit, kvm guest, virtio
		#
		case "$SUBTARGET" in
			legacy)
				QEMU="qemu-system-i386"
				;;
			generic|\
			64)
				QEMU="qemu-system-x86_64"
				;;
			*)
				__errmsg "target $TARGET: subtarget $SUBTARGET: cannot decide qemu executable to use"
				exit 1
				;;
		esac
		case "$SUBTARGET" in
			64|\
			generic)
				$QEMU -nographic -m "$OPT_MEM" \
					-netdev bridge,id=lan,br="$BR_LAN,helper=$HELPER" -device virtio-net-pci,id=devlan,netdev=lan,mac="$MAC_LAN" \
					-netdev bridge,id=wan,br="$BR_WAN,helper=$HELPER" -device virtio-net-pci,id=devwan,netdev=wan,mac="$MAC_WAN" \
					-drive "file=$IMG,format=raw,if=virtio" \
					-device virtio-balloon-pci \
					$OPT_QEMU_EXTRA

				;;
			legacy)
				# use IDE (PATA) disk instead of AHCI (SATA).  Refer to link
				# [1] for related discussions
				#
				# To use AHCI interface
				#
				#	-device ich9-ahci,id=ahci \
				#	-device ide-drive,drive=drv0,bus=ahci.0 \
				#	-drive "file=$IMG,format=raw,id=drv0,if=none" \
				#
				# [1] https://dev.openwrt.org/ticket/17947
				$QEMU -nographic -m "$OPT_MEM" \
					-netdev bridge,id=lan,br="$BR_LAN,helper=$HELPER" -device e1000,id=devlan,netdev=lan,mac="$MAC_LAN" \
					-netdev bridge,id=wan,br="$BR_WAN,helper=$HELPER" -device e1000,id=devwan,netdev=wan,mac="$MAC_WAN" \
					-device ide-drive,drive=drv0 \
					-drive "file=$IMG,format=raw,id=drv0,if=none" \
					$OPT_QEMU_EXTRA

				;;
			*)
				__errmsg "target $TARGET: subtarget $SUBTARGET is not supported yet"
				exit 1
				;;
		esac
		;;
	realview)
		IMG="bin/targets/$TARGET/$SUBTARGET/lede-$TARGET-vmlinux-initramfs.elf"
		qemu-system-arm -M realview-eb-mpcore -nographic -m "$OPT_MEM" \
			-kernel "$IMG" \
			$OPT_QEMU_EXTRA

		;;
	*)
		__errmsg "target $TARGET is not supported yet"
		exit 1
		;;
esac