setup-tap.sh

#! /bin/bash

set -e

# Deny non-root run
if [ "$EUID" -ne 0 ]; then
  echo "ERROR: Please run as root"
  exit
fi

# Parse command line arguments
while [[ "$#" -gt 0 ]]; do
  case $1 in
    --bridge=) LIBVIRT_BRIDGE="$2"; shift ;;
    --tap=) QEMU_TAP="$2"; shift ;;
    *) echo "Unknown parameter passed: $1"; exit 1 ;;
  esac
  shift
done

if [ -z "${LIBVIRT_BRIDGE}" ]; then
  LIBVIRT_BRIDGE="virbr0"
fi

if [ -z "${QEMU_TAP}" ]; then
  QEMU_TAP="qtap"
fi

# Avoid configuring if TAP already exists
if [ `ip --oneline link list | grep ${QEMU_TAP} | wc -l` -ne 0 ]; then
  echo "Tap '${QEMU_TAP}' already exists. Exiting."
  exit
fi

# Create TAP, turn it on, attach to libvirt managed bridge
ip tuntap add dev ${QEMU_TAP} mode tap
ip link set ${QEMU_TAP} up
ip link set dev ${QEMU_TAP} master ${LIBVIRT_BRIDGE}