_list_etc_network_interfaces() {
  local file

  for file in /etc/network/interfaces /etc/network/interfaces.d/*; do
    if ! [ -f "$file" ]; then
      continue
    fi
    case "${file##*/}" in
    *[^-a-zA-Z0-9_]*)
      continue
      ;;
    esac
    echo "$file"
  done
}

_add_etc_network_interfaces() {
  local file
  test -f /etc/network/interfaces || return 0

  echo '** Network interface configuration:' >&3

  while read file; do
    if ! [ -r "$file" ]; then
      echo "*** $file: unreadable" >&3
      echo >&3
      continue
    fi
    echo "*** $file:" >&3
    # Hide passwords/keys
    awk '$1 ~ /key|pass|^wpa-(anonymous|identity|phase|pin|private|psk)/ { gsub(".", "*", $2); }
         $1 == "ethtool-wol" { gsub(".", "*", $3); }
         !/^[[:space:]]*\#/ { print; }
        ' <"$file" >&3
    echo >&3
  done < <(_list_etc_network_interfaces)
}

add_network() {
  yesno "Include network configuration and status from this computer? " nop
  test $REPLY = yep || return 0

  _add_etc_network_interfaces
  echo '** Network status:' >&3
  if command -v ip >/dev/null; then
    echo '*** IP interfaces and addresses:' >&3
    ip address show >&3
    echo >&3
  fi
  echo '*** Device statistics:' >&3
  cat /proc/net/dev >&3
  echo >&3
  if command -v netstat >/dev/null; then
    echo '*** Protocol statistics:' >&3
    netstat -s >&3 || true
    echo >&3
  fi
  echo >&3
}

ask_network() {
  test $same_system = yep || return 0
  test -f /etc/network/interfaces || return 0

  yesno "Include network configuration from this computer? " nop
  test $REPLY = yep || return 0

  _add_etc_network_interfaces
}