auto disconnects clients with a low signal strength on LEDE / OpenWRT

angry_wifi.sh

#!/bin/ash
#
# angry_wifi.sh
#
# auto disconnects clients with a low signal strength on LEDE / OpenWRT. great
# for clients who hold onto a lower-signal-strength accesspoint instead of
# roaming. before running, make sure to download the latest MAC addresses with:
#
#   wget --no-check-certificate -O - 'https://services13.ieee.org/RST/standards-ra-web/rest/assignments/download/?registry=MAC&text=apple' | cut -d, -f2 > apple_mac_addresses
#
# some notes:
# - only Apple clients will be disconnected
# - clients won't be re-disconnected for 1 minute if they end up re-connecting
# - be careful with this script, if you don't have solid wifi everywhere clients
#   will constantly be disconnected

IFS=$'\n'
while true; do
  for LINE in $(iwinfo wlan0 assoclist | grep SNR); do
    MAC=$(echo "$LINE" | awk '{ print $1 }')
    SIGNAL=$(echo "$LINE" | awk '{ print $2 }')
    MAC_PREFIX=$(echo "$MAC" | sed -e 's/://g' | cut -c1-6)

    if [ "$SIGNAL" -lt "-80" ]; then
      if find . | grep "angry_wifi_client_$MAC" > /dev/null; then
        date ; logger -s -t angry_wifi "Low signal client $MAC ($SIGNAL) is back, not disconnecting yet."

      # Only allow Apple devices to roam
      elif grep "$MAC_PREFIX" apple_mac_addresses; then
        date ; logger -s -t angry_wifi "Low signal client $MAC ($SIGNAL) being disconnected."
        ubus call hostapd.wlan0 del_client "{'addr':'$MAC', 'reason':5, 'deauth':false, 'ban_time':0}"

        # Add to do-not-disconnect list
        touch "angry_wifi_client_${MAC}_$(date +%s)"
      fi
    fi
  done

  # Remove from the do-not-disconnect list
  CURDATE=$(date +%s)
  for FILE in $(find . | grep angry_wifi_client); do
    TIME=$(echo "$FILE" | cut -d'_' -f 5)
    TIME_SINCE=$((CURDATE - TIME))
    MAC=$(echo "$FILE" | cut -d'_' -f 4)

    if [ "$TIME_SINCE" -gt "60" ]; then
      date ; logger -s -t angry_wifi "Low signal client $MAC removed from do-not-disconnect."
      rm "$FILE"
    fi
  done

  sleep 1
done

I needed something more robust, so I got concepts from this gist and https://github.com/mk248/lede-modhostapd and created a pure-Lua script that uses /etc/config/wireless, taking signal OR signal-noise-ratio, supports whitelists (like Apple devices), blacklists and is a bit more efficient, not touching the filesystem to persist state.

https://github.com/barbieri/barbieri-playground/tree/master/openwrt/wifi-disconnect-low-signal

however I really hope OpenWRT/LEDE will integrate the modhostapd patch, then we can avoid an extra process in the system.