Cacti/OpenWRT

/etc/config/snmpd

config exec
        option name     iwinfo
        option prog     /usr/local/bin/iwinfo.sh
        option args     wlan0

config exec
        option name     iwinfo
        option prog     /usr/local/bin/iwinfo.sh
        option args     wlan1

/usr/local/bin/iwinfo.sh

#!/bin/bash

if [ ${#} -ne 1 ]; then
  echo "Usage: $0 <interface>"
  exit 0
fi

INFO=`iwinfo ${1} info`
CHANNEL=`echo "${INFO}" | sed -n 's/.*Channel:\ \(.*\)\ (.*)/channel:\1/p'`
TXPOWER=`echo "${INFO}" | sed -n 's/.*Tx-Power:\ \(.*\)\ dBm.*/txpower:\1/p'`
SIGNAL=`echo "${INFO}" | sed -n 's/.*Signal:\ -\(.*\)\ dBm\ \ Noise.*/signal:\1/p'`
NOISE=`echo "${INFO}" | sed -n 's/.*Noise:\ -\(.*\)\ dBm.*/noise:\1/p'`
BITRATE=`echo "${INFO}" | sed -n 's/.*Bit\ Rate:\ \(.*\)\ MBit.*/bitrate:\1/p'`

echo "${CHANNEL} ${TXPOWER} ${SIGNAL} ${NOISE} ${BITRATE}"
exit 0