Limit traffic based on WiFi network name

Question

I would like to be able to automatically disable or block traffic from my bittorrent application when I'm connected to WiFi network "A," and automatically enable it when I'm connected to network "B." Is this possible? I'm using Transmission.app in a Mac.

Answer 1

This is how I did it in Lion OSX. Anything that could be improved?

#!/usr/bin/env bash
set -o nounset -o pipefail

WIFI_NAME="MyWifiName"
while [[ 1 ]]; do
SSID_NAME="$(/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | sed -e "s/^  *SSID: //p" -e d)"
if [[ $SSID_NAME != $WIFI_NAME ]] ; then

    TRANSMISSION="$(ps aux | grep Transmission | grep -v "grep" | head -n1 | awk '{print $2}')"

    if [[ $TRANSMISSION != "" ]]; then
        kill -9 $TRANSMISSION
    fi
fi

done