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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 in a Mac.

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migrated from Sep 2 '11 at 9:04

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Abarnert's answer at… demonstrates a more eventful approach to detecting such changes (though nachochab's infinite loop is, perhaps, a less finicky solution). – chbrown Dec 8 '12 at 17:19

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up vote 0 down vote accepted

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

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

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


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