Automatically update theos device settings and kill/open Dropbox on network change (macOS)

networkchange.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" \
 "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>networkchange</string>
  <key>LowPriorityIO</key>
  <true/>
  <key>ProgramArguments</key>
  <array>
    <string>/Users/andeh/Dropbox/bin/updateIP.sh</string>
  </array>
  <key>WatchPaths</key>
  <array>
    <string>/etc/resolv.conf</string>
    <string>/var/run/resolv.conf</string>
    <string>/private/var/run/resolv.conf</string>
  </array>
  <key>RunAtLoad</key>
  <true/>
</dict>
</plist>

updateIP.sh

# Get IP
IP=`ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'`
echo "IP is $IP"

# Get SSID - Only works on Mac
SSID=`/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | awk '/ SSID/ {print substr($0, index($0, $2))}'`
echo "SSID is $SSID"

case $IP in
    "192.168.0."*) # Home
        open -a "Dropbox"
        DEVICE_IP="192.168.0.96"
        DEVICE_PORT="22";;
    "192.168.1."*) # CH
        open -a "Dropbox"
        DEVICE_IP="192.168.1.96"
        DEVICE_PORT="22";;
    "192.168.32."*) # 4G-router
        osascript -e 'tell application "Dropbox" to quit'
        DEVICE_IP="192.168.32.151"
        DEVICE_PORT="22";;
    "172.20.10."*) # Tethering
        osascript -e 'tell application "Dropbox" to quit'
        DEVICE_IP="172.20.10.1"
        DEVICE_PORT="22";;
    *)
        case $SSID in
            "Comentor")
                open -a "Dropbox"
                DEVICE_IP="10.0.1.5"
                DEVICE_PORT="22";;
            *) # USB, eduroam does not allow SSH
                open -a "Dropbox"
                DEVICE_IP="localhost"
                DEVICE_PORT="2222";;
        esac;;
esac

echo "Setting the device IP to $DEVICE_IP"

DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
echo "export THEOS_DEVICE_IP=${DEVICE_IP}" > "$DIR/theos.sh"
echo "export THEOS_DEVICE_PORT=${DEVICE_PORT}" >> "$DIR/theos.sh"

Adapt the script to your liking.

Simply run

launchctl load networkchange.plist
launchctl start networkchange

afterwards. Remember to change the directory to the shell script in the plist.