add option to drop the default route on providers, that do not override it properly

README.md

@@ -367,3 +367,12 @@ $ sudo systemctl stop transmission-openvpn.service
 # Later ...
 $ sudo systemctl start transmission-openvpn.service
 ```
+
+## Drop the default route
+
+Some VPNs do not override the default route, but rather set other routes with a lower metric.  
+This might lead to te default route (your untunneled connection) to be used.
+
+To drop the default route set the environment variable `DROP_DEFAULT_ROUTE` to `true`.
+
+*Note*: This is not compatible with all VPNs. Please check yourself if your provider overrides the default route properly.

transmission/environment-variables.tmpl

@@ -81,3 +81,6 @@ export PGID={{ .Env.PGID }}
 
 # Support custom web frontend
 {{ if .Env.TRANSMISSION_WEB_HOME }} export TRANSMISSION_WEB_HOME={{ .Env.TRANSMISSION_WEB_HOME }} {{end}}
+
+# Support dropping the default route after connection
+export DROP_DEFAULT_ROUTE={{ .Env.DROP_DEFAULT_ROUTE }}

transmission/start.sh

@@ -38,6 +38,11 @@ fi
 
 . /etc/transmission/userSetup.sh
 
+if [ "true" = "$DROP_DEFAULT_ROUTE" ]; then
+  echo "DROPPING DEFAULT ROUTE"
+  ip r del default || exit 1
+fi
+
 echo "STARTING TRANSMISSION"
 exec sudo -E -u ${RUN_AS} /usr/bin/transmission-daemon -g ${TRANSMISSION_HOME} --logfile ${TRANSMISSION_HOME}/transmission.log &