add contrib

contrib/systemd/capport-enforcement.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=Captive Portal enforcement service
+Wants=basic.target
+After=basic.target network.target
+ConditionFileIsExecutable=/var/lib/python-capport/start-control.sh
+ConditionPathIsDirectory=/var/lib/python-capport/venv
+
+# TODO: start as unprivileged user but with CAP_NET_ADMIN ?
+[Service]
+Type=notify
+WatchdogSec=10
+ExecStart=/var/lib/python-capport/start-control.sh
+Restart=always
+ProtectSystem=full
+ProtectHome=true
+
+[Install]
+WantedBy=multi-user.target