[curl] Added --interface argument to improve IPv6 support

Author: klukonin

openwisp-config/files/openwisp.agent

@@ -69,7 +69,7 @@ STATUS_REPORT="$WORKING_DIR/status_report"
 APPLYING_CONF="$WORKING_DIR/applying_conf"
 REGISTRATION_URL="$URL/controller/register/"
 UNMANAGED_DIR="$WORKING_DIR/unmanaged"
-FETCH_COMMAND="curl -s --connect-timeout $CONNECT_TIMEOUT --max-time $MAX_TIME"
+FETCH_COMMAND="curl -s --connect-timeout $CONNECT_TIMEOUT --max-time $MAX_TIME --interface $MAC_INTERFACE"
 mkdir -p $WORKING_DIR
 mkdir -p $UNMANAGED_DIR