Avoid setting default gateway on Linux

Avoid setting it, as it will mess up the other network interfaces.
However it is possible to override this new behavior in the
corresponding bash script.

src/ports/linux/set_network_parameters

@@ -37,13 +37,17 @@ SET_VALUES_PERMANENTLY=$6
 # name as station name internally.
 SKIP_SETTING_HOSTNAME=true
 
+# The default gateway is typically used for non-Profinet traffic
+SKIP_SETTING_DEFAULT_GATEWAY=true
+
 echo "Network script for ${INTERFACE}: " \
    "Set IP ${IP_ADDRESS}  " \
    "Netmask ${NETMASK}  " \
    "Gateway ${DEFAULT_GATEWAY}  " \
    "Permanent: ${SET_VALUES_PERMANENTLY}  " \
    "Hostname: ${HOSTNAME}  " \
-   "Skip setting hostname: ${SKIP_SETTING_HOSTNAME}"
+   "Skip setting hostname: ${SKIP_SETTING_HOSTNAME}  " \
+   "Skip setting default gateway: ${SKIP_SETTING_DEFAULT_GATEWAY}"
 
 # There is no need to set the changes permanently,
 # as the p-net stack will set the IP parameters on each start.
@@ -64,13 +68,15 @@ if ! ip link set dev $INTERFACE up; then
    exit 1
 fi
 
-if [ "${DEFAULT_GATEWAY}" != "0.0.0.0" ]; then
-   if ! ip route add default via $DEFAULT_GATEWAY; then
-      echo "Failed to set default gateway"
-      exit 1
+if [ "$SKIP_SETTING_DEFAULT_GATEWAY" = false ]; then
+   if [ "${DEFAULT_GATEWAY}" != "0.0.0.0" ]; then
+      if ! ip route add default via $DEFAULT_GATEWAY; then
+         echo "Failed to set default gateway"
+         exit 1
+      fi
+   else
+      echo "No valid default gateway given. Skipping setting default gateway."
    fi
-else
-   echo "No valid default gateway given. Skipping setting default gateway."
 fi
 
 if [ "$SKIP_SETTING_HOSTNAME" = false ]; then