Create directory if needed

src/freedombone-utils-firewall

@@ -36,6 +36,9 @@ EXTERNAL_IPV4_ADDRESS=
 function save_firewall_settings {
     iptables-save > /etc/firewall.conf
     ip6tables-save > /etc/firewall6.conf
+    if [ ! -d /etc/network/if-up.d ]; then
+        mkdir /etc/network/if-up.d
+    fi
     printf '#!/bin/sh\n' > /etc/network/if-up.d/iptables
     printf 'iptables-restore < /etc/firewall.conf\n' >> /etc/network/if-up.d/iptables
     printf 'ip6tables-restore < /etc/firewall6.conf\n' >> /etc/network/if-up.d/iptables