diff --git a/netflow/iptables.sh b/netflow/iptables.sh
index afd9357..ec119d4 100644
--- a/netflow/iptables.sh
+++ b/netflow/iptables.sh
@@ -18,6 +18,10 @@ __main() {
 			$cmd -t mangle -A OUTPUT -m mark ! --mark 0x0 -j "$_chain"
 		fi
 
+		if ! $cmd -t mangle -C FORWARD -m mark ! --mark 0x0 -j "$_chain" 2>/dev/null; then
+			$cmd -t mangle -A FORWARD -m mark ! --mark 0x0 -j "$_chain"
+		fi
+
 		if ! $cmd -t mangle -C "$_chain" -j RETURN 2>/dev/null; then
 			$cmd -t mangle -A "$_chain" -j RETURN
 		fi