diff --git a/docker-data/wireguard/custom-cont-init.d/10-forwarding.sh b/docker-data/wireguard/custom-cont-init.d/10-forwarding.sh
new file mode 100755
index 0000000..5e83e5e
--- /dev/null
+++ b/docker-data/wireguard/custom-cont-init.d/10-forwarding.sh
@@ -0,0 +1,17 @@
+#!/bin/sh
+# Enable forwarding between Docker network and WireGuard tunnel
+# Idempotent: check before adding to prevent duplicates on restart
+iptables -C FORWARD -i eth0 -o wg0 -j ACCEPT 2>/dev/null || iptables -A FORWARD -i eth0 -o wg0 -j ACCEPT
+iptables -C FORWARD -i wg0 -o eth0 -j ACCEPT 2>/dev/null || iptables -A FORWARD -i wg0 -o eth0 -j ACCEPT
+
+# Block cross-subnet traffic on wg0 (tenant isolation)
+# Peers in 10.10.1.0/24 cannot reach peers in 10.10.2.0/24
+iptables -C FORWARD -i wg0 -o wg0 -j DROP 2>/dev/null || iptables -A FORWARD -i wg0 -o wg0 -j DROP
+
+# Block IPv6 forwarding on wg0 (prevent link-local bypass)
+ip6tables -C FORWARD -i wg0 -j DROP 2>/dev/null || ip6tables -A FORWARD -i wg0 -j DROP
+
+# NAT for return traffic
+iptables -t nat -C POSTROUTING -o wg0 -j MASQUERADE 2>/dev/null || iptables -t nat -A POSTROUTING -o wg0 -j MASQUERADE
+
+echo "WireGuard forwarding and tenant isolation rules applied"