initial: ZeroTier-like P2P mesh VPN server with multi-tenant Web UI

internal/vl2/mac.go

@@ -0,0 +1,19 @@
+package vl2
+
+import (
+	"net"
+
+	"zeromesh/internal/identity"
+)
+
+// GenerateMAC creates a deterministic MAC address from network ID and node address.
+func GenerateMAC(networkID uint32, nodeAddr identity.Address) net.HardwareAddr {
+	mac := make(net.HardwareAddr, 6)
+	mac[0] = 0x02 // locally administered, unicast
+	mac[1] = byte(networkID >> 16)
+	mac[2] = byte(networkID >> 8)
+	mac[3] = byte(networkID)
+	mac[4] = nodeAddr[3]
+	mac[5] = nodeAddr[4]
+	return mac
+}