diff --git a/README.md b/README.md
index a287937..fa4e2a5 100644
--- a/README.md
+++ b/README.md
@@ -207,6 +207,54 @@
 
 ```
 
+## Webserver
+
+### DUID
+
+For port forwarding rule to work, set MAC address of primary interface (for DHCPv4) and DHCP DUID (for DHCPv6), to retrieve fixed address from gateway.
+
+edit the beginning line of
+
+`/var/lib/dhcp/dhclient.<INTERFACE_NAME>.leases` 
+
+`/var/lib/dhcp/dhclient6.<INTERFACE_NAME>.leases`
+
+set to
+
+```properties
+default-duid "\000\001\000\001)\361\037w\200\030D\345\020\230";
+```
+
+set MAC address to `00:11:22:33:44:55` (see below)
+
+### Network interfaces
+
+```properties
+# This file describes the network interfaces available on your system
+# and how to activate them. For more information, see interfaces(5).
+
+source /etc/network/interfaces.d/*
+
+# The loopback network interface
+auto lo
+iface lo inet loopback
+
+# Primary interface
+auto eno1
+iface eno1 inet manual
+
+# Main network bridge (v4, v6)
+auto br-lan
+iface br-lan inet dhcp
+    bridge_ports eno1
+    bridge_stp off
+
+    hwaddress 00:11:22:33:44:55
+
+iface br-lan inet6 dhcp
+    accept_ra 2
+```
+
 # 域名
 
 [TODO]