Update 'README.md'

README.md

@@ -119,6 +119,47 @@ ufw allow from 192.168.1.10 to any port 22 proto tcp
 ufw allow in on tailscal0 to interfaceip port 22 from otherdeviceip
 ufw reset
 ```
+## Linux VLANs
+
+`sudo apt install vlan`
+
+Add the following lines to allow multiple VLANs to create routing tables:
+
+`echo "500 firsttable" | sudo tee -a /etc/iproute2/rt_tables`
+
+Load the 8021q kernel module:
+
+`sudo modprobe 8021q`
+
+Confirm the module is loaded:
+
+```bash
+$ lsmod | grep 8021q
+8021q                  40960  0
+garp                   16384  1 8021q
+mrp                    20480  1 8021q
+```
+
+`sudo nano /etc/network/interfaces`
+
+```
+# Source custom network configuration files
+source /etc/network/interfaces.d/*
+
+# The loopback network interface
+auto lo
+iface lo inet loopback
+
+# The first VLAN interface
+auto eno1.503
+iface eno1.503 inet static
+    address 172.20.20.10
+    netmask 255.255.255.240
+    gateway 172.20.20.1
+    dns-nameservers 8.8.8.8 8.8.4.4
+```
+
+`sudo ifup eno1.503`
 
 ## List ports Linux is listening on