You can secure your WiFi networks both LAN and WAN by following these instructions

•    The first thing you must do after setting up your wireless network is to change the administrator interface login and password of your WiFi router or access point.

Most of the WiFi routers and access points come with default administrator interface in which the administrator user name is usually set to be "admin" and the password is also the same or a simple string of characters or numbers.

These password and username are set for all the devices of a particular manufacturer and are highly insecure since everybody knows what they are.

Set your username to something that cannot be easily guessed.

Similarly use a strong password which contains a combination of letters, numbers and special characters for increased security. You can also set up multiple accounts other than the admin account with limited functionality to provide ease of access to users.

•    Change the name of your network immediately. Your router or access point comes with a default name called SSID.

For example the SSID for the routers manufactured by the company Aztech is "Aztech". Change the name of your SSID to a more specific and secure name.

Also turn off broadcasting your SSID. By doing so your network would become invisible to unauthorized users.

•    Always enable encryption. WPA (Wifi Protected Access) is the best available encryption. But if it is unavailable then WEP (Wired Equivalence privacy) is a better option.

But you must never leave your WiFi unprotected. If you are using WEP use a strong encryption key that is almost impossible to guess and can not be cracker easily.

•    Reduce the signal strength of your wireless router or access point to area that your need. Increasing the strength of your WiFi network signals make it vulnerable to attackers.

•    Assign static IPs to all the authorized users of your WiFi and do not allow any other IP to connect to your network without proper authentication and verification

•    Enable personal firewall on all the connected computers of WiFi network and the router or access point and enable MAC filtering in your WiFi  network.

•    Put your router or access point at a safe place and turn it off when you are not using your WiFi network.