Wireless Security
In terms of security things are a little bit more complicated. It should be obvious why I recommended to leave a router or an AP (access point) without a wireless method of security.
There are however some "advice" that I recommended to follow. You might hear your friends telling you to filter access to your wireless network based on the MAC address. And here you have a problem exactly the same as in the LAN. The MAC can be seen and duplicated.
Another wrong practice because it's totally ineffective is hide the SSID. SSID is the name that it uses the AP to "present" posibilor clients. It's ineffective because it can be learned without the AP broadcasting it.
There are several protocols used for the security of wireless networks. The first protocol is WEP (Wired Equivalent Privacy). Wep uses keys to encrypt traffic between 2 points. It's outdated and can be hacked in minutes bygenerating traffic wireless network. It is not recommended to use WEP except for educational purposes only. Personally I think you'd better leave your router without any to security, that way nobody will be tempted to try and hack your wireless network.
Another security system is WPA (2) (Wi-Fi Protected Access). There are 2 types, WPA-Enterprise and WPA-Personal (PSK). For WPA-Enterprise it is necessary to have a 802.1x authentication server (eg Radius). Mode "Personal" uses "Pre-Shared Key" where abbreviation PSK (that's how you'll find iton most routers). WPA-Enterprise uses a different key (passphrase) for each client. WPA-Personal uses a common key for all clients. The main advantage of WPA is offered TKIP (Temporal Key Integrity Protocol). TKIP key dynamically change. This way the recovery of the key by using WEP methods is practically impossible. If the password is weak a "brute force" attack can be successful. It is therefore recommended to use a more secure password (over 20-30 characters).
There are ways to secure a wireless network, however, even if network access is free. If you have equipment, knowledge and the necessary time can have a free wireless network without problems. You can limit access to external resources, speed, can take the "open" network away from your internal network. Most wireless networks have free back limitations as those described above. Unless you need wireless do not install it. A poorly configured wireless network can give you more headaches than a classic "wired" network.