WiFi & Bluetooth
WiFi and Bluetooth are two of the most common ways of connecting devices wirelessly — that is, without being connected by a physical cable. Both enable you to send and receive data, but differ in their scope and how they work.
To join a WiFi network, your computer either needs built-in hardware that can receive and transmit the necessary signals, or a dongle that can.
WiFi is used to connect to a network. The physical location you are connecting to is provided by a WiFi access point (or hotspot), which is itself connected to the network router. In domestic settings, the router and access point are often the same physical device. Effectively, WiFi is the wireless alternative to using an Ethernet cable.
There are different versions of WiFi, but they are all managed by a consortium of manufacturers who comply with agreed standards in order to display the WiFi Alliance logo.
Although you’re technically connecting to the local area network, often you join the WiFi in order to access the internet. If this works, it is because the local network is itself connected, via its router, to the external services of an ISP (Internet Service Provider). It follows that it’s possible to connect to the WiFi but be unable to access the internet. This might happen if the local network’s outgoing connection is broken, or its firewall is preventing traffic flowing back to your machine.
For your computer to connect to another device over Bluetooth, both must have Bluetooth capability, and the Bluetooth must be enabled at both ends of the connection. Similarly to WiFi, if your computer doesn’t have Bluetooth, you can connect a dongle that does.
Bluetooth operates over a shorter range than WiFi, and is used to connect two devices by pairing them. Once connection has been established, they can send data to and from each other.
When you need to connect wirelessly, make sure your Bluetooth or WiFi is switched on.
It’s potentially troublesome if any device can connect to your computer without your permission, because that second device might behave maliciously. This is why it’s common for Bluetooth to require your confirmation (and possibly an identifying passcode) before a connection will be established.
Discoverability and spoofing
Typically you can join a WiFi network because it broadcasts its presence publicly. There might be more than one network available, so you pick the one you want to join using the name it identifies itself with. You might be required to provide authorisation (such as a username and password).
Bluetooth works in a similar way, but often it’s your own computer that is broadcasting its availability. When you aren’t inviting other devices to connect, you don’t need to make your machine “discoverable”. Not broadcasting your Bluetooth availability does not affect any connections you have already established, or paired, with other devices.
In both cases, a malicious device can exploit your trust by tricking you into allowing a connection by presenting itself with a misleading name (including “spoofing” by using the name of a device or network you already trust). Be careful when making connections in public places where this might be happening.