Bandwidth Theft

This can be a problem here in SA, and having come across a few people lately who've been having a problem I typed up the following explanation to send to them. It's brief, but covers the main points; if you think I've left anything out or gotten anything wrong, feel free to say so in the comments!

There are basically 3 levels where bandwidth can be stolen:
1) On your PC - if you have a trojan, spyware, or a bot that's installed itself and is sending or receiving data
2) People tapping into your network - particularly if you have wi-fi enabled
3) People using your account name and password on their own network

If it's something on your PC, you should pick up the increased usage on netmeter. The best thing to do is install an anti-virus package, and something like Spybot or Ad-Aware, and run both to make sure your system is clean.

If it's someone tapping into your network, the best option is to disable wi-fi if you're not using it. If you do use it, make sure you have security enabled (use WPA rather than WEP).

If someone's using your details on their own network, the best steps to take are:
1) Change your router username and password (keep them somewhere safe!) so that no-one can access your router settings.
2) Change your account password. This will have to be done via your ISP; if they have a control panel you might be able to change it yourself. The biggest problem here is that many ISP's don't encrypt your password; they do this so that if you forget your password they can give it to you over the phone. The problem is that they then know your username and password, and can use it themselves if they're less than trustworthy.