Infocards

Skype, Your Bandwidth Limit, and You
Written by Andrew Chang on 11/07/06

Hello residents!

As you know, you have a 12GB limit on your weekly bandwidth. Now normally, a user wouldn't use all of this bandwidth through normal usage. This includes web surfing, email, instant messaging and even video/audio chat. However, some of you might be getting shut-off without really knowing why. All you did was check your email and chat, right? Well if you've you been using Skype, that might be the reason why you're getting shut-off in less than a day.

Skype is a free video/audio chat program for all operating systems. It lets you make calls to anyone and anywhere either for free if they also have the Skype client or for a small fee to phones. Many students have found it useful to stay in touch with home and friends. But there is a hidden side to the Skype interface that is causing a surge in your bandwidth consumption.

Some of you are familiar with P2P networks such as KaZaa and Limewire; Skype functions on a similar concept in that everyone that is part of the Skype network can be a client or a server. However, there are some users that use Skype while behind a firewall, which would normally prevent Skype from functioning properly. To get around this, users that are not behind a firewall that blocks Skype's connections become an enormous hub in which others connect to. You can think of it as... Friend A is on one side of a large wall and Friend B is on the other side, but they want to talk. So what happens is, a total stranger sitting on top of the wall listens to Friend A, and then yells down to Friend B the message, complete with pictures and vice versa. This continues until Friend A and Friend B finish their conversation. This way, Friend A and B can circumvent the wall that would normally prevent them from communicating.

So how does this affect you? As a resident, you're part of the UC Berkeley ResComp network and we do not firewall your connections, which is why we hope you installed BeSecure so that you can keep yourself safe. Since you're not behind a firewall, your computer can act as the person sitting on the wall, only, because of the way Skype is designed, you're not the intermediary for just two friends. It's more than likely that you're the intermediary for hundreds if not thousands of friends. So your computer is accepting lots and lots of messages that you yourself are not seeing, and each of these messages takes up a portion of your bandwidth. Such a large number can easily sap you of all of your bandwidth, leaving you internet-less and behind in your email, not to mention Facebook!

But fear not! For we have a fix for this problem. You can actually prevent Skype from eating up every last drop of your bandwidth by following these simple steps:

Open up Skype, go to the "Tools" menu, and select "Options"
Make sure the "Use Port 80 and 443" option is unchecked and the text field left blank. If leaving the text field blank doesn't work for you, just enter any 5-digit port (i.e. 33220).

Now that you've done all of this, Skype shouldn't become a hub for hundreds of other users, thus saving you from being shut-off by Skype's hidden actions. Remember not to leave Skype running in the background if you're not using it in order to prevent Skype from consuming extra bandwidth!