Peer-to-Peer Networking

Bandwidth abuse through peer-to-peer (P2P) file-sharing programs such as Kazaa, Morpheus, WinMX and BearShare can be prevented in the following ways:

• Make it impossible to install new programs on campus computers. By not giving regular users administrative access to PC workstations, it is possible to prevent the installation of programs such as Kazaa. Many institutions also standardize on a desktop build, where they install the required operating system on one PC. They then install all the necessary applications on it, and configure these in an optimal way. The PC is also configured in a way that prevents users from installing new applications. A disk image of this PC is then cloned to all other PCs using software such as Partition Image (see www.partimage.org) or Drive Image Pro (see www.powerquest.com).

  From time to time, users may succeed in installing new software or otherwise damaging the software on the computer (causing it to hang often, for example). When this happens, an administrator can simply put the disk image back, causing the operating system and all software on the computer to be exactly as specified.

• Blocking these protocols is not a solution. This is because Kazaa and other protocols are clever enough to bypass blocked ports. Kazaa defaults to port 1214 for the initial connection, but if that is not available it will attempt to use ports 1000 to 4000. If these are blocked, its uses port 80, making it look like web traffic. For this reason, ISPs don't it but "throttle it", using a bandwidth-manager product (see chapter three).
• If rate-limiting is not an option, change the network layout. If the proxy server and mail servers are configured with two network cards (as described in chapter three) and these servers are not configured to forward any packets, this would block all P2P traffic. It would also block all other types of traffic, such as Microsoft NetMeeting, SSH, VPN software, and all other services not specifically permitted by the proxy server. In low bandwidth networks it may be decided that the simplicity of this design will outweigh the disadvantages. Such a decision may be necessary, but shouldn't be taken lightly. Network administrators simply cannot predict how users will make innovative use of a network. By preemptively blocking all access, you will prevent users from making use of any services (even low-bandwidth services) that your proxy does not support. While this may be desirable in extremely low bandwidth circumstances, it should never be considered as a good access policy in the general case.