Questions[bittorrent](server)

How can one block, or severely slow down, BitTorrent and similar peer-to-peer (P2P) services on one's small office network?

In searching Server Fault I wasn't able to find a question that served as a rallying point for the best technical ideas on this. The existing questions are all about specific situations, and the dominant answers are social/legal in nature. Those are valid approaches, but a purely technical discussion would be useful to a lot of people, I suspect. Let's assume that you don't have access to the machines on the network.

With encryption use increasing in P2P traffic, it seems like stateful packet inspection is becoming a less workable solution. One idea that seems to make sense to me is simply throttling down heavy users by IP, regardless of what they're sending or receiving -- but it doesn't seem many routers support that functionality at the moment.

How can you throttle P2P/BitTorrent traffic?

I have 1 source server that contains about 30GB of files that I want to copy to 7 other servers. I currently SCP the files over to the first four servers and when that transfer is complete SCP to the last 3 servers.

Would using BitTorrent be faster to distribute the files to all 7 at once? The connection internally is already fast and consistent between each of the servers. I know it would probably take some load off the source server, but would it just take longer to distribute the files?

What's a good scriptable client I could use from the shell? I'd want everyone to stop seeding after 100%.

I'm considering a file distribution between branch offices that uses Bittorrent. I understand that a Bittorrent client needs ports in the range of 6881-6999 to be forwarded to the internet to make the transfer faster.

What I don't understand is: how does this make things faster? I could understand if failing to provide proper means of communication between clients would prevent them from speaking to each other. But everywhere I look I just see the advice "Just forward the ports and the transfer will speed up".

Sorry if this seems off topic, but it strikes me as network related.

Here is an interesting problem/scenario that some sysadmins out there might enjoy:

An apartment building owner is giving away free internet access to his tennants. Basically he has a T1 coming to the building and every apartment has a CAT5 plug in the wall. The internet access is "free" (included in the rent or whatever) to the tennants.

The problem is, several of the tennants are downloading illegal movies/music via bittorrent. As a result, the MPAA and RIAA is sending "nastygrams" to the owner of the internet connection (ie. apartment owner) concerning the illegal downloads.

The apartment owner has blocked lists of torrent sites as well as several file extensions at the router level but the problem persists.

What I'd like to know is if anyone out there has a clever/inexpensive solution for this problem? QoS apparently only works up to a point because bittorrent can use pretty much any port it wants. Packet inspection doesn't work on encrypted connections, etc.

The apartment owner did say he would be happy if he could simply see the upload/download traffic (ie. potential abusers) of the individual apartment units.

Any ideas?

UPDATE: Not interested in discussing the legal/lawyer/social issues as much as the actual technical solutions (whatever they may be). I would kindly request you vote up the TECHNICAL discussions over the legal/social ones. Thanks!

ANSWER: Selected Justin Scott's answer as the correct answer because of his suggestion to use managed switches and MRTG. While it would have been nicer to block bittorrent or at least make it EXTREMELY difficult MRTG and a managed switch will allow us to easily identify the offender(s).

I manage the network in a small office (SW dev is my "real job"), and there are a couple of users who beat the hell out of our internet connection by running bittorrent. Between the almost crippling effect on the upload side (20Mbps) and the potential liability, I want to shut this down as much as possible.

Some quick details in anticipation of questions or suggestions:

• we have 2 routers (1 Linksys, 1 Buffalo) running the latest DD-WRT, and one D-Link DIR-655 running whatever the latest factory software is

• internet is FiOS 20/20 plan

• users connect via WiFi & wired, everyone uses DHCP

• acquiring new hardware (let's say < $1000) that really does the trick reliably is an option

• we have an internet usage policy in place, yes, but I want to enforce it as much as possible via IT because we all know that some people just can't follow the rules. Yes I know that dealing with this is a social issue, but this part is out of my authority/control.

• the common strategies (completely block access by MAC / IP, block ports, etc..) won't work. At least 2 of the people routinely re-program the MAC addresses on their Ethernet interfaces.

I understand that BT clients can be configured to use other ports, so just blocking the standard BT port range is weaksauce.

I can't believe I'm the first person to skin this cat. Or maybe only IT depts. with large equipment budgets can skin this cat?

Thanks for your help!