throttling my own bittorrent traffic the hard way

Question

I need to throttle in an almost binary way my bittorrent traffic.

I have seen some posts on the subject on how to deal with nasty users - the answers are more targeted at how to make their life difficult than on the limitation itself. I read M0n0wall and pfSense articles mentioned in other posts but they do not address my specific need. I also searched on google and read on tc (with limited understanding)

So I must not be too clever but I still fail to understand in practical words how to achieve:

• an untamed bittorrent traffic on certain ports (which I can set) when nobody is using other protocols (read HTTP) on the network

• a squeeze of the availble bandwidth for bittorrent (down to almost zero) when there is other traffic.

I am specifically looking for a "squeeze" of the bandwidth, not hard limits. I can only estimate the upload/download on my link as it changes form reboot to reboot of the ADSL box.

I use a linux (debian) server which also acts as router / firewall / wifi access point -- so I guess that it is the ideal setup as all the traffic sources are plugged right on it. This is a home LAN where i control all the activities (namely - I do bittorrent in a headless way (with deluge) and other users (as well as myself) browse the web). Since the ADSL connection is poor I need to restrict p2p to have workable web access.

Answer 1

The simplest (but probably uneffective) way is to use 'connection limit' criteria. You may identify and restrict overactive p2p-users, which will create a lot of connections to peers.

Another approach is using some p2p detection algorithms as an iptables extension. There are: ipp2p and l7-filter (can be used apart or simultaneously), but usually they require more resources from system.

Answer 2

Do you want automatic throttling? That is, whenever there is non-BitTorrent traffic, it should be prioritised over BitTorrent. Or would throttling during certain hours, i.e. afternoons/mornings when there are likely to be people using other protocols, be acceptable? If the latter, many BitTorrent clients can be set to throttle aggregate bandwidth used, and do so at scheduled times, e.g. limit themselves to 20KB/s up and downstream during office hours, and run unlimited (i.e. normally) outside of those hours.

The different approaches are performed in different places - traffic prioritisation would happen on your gateway, while client throttling would happen on, well, a client machine (though of course in your case the Debian host could be both the BitTorrent client and the gateway...)