See the key to blocking torrent downloading is not allow masquerading.
hope it helps.

I didnot get ur point :-(

Have implemented squid using similar rules in iptables:-

#iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

#iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j REDIRECT --to-port 3128

eth0(internet adapter)
eth1(internal network)

Thanks for proving my point...you cannot block torrents with Squid. You're doing a redirect with iptables, which is not the same thing. Also, you can still download torrents with what you have stated above. Torrents are specifically designed to be hard to block, which is why layer seven filters exist, and which is why even ISP's have a hard time blocking/tracking them.

There are IPtables rules you can use with regex'es to TRY to block things, but even they don't work.

Yes i have implemented the same iptables rule.

see if you will not use this command:
#iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

and manually feed proxy settings in client browser than only browser will be able to use internet and torrent programs will not get internet.

Again, no. You are NOT using squid to block torrents, rather an IP tables rule. And again, you can run a torrent client and simply put the proxy port in, and bypass it, since by using your rules, all you're doing is a redirect. You're not blocking the ports used by torrent clients.

First of all I am using squid to provide internet on limited ports. (ok)
Than I agree that any one can run a torrent client and simply put the proxy port in, and bypass it. But if you will use delay pools than torrent download speed can be limited.

I suggest you try it practically. Than give me your feedback.

I suggest you read the question, and read what you just posted. The OP posted that they want to BLOCK (that is TOTALLY STOP) torrent downloading. You CANNOT DO THAT WITH SQUID, PERIOD. You even then follow up by saying you KNOW it won't work, and the best your solution can do is limit the SPEED of downloading, providing that they do it through a web browser. Again, your 'solution' lets a torrent client BYPASS squid totally...and if you bypass squid, how exactly would the squid rules apply to that download????

I HAVE tried what you posted, a good while back, and so I KNOW it doesn't work.

First try it. See if torrent downloading speed is reduced beacuse of delay pools.
Practically testing is far better than Arguments.

And if you read what I posted before, I HAVE TRIED IT, and it doesn't work. Again, if you bypass Squid, the squid rules don't apply.

And again, you have not addressed the OP's question. They want to BLOCK...not 'slow down'...torrent downloads. Your 'solution', does NOT BLOCK IT, so it DOES NOT WORK.

It worked for me as most user don't know to bypass it. I just wanted to help.