Argthtjtr

I have flashed DD-WRT firmware to my TP-Link WRT841-N router, set the basic network configuration & wireless. I want to limit bandwidth on a user who is always using torrents which is causing my network connection slowdown. Or is there any way to block these bit-torrent clients?

I am surprised no one answered this.

Yes this is possible, there are a couple ways of achieving what you are trying to do. in my experience, when you do this with roommates who are splitting costs with you, you end up being viewed as an internet connection dictator. There are three ways to do this.

1. Content filtering - This would block all P2P on the network, and may just start a cold war of people trying to bypass the measures you put in place. and i don't think it catches encrypted P2P traffic.

Under Access restrictions, Create a new policy.

PC's> edit list of clients> put traffic offenders in here specific or range

Days = everyday

Time = 24 hours

Catch all P2P protocols = checked

Website Blocking by Keyword = tracker announce and d1:ad2

2. Quality of Service - This acts dynamically as opposed to static bandwidth settings, if no one else is using a priority service then the other users can P2P their hearts out. but as soon as someone uses a priority service the router automatically throttles the p2p to whatever is left over from legitimate traffic.

before enabling QOS you need to get an accurate speed test of your connection. either test it while no one is using the connection or disconnect the other users while you are doing it. write down the maximum download and upload speed. (usually displayed in Mbps) convert what you wrote down to kbps. it will be used in the config

Under the NAT/QOS tab > QOS

Start QOS = Enable

Packet Scheduler = HFSC

Max up = 10% less than your upload speed test

Max down = 10% less than your download speed test

Optimize for Gaming = your choice

under services priority, start adding services you don't want other traffic interfering with.

example:

Google Voice - Premium

Skype - Express

Http/Https - Standard

ftp - Bulk

any traffic not delineated goes to the lowest queue.

3. MAC-address guaranteed bandwidth - This is the easiest to set up, but its not dynamic. any reservation you set here will forevermore limit the device with this MAC-Address. for instance, if you and another person are sharing a ISP connection, you could set two MAC addresses here for two PC's to get half of all the available bandwidth. neither PC would be able to go over that cap,
   even if the other roommates PC was turned off. you would not be able to access the additional bandwidth.

its also under NAT/QOS > QOS > all the way at the bottom of the page.

Start QOS = Enable

Packet Scheduler = HFSC

Max up = 10% less than your upload speed test

Max down = 10% less than your download speed test

Optimize for Gaming = your choice

this is done under the MAC priority section. add the mac of the offending client end station. enter MAX up and DOWN in kbps. save and apply.
You may or may not have to reboot the router for the changes to take effect, and you're done.