Reducing the impact of P2P users on home network

Discussion in 'Wireless Internet' started by Mike S., Dec 21, 2006.

  1. Mike S.

    Mike S. Guest

    Amateur though I am, I've become the default manager for internet access
    in our large home. The hardware consists of a cable modem and older model
    WRT54G with updated firmware. All but my own PC (which connected via the
    local ethernet port on the router) are using wireless. This has worked
    quite well until the two college-age folks in the house started getting
    heavy into P2P (Limewire and Sharezaa). This has had a noticeable performance
    impact on net access, and I'd like to try to improve things.

    I am not in a position to prohibit these kids from using P2P, and polite
    efforts to get them to limit the number of connections, and to postpone
    heavy transfers to off-hours has not worked for very long. I understand
    that various port blocking rules within the router are largely ineffective
    because the P2P clients use port-hopping, and can even use port 80 if
    notinh else works. I was wondering if a more sophisticated hardware solution
    might help us.

    My first understanding is that the limited CPU power and RAM in an
    inexpensive router get overwhelmed by such a large number of connections.
    Would a more robust hardware (NAT router) be likely to help? If yes, and
    specific suggestions?

    From what I gather, true hardware firewall appliances allow the use of
    rules that can limit the number of connections and the bandwidth allotted
    to each client IP address. This, to me, seems very attractive (although
    more expensive) and I was wondering if interposing a firewall between the
    cable modem and the router (or discarding the modem and using the firewall
    with an access point) would achieve the desired end. Any specific
    Mike S., Dec 21, 2006
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  2. Mike S.

    Seth Goodman Guest

    Since you have a WRT54G, the first thing I would try (assuming you've
    ruled out beatings and electro-shock), is to flash the *free* DD-WRT
    third party firmware onto your WRT54G. DD-WRT has a slew of Quality of
    Service settings, including the ability to limit bandwidth by MAC
    address, which sounds right up your alley.

    The main DD-WRT wiki page is at:

    The QoS settings are described here:

    and you can download DD-WRT from:

    I use DD-WRT myself, and recommend it highly. And, you can't beat the

    Good luck!
    Seth Goodman, Dec 21, 2006
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  3. Mike S.

    Mike S. Guest

    [woops ... I meant discarding the ROUTER]
    Thanks. The WRT54G does have some QOS facility in the recent firmware but
    the DD-WRT seems to be more comprehensive. Since everything is on DHCP
    right now, I suppose the priorities for the two problem users could be
    assigned based on MAC address, as the IP's are always changing.

    Is the DD-WRT flash a one-way deal - i.e. is it possible to go back to
    Linksys factory F/W afterward?
    Mike S., Dec 21, 2006
  4. Mike S.

    Seth Goodman Guest

    You can revert at any time - just flash with the stock firmware from the
    Linksys site.
    Seth Goodman, Dec 21, 2006
  5. You have my sympathy.
    Noticeable? I suspect your network comes to a complete stop when
    they're serving out stolen music and movies.
    Are you in a position to send them an invoice proportional to their
    usage? Instead of interposing a bandwidth manager, it might be better
    to simply charge them for their over-use. If you switch to
    alternative firmware for your WRT54G such as DD-WRT:
    it will add SNMP as a feature. You can then use any of an assortment
    of SNMP based traffic monitoring and measuring tools such at MRTG or
    preferably RRDTool.
    Just setup pre-assigned DHCP IP addresses to all the equipment. Then,
    Just monitor the traffic for the month by IP address, calculate the
    proportional usage, and send them a giant bill. Be sure to amortize
    the cost of the added equipment and your time playing policeman. My
    guess(tm) is that it will probably equal the cost of them getting
    their own DSL or cable service.
    Generally true. However, if you can identify the specific computers
    that are consistently doing the downloading, you can also apply QoS
    (Quality of Service) limits to those IP's, regardless of how many IP
    ports they open. QoS options for DD-WRT:
    Of course, if they change their MAC address, or introduce a new
    computer, such QoS by IP address or MAC address is useless.
    That's just one problem. Most file sharing software opens a huge
    number of ports and buffers. The result is that they also allocate a
    huge number of buffers in the router. If the router firmware hasn't
    been tested for such unusual operation, it might crash. The best way
    to prevent this is to tweak the file sharing client to limit the
    number of simultaneous connections, and the number of streams.

    The other major problem is that file sharing that it tends to saturate
    your uplink. Your cable modem may have 6MBits/sec or more of incoming
    bandwidth, but if the 384k or 512kbits/sec of uplink bandwidth is
    saturated, incoming bandwidth will appear useless because the outgoing
    ACK's and responses will probably be lost or delayed by the
    constipated uplink.
    If you like spending money, there are several dedicated bandwidth
    managers on the market. All will require a dedicated PC to run the
    (Lots more. Search Google for "bandwidth manager").

    Otherwise, you already have a router that can do QoS. I suggest that
    1. Replace WRT54G firmware with DD-WRT v23 SP2.
    2. Setup fixed MAC to IP address DHCP mapping in WRT54G.
    3. Implement QoS by IP address or MAC address.
    4. Setup monitoring so you can document abuse and bill accordingly.
    Jeff Liebermann, Dec 21, 2006
  6. This is one of the few places where MAC-address based permissioning on
    the router is useful.
    Mark McIntyre, Dec 21, 2006
  7. Yep. However, it's easy enough for a user to change their MAC
    address, making this a rather awkward method of monitoring. I've
    recently been installing arpwatch into DD-WRT to detect any "unusual"
    new users:

    Make sure to first enable JFFS2 support on the:
    Admin -> Management
    page. It won't stop the users for changing their MAC address, but it
    will detect them when they try.

    Argh.... "ipkg update" doesn't seem to be working for me today. Now,
    what did I do wrong this time? Oh, no flash space. It's full.
    Jeff Liebermann, Dec 21, 2006
  8. Mike S.

    Tony Guest

    Obviously a large home to you is quite different than a large home to me. I can't
    use a wireless router my main house is too big.
    Tony, Dec 21, 2006
  9. If they are smart enough, they can find out what MAC addresses other
    users equipment have and "borrow" one of these.
    Axel Hammerschmidt, Dec 21, 2006
  10. And he might also ask them to sign an agreement indemnifying him and the
    other residents of the house for any fines, settlements, legal fees, or
    other expenses incurred in case the RIAA et al should come knocking at
    the door.
    Neill Massello, Dec 22, 2006
  11. At which point the OP could put limits on all devices and announce that
    this had been done to preserve some measure of service for all users.
    This might encourage the other residents of the house to evict the two
    P2P fiends.
    Neill Massello, Dec 22, 2006
  12. Mike S.

    Mike S. Guest

    Well, there are 3 floor plus basement. Except for a couple of dead spots
    in the basement (I'm using a high gain directional antenna down there)
    we've been quite impressed with the coverage.
    Mike S., Dec 22, 2006
  13. He could do that without first installing dd-wrt :)
    Axel Hammerschmidt, Dec 22, 2006
  14. And some people use square feet :)
    Axel Hammerschmidt, Dec 22, 2006
  15. Too bad you can't afford additional access points.
    Neill Massello, Dec 22, 2006
  16. Mike S.

    Peter Pan Guest

    My feet are flat... Guess I use a non-standard flat feet measurement :)
    Peter Pan, Dec 22, 2006
  17. What I meant was to restrict the list of MACs that can get IPs from
    the router, then set up QoS rules on each of those. If your students
    change their MAC, they can't get an IP. Obviously they could clone the
    MAC of someone else in the house but then that person would get locked
    out and they'd complain.
    Mark McIntyre, Dec 22, 2006
  18. If they are smart enough, they can find out what MAC addresses other
    users equipment have and "borrow" one of these.[/QUOTE]

    Sure, but then the other person would get locked out, and complain.
    It'd be a quick job to ID who was 'stealing' access, and permanently
    exclude them.

    Myself, I just block all P2P use by edict, and if I were to catch
    anyone at it (detectable by large upload volumes) I'd take away their
    net access for a month, or require them to pay the bill, or both. This
    is my house, I'm in charge!
    Mark McIntyre, Dec 22, 2006
  19. And he might also ask them to sign an agreement indemnifying him and the
    other residents of the house for any fines, settlements, legal fees, or
    other expenses incurred in case the RIAA et al should come knocking at
    the door.[/QUOTE]

    We have a lodger and our agreement with them contains exactly such a
    Mark McIntyre, Dec 22, 2006
  20. Mike S.

    David Smith Guest

    Or high gain antennas
    David Smith, Dec 22, 2006
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