Re: [2.4 PATCH] bugfix: ARP respond on all devices

From: Bill Davidsen (davidsen_at_tmr.com)
Date: 08/20/03

  • Next message: David Wuertele: "2.4.18 usb-storage hotplug implementation question"
    Date:	Wed, 20 Aug 2003 15:08:03 -0400 (EDT)
    To: "David S. Miller" <davem@redhat.com>
    
    

    On Wed, 20 Aug 2003, David S. Miller wrote:

    > On Wed, 20 Aug 2003 12:49:14 -0400 (EDT)
    > Bill Davidsen <davidsen@tmr.com> wrote:
    >
    > > On 19 Aug 2003, Daniel Gryniewicz wrote:
    > >
    > > I have been asking for a similar thing as well, David mentioned some
    > > things that would break, but I believe they break if you use source
    > > routing, so that seems not to be a real objection.
    >
    > It's not about source routing. It's about failover and being
    > able to use ARP on interfaces which don't have addresses assigned
    > to them yet.

    David mentioned that you could solve the problem by using *rp_filter and
    source routing. I don't think that's entirely true, but doing so has the
    same drawbacks and breaks the same things as a flag to make Linux behave
    like Sun/BSD/Windows (and work with Cisco is the cases previously
    mentioned).

    >
    > > I find it interesting that we can't change networking because a few
    > > complex systems would have to be reconfigured, but we *can* change modules
    > > which requires config changes on probably 90% of all systems (commercial
    > > distributions).
    >
    > Decisions about Networking will always be in a different domain
    > because the way one behaves has effects upon other systems not
    > just the local one.

    Yes, that's exactly the point, the way Linux works has bad effects on
    certain other machines, as in leaves them disconnected to the Linux
    system.

    >
    > BTW, another thing which makes the source address selection for
    > outgoing ARPs a real touchy area is the following. Some weird
    > configurations actually respond with different ARP answers based upon
    > the source address in the ARP request. You can ask Julian Anastasov
    > about such (arguably pathological) setups.
    >

    I don't think anyone is asking for a change in the default behaviour
    (although my point about breaking modules does apply), people would be
    satisfied, even ecstatic, if we had a simple way (flag) to set to make
    Linux work without setting /proc filters, using arpfilter, applying source
    routes (David's suggestion) and generally jumping through hoops.

    -- 
    bill davidsen <davidsen@tmr.com>
      CTO, TMR Associates, Inc
    Doing interesting things with little computers since 1979.
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