Re: [patch] 2.4 version of my duplicate IP and MAC detection patch

From: Marc MERLIN (marc@merlins.org)
Date: Thu Sep 21 2000 - 19:07:57 EST


On Fri, Sep 22, 2000 at 01:31:06AM +0200, Andi Kleen wrote:
> You added a linear IP search to fast path ARP processing. The people running
> thousands of IP aliases will surely love you. You could at least use the
> ip_route_input output instead that arp_rcv computes anyways and check
> for RTN_LOCAL.
 
While you actually don't get broadcast ARP request very often (more than a
few per minute is rare), even on a busy net, making it faster doesn't hurt.
I'll write a new patch, thanks.
 
> BTW, the idea of doing it in user space is not to have a daemon running
> but just to do DAD once when you configure the ip address, like most other
> OSes do [as easily done with arping and a small script, see ipcfg from
> iproute2].
 
I know about this. It only helps you not to steal someone else's IP, it
doesn't help when someone else just stole your IP.
Take a Solaris box, an IRIX one, or windows (these are the only ones I have
access to for testing) and they'll all complain and notice if I steal their
IP.
I find it useful that a server syslogs the fact that its IP was stolen. I
can use that info to bring up a temporary DHCP IP, and send a message to a
central network monitor which will trace the culprit MAC address and
optionally turn off the switched port it came from.
 
Marc

-- 
Microsoft is to software what McDonalds is to gourmet cooking
 
Home page: http://marc.merlins.org/ (friendly to non IE browsers)
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