Re: Linux ping flood on localhost

Richard B. Johnson (root@chaos.analogic.com)
Fri, 16 Apr 1999 08:44:07 -0400 (EDT)


On Fri, 16 Apr 1999, Tigran Aivazian wrote:

> Hi,
>
> You said:
>
> >Ummm, If I remember correctly it was a bug in the ping program itself and
> > not in the kernel.
> > Just upgrade your version of ping.
>
> Yes, we know it is an FAQ and everybody knows the correct answer "get the
> latest ping" but, even the best Linux distributions (you know who you
> are!) still come with the ping(8) that says 95% packet loss on lo.
>
> Hope they take notice of this and correct their behaviour (while they are
> at it I hope they also trim down the /etc/rc.d/rc.sysinit file which I
> always have to manually shorten (by almost an order of magnitude)).
>

I think the latest ping will produce 90% packet loss on a flood to
localhost. This was some kind of 'feature' (a side-effect) introduced
around 2.2.x (Alan responded to this). As I understand it, ICMP replies
are delayed by a HZ, so the maximum response-rate is 100/second. Ping
flood tries 1000/second so you lose the flood-game.

Cheers,
Dick Johnson
***** FILE SYSTEM WAS MODIFIED *****
Penguin : Linux version 2.2.5 on an i686 machine (400.59 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.

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