Messages in this thread | | | Date | Sat, 17 Apr 1999 00:19:17 +1000 | From | Anthony Towns <> | Subject | Re: Linux ping flood on localhost |
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On Fri, Apr 16, 1999 at 08:44:07AM -0400, Richard B. Johnson wrote: > On Fri, 16 Apr 1999, Tigran Aivazian wrote: > > >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.
FWIW, Debian's current stable release (slink, 2.1) ships with a working ping.
(Now, if that's not the *lamest* piece of evangelism I've ever seen... ;)
> 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.
] [aj@sapphire ~/project/netbase]$ sudo ping -c 10000 -f localhost ] Password: ] PING localhost (127.0.0.1) from 127.0.0.1 : 56 data bytes ] . ] --- localhost ping statistics --- ] 10000 packets transmitted, 10000 packets received, 0% packet loss ] round-trip min/avg/max = 0.0/0.1/53.8 ms
IIRC, the real problem is that when listening on a raw socket you now get to see your outgoing pings as well as the incoming responses, so a new ping gets sent off every time it sends a ping as well as every time it receives a ping, which just leads to confusion all around.
Cheers, aj
-- Anthony Towns <aj@humbug.org.au> <http://azure.humbug.org.au/~aj/> I don't speak for anyone save myself. PGP encrypted mail preferred.
``Like the ski resort of girls looking for husbands and husbands looking for girls, the situation is not as symmetrical as it might seem.''
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