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Re: lug-bg: dst cache overflow
- Subject: Re: lug-bg: dst cache overflow
- From: stoyan@xxxxxxxxxxxxxxx (Stoyan Jekov)
- Date: Wed, 04 Jul 2001 08:54:24 +0900
> > Niakoi da ima ideia kakwo znachi slednia otkas ot /var/log/messages:
> >
> > Jul 3 15:48:27 apic5 kernel: possible SYN flooding on port 80. Sending
> > cookies.
> > Jul 3 15:49:07 apic5 kernel: dst cache overflow
Ot arhivite na linux-kernel mailing list:
"This appears
to happen more frequently when the machines are loaded down CPU wise and
usually sustain over 3Mbits/sec of network traffic. This is happening
on
several machines with similar configurations. Each machine has about
2000
active tcp connections on them and CPU usage is typically over 75%."
Vuzmozno re6enie:
URL: [ http://search.luky.org/linux-kernel.2000/msg09243.html ]
George Danchev wrote:
>
> predpolagam problema e 4e si razreshil i compiliral v kernel-a s support na:
> IP: TCP syncoockie support
>
> koeto moje da dovede do problemi ako mashinata e natowarena
> opitai da go izklu4ish :
>
> echo 0 > /proc/sys/net/ipv4/tcp_syncoockie
>
Syncoockies niamat ni6to ob6to s problema. Syncookies sa prosto
izbrani po specialen na4in id-ta za SYN packetite (opit za
na4alo na connection), na koito client triabva da otgovori.
Prilozenieto im: anti-DoS -> server zapo4va da priema samo paketi,
koito otgovariat s pravilen ACT na SYN (TCP/IP three-way handshake)
--
Stoyan Jekov stoyan [AT] silveregg [DOT] co [DOT] jp
SilverEgg Technology Co.,Ltd. http://www.silveregg.co.jp/
Phone: 06-6386-1931 Fax: 06-6386-2101
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