Watched a DDoS attack for hours and couldn't do much :S
admin at antiproxy.com
Mon Nov 27 18:16:46 CET 2006
Actually, it's an external attack, apparently from a whole bunch of
One thing i thought off, was to pipe tcpdump's output into a couple awks
and seds and generate IPTABLE rules on the fly..
let's see how this goes
On Mon, 2006-11-27 at 08:38 +0000, G.W. Haywood wrote:
> Hi there,
> On Mon, 27 Nov 2006 AntiProxy wrote:
> > One of my servers was hit by a DDoS attack earlier today,
> > and the pattern was different to these i've seen before.
> > netstat doesn't show any TCP or UDP connections in any state.
> > however, TCPDUMP shows the following (i'm posting a few lines of
> > millions):
> > [...]
> > what does it tell you?
> Somebody is trying to spoof a machine on your network?
> I'd have thought a reasonable box could drop 15k packets/second OK but
> you might need to put rules in the INPUT chain to drop everything from
> the offending IPs. For this kind of thing I use a Perl script to scan
> the logs and insert rules into iptables in real time. Its input is
> piped from syslog-ng. It takes a bit of setting up but it's worth it.
> If there are large numbers (thousands) of attacking IPs you'll need to
> look at something like ipset as iptables will begin to creak a bit.
> If this continues you might want to contact your upstream provider.
> They will want to help if they're at all reputable.
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